THE QUANTITATIVE IMPORTANCE OF STEMFLOW: AN EVALUATION OF PAST RESEARCH AND RESULTS FROM A STUDY IN LODGEPOLE PINE (PINUS CONTORTA VAR. LATIFOLIA) STANDS IN SOUTHERN BRITISH COLUMBIA by Adam Jon McKee B.A. Thompson Rivers University, 2008 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE (ENVIRONMENTAL SCIENCE) Thesis examining committee: Darryl Carlyle-Moses (Ph.D.), Thesis Supervisor, Assistant Professor, Dept. of Geography, Thompson Rivers University Karl Larsen (Ph.D.), Committee Member, Associate Professor, Dept. of Natural Resource Sciences, Thompson Rivers University Rita Winkler (Ph.D., R.P.F.), Committee Member, Adjunct Professor, Dept. of Natural Resource Sciences and Research Hydrologist, BC Ministry of Forests and Range Delphis F. Levia (Ph.D.), External Examiner, Associate Professor, Depts. of Geography & Plant and Soil Science, University of Delaware Spring Convocation 2011 Thompson Rivers University © Adam Jon McKee, 2010 Thesis Supervisory Committee ________________________ Dr. Darryl Carlyle-Moses, Supervisor ________________________ Dr. Karl Larsen, Committee Member ________________________ Dr. Rita Winkler, Committee Member This thesis by Adam Jon McKee was defended successfully in an oral examination on December 9, 2010 by a committee comprising: ________________________ Dr. Delphis F. Levia, External Examiner ________________________ Dr. Darryl Carlyle-Moses, Supervisor ________________________ Dr. Karl Larsen, Committee Member ________________________ Dr. Rita Winkler, Committee Member ii ________________________ Dr. Lauchlan Fraser, Chair/Coordinator of Graduate Program Committee ________________________ Dr. Tom Dickinson, Dean of Science ________________________ Dr. Peter Tsigaris, Chair of the Examining Committee This thesis is accepted in its present form by the Office of the Associate Vice President, Research and Graduate Studies as satisfying the thesis requirements for the degree Master of Science, Environmental Science. ……………………………… Dr. Nancy A. Van Wagoner Associate Vice President, Research and Graduate Studies iii I, Adam Jon McKee, grant non-exclusive permission to the University Librarian of Thompson Rivers University to reproduce, loan or distribute copies of my thesis in microform, paper or electronic formats on a non-profit, royalty-free basis for the full term of copyright protection. I, however, retain the copyright in my thesis. ________________________ Author ________________________ Supervisor ________________________ Date iv ACKNOWLEDGEMENTS I would like to thank my supervisor, Dr. Darryl Carlyle-Moses, for inviting me to join his research program, and for his input, support, and knowledge that made the completion of this thesis possible. Thanks to my thesis committee for their time and guidance: Dr. Rita Winkler, Dr. Karl Larsen, and Dr. Delphis Levia. Special thanks to the entire research team for help with equipment setup, data collection, and for two great summers: Chad Lishman, Pearce Sanders, Andrew Pillar, Jenn Golden, Warren Giesbrecht, and Sarah Ostoforoff. I would like to thank my family for their support over the past two years and everyone that had to listen to me talk about “trees, water, and dirt”. Special thanks to Katie Tallon for her support, editing skills, and field assistance when an extra person was needed. This project would not have been possible without the funding support provided by the NSERC (Natural Sciences and Engineering Research Council of Canada) Discovery Grant and the FIA-FSP (Forest Investment Account – Forest Science Program) funds awarded to Dr. Darryl Carlyle-Moses. v ABSTRACT Stemflow is a focused point source input of precipitation and nutrients at the base of a tree or plant, and can have a significant impact on site hydrology. A review paper examining the quantitative importance of stemflow, and a stemflow modelling paper focused on juvenile lodgepole pine are presented in this thesis. Stemflow production information from 145 different studies is presented in table format with the addition of author-calculated funnelling ratios and plateau funnelling ratios when applicable. Plateau funnelling ratios were calculated to provide an estimation of the rainfall depth required to satisfy the storage capacity of a tree. Reference tables were used to identify interclimatic, inter-genera, and intra-genera variations in stemflow production. Plateau funnelling ratios were used to identify shortcomings in current canopy interception models. Finally, the reference tables were used to identify areas of the stemflow literature where knowledge remains fairly weak. To date, no known studies have modelled stemflow production for juvenile lodgepole pine (Pinus contorta var. latifolia). Meteorological conditions, tree characteristics, and stemflow were sampled for two juvenile lodgepole pine stands over the course of the 2009 growing season. Step-wise multiple regression was used to assess which meteorological and tree architecture variables influenced stemflow production for each research plot. Once predictor variables were identified, models were produced for each stand and a generic model was produced that applied to both plots. A model employing precipitation depth and crown projection area successfully explained 71.3 % of the variation in stemflow production from sampled trees. Key words: Lodgepole pine (Pinus contorta var. latifolia), stemflow, stemflow funnelling ratio, plateau funnelling ratio, forest hydrology vi TABLE OF CONTENTS ACKNOWLEDGEMENTS ...................................................................................................... v ABSTRACT ............................................................................................................................. vi TABLE OF CONTENTS ........................................................................................................ vii LIST OF TABLES ................................................................................................................... ix LIST OF FIGURES ................................................................................................................. xi LIST OF SYMBOLS .............................................................................................................. xii CHAPTER 1. INTRODUCTION ............................................................................................. 1 LITERATURE CITED ......................................................................................................... 4 CHAPTER 2. A SYNTHESIS AND EVALUATION OF PAST RESEARCH ON THE QUANTITATIVE IMPORTANCE OF STEMFLOW ............................................................. 7 INTRODUCTION ................................................................................................................ 7 METHODS ........................................................................................................................... 9 RESULTS ........................................................................................................................... 12 1. Temperate deciduous .................................................................................................. 12 2. Temperate coniferous and boreal ................................................................................ 14 3. Mixed deciduous and coniferous stands ..................................................................... 15 4. Tropical ....................................................................................................................... 16 5. Mediterranean ............................................................................................................. 16 6. Arid and semi-arid environments................................................................................ 18 7. Agroforestry ................................................................................................................ 19 DISCUSSION ..................................................................................................................... 19 CONCLUSION ................................................................................................................... 22 LITERATURE CITED ....................................................................................................... 23 APPENDIX – REFERENCE TABLES .............................................................................. 39 CHAPTER 3. MODELLING STEMFLOW PRODUCTION BY JUVENILE LODGEPOLE PINE (PINUS CONTORTA VAR. LATIFOLIA) TREES IN SOUTHERN BRITISH COLUMBIA, CANADA........................................................................................ 79 INTRODUCTION .............................................................................................................. 79 MATERIALS AND METHODS ........................................................................................ 81 Site description................................................................................................................ 81 vii Meteorological data ........................................................................................................ 82 Stemflow collection ........................................................................................................ 84 Tree characteristics ......................................................................................................... 86 Statistical analysis ........................................................................................................... 87 Modelling procedure ....................................................................................................... 87 RESULTS ........................................................................................................................... 88 Funnelling ratios for lodgepole pine ............................................................................... 88 Abiotic and biotic influences on stemflow and the simulation of stemflow production ....................................................................................................................... 89 Stemflow produced by a branchless tree ........................................................................ 99 DISCUSSION ................................................................................................................... 100 Lodgepole pine stemflow production ........................................................................... 101 Model assessment ......................................................................................................... 102 CONCLUSION ................................................................................................................. 104 LITERATURE CITED ..................................................................................................... 105 CHAPTER 4. CONCLUSION.............................................................................................. 109 LITERATURE CITED ..................................................................................................... 112 viii LIST OF TABLES Table 2.1. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for temperate deciduous studies 39 Table 2.2. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for temperate deciduous studies 42 Table 2.3. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for coniferous and boreal studies 46 Table 2.4 Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for coniferous and boreal studies 49 Table 2.5. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for mixed deciduous and coniferous stands 52 Table 2.6. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for mixed deciduous and coniferous stands 52 Table 2.7. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for tropical studies 53 Table 2.8. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for tropical studies 57 ix Table 2.9. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for Mediterranean studies 61 Table 2.10. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for Mediterranean studies 66 Table 2.11. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for arid and semiarid studies 72 Table 2.12. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for arid and semi-arid studies 74 Table 2.13. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for agroforestry studies 76 Table 2.14. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for agroforestry studies 77 Table 3.1. Stand characteristics for Plots E and D 82 Table 3.2. Coefficient of determination (R2) and p-values associated with statistically significant abiotic predictor variables of stemflow production for individual study trees. 90 x LIST OF FIGURES Figure 3.1. View of Plot E from the northwest corner of the plot 83 Figure 3.2. View of Plot D from the centre looking south 83 Figure 3.3. Stemflow collar and collection container used in Plots E and D 85 Figure 3.4. Season-long stemflow funnelling ratios versus tree diameter for all healthy lodgepole pine trees in Plots E, D, C, and B 89 Figure 3.5. Power relationship between slope values and tree diameter for healthy lodgepole pine trees 91 Figure 3.6. Intercept values versus diameter showing a weak linear relationship and not the power relationship shown by Park and Hattori (2002) 92 Figure 3.7. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot E ( ) and the 1:1 line (------) 94 Figure 3.8. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D employing the Plot E model ( ) and the 1:1 line (------) 94 Figure 3.9. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D ( ) and the 1:1 line (------) 95 Figure 3.10. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot E employing the simplified model ( ) and the 1:1 line (------) 96 Figure 3.11. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D employing the simplified model ( ) and the 1:1 line (------) 97 Figure 3.12. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for lodgepole pines in Plots E and D employing the generic model ( ) and the 1:1 line (------) 98 Figure 3.13. The percentage of rainfall that became stemflow versus rainfall depth at the stand scale for Plot E ( ) and Plot D (------), highlighting the rainfall depth required for the commencement of stemflow production (1.6 mm) 99 xi LIST OF SYMBOLS #Brch – Number of branches n – Number of samples ̅ – Average horizontal distance 𝐷 nstems – Number of stems ̅ – Average height 𝐻 P – Precipitation A – Agroforestry P’g – Rainfall depth required for A – Canopy area canopy saturation a – Slope PA – Annual rainfall Angle2/3 – Branching angle at two Pg – Rainfall thirds the height of the tree PS – Study period rainfall Anglebottom – Branching angle at the S – Semi-arid and arid bottom of the tree SF – Stemflow b – Y-intercept T – Tropical BA – Basal area TF - Throughfall C – Temperate coniferous and boreal V – Canopy volume CBH – Circumference at breast height X – Mixed deciduous and coniferous CPA – Crown projection area stands D – Temperate deciduous β1 – Regression coefficient D – Tree diameter at the base β2 – Regression coefficient DBH – Diameter at breast height Density – Tree density Diam. – Tree or shrub diameter F – Funnelling ratio H – Tree height I – Rainfall intensity LAI – Leaf area index M – Mediterranean M – Proximity metric xii CHAPTER 1 INTRODUCTION Rainfall intercepted by vegetation cover either passes through or drips from the canopy as throughfall, moves down the bole or stem of the vegetation and reaches the ground as stemflow, or remains on the vegetation canopy and is subsequently evaporated. Of the aforementioned components, stemflow has received the least attention in the hydrologic literature (Park and Hattori, 2002; Levia and Frost, 2003; Llorens and Domingo, 2007). This is likely due to stemflow being volumetrically insignificant when compared to throughfall and evaporation; however, its importance is far from irrelevant. The first research examining the movement of intercepted rainfall down a tree’s bole was conducted in the late 19th and early 20th centuries by Hoppe (1896) and Horton (1919). This process was later termed “stemflow”, and is the focus of this thesis. Despite a lower volume of water when compared to the other components of the canopy water balance, stemflow is of hydrologic importance due to it being a focused point source input of water at the base of a tree or plant (Herwitz, 1986). A principle focus of this thesis deals with the stemflow funnelling ratio. The stemflow funnelling ratio was first introduced in 1986 by Herwitz (1986) as a measure of how efficient a tree or bush is at producing stemflow. The ratio is one that expresses the amount of water directed to the base of a tree or plant during a rainfall event relative to the volume of rainfall that would have been captured by an unobstructed rain gauge with a receiving area equal to that of the tree / plant basal area. The stemflow funnelling ratio is calculated as: F= SF/(Pg ∙BA) (1.1) where F is the funnelling ratio (dimensionless), SF is stemflow volume (L), Pg is rainfall (mm), and BA is the basal area of the tree’s truck or shrub’s stem (m2). Stemflow research has been conducted worldwide focusing on a large variety of species under varying climatic and hydrologic regimes. Findings have shown that stemflow can be of hydrologic and biogeochemical significance, at least in certain 1 environments. Stemflow is an important source of moisture for plant growth and ground water recharge as highlighted by a number of studies (Voigt, 1960; Tanaka et al., 1996; Taniguchi et al., 1996; Whitford et al., 1997). For a Pinus densiflora (Japanese red pine) forest in Japan, Taniguchi et al. (1996) found that stemflow was responsible for 20 % of the groundwater recharge rate. Along with deriving the stemflow funnelling ratio, Herwitz (1986) found that large volumes of stemflow could overwhelm the infiltration capacity of soil and result in Hortonian overland flow and subsequently cause surface erosion. Once thought to only occur under rainfall conditions, Herwitz and Levia (1997) found that stemflow was also produced under winter conditions, with increased stemflow volumes associated with mixed precipitation. Stemflow has been found to be a concentrated source of nutrients and, in some cases, pollutants (Brinson et al., 1980; Chang and Matzner, 2000; Schroth et al., 2001; Johnson and Lehmann 2006). Brinson et al. (1980) found that stemflow contained high levels of organic carbon and phosphorus, 20.2 % and 16.8 %, respectively, of the total amount of organic carbon and phosphorus reaching the forest floor. Stemflow can be important not only for the producer, but also for surrounding vegetation. Stemflow and the nutrients contained within have been found to create a “fertile island” effect, resulting in vegetation growth around a stemflow producing tree or bush (Whitford et al., 1997). Stemflow models developed to date include a variety of different predictor variables and have been produced for a number of different tree and plant species. Depending on tree architecture and geographic location of the tree(s) studied, a number of different predictor variables were employed by each study. Branching angle (Herwitz, 1987; Návar, 1993; Martínez-Meza and Whitford, 1996), number of branches (Návar, 1993), tree height (Brown and Baker, 1970), storm duration and intensity (Brown and Baker, 1970; Crockford and Richardson, 2000), crown projection area (Brown and Baker, 1970; Aboal et al., 1999; Park and Hattori, 2001; Pressland, 1973), and bark roughness (Horton, 1919; Aboal et al., 1999), are just some of the variables that have been found to influence stemflow production across a number of different species. Due to the variety of variables included in models produced to date, it is difficult to transfer models between species. Also, when producing a model, it is 2 important to consider a large array of predictor variables. The stemflow production ability of different species from around the globe, and the modelling of stemflow production for juvenile lodgepole pine are the foci of this thesis. Chapter 2 is a comprehensive review paper of stemflow production information for research published prior to June 30, 2010. The goal of this paper was to compile information relating to stemflow production for as many tree and plant species as possible. Once compiled, this information was organized alphabetically by species within seven different climate and vegetation classifications for ease of reference. This information was then used to identify inter-climatic, inter-genera, and intra-genera variations in stemflow production. Stemflow funnelling ratios were calculated for studies that did not contain these metrics ratios, but contained the required information for their calculation. Plateau funnelling ratios, the point at which funnelling ratios plateau, and the associated rainfall depth, were calculated for entries that provided the necessary information. This comprehensive review of stemflow production information will aid future researchers and improve our understanding of inter- and intraspecific variations in stemflow production. Past reviews have been conducted that provided stemflow production information in table format, however, these tables simply summarized stemflow production information related to the author(s)’ research or focused on a particular region. Chapter 3 is a stemflow modelling paper based on original field observations conducted on the Bonaparte Plateau, north of Kamloops, British Columbia, Canada. The goal of this chapter was to model stemflow production for juvenile lodgepole pine. Two research plots were used to model stemflow production for trees with crown projected areas ranging from 0.1 to 3.5 m3. The generic model produced explained 71.3 % of the variation in stemflow production for individual lodgepole pines, or for entire stands fitting the model criteria. In addition to the generic model, models for the individual research plots are also presented, along with the findings that canopy structure in combination with rainfall depth accurately explained variations in stemflow production for juvenile lodgepole pine. 3 The rationale for Chapter 3 was the lack of knowledge concerning juvenile lodgepole pine stemflow production, and the current mountain pine beetle (Dendroctonus ponderosae) epidemic impacting British Columbia. The mountain pine beetle epidemic is expected to kill 77 % of all merchantable pine in the Province by 2014 (BC Ministry of Water, Land and Air Protection, 2004; Walton et al., 2007). The landscape of the Interior of British Columbia will not only be changed visually for decades to come, site hydrology will also change drastically as mature stands are replaced by juvenile stands at various stages of regrowth. Past research has shown that mature lodgepole pine are inefficient stemflow produces and do not produce large volumes, however little is known about the stemflow production of juvenile lodgepole pines (Spittlehouse, 1998; McKee and Carlyle-Moses, 2010). Due to the shift in stand composition that will occur over the coming years, understanding how stands of juvenile lodgepole pine partition rainfall is important as this may have impacts on streamflow production and thus potentially impact water resource supplies and aquatic ecosystem health. LITERATURE CITED Aboal JR, Jimenez MS, Morales D, Hernandez JM. 1999. Rainfall interception in laurel forest in the Canary Islands. Agricultural and Forest Meteorology 97: 73-86. BC Ministry of Water, Land and Air Protection. 2004. Weather, Climate and the Future: BC’s Plan. http://www.env.gov.bc.ca/air/climate/index.html#1 Brinson MM, Bradshaw HD, Holmes RN, Elkins JB Jr. 1980. Litterfall, stemflow, and throughfall nutrient fluxes in an alluvial swamp forest. Ecology 61(4): 827-835. Brown JH Jr., Barker AC Jr. 1970. An analysis of throughfall and stemflow in mixed oak stands. Water Resources Research 6(1): 316-323. Chang S, Matzner E. 2000. The effect of beech stemflow on spatial patterns of soil solution chemistry and seepage fluxes in a mixed beech/oak stand. Hydrological Processes 14: 135-144. Crockford RH, Richardson DP. 2000. Partitioning of rainfall into throughfall, stemflow and interception: effect of forest type, ground cover and climate. Hydrological Processes 14: 2903-2920. 4 Herwitz SR. 1986. Infiltration-excess caused by stemflow in a cyclone-prone tropical rainforest. Earth Surface Processes and Landforms 11: 401-412. Herwitz SR. 1987. Raindrop impact and water flow on the vegetative surfaces of trees and the effects on stemflow and throughfall generation. Earth Surface Processes and Landforms 12: 425-432. Herwitz SR, Levia DF Jr. 1997. Mid-winter stemflow drainage from bigtooth aspen (Populus grandidentata michx.) in central Massachusetts. Hydrological Processes 11: 169-175. Hoppe E. 1896. Regenmessung unter Baumkronen. Mitt. Aus des Forstlichen Versuchswesen Oesterreichs 21: 1-75. Horton RE. 1919. Rainfall Interception. Monthly Weather Review 47(9): 608-623. Johnson MS, Lehmann J. 2006. Double-funnelling of trees: Stemflow and root-induced preferential flow. Ecoscience 13(3): 324-333. Levia DF Jr., Frost EE. 2003. A review and evaluation of stemflow literature in the hydrologic and biogeochemical cycles of forest and agricultural ecosystems. Journal of Hydrology 274: 1-29. Llorens P, Domingo F. 2007. Rainfall partitioning by vegetation under Mediterranean conditions. A review of studies in Europe. Journal of Hydrology 335: 37-54. Martínez-Meza E, Whitford WG. 1996. Stemflow, throughfall and channelization of stemflow by roots in three Chihuahuan desert shrubs. Journal of Arid Environments 32: 271-287. McKee AJ, Carlyle-Moses DE. 2010. Stemflow: A potentially important point source of water for growth. Linking Innovations and Networking Knowledge 11(2): 11-12. Návar J. 1993. The causes of stemflow variation in three semi-arid growing species of northeastern Mexico. Journal of Hydrology 145: 175-190. Park H, Hattori S. 2002. Applicability of stand structural characteristics to stemflow modelling. Journal of Forest Research 7: 91-98. Pressland AJ. 1973. Rainfall portioning by an arid woodland in South-Western Queensland. Australian Journal of Botany 21: 235-245. 5 Schroth G, Elias MEA, Uguen K, Seixas R, Zech W. 2001. Nutrient fluxes in rainfall, throughfall and stemflow in tree-based land use systems and spontaneous tree vegetation of central Amazonia. Agriculture, Ecosystems and Environment 87: 3749. Spittlehouse D. 1998. Rainfall interception in young and mature conifer forests in British Columbia. Proceedings 23rd Conference on Agricultural and Forest Meteorology. Tanaka T, Taniguchi M, Tsujimura M. 1996. Significance of stemflow in groundwater recharge. 2: A cylindrical infiltration model for evaluating the stemflow contribution to groundwater recharge. Hydrological Processes 10: 81-88. Taniguchi M, Tsujimura M, Tanaka T. 1996. Significance of stemflow in groundwater recharge. 1: Evaluation of this stemflow contribution to recharge using a mass balance approach. Hydrological Processes 10: 71-80. Voigt GK. 1960. Distribution of rainfall under forest stands. Forest Science 6(1): 2-10. Walton A, Hughes J, Eng M, Fall A, Shore T, Riel B, Hall P. 2007. Provincial-level projection of the current Mountain Pine Beetle outbreak: Update of the infestation projection based on the 2006 provincial aerial overview of forest health and revisions to the “model” (BCMPB.v4).http://www.for.gov.bc.ca/hre/bcmpb/BCMPB.v4.BeetleProjection. Update.pdf Whitford WH, Anderson J, Rice PM. 1997. Stemflow contribution to the ‘fertile island’ effect in creosotebush, Larrea tridentate. Journal of Arid Environments 35: 451457. 6 CHAPTER 2 A SYNTHESIS AND EVALUATION OF PAST RESEARCH ON THE QUANTITATIVE IMPORTANCE OF STEMFLOW INTRODUCTION The first notable research examining the manner in which tree canopies partition rainfall was conducted in the late 19th and early 20th centuries by Hoppe (1896) and Horton (1919). These papers identified that a portion of intercepted rainfall was diverted down the trunk of the vegetation in question, a process later termed "stemflow". Despite recent studies and reviews that have highlighted the hydrologic importance of stemflow, it has received relatively little attention in the hydrologic literature when compared to the two other canopy water balance components: throughfall and canopy interception loss (Park and Hattori, 2002; Levia and Frost, 2003; Llorens and Domingo, 2007). Due to its delivery being concentrated at the base of vegetation, stemflow has been found to be an important point source input of water for soil moisture and groundwater recharge (Voigt, 1960; Tang, 1996; Taniguchi et al., 1996), a cause of Hortonian overland flow in certain environments (Herwitz, 1986), and a significant source of nutrients and pollutants (Brinson et al., 1980; Price and Watters, 1989; Chang and Matzner, 2000; Johnson and Lehmann, 2006). The ability of vegetation to concentrate stemflow at their bases can be expressed quantitatively using the stemflow funnelling ratio (Herwitz, 1986): F = SF/(Pg ∙BA) (2.1) where F is the funnelling ratio (dimensionless), SF is stemflow volume (L), Pg is rainfall (mm), and BA represents the tree basal area (m2). Carlyle-Moses and Price (2006), in a northern hardwood stand in southern Ontario under growing season conditions, found that stemflow funnelling ratios increased with increasing rainfall depth until a peak was reached with funnelling ratios declining with greater rainfalls. Similar results have been found for semi-arid shrubs in China (Li et al., 2008) and in tropical tree plantations in Panama (Carlyle-Moses et al., 2010). 7 Carlyle-Moses and Price (2006) suggest that the peak funnelling ratio is reached once the canopy becomes saturated and all areas capable of producing stemflow are doing so at their maximum capacity. At greater rainfall depths the funnelling ratios should be expected to decline since the numerator in Eq. 2.1 will be limited by the contributing area of the canopy, while the denominator will increase in a linear fashion. Thus, the derivation of stemflow funnelling ratios is not only of importance with regards to determining the quantitative significance of stemflow as a point source of water for soil moisture, groundwater and plant growth, but may also be used to determine the rainfall depth required for the complete saturation of vegetation canopies and thus can aid in canopy interception loss process and modelling studies (e.g. Carlyle-Moses et al., 2010). A number of stemflow review papers have been published to date. Levia and Frost (2003) provided a comprehensive overview of stemflow research by summarizing and evaluating the different aspects of stemflow research. Levia and Frost (2003) also provided recommendations for future research by drawing attention to areas where further study is required and highlighting those areas that have already received considerable attention. Other review papers and studies containing reviews have taken a more focused approach, examining specific regions, climates, or species. Llorens and Domingo (2007), for example, provided an in-depth review of stemflow research conducted in the Mediterranean. Wei et al. (2005) reviewed a number of stemflow studies conducted in China, while Johnson and Lehmann (2006) provided a review of several different species under differing environmental conditions. Zinke (1967) reviewed studies examining canopy interception in the United States, which included stemflow production information for a number of different species. Barbier et al. (2009) reviewed the canopy water balance differences between coniferous and broadleaved species. All of these reviews provided valuable information regarding stemflow production; however, none provided a comprehensive summary of stemflow production data. Llorens and Domingo (2007) provided vast amounts of data for the Mediterranean; however, they do not employ the stemflow funnelling ratio in their paper. A comprehensive stemflow production review utilizing both stemflow as a percentage of 8 rainfall and stemflow funnelling ratios has not been undertaken to date and would therefore be a valuable addition to the current knowledge base concerning this canopy water balance component. It was the goal of this review to provide a reference that summarizes the ability of different tree species to produce stemflow. The purpose of this review was fourfold: (1) to review the stemflow literature for papers containing information regarding stemflow production; (2) to develop stemflow equations if the information was provided and the author(s) had not already done so; (3) to calculate season-long funnelling ratios and plateau funnelling ratios if the required information was provided by the author(s); (4) to compile information relevant to a species’ ability to produce stemflow into table format. It is my objective that a stemflow reference guide will be used by future researchers not only to save time when conducting research, but also to aid in identifying inter- and intraspecific variations in stemflow production by comparing studies of similar species. METHODS The Web of Science database by ISI Web of Knowledge and Google Scholar were searched using the terms “stemflow”, “stem flow”, “funnelling ratio”, and “funneling ratio”. Over 600 publications containing one or more of the above terms were identified. Just over 100 of these publications published prior to June 30, 2010 were included in this review. The reference sections of the publications found in the aforementioned databases were then inspected for relevant studies not found in the academic database search. Prior to their inclusion in this review, publications were scrutinized to ensure that the data contained within was suitable for comparison with other studies. In total, 145 studies containing stemflow data for a variety of species were included in this review. Publications were examined for stemflow production information, specifically: stemflow equations (relating stemflow to another variable), stemflow funnelling ratios, the percentage of rainfall that became stemflow, and the information required to produce a stemflow equation or stemflow funnelling ratio. If a publication contained at least one of the aforementioned pieces of information it was 9 included in the reference table along with relevant stand, meteorological, and geographic information including: tree species, geographic location, climate, tree diameter, tree density, basal area, annual precipitation, study period precipitation, and, finally, the citation. Information originally published in imperial units was converted to metric units before being entered into the reference table; any data that underwent conversion was followed by a superscript “con”. If a stemflow equation was not provided by the author(s) of a specific study one was calculated if individual event rainfall depth and accompanying stemflow measurements were provided. Any calculated stemflow equations were followed by a superscript “calc” in the reference tables provided in the Results section of this review. For the purpose of inter- and intraspecific comparisons, stemflow funnelling ratios were calculated when possible if the author(s) of a specific study did not provide them. Calculated funnelling ratios were followed by a superscript “calc” in the reference tables. Stemflow funnelling ratios were calculated in two ways depending on the data provided by the author(s): if study period rainfall depth, percentage of rainfall that became stemflow, and stand basal area were provided, then a stand level funnelling ratio for the entire research period was calculated using Eq. 2.1 (e.g. 64.3calc); if a stemflow equation relating stemflow volume or depth to rainfall depth was provided in conjunction with the basal area for a stand or individual tree then a range of funnelling ratios were calculated using rainfall depth values starting at 1 mm and increasing by 1 mm rainfall increments until the funnelling ratios “plateaued”. For the purposes of this review the point at which funnelling ratios plateaued occurred when the funnelling ratio value increased by < 1 % compared to its previously calculated value at a rainfall depth 1 mm less. Once the plateau was identified, the corresponding funnelling ratio and rainfall depth were recorded in the reference table (e.g. 48.6 at 35 mmcalc). Based on the results of CarlyleMoses and Price (2006), these plateau values and associated rainfall depths are assumed to be the maximum funnelling ratios produced when the canopy reaches full saturation and the required rainfall to saturate the canopy, respectively. 10 Some entries in the reference tables contained more than one species; this is because certain studies only provided multi-species stand scale stemflow production data. For linear equations with a positive y-intercept, plateau values were not calculated because a positive y-intercept implies that a tree has no storage capacity. If the information required to calculate both the season-long and plateau funnelling ratios was provided, both were included in the reference tables. Special attention was paid to the methodology and results sections of selected papers to determine if the stemflow information presented was at the individual or stand scale level. Studies that provided stemflow information for an individual tree had “Lone” entered under the tree density column of the reference tables and studies that provided stemflow information for multiple individuals but with no reference to the entire stand were identified as “Lone trees” or “Lone shrubs”. All other entries not marked as either “Lone”, “Lone trees”, or “Lone shrubs” focused on the stand scale. In addition to the percentage of rainfall that became stemflow for the study period or a range of values if the author(s) did not provide a study period value, other information can be found in the SF (%) column. The percentage of rainfall that became stemflow for specific periods or stand conditions was provided for some studies, for example, leaved and leafless or growing and dormant season periods, unlogged and logged, or summer and winter conditions. In addition to season-long funnelling ratios and plateau funnelling ratios, the funnelling ratio (F) column contains additional information for some studies. The event high funnelling ratio, representing the maximum funnelling ratio observed for an individual tree/shrub for a single event, was recorded for some entries. If multiple stemflow percentages, funnelling ratios, or formulae are contained within one entry this is because the entry contains information for multiple trees of the same species or data for multiple years. Once the comprehensive reference table was compiled, the information it contained was organized by climate and vegetation type. Seven classifications were used to organize the 326 entries: temperate deciduous (D), temperature coniferous and boreal (C), mixed deciduous and coniferous stands (X), tropical (T), Mediterranean (M), semi- 11 arid and arid (S), and agroforestry (A). For each climate/vegetation classification two tables were produced: one table containing stand information along with author(s); the other containing stemflow production and meteorological data. Entries were sorted alphabetically by species and given a code for ease of referencing and comparison between tables. Within the seven categories, average, median, and a range of values were calculated for stemflow and funnelling ratio values and compared at the genera and category levels. If a single entry contained multiple years of data an average was produced across those years for comparison with other entries. If a single entry contained only a range of stemflow data it was not included in comparative analyses. RESULTS 1. Temperate deciduous From the available literature, stand-scale stemflow was found to average 5.1 % (median = 3.9 %, n = 34) of growing-season or annual rainfall in temperate deciduous forests, ranging from < 0.5 % in a Crataegus sativa – Acer campestre stand in southwest England (Herbst et al., 2006, D10) to 17.1 % in an evergreen-broadleaf forest in Osaka, Japan (Masukata et al., 1990, D11). Mean stemflow as a percentage of growing-season or annual rainfall from nine studies conducted in Quercus genera dominated stands was 6.0 % (median = 4.0 %, range = 0.5 – 15.5 %), while it accounted for an average of 5.0 % (median = 5.0 %, range = 2.0 – 9.6 %, n = 5) in Fagus forests. A notably high annual stemflow value of 26 % was reported for a lone Stewartia monadelpha in Japan (Liang et al., 2009, D63). Additional stemflow percentage values for other genera dominated and mixed deciduous stands are presented in Table 2.1 and Table 2.2 found in this chapter’s appendix. The proportion of rainfall that contributes to stemflow typically increases under leafless periods compared to leafed periods. For example, in a Q. alba – Q. velutina forest in Rhode Island stemflow increased from 3.9 % of rainfall during the growing season to 4.8 % under dormant conditions (Brown and Barker, 1970, D48). Similar results were also found in a Nyssa aquatic - Taxodium distichum - Fraxinus caroliniana 12 stand in North Carolina, where stemflow averaged 2.5 % of the 639 mm of rainfall under leafed-conditions and 4.5 % of the 466 mm of rainfall during the leafless period of the study (Brinson et al., 1980, D 42). Calculated stand-scale funnelling ratios for the latter stand increased from 3.6 during the leaved period to 6.5 during the leafless period. Calculated and author-provided stand-scale growing season or annual funnelling ratios in temperate deciduous forests averaged 26.6 (median = 15.6, n = 12), ranging from 2.3 in a F. orientalis forest in Nowshahr, Iran (Ahmadi et al., 2009, D21) to 64.3 in a Alnus glutinosa forest in Lancaster, England (Cape et al., 1991, D05). Growing season or annual funnelling ratios for Quercus stands averaged 36.8 (median = 50, n = 5), ranging from 7.6 to 61.3. A study examining individual Q. rubra reported season-long funnelling ratios averaging 8.8 (median = 7.6, n = 7), with a range of 6.1 to 13.7 (CarlyleMoses and Price, 2006). Growing season funnelling ratios averaged 12.1 (median = 8.6, range = 2.3 – 25.4, n = 3) for Fagus stands, and 32.7 (median = 32.4, range = 15.8 – 47.2, n = 9) for individual trees. An entry for Acer saccharum (Carlyle-Moses and Price, 2006, D03) had a notably high season-long funnelling ratio of 108.6 for an individual tree, however the average season-long funnelling ratio for all A. saccharum trees included in the study averaged 31.6 (median = 21.6, n = 7). For temperature deciduous stands, calculated plateau funnelling ratios for the growing season averaged 23.4 at 17 mm (median = 17.6 at 15 mm, n = 4) with a range of 9.0 at 12 mm for a mixed deciduous forest in Ontario, Canada (Price and Carlyle-Moses, 2003, D39), to 48.6 at 35 mm for a stand of A. glutinosa in Lancaster, England (Cape et al., 1991, D05). Calculated plateau funnelling ratios for individual trees during the growing season were much higher than those for stands. Plateau funnelling ratios averaged 40.2 at 15 mm (median = 38.7 at 13 mm, n = 9), ranging from 1.6 at 27 mm for a lone Liriodendron tulipifera in Maryland (Levia et al., 2010, D30) to 91.5 at 7 mm for a lone Q. suber in California (Xiao et al., 2000, D62). Growing season plateau funnelling ratios were calculated for three studies that examined individual Fagus which averaged 55.0 at 13 mm (median = 50.0 at 13 mm, n = 4), ranging from 42.1 at 16 mm (Staelens et al., 2008, D27) to 82.3 at 13 mm (André et al., 2008, D23) for two F. sylvatica studies. 13 Quercus and Fagus are the two genera in temperate deciduous forests that have received the greatest study in regards to stemflow with 16 entries each (Table 2.1; Table 2.2). Liriodendron, Acer, Nothofagus, Populus, and Betula also have multiple entries, albeit less than Quercus and Fagus, while other genera, including Alnus and Stewartia have only one entry. Some studies included a mix of genera with no discernable means of separating the results in a genera specific fashion. 2. Temperate coniferous and boreal For studies conducted in temperate coniferous and boreal stands, study period stand scale stemflow averaged 5.0 % (median = 3.7 %, n = 50) of rainfall, with a range of < 0.1 % for a stand of Larix cajanderi in Siberia, Russia (Toba and Ohta, 2005, C11) to 27 % for a stand of Picea sitchensis in Dumfriesshire, Scotland (Ford and Deans, 1978, C21). Mean stemflow as a percentage of rainfall from 19 studies conducted in Pinus dominated stands was 4.2 % (median = 2.7 %, range = < 0.1 – 15 %, n = 23). Studies examining Picea and Larix reported season averages above and below Pinus, respectively. Average stemflow as a percentage of rainfall from nine studies of Picea dominated stands was 8.8 % (median = 6.4 %, range = 0.5 – 27 %, n = 9), while it accounted for 2.0 % (median = 1.6 %, range = < 0.1 – 4 %, n = 5) for four studies of Larix dominated stands. The two highest average annual stemflow values of 27.0 % (Ford and Deans, 1978, C21) and 16.7 % (Teklehaimanot et al., 1991, C24) were reported from P. sitchensis dominated stands in Scotland. Additional stemflow percentage values for other genera dominated and mixed temperate coniferous stands are presented in Tables 2.3 and 2.4. Calculated and study provided stand-scale growing season or annual funnelling ratios in temperature coniferous and boreal forests averaged 22.1 (median = 14.4, n = 12), ranging from 0.9 for a stand of P. abies in Vosges, France (Viville et al., 1993, C16) to 69.8 for a stand of Ilex pedunculosa in Kyoto, Japan (Park and Hattori, 2002, C09). In comparison to temperate deciduous stands, little stemflow funnelling ratio data has been reported for temperate coniferous and boreal forests. Two studies (Cape et al., 1991; 14 McKee and Carlyle-Moses, 2010) reported season-long funnelling ratio averages for Pinus of 19.7 (median = 17.2, range = 14.9 – 34.1, n = 4) and two studies (Cape et al., 1991; Viville et al., 1993) for Picea averaging 16.1 (median = 10.4, range = 0.9 – 37.1, n = 3). A nine year old stand of Chamaecyparis obtuse (Murakami, 2009, C05) had a notably high season-long funnelling ratio of 81.3, however, over the next three years of stand growth the season-long funnelling ratio dropped to 29.0. Calculated plateau funnelling ratios for temperate coniferous and boreal stands during the growing season averaged 12.4 at 51 mm (median = 8.8 at 47 mm, n = 7), ranging from 0.8 at 59 mm for a stand of L. decidua (Cape et al., 1991, C13) to 26.1 at 39 mm for a stand of P. sylvestris (Cape et al., 1991, C47). Three stands of P. sylvestris had average growing season plateau funnelling ratios of 15.8 at 51 mm (median = 13.7 at 39 mm, n = 3) and average winter plateau funnelling ratios of 22.6 at 35 mm (median = 19.2 at 37 mm, n = 3). Pinus was found to be the dominant genus studied within the temperate coniferous and boreal stands examined, followed by Picea (Table 2.3; Table 2.4). Larix, Pseudotsuga, and Abies all had multiple entries; however they received far less attention when compared to Pinus. 3. Mixed deciduous and coniferous stands Studies that presented stemflow values for mixed coniferous and deciduous stands were rare, with most studies providing data for individual species if the study stand contained both coniferous and broadleaf species. Studies that did not separate data for individual species within a mixed stand were assigned to this category. Stemflow as a percentage of annual rainfall for four studies averaged 2.6 % (median = 2.5 %, range = 0.5 – 7 %, n = 5). A study in a coastal redwood forest in California (Reid and Lewis, 2009, X05) reported the only study period funnelling ratio in this category of 2.6. Supplementary information for the presented stemflow data can be found in Tables 2.5 and 2.6. 15 4. Tropical For interception studies conducted in tropical climates, annual stemflow values at the stand level averaged 4.0 % (median = 1.6 %, n = 46), ranging from < 0.1 % for a tropical montane rainforest in Columbia (Veneklass and Van Ek, 1990 as cited in Levia and Frost, 2003, T57) to 30.5 % for a subtropical forest in Okinawa, Japan (Xu et al., 2005, T05). Study period stemflow values from studies that examined individual trees averaged 8.2 % (median = 2.7 %, n = 17), ranging from 0.01 % for a lone Cecropia peltata in Puerto Rico (Holwerda et al., 2006, T06) to 39.7 for a lone Elaeocarpus foveolatus in Queensland, Australia (Herwitz, 1986, T15). Additional stemflow percentage values for other genera dominated and mixed tropical stands are presented in Tables 2.7 and 2.8. Calculated and published study period stemflow funnelling ratios at the stand level averaged 18.7 (median = 12.4, n = 8) with a range of 0.8 for a natural montane forest in Central Sulawesi, Indonesia (Dietz et al., 2006, T32) to 53.0 for a subtropical forest in Okinawa, Japan (Xu et al., 2005, T05). Study period funnelling ratios for individual trees averaged 41.2 (median = 11.0, n = 35), ranging from 0.5 for a Dacryodes excelsa in Puerto Rico (Holwerda et al., 2006, T15) to 275.7 for a Prestoea montana in Puerto Rico (Holwerda et al., 2006, T44). At the stand scale only two plateau funnelling ratios could be calculated, 3.1 at 24 mm for a terra firme rainforest in Manus, Brazil (Cuartas et al., 2007, T58) and 8.7 at 22 mm for a lowland tropical forest in Sarawak, Malaysia (Manfroi et al., 2004; Manfroi et al., 2006). At the individual level, plateau funnelling ratios averaged 46.8 at 23 mm (median = 11.2 at 19 mm, n = 27), ranging from 0.7 at 34 mm for a D. excelsa in Puerto Rico (Holwerda et al., 2006, T11) to 272.8 at 2 mm for a P. montana in Puerto Rico (Holwerda et al., 2006, T40). 5. Mediterranean Studies conducted in regions with Mediterranean climates reported annual stand scale stemflow values that averaged 4.4 % (median = 3.0 %, n = 77), ranging from 0.2 % 16 for a stand of Eucalyptus melliodora in Canberra, Australia (Crockford et al., 1996, M09) to 22.0 % for a stand of Juniperus oxycedrus in El Ardal, Spain (Belmonte, 1997; Belmonte and Romero, 1998 as cited by Llorens and Domingo, 2007, M25). Study period stemflow values for individual trees averaged 11.6 % (median = 4.8 %, n = 10), ranging from 0.6 % for a Q. pyrenaica in Villasrubias, Spain (Moreno et al., 2001 as cited by Llorens and Domingo, 2007, M84) to 42.5 % for a Rosmarinus officinalis in El Ardal, Spain (Belmonte, 1997; Belmonte and Romero, 1998 as cited by Llorens and Domingo, 2007, M86). Annual stemflow values for stands of Pinus averaged 4.4 % (median = 3.0 %, range = 0.3 – 22.0 %, n = 29), while stands of Quercus averaged 3.5 % (median = 2.8 %, range = 0.3 – 12.5 %, n = 16). Stemflow values from four studies of Eucalyptus averaged 2.2 % (median = 2.9 %, range = 0.2 – 4.0 %, n = 12), while five studies of Fagus averaged 7.9 % (median = 6.5 %, range = 1.1 – 20.4 %, n = 8). Additional stemflow percentage values for other genera dominated and mixed Mediterranean stands are presented in Tables 2.9 and 2.10. Calculated and previously published stand scale season-long funnelling ratios for Mediterranean stands averaged 14.8 (median = 14.7, n = 51), ranging from 1.7 for P. sylvestris stand in the Sierra de la Demanda (Santa Regina and Tarazona, 2001, M63) to 41.1 for Q. cerris in south-western Spain (Moreno et al., 2001 as cited by Llorens and Domingo, 2007, M68). Individual trees averaged 47.8 (median = 34, n = 13), ranging from 16.7 to 137 for two Q. ilex individuals (Bellot and Escarré, 1998, M70). Seasonlong funnelling ratios for Pinus dominated stands averaged 16.1 (median = 15.4, range = 1.7 – 32, n = 18), while stands of Quercus averaged 13.6 (median = 11.3, range = 3.1 – 41.1, n = 11). In contrast to the aforementioned Quercus stands, individual Quercus had average study period funnelling ratios of 42.5 (median = 30.5, range = 16.7 – 137, n = 10). Study period stand scale funnelling ratios from Eucalyptus averaged 13.6 (median = 13.1, range = 4 – 21, n = 10), while Fagus stands averaged 16.4 (median = 11.9, range = 2.7 – 39.1, n = 4). For Mediterranean vegetation at the stand level, only three plateau funnelling ratios were calculated averaging 21.9 at 15 mm. Plateau funnelling ratios for individual 17 trees averaged 62.4 at 26 mm (median = 47.9 at 29, n = 17), ranging from 16.4 at 29 mm for Q. ilex rotundifolia (Bellot and Escarré, 1998, M70) to 137.9 at 17 mm for E. globulus (Bellot and Escarré, 1998, M01). Plateau funnelling ratios for individual Phyllirea media averaged 76.1 at 27 mm (median = 77.6 at 30 mm, range = 19.9 at 22 – 118.1 at 9 mm, n = 5), while individual Quercus averaged 43.3 at 27 mm (median = 27.9 at 29 mm, range = 16.4 at 29 – 129.6 at 9 mm, n = 9). Forests comprised predominantly of Pinus are the most studied in Mediterranean climates (30 entries in total, Table 2.9; Table 2.10). Quercus, Eucalyptus, and Fagus are also well represented in this category with 18, 11, and 8 entries, respectively. 6. Arid and semi-arid environments Stemflow values for arid and semi-arid communities averaged 5.9 % (median = 5.9 %, n = 18), ranging from 0.7 % for Grevillea robusta in Machakos, Kenya (Jackson, 2000, S16) to 18.0 % for Acacia aneura in Queensland, Australia (Pressland, 1973, S01). Individual plants had higher values averaging 7.7 % (median = 6.3 %, n = 10), ranging from 0.6 % for a Prosopis laevigata in Nuevo Leon, Mexico (Návar, 1993; Návar and Bryan, 1990, S28) to 20 % for a Anthyllis cytisoides in Almería, Spain (Domingo et al., 1994; Llorens and Domingo, 2007, S05). Additional stemflow percentage values for other genera dominated and mixed arid or semi-arid communities are presented in Tables 2.11 and 2.12. Calculated and previously published season-long funnelling ratios at the community level averaged 61.3 (median = 51.0, n = 8) with a range of 21.1 for a matorral community of the Sierra Madre Oriental , Mexico (Carlyle-Moses, 2004, S22) to 153.5 for Caragana korshinskii in Gaolan, China (Li et al., 2008, S08). Only three entries provided funnelling ratio data for individual plants, averaging 28.7 (median = 16.8, n = 3) and ranging from 11.7 for a A. farnesiana in Nuevo Leon, Mexico (Návar, 1993; Návar and Bryan, 1990, S02) to 57.7 for a D. texana in Nuevo Leon, Mexico (Návar, 1993; Návar and Bryan, 1990, S13). One plateau funnelling ratio was calculated for a tree in an arid or semi-arid climate. A lone Ficus benjamina in an urban setting (Queretaro City, 18 Mexico) had a plateau funnelling ratio of 16.8 at 5 mm (Guevara-Escobar et al., 2007, S14). 7. Agroforestry Eight studies that examined a variety of crop species reported an average study period stemflow value of 7.3 % (median = 1.5 %, n = 14) with a range of 0.6 % for a plot of Zea mays and Grevillea robusta in Kenya, Africa (Jackson, 2000, A12) to 24.7 % for a plantation of Bactris gasipaes in Manaus, Brazil (Schroth et al., 1999; Schroth et al., 2001, A02). Calculated or previously published study period funnelling ratios for three studies averaged 10.8 (median = 8.1, n = 5), ranging from 3.8 for an agroforest in Central Sulawesi, Indonesia (Dietz et al., 2006, A01) to 25.3 for a Musa sp. plantation in Guadeloupe (Cattan et al., 2007, A08). Supplementary information for the presented stemflow data can be found in Tables 2.13 and 2.14. DISCUSSION Carlyle-Moses and Price (2006) were the first to note that stemflow funnelling ratios could be used to determine the depth of rainfall required to satisfy the storage capacity of a tree. Once the canopy of a tree has reached complete saturation, the stemflow funnelling ratio will plateau and decrease if rainfall continues. The rainfall depth that corresponds to the funnelling ratio plateau indicates the point at which the canopy has reached complete saturation. Calculated plateau funnelling ratios are only as accurate as the linear equations on which they are based; therefore, the rainfall depth provided with each plateau funnelling ratio is an estimation of the point at which complete canopy saturation occurred. Holwerda et al. (2006, T40) provided a linear equation that produced a plateau funnelling ratio of 272.8 at 2 mm. Such a small storage capacity is either due to large amounts of scatter not reflected in the linear equation, or the plant in question had a much lower storage capacity compared to similar plants included in the study. The limitations of using a linear equation to determine funnelling ratio plateaus can be seen in some table entries where the author provided season-long 19 funnelling ratios that were higher than calculated plateau values. Bellot and Escarré (1998) provided season-long funnelling ratios for Q. ilex (M70) which in some instances were up to 7 times higher than the plateau funnelling ratio. Calculated plateau values may in reality be higher or lower due to scatter that is not reflected in a linear equation but is observed when values are graphed. The use of plateau funnelling ratios to identify the rainfall depth required to satisfy the storage capacity of a tree has implications for canopy water balance modelling. Current canopy water balance models underestimate the amount of rainfall required to reach complete canopy saturation (Carlyle-Moses and Price, 2007). Carlyle-Moses et al. (2010) suggested that stemflow funnelling ratios could be used to provide a more accurate estimation of the rainfall depth required to saturate the canopy (P’g). Using the improved Gash model, Carlyle-Moses et al. (2010) produced P’g values for five species in a tropical forest in Panama. Calculated P’g values for A. mangium, G. sepium, G. ulmifolia, O. pyramidale, and P. quinata were 1.33 mm, 1.10 mm, 1.18 mm, 0.93 mm, and 1.00 mm, respectively, however, author calculated funnelling ratios plateaued at rainfall depths of 14.5 mm, 18.3 mm, 18.8 mm, 14.8 mm, and 26.8 mm, respectively. The calculated plateau funnelling ratios and the accompanying rainfall depths found in this paper further support the initial findings by Carlyle-Moses and Price (2006) that stemflow funnelling ratios increase until a threshold rainfall depth is reached, subsequently identifying the rainfall depth required for canopy saturation. Based on the available data, genera comparisons between climate classes were only possible for Quercus, Fagus, and Pinus. Intra-genera analyses showed that there was no statistical difference for Quercus (p = 0.23), Fagus (p = 0.28), and Pinus (p = 0.77) between the different climate/vegetation classifications. Quercus in the temperate deciduous class had stemflow values that averaged 5.7 % (median = 4.0 %) while Quercus in the Mediterranean class averaged 3.5 % (median = 2.8 %). Ranges reported in both classes were similar at 0.5 – 15.5 % and 0.3 – 12.5 %, respectively. Fagus in the temperate deciduous class averaged 5.0 % (median = 5.0 %) while Mediterranean Fagus values averaged 7.9 % (median = 6.5 %). Values for Fagus were reported at 2.0 – 9.6 % 20 for temperate deciduous and 1.1 – 20.4 % for Mediterranean. In keeping with the findings for broadleaved genera, Pinus varied only slightly between classes. Temperate coniferous Pinus had stemflow values that averaged 4.1 % (median = 2.7 %) while Mediterranean values averaged 4.4 % (median = 3.0 %). Reported temperate coniferous and Mediterranean Pinus values had ranges of < 0.1 – 14.0 % and 0.3 – 22.0 %, respectively. Inter-climatic variation between stemflow values did not vary as greatly as expected and no statistical difference was observed between climate/vegetation classifications. Average stemflow values for climate classes ranged from 2.6 % for mixed stands to 7.3 % for agroforestry, while median values ranged from 1.5 % for agroforestry to 5.9 % for semi-arid and arid environments. Excluding the classes with limited entries (agroforestry and mixed stands) average stemflow values ranged only 1.9 %, from 4.0 % for Tropical to 5.9 % for arid and semi-arid communities; however, median values had a range of 4.3 %. Values for temperate deciduous stands were expected to differ from temperate coniferous and boreal stands; however, as previously stated, no statistical difference was observed (p = 0.90). Both categories had similar reported stemflow values, averaging 5.1 % (median = 3.9 %) and 5.0 % (median = 3.7 %), respectively. Reported stemflow funnelling ratios for these two classes were also very similar with an average of 26.6 (median = 15.6) for temperate deciduous stands and 22.1 (median = 14.4) for temperate coniferous and boreal stands. These findings are not in keeping with those of Barbier et al. (2009) that found broadleaved species to have higher stemflow values when compared to coniferous species. Similar average values for temperate deciduous and temperate coniferous and boreal stands presented in this review may be due in part to an inherent bias. Only publications containing measured stemflow data were included, therefore those that stated stemflow was insignificant or used findings from a previous study were given no weight. From the available literature it appears that the majority of water balance studies that do not measure stemflow do so for coniferous stands (Baker et al., 1985; Fenn et al., 2000; Gholz et al., 1985; Johannes et al., 1986; Lankreijer et al., 1999; Pypker et al., 2005). This trend is due to the generalization that all mature conifers 21 have low stemflow production, and because some studies employ data from previous studies due to similarities in location or vegetation. CONCLUSION Stemflow production data for a multitude of tree and shrub species was organized into table format totalling 326 entries. Information was sorted alphabetically by species and given a reference code within seven different climate and vegetation classifications. Reference tables were designed in such a way that future researchers will be able to quickly access information of interest to aid in comparisons between differing studies and species. Stemflow production was found to be highly variable for categories with a large number of entries; these findings are in keeping with the findings of Llorens and Domingo (2007) for studies conducted in the Mediterranean. As noted by Llorens and Domingo (2007) a lack of standardization makes combining and comparing information in a comprehensive review difficult. Specifically, the way in which stemflow production is reported yields problems because stemflow as a percentage of rainfall cannot be compared directly to a funnelling ratio. The funnelling ratio is the superior method for reporting stemflow production when compared to reporting stemflow as a percentage of gross rainfall, however, stemflow as a percentage of gross rainfall is a more widely used method. This is partly due to the fact that the funnelling ratio was not introduced until 1986 (Herwitz, 1986). It is paramount that authors report detailed stand characteristics and stemflow funnelling ratios along with percentages of rainfall that became stemflow. Detailed stand characteristics allow for more accurate comparisons between studies and take up little space in one’s publication. Stemflow funnelling ratios should be reported because they aid in comparisons between individual trees or stands. The stemflow funnelling ratio allows for the assessment of stemflow production efficiency across species due to the inclusion of basal area in the funnelling ratio calculation. A review of the information contained within the reference tables highlighted several areas of stemflow research that remain understudied. As noted by Levia and Frost 22 (2003), knowledge regarding winter stemflow generation for both deciduous and coniferous species remains weak to date. In temperate coniferous climates, our knowledge of stemflow production for genera other than Picea, Pinus, Pseudotsuga, Larix, and Abies is limited. Studies of deciduous species focused heavily on Quercus and Fagus, therefore future research involving different deciduous genera would add new information to the existing stemflow literature. Due to the species diversity found in tropical forests these ecosystems require more attention to further our understanding of interspecific variation in stemflow production. However, it is understandable that tropical forests with high species diversity have received less attention when compared to other forest types due to the logistical challenges of accurately sampling stemflow in these diverse forests. Stemflow can be beneficial or detrimental to agriculture depending on differing circumstances, therefore, the further examination of rainfall portioning for agroforests and crop species is recommended. For many tree and bush species found in the Interior of British Columbia the stemflow literature is lacking. Particularly abundant, the sagebrush (Artemisia tridentata) has received no attention in the stemflow literature; however, other members of the genera have been examined in China (Yang et al., 2008). Pine species found in the Interior of British Columbia have also received little attention when compared to other species in the genera. Due to the hydrologic importance of stemflow it is paramount that we continue to enhance the stemflow literature by examining species and aspects of stemflow production that have received little or no attention. LITERATURE CITED Aboal JR, Jimenez MS, Morales D, Hernandez JM. 1999. Rainfall interception in laurel forest in the Canary Islands. Agricultural and Forest Meteorology 97: 73-86. Aboal JR, Jimenez MS, Morales D, Hernandez JM. 2002. New below canopy fluxes in Canarian laural forest canopies. Journal of Hydrology 264: 201-212. 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Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for temperate deciduous studies. 23.0 22.2 ± 0.6 Density (Trees/ha) 2470 403 BA (m2/ha) 1.1 - Lone trees 8.9 Code Species Location Diam. (cm) D01 D02 Acer rubrum Acer rubrum D03 Acer saccharum New Brunswick, Canada Eastern Kentucky, USA Mississauga, Ontario, Canada Author Mahendrappa (1974) Alexander and Arthur (2010) Carlyle-Moses and Price (2006) California, USA - - - Rowe (1948) (Zinke, 1967) D05 D06 Aesculus californica Ceanothus cuneatus Alnus glutinosa Betula papyrifera Lancaster, England New Brunswick, Canada 15.0 2510 4303 14 - D07 Betula platyphylla Mao'er Shan, China - - - Cape et al. (1991) Mahendrappa (1974) Wei & Zhou (1991) (Wei et al., 2005) Massachusetts, USA - Lone trees - Levia (2004) Bristol, UK - 632 - Davie and Durocher (1997) Swindon, U.K. - - - Herbst et al. (2006) Osaka, Japan 10 - 20 767 - Masukata et al. (1990) - Lone trees 3.3 74.9 10.3 15.2 14.4 29.6 48.6 - Lone Lone Lone Lone Lone Lone - D04 D08 D09 D10 D11 Broad-leaved deciduous forest Castanea sativa Quercus rubra Crataegus monogyna Acer campestre Evergreen-broadleaf forest D12 Fagus grandifolia D13 D14 D15 D16 D17 D18 D19 Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Mississauga, Ontario, Canada Maryland, USA Maryland, USA New Haven, Connecticut Maryland, USA Maryland, USA Maryland, USA Maryland, USA Carlyle-Moses and Price (2006) Levia et al. (2010) Levia et al. (2010) Voigt (1960) Van Stan and Levia (2010) Van Stan and Levia (2010) Van Stan and Levia (2010) Van Stan and Levia (2010) 39 1651con 1458con 1789con 112 - 32.8con 30.3con 29.6con 86.2 - Ahmadi et al. (2009) André et al. (2008) D21 D22 Fagus grandifolia Acer saccharum Betula alleghaniensis Fagus orientalis Fagus sylvatica D23 Fagus sylvatica Chimay, Belgium D24 D25 Fagus sylvatica Fagus sylvatica Steigerwald, Germany Thuringia, Germany 49.5 17.8 29.3 37 D26 Fagus sylvatica Hampshire, UK - - - D27 Fagus sylvatica Ghent, Belgium 68 - D28 Hardwood forest Georgia, USA 5 - 23 - Bryant et al. (2005) D29 D30 D31 D32 D33 D34 D35 Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Maryland, USA Maryland, USA Maryland, USA Maryland, USA Maryland, USA Maryland, USA Maryland, USA 73.1 71.1 33.7 16.5 27.3 67.5 - Lone 1200 1150 975 Lone Lone Lone Lone Lone Lone Lone Chang and Matzner (2000) Krämer and Hölsher (2009) Neal et al. (1991); Neal et al. (1993) Staelens et al. (2008) - Levia et al. (2010) Levia et al. (2010) Levia et al. (2010) Van Stan and Levia (2010) Van Stan and Levia (2010) Van Stan and Levia (2010) Van Stan and Levia (2010) D36 Lithocarpus-Castanopsis association with bryophytes China - - - Liu et al. (2002) (Johnson and Lehmann, 2006) D37 Lithocarpus-Castanopsis association with bryophytes China - - - Liu et al. (2003) (Johnson and Lehmann, 2006) Reefton, New Zealand - - - Rowe (1979) Mississauga, Ontario, Canada - 442 38.5 Price and Carlyle-Moses (2003) D20 D38 D39 Mixed beech-podocarphardwood stand Mixed deciduous forest Quercus rubra Acer saccharum Fagus grandifolia Acer rubrum New Hampshire, USA - Leonard (1961) Nowshahr, Iran Chimay, Belgium Lone trees - André et al. (2008) 286 228 20.5 36 40 Oyarzún et al. (2004) (Johnson and Lehmann, 2006) Godoy et al. (1999) (Johnson and Lehmann, 2006) D40 Nothofagus betuloides Chile - - - D41 Nothofagus pumilio Chile - - - D42 Nyssa aquatica Taxodium distichum Fraxinus caroliniana Pitt County, North Carolina, USA > 2.5 < 2.5 2730 2681 69 Brinson et al. (1980) Lone trees - Herwitz and Levia (1997) 5649 Lone 350 - Mahendrappa (1974) Dunford and Niederhof (1944) Xiao et al. (2000) Toba and Ohta (2005) 2595 2916 2520 1087 1236 840 1507 1804 2150 11.8 14.7 13.4 16.0 19.6 22.3 22.4 24.0 19.9 Brown and Barker (1970) D43 Populus grandidentata New Braintree, Massachusetts, USA D44 D45 D46 D47 Populus grandidentata Populus sp. Pyrus calleryana Quercus acutissima New Brunswick, Canada Colorado, USA California, USA Nagoya, Japan 37.0 37.5 35.0 34.8 32.0 16.0 22 D48 Quercus alba Quercus velutina Rhode Island, USA Stand 1a: 7.1 1b: 7.4 1c: 7.4 2a: 11.2 2b: 10.9 2c: 16.8 3a: 9.7 3b: 9.1 3c: 7.4 D49 Quercus coccinea Eastern Kentucky, USA 27.7 ± 0.5 - - D50 Quercus mongolica Mao'er Shan, China - - - D51 D52 D53 Quercus montana Quercus petraea Quercus petraea 26.1 ± 0.6 - 5000 20 D54 Quercus rubra Eastern Kentucky, USA Chimay, Belgium Lancaster, England Mississauga, Ontario, Canada - Lone trees 20.7 D55 Quercus rubra - - - - D56 Quercus rubra Massachusetts, USA 63.8 Lone - Alexander and Arthur (2010) Wei and Zhou (1991) (Wei et al., 2005) Alexander and Arthur (2010) André et al. (2008) Cape et al. (1991) Carlyle-Moses and Price (2006) Durocher (1990) (Levia and Frost, 2003) Levia (2004) 41 D57 D58 D59 Quercus serrata Quercus serrata Quercus serrata Shirasaka, Japan Yamashiro, Japan Nagoya, Japan 7.2 6.9 5070 3502 2852 - D60 Quercus sp. Miyaluo, China - - - D61 D62 Quercus spp. Quercus suber Nuevo Leon, Mexico California, USA 312 Lone - D63 Stewartia monadelpha Kyoto, Japan 16.1 12.5 S1 - 22.3 S2 - 23.7 S3 - 29.1 S4 - 21.8 S5 - 20.3 S6 - 27.9 Park and Hattori (2002) Park and Hattori (2002) Toba and Ohta (2005) Lei et al. (1994a,b) (Wei et al., 2005) Silva and Rodrigues (2001) Xiao et al. (2000) Lone trees - Liang et al. (2009) Table 2.2. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for temperate deciduous studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) D01 D02 Acer rubrum Acer rubrum 1130 - 5.6 - - D03 Acer saccharum 785 213.80 - 21.5 P > 4.3 mm 21.6 7.2 30.5 108.6 16.1 22.7 14.6 D04 Aesculus californica Ceanothus cuneatus - - 14.6 - SF = 6.02 lnP - 0.071I - 8.9a b c Units: SF (L) P (mm) I (mm/h) - 42 D05 Alnus glutinosa - 1983/84: 1583 1984/85: 1690 D06 D07 Betula papyrifera Betula platyphylla Broad-leaved deciduous forest Castanea sativa Quercus rubra Crataegus monogyna Acer campestre 676 - 3.9 4.6 48.6 at 35 mmcalc 64.3calc 38.6 at 37 mmcalc 64.3calc - 1210 - - Winter: 6 - 21 - - 31 2.4 - - 650 1350 < 0.5 - SF (mm) = 0.0015P (mm) - 0.0118 1467 1976: 1726.5 1977/78: 974.1 20.3 13.8 - SF (mm) = 0.18(P (mm) - 3.6) SF (mm) = 0.145(P (mm) - 5.8) D08 D09 D10 D11 Evergreen-broadleaf forest 9±2 9±2 D12 Fagus grandifolia 785 213.80 - D13 D14 D15 D16 D17 D18 D19 1221 1221 1143 1200 1200 1200 1200 - 9.6 - 1270 - 5.0 D21 Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Fagus grandifolia Acer saccharum Betula alleghaniensis Fagus orientalis - 309.9 2.0 P > 4.3 mm 15.8 24.0 32.4 39.3 57.0 at 10 mmcalc 38.2 47.2 26.9 37.4 15.5 at 11 mmcalc 16.8 at 11 mmcalc 17.1 at 11 mmcalc 2.3calc D22 Fagus sylvatica 1044 - - - D20 Summer: SF (mm) = 0.092P (mm) 0.837 Winter: SF (mm) = 0.074P (mm) 0.74 - SF = 14.50 ln P - 0.15I - 20.8 Units: SF (L) P (mm) I (mm/h) SF (L) = 5.82 P (mm) + 5.75calc SF (L) = 0.52 P (mm) - 0.45calc SF (mm) = 0.0563P (mm) - 0.061con SF (mm) = 0.0029P1.7315 (mm) Leaved: SF (L/mm) = 0.09CBH (cm) - 4.31d Leafless: SF (L/mm) = 0.17CBH (cm) - 9.16 43 D23 Fagus sylvatica 1044 - - D24 D25 D26 Fagus sylvatica Fagus sylvatica Fagus sylvatica 750 544 - 662 800 691 1223 640 5.2calc 3.1calc 5.0 D27 Fagus sylvatica 755 Leafed: 769.9 Leafless: 677.9 6.4 9.5 D28 D29 D30 D31 D32 D33 D34 D35 Hardwood forest Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera Liriodendron tulipifera 830 1221 1221 1221 1200 1200 1200 1200 752.8 - 0.7 - 38.7 at 13 mmcalc 82.3 at 13 mmcalc 25.4calc 8.6calc 42.1 at 16 mmcalc 31.7calc 61.4 at 13 mmcalc 47.1calc 3.3 at 28 mmcalc 1.6 at 27 mmcalc 8.5 at 21 mmcalc 19.2 14.4 3.1 12.2 D36 Lithocarpus-Castanopsis association with bryophytes 2165 - 2.8 - - D37 Lithocarpus-Castanopsis association with bryophytes 2165 - 2.0 - - 1950 6220 1.5 - - 785 259.3 3.7 ± 0.9 9.0 at 12 mmcalc 9.6calc SF (mm) = 0.039P (mm) - 0.005 7111 5332 - 1.4 9.0 - - D38 D39 D40 D41 Mixed beech-podocarphardwood stand Mixed deciduous forest Quercus rubra Acer saccharum Fagus grandifolia Acer rubrum Nothofagus betuloides Nothofagus pumilio SF (L) = 1.09P (mm) - 1.65 SF (L) = 6.29P (mm) - 9.65 SF (L) = 0.41 DBH2.04 (cm)e SF (mm) = 0.098P (mm) - 0.209 SF (mm) = 0.140P (mm) - 0.209 SF (L) = 1.78P (mm) - 11.19calc SF (L) = 0.81P (mm) - 4.70calc SF (L) = 0.92P (mm) - 3.47calc - 44 D42 Nyssa aquatica Taxodium distichum Fraxinus caroliniana - 466 639 D43 Populus grandidentata 1190 - D44 D45 D46 D47 Populus grandidentata Populus sp. Pyrus calleryana Quercus acutissima 599.4 446 - 487.7 428 Leafless: 4.5 Leaved: 2.5 3.3 6.5calc 3.6calc 4.8calc 5.4 9.0 9.9 7.8 8.4 6.1 1.1 8 2.5 5.2 12.0 8.5 9.9 14.7 37.2 at 1 mmcalc 18.8 at 19 mmcalc 36.7 at 16 mmcalc 21.0 at 20 mmcalc 30.2 at 15 mmcalc Leafless: SF (L) = 6.287DBH (cm) 2.421 Leaves: SF (L) = 0.864DBH (cm) 50.512 - SF (mm) = 0.0794P (mm) - 0.0012 Growing all: SF = 0.041P - 0.127 Dormant S1: SF = 0.057P - 0.127 Dormant S2: SF = 0.048P - 0.152 Dormant S3: SF = 0.077P - 0.152 All units in mm Leaved: SF (L/mm) = 0.08CBH (cm) - 4.62 Leafless: SF = 0.16CBH (cm) 10.20 D48 Quercus alba Quercus velutina 1119.38 - Growing: 3.9 Dormant: 4.8 D49 D50 D51 Quercus coccinea Quercus mongolica Quercus montana 1130 450 - 550 1130 - 15.5 - 9.5 7.6 D52 Quercus petraea 1044 - - - - 1983/84: 1583 1984/85: 1690 10 ± 2 10 ± 2 50calc 43.2 at 28 mmcalc 50calc Summer: nd Winter: SF (mm) = 0.11P (mm) 0.66 - P > 4.3 mm 10.4 7.4 7.6 7.0 9.3 6.1 13.7 SF = 25.55 lnP - 0.50I - 38.6 Units: SF (L) P (mm) I (mm/h) D53 D54 Quercus petraea Quercus rubra 785 213.80 45 D55 D56 Quercus rubra Quercus rubra 1210 - 4.0 - Event high: 70.0 D57 Quercus serrata - 4187.9 9.9 61.3 D58 Quercus serrata - 2955.5 5.0 55.6 D59 Quercus serrata 735.4 3.0 - D60 Quercus sp. - 2.3 - - D61 D62 Quercus spp. Quercus suber 700 1000 639 446 SF (mm) = (0.0124(DBH (cm))1.455) Pg - (0.018(DBH (cm))1.825) SF (mm) = (0.0077(DBH (cm))1.500) P (mm) - (0.0195(DBH (cm))2.031) - 974 - 91.5 at 7 mmcalc SF (mm) = 0.148P (mm) - 0.0589 D63 Stewartia monadelpha 1523 - 0.5 15 S1 - nd S2 - 26.0 S3 - 10.3 S4 - 14.7 S5 - 3.3 S6 - 6.6 - - a SF = Stemflow P = Precipitation c I = Rainfall intensity d CBH = Circumference at breast height e DBH = Diameter at breast height b Table 2.3. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for coniferous and boreal studies. 18.0 Density (Trees/ha) 2959 BA (m2/ha) - New Hampshire, USA - - - - - - - Code Species Location Diam. (cm) C01 Abies balsamea New Brunswick, Canada C02 Abies balsamea C03 Abies lasiocarpa Author Mahendrappa (1974) Olson et al. (1981) Niederhof and Wilm (1943) (Zinke, 1967) 46 C04 Abies lasiocarpa Picea glauca x engelmannii Penticton, BC, Canada - 1470 - Spittlehouse (1998) C05 Chamaecyparis obtusa Honshu, Japan 1997: 5.8 1999: 7.0 2000: 8.1 2944 - Murakami (2009) C06 Chamaecyparis obtusa Tokyo, Japan 21.5 932 - C07 Chamaecyparis obtusa Tokyo, Japan 21.5 932 - C08 Fitzroya cupressoides C09 Koichiro et al. (2001); Kuraji et al. (2001) Koichiro et al. (2001); Kuraji et al. (2001) - - - Oyarzún et al. (1998) Ilex pedunculosa Cordillera de la Costa, Chile Kyoto, Japan 3.5 15 - Park and Hattori (2002) C10 Juniperus sp. Texas, USA - - - Owens et al. (2006) C11 Larix cajanderi Siberia, Russia - 840 - Toba and Ohta (2005) C12 Larix decidua Edinburgh, Scotland - 3900 30 Cape et al. (1991) C13 Larix decidua Aberdeen, Scotland - 1600 50 Cape et al. (1991) C14 Larix gmelinii Genhe, China - - - C15 Larix laricina Canada - - - C16 Picea abies Vosges, France - 575 53.3 Zhou (2003) (Wei et al., 2005) Lilienfein and Wilcke (2004) (Johnson and Lehmann, 2006) Viville et al. (1993) C17 Picea abies Lancaster, England - 3200 35 C18 Picea engelmannii - - - - C19 Picea glauce New Brunswick, Canada 17.0 3767 - Cape et al. (1991) Niederhof and Wilm (1943) (Zinke, 1967) Mahendrappa (1974) C20 Picea rubens New Brunswick, Canada 16.0 4841 - Mahendrappa (1974) C21 Picea sitchensis Dumfriesshire, Scotland 25 - 36 - - Ford and Deans (1978) C22 Picea sitchensis - - - Johnson (1990) C23 Picea sitchensis Balquhidder, Scotland Carnation Creek, BC, Canada - 1500 - Spittlehouse (1998) 15 156 277 625 3000 - Teklehaimanot et al. (1991) C24 Picea sitchensis Edinburgh, Scotland 47 C25 Picea sitchensis Aberdeen, Scotland - 3600 125 C26 Pinus arandi Miyaluo, China - - - C27 Pinus contorta 2.0 - 14.6 - - C28 Pinus contorta Mayson Lake, British Columbia, Canada Penticton, BC, Canada - 720 - C29 Pinus contorta - - - - C30 Pinus contorta Colorado, USA Pinus densiflora Tsukuba, Japan - Taniguchi et al. (1996) C32 Pinus densiflora Northern Japan 2300 1700 1444 - C31 20.4 19.8 - Cape et al. (1991) Lei et al. (1994a,b) (Wei et al., 2005) McKee and Carlyle-Moses (2010) Spittlehouse (1998) Wilm and Dunford (1948) (Zinke, 1967) Dunford and Niederhof (1944) - Toba and Ohta (2005) C33 Pinus densiflora Northern Japan - 1678 - Toba and Ohta (2005) C34 Pinus densiflora Northern Japan - 355 - Toba and Ohta (2005) C35 Pinus elliottii Guangzhou, China 30 400 - C36 Pinus koraiensis Mao'er Shan, China - - - C37 Pinus palustri Georgia, USA 10 2050 - Tang (1996) Zhou et al. (1994) (Wei et al., 2005) Bryant et al. (2005) C38 Pinus pseudostrobus Nuevo Leon, Mexico 32.4 246 - C39 Pinus radiata plantation - - - - C40 Pinus radiata - - - - C41 Pinus resinosa New Brunswick, Canada 22.0 1882 - Silva and Rodrigues (2001) Crockford and Khanna (1997) (Levia and Frost, 2003) Crockford and Richardson (1990) (Levia and Frost, 2003) Mahendrappa (1974) C42 Pinus resinosa New Haven, Connecticut 20.3 500 - Voigt (1960) C43 Pinus strobus New Brunswick, Canada 21.0 2151 - Mahendrappa (1974) C44 Pinus strobus North Carolina, USA - - - Helvey (1967) C45 Pinus sylvestris Siberia, Russia - 1492 - Toba and Ohta (2005) C46 Pinus sylvestris Lancaster, England - 2270 36 Cape et al. (1991) C47 Pinus sylvestris Edinburgh, Scotland - 3900 44 Cape et al. (1991) C48 Pinus sylvestris Aberdeen, Scotland - 2700 95 Cape et al. (1991) 48 C49 Pinus tabulaeformis Miyaluo, China - - - C50 Pinus taeda - - - C51 Pinus taeda Pinus palustris Georgia, USA 14 - 21 - Bryant et al. (2005) C52 Pinus wallichiana Himachal Pradesh, India - 556 367 189 1200 Lei et al. (1994a,b) (Wei et al., 2005) Hoover (1953) (Zinke, 1967) 29 Singh (1987) C53 Pseudotsuga menziesii Malalcahuello, Chile 25.9 1143 60.3 Iroumé and Huber (2002) C54 Pseudotsuga menziesii Oregon, USA - - - Rothacher (1963) (Zinke, 1967) C55 Pseudotsuga menziesii - 1050 - Spittlehouse (1998) C56 Pseudotsuga menziesii - 1090 - Spittlehouse (1998) C57 Tsuga canadensis 24.1 - - Voigt (1960) C58 Tsuga heterophylla - 480 - Spittlehouse (1998) Cowichan Lake, BC, Canada Cowichan Lake, BC, Canada New Haven, Connecticut Carnation Creek, BC, Canada Table 2.4. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for coniferous and boreal studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) C01 C02 C03 Abies balsamea Abies balsamea Abies lasiocarpa Abies lasiocarpa Picea glauca x engelmannii - 389 - 3.5 3-8 - - SF (L) = 2.312P (mm) - 6.342con 3316 454 < 0.5 - - C04 49 C05 Chamaecyparis obtusa 1467.7 C06 C07 C08 Chamaecyparis obtusa Chamaecyparis obtusa Fitzroya cupressoides 2279 2279 4000 1997: 1259.7 1998: 1509.4 1999: 1673.2 2000: 1431.2 2156.4 1862.9 4098 C09 Ilex pedunculosa - - - 69.8 C10 C11 Juniperus sp. Larix cajanderi 600 - 900 - 1176 - 3209 59.13 5.0 0.0 - SF (mm) = (0.0047(DBH (cm))2.174) Pg (0.0428(DBH(cm))1.150) SF (mm) = 3.5 x (1 - e-0.103 x P) (mm) Slope = 0.62 x 10-4 C12 Larix decidua - 1984/85: 783 1985/86: 1053 4±1 3±1 8.5 at 63 mmcalc 13.3calc 15.3 at 52 mmcalc 10.0calc Summer: SF (mm) = 0.041P (mm) - 0.984 Winter: SF (mm) = 0.07P (mm) - 1.26 C13 Larix decidua - C14 C15 C16 Larix gmelinii Larix laricina Picea abies 1400 1984/85: 1023 1985/86: 986 1710.6 1±0 0.4 ± 0.1 3.3 1.6 0.5 0.8 at 59 mmcalc 2.0calc 3.2 at 72 mmcalc 0.8calc 0.9calc Summer: SF (mm) = 0.006P (mm) - 0.132 Winter: SF (mm) = 0.027P (mm) - 0.81 - C17 Picea abies - 1983/84: 1583 1984/85: 1690 13 ± 3 14 ± 3 21.1 at 47 mmcalc 37.1calc 34.6 at 33 mmcalc 40calc Summer: SF (mm) = 0.16P (mm) - 2.4 Winter: SF (mm) = 0.16P (mm) - 1.28 C18 C19 C20 C21 C22 C23 Picea engelmannii Picea glauce Picea rubens Picea sitchensis Picea sitchensis Picea sitchensis - - 2130 3316 454 - SF (L) = 0.668P (mm) - 4.933con - C24 Picea sitchensis 1000 441.78 6.4 2.3 27.0 3.0 9.0 0.5 1.0 2.9 16.7 - - 1639 5.9 2.8 3.8 4.3 12.0 12.0 2.0 81.3 30 31.4 29 - - 50 C25 Picea sitchensis C26 Pinus arandi C27 C28 C29 C30 - 1984/85: 1023 1985/86: 986 13 ± 3 14 ± 3 8.8 at 37 mmcalc 10.4calc 10.4 at 15 mmcalc 11.2calc Summer: SF (mm) = 0.15P (mm) - 1.5 Winter: SF (mm) = 0.15P (mm) - 0.3 - 5.0 - - Pinus contorta Pinus contorta Pinus contorta Pinus contorta 700 1000 600 3316 599.4 52.3 454 396 14.9 - C31 Pinus densiflora 1222 1291 C32 C33 C34 C35 C36 C37 C38 1500 676 830 639 152.2 269 174.6 724.8 974 - SF (mm) = 0.0136P (mm) – 0.0896 SF (mm) = 0.0061P (mm) – 0.0729 slope = 0.16 SF (mm) = 0.088P (mm) – 0.432 - - - 3.1 - 3.9 - - - - 11.2 - - C41 C42 C43 Pinus densiflora Pinus densiflora Pinus densiflora Pinus elliottii Pinus koraiensis Pinus palustri Pinus pseudostrobus Pinus radiata plantation Pinus radiata plantation Pinus resinosa Pinus resinosa Pinus strobus < 0.5 1.5 0.5 1.2 5.2 2.7 3.3 9.4 3.8 2.0 0.6 1143 - - 0.7 1.2 5.3 - C44 Pinus strobus - - 8.8 4.3 2.3 - C45 Pinus sylvestris - C46 Pinus sylvestris - 49.75 1983/84: 1583 1984/85: 1690 0.0 7±1 6±1 13.7 at 76 mmcalc 19.4calc 19.2 at 28 mmcalc 16.7calc 10 yrs old - SF = 0.00 + 0.09Pcon 35 yrs old - SF = -0.254 + 0.06Pcon 60 yrs old - SF = -0.254+ 0.03Pcon All units (mm) Slope = 0.31 x 10-3 Summer: SF (mm) = 0.087P (mm) - 2.871 Winter: SF (mm) = 0.088P (mm) - 0.528 C47 Pinus sylvestris - 1984/85: 783 1985/86: 1053 15 ± 3 13 ± 3 26.1 at 39 mmcalc 34.1calc 38.6 at 41 mmcalc 29.5calc Summer: SF (mm) = 0.16P (mm) - 1.76 Winter: SF (mm) = 0.24P (mm) - 2.88 C39 C40 - 51 C48 Pinus sylvestris C49 Pinus tabulaeformis C50 Pinus taeda Pinus taeda Pinus palustris Pinus wallichiana C51 C52 1984/85: 1023 1985/86: 986 10 ± 2 8±2 7.5 at 37 mmcalc 10.5calc 10.0 at 37 mmcalc 8.4calc Summer: SF (mm) = 0.098P (mm) - 0.98 Winter: SF (mm) = 0.13P (mm) - 1.3 - 2.6 - - - - - SF (mm) = 0.222 P (mm) - 0.457con 830 752.8 0.5 - - - - 2.7 - 700 1000 - C53 Pseudotsuga menziesii 2341 3805 6.0 C54 C55 C56 C57 C58 Pseudotsuga menziesii Pseudotsuga menziesii Pseudotsuga menziesii Tsuga canadensis Tsuga heterophylla 3316 3316 1143 3316 454 454 454 0.3 9.0 4.0 5.9 1.0 9.3 at 15 mm calc 10 calc SF (mm) = 0.065P (mm) - 0.131 - - Table 2.5. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for mixed deciduous and coniferous stands. Code Species Location Diam. (cm) Density (Trees/ha) BA (m2/ha) Author X01 Dry sclerophyll forest - - - - Crockford and Richardson (1990) (Levia and Frost, 2003) Ibaraki, Japan - - - Iida et al. (2005) Georgia, USA 16 - 18 711 - Bryant et al. (2005) Georgia, USA 14 60 1411 - Bryant et al. (2005) Fort Bragg, California, USA - 341 108 89 61 31 5.5 Reid and Lewis (2009) X02 X03 X04 X05 Pinus densiflora Quercus myrsinaefolia Eurya japonica Quercus alba Pinus taeda Quercus berberidifolia Pinus palustris Sequoia sempervirens Pseudotsuga menziesii Lithocarpus densiflorus 52 Table 2.6. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for mixed deciduous and coniferous stands. Code Species PA (mm) PS (mm) SF (%) F Formula(s) X01 Dry sclerophyll forest Pinus densiflora Quercus myrsinaefolia Eurya japonica Quercus alba Pinus taeda Quercus berberidifolia Pinus palustris Sequoia sempervirens Pseudotsuga menziesii Lithocarpus densiflorus - - 4.8 - - 1207 1984/1985: 1213 2001/2002: 1246 1.2 8.5 - SF (mm) = 0.0186P (mm) – 0.119 SF (mm) = 0.101P (mm) – 0.297 830 684.9 0.5 - - 830 724.8 0.5 - - 1285 1316 2.5 2.6calc - X02 X03 X04 X05 Table 2.7. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for tropical studies. Code Species Location Diam. (cm) Density (Trees/ha) BA (m2/ha) Author T01 Acacia mangium Soberania, Panama - Lone - Park and Cameron (2008); Carlyle-Moses et al. (2010) T02 Amazonian terra firme rainforest Manaus, Amazonas, Brazil - 3000 - Lloyd et al. (1988) T03 Balanops australiana 27.9 39.1 Lone trees - Herwitz (1986) T04 Cardwellia sublimis Northeast Queensland, Australia Northeast Queensland, Australia 40.2 Lone - Herwitz (1986) 53 Castanopsis sieboldii, Schima wallichii, and Rapanea neriifolia dominated stand Ryukyus, Japan > 3.0 6625 57.5calc Xu et al. (2005) T06 Cecropia peltata Luquillo Mountains, Puerto Rico 21 24 19 18 Lone trees - Holwerda et al. (2006) T07 Cecropia peltata Rio Piedras, Puerto Rico - - - Scatena (1990) T08 Ceratopetalum virchowii Northeast Queensland, Australia 25.0 46.1 43.3 Lone trees - Herwitz (1986) T09 Cerrado (native savanna) Brazil - - - Lilienfein and Wilcke (2004) (Johnson and Lehmann, 2006) T10 Cunningshamia lanceolata plantation Huitong, China - - - Tian et al. (1994) (Wei et al., 2005) Lone trees - Holwerda et al. (2006) - - Scatena (1990) T05 32 54 49 32 41 59 - T11 Dacryodes excelsa Luquillo Mountains, Puerto Rico T12 Dacryodes excelsa Rio Piedras, Puerto Rico T13 Dimorphandra macrostachya and Euceraea nitida Canaima, Venezuela > 10 < 10 950 4530 29.7 9.2 Dezzeo and Chacón (2006) T14 Dimorphandra macrostachya and Euterpe sp. Canaima, Venezuela > 10 < 10 1060 3400 40 7 Dezzeo and Chacón (2006) T15 Elaeocarpus foveolatus 48.1 Lone - Herwitz (1986) T16 Elaeocarpus sp. 45.0 Lone - Herwitz (1986) Northeast Queensland, Australia Northeast Queensland, Australia 54 T17 Eschweilera spp. Manaus, Brazil 21.0 - - Schroth et al. (1999); Schroth et al. (2001) T18 Eucalyptus melanophloia Australia - - - T19 Eucalyptus mixed cross Congo - - - T20 Eucommia ulmoides 4.5 ± 1.1 6478 - T21 Evergreen montane forest Hunan Province, China Zamora-Chinchipe, Ecuador Prebble and Stirk (1980) (Johnson and Lehmann, 2006) Laclau et al. (2003) (Johnson and Lehmann, 2006) Cao et al. (2008) - - - Fleischbein et al. (2005, 2006) T22 Gliricidia sepium Soberania, Panama - Lone - T23 Guazuma ulmifolia Soberania, Panama - Lone - T24 Large timber extraction forest Central Sulawesi, Indonesia - 5495 3740 4052 41.1 53.6 34.6 Dietz et al. (2006) Park and Cameron (2008); Carlyle-Moses et al. (2010) Park and Cameron (2008); Carlyle-Moses et al. (2010) Lowland dipterocarp forest Lowland evergreen rain forest Malaysia - - - Manokaran (1979) Central Kalimantan, Indonesia > 10 - - Vernimmen et al. (2007) T27 Lowland tropical forest Kalimantan, Indonesia - Unlogged: 581 Logged: 278 38.6 13.8 Asdak et al. (1998) T28 Lowland tropical forest Sarawak, Malaysia - 6856 43.3 Manfroi et al. (2004); Manfroi et al. (2006) T29 Mixed pine broadleaf Dinghushan, China - - - Yan et al. (2003) (Wei et al., 2005) T30 Monsoon evergreen broadleaf Dinghushan, China - - - Yan et al. (2003) (Wei et al. 2005) T31 Monsoon pine forest Dinghushan, China - - - Yan et al. (2003) (Wei et al. 2005) T32 Natural montane forest Central Sulawesi, Indonesia - 2272 1806 3455 68.6 50 51.1 Dietz et al. (2006) T33 Nectandra sp. La Mancha, Veracruz, Mexico - - - Kellman and Roulet (1990) T25 T26 55 T34 Nectandra sp. La Mancha, Veracruz, Mexico - - - Kellman and Roulet (1990) T35 Ochroma pyramidale Soberania, Panama - Lone - Park and Cameron (2008); Carlyle-Moses et al. (2010) T36 Oenocarpus bacaba Manaus, Brazil 15.5 - - Schroth et al. (1999); Schroth et al. (2001) T37 Pachira quinata Soberania, Panama - Lone - Park and Cameron (2008); Carlyle-Moses et al. (2010) T38 Pinus canariensis - - - Kittredge et al. (1941) (Zinke, 1967) T39 Pinus massoniana Hunan Province, China 2628 T40 Prestoea montana Luquillo Mountains, Puerto Rico 9.2 ± 3.4 15 16 16 15 18 17 15 17 T41 Quercus copeyensis Costa Rica T42 Quercus copeyensis T43 T44 T45 T46 T47 Cao et al. (2008) Lone trees - Holwerda et al. (2006) - - - Costa Rica - - - Quercus copeyensis Costa Rica - - - Rain forest Rain forest with high abundance of ectomycorrhizal trees Rain forest with low abundance of ectomycorrhizal trees Semi-deciduous monsoon forests Sabah, Malaysia - - - Hölscher et al. (2003) (Johnson & Lehmann, 2006) Hölscher et al. (2003) (Johnson & Lehmann Hölscher et al. (2003) (Johnson & Lehmann Sinun et al. (1992) Korup, Cameroon >5 301 - Chuyong et al. (2004) Korup, Cameroon >5 303 - Chuyong et al. (2004) Jianfengling, China - - - Zeng (1994) (Wei et al., 2005) 56 Sloanea berteriana Luquillo Mountains, Puerto Rico Rio Piedras, Puerto Rico Lone trees - T50 Small timber extraction forest Central Sulawesi, Indonesia - T51 Stunted heath forest T52 Stunted heath forest T53 Tall heath forest T54 Terra firme rainforest T55 Tristania sp. T56 Tropical dry forest T48 Sloanea berteriana T49 T57 T58 T59 T60 T61 T62 T63 T64 382 - Holwerda et al. (2006) 2020 3855 2420 55.5 67 41.4 Scatena (1990) > 10 - - Vernimmen et al. (2007) Small trees - - Vernimmen et al. (2007) > 10 - - Vernimmen et al. (2007) > 10 670 33.7 Cuartas et al. (2007) - - - Vernimmen et al. (2007) - - - Kellman and Roulet (1990) Columbia - - - Manaus, Brazil San Carlos de Rio Negro, Venezuela San Carlos de Rio Negro, Venezuela Araracuara, Colombia 3.8 - 52.2 3000 - Veneklaas and Van Ek (1990) (Levia and Frost, 2003) Lloyd and de Marques (1988) - 11217 - Jordan (1978) - 2736 - Jordan (1978) - - - Marin et al. (2000) Vernicia fordii Vismia guianensis, Myrcia sp. Clusia sp. Hunan Province, China 7.3 ± 2.1 2000 - Cao et al. (2008) Canaima, Venezuela > 10 < 10 130 1030 2 2 Dezzeo and Chacón (2006) Vismia spp. Manaus, Brazil 3.5 19500 Tropical montane rainforest Tropical rain forest Tropical rain forest (228 species) Tropical rain forest (100 species) Tropical rainforest Central Kalimantan, Indonesia Central Kalimantan, Indonesia Central Kalimantan, Indonesia Manaus, Brazil Central Kalimantan, Indonesia La Mancha, Veracruz, Mexico Dietz et al. (2006) Schroth et al. (1999); Schroth et al. (2001) 57 Table 2.8. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for tropical studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) T01 Acacia mangium Amazonian terra firme rainforest 2127 158.1 2.7 ± 2.0 38.7 at 14.5 mm 20.3calc - 2391 4804 - - SF (mm) = 0.036P (mm) - 0.15 T02 calc 7800 25.2 3.3calc 3.8calc 112 7 11 1998: 4320 1999: 2231 2000: 3424 32.1 27.6 31.7 55.8calc 48.0calc 55.1calc SF (L) = 0.07P (mm) - 0.58 SF (L) = 0.14P (mm) - 1.49 SF (L) = 0.13P (mm) - 0.92 SF (L) = 0.14P (mm) - 0.03 T03 Balanops australiana 6500 7800 T04 Cardwellia sublimis Castanopsis sieboldii Schima wallichii Rapanea neriifolia dominated stand 6500 2680 T05 - T06 Cecropia peltata 3000 - 4000 2246 0.01 1.5 at 33 mmcalc 1.2calc 2.2 at 38 mmcalc 1.6calc 3.5 at 30 mmcalc 3.0calc 5.3 at 5 mmcalc 5.5calc T07 Cecropia peltata - - 9.8 - - calc T08 Ceratopetalum virchowii 6500 7800 18.6 26.2calc 7.7calc 100 33 20 - T09 Cerrado (native savanna) 1656 - 0.8 - - T10 Cunningshamia lanceolata plantation 1550 - 0.2 - - 3.9 at 36 mmcalc 2.9calc 2.3 at 19 mmcalc 2.2calc 1.8 at 30 mmcalc 1.5calc 0.7 at 34 mmcalc 0.5calc 1.9 at 38 mmcalc 1.4calc 1.7 at 35 mmcalc 1.2calc - SF (L) = 0.43P (mm) - 4.14 SF (L) = 0.63P (mm) - 1.95 SF (L) = 0.44P (mm) - 3.12 SF (L) = 0.08P (mm) - 0.69 SF (L) = 0.35P (mm) - 3.65 SF (L) = 0.62P (mm) - 5.72 - T11 Dacryodes excelsa 3000 - 4000 2246 0.3 T12 Dacryodes excelsa - - 1.5 58 T13 T14 T15 Dimorphandra macrostachya and Euceraea nitida Dimorphandra macrostachya and Euterpe sp. Elaeocarpus foveolatus 2548 2215 6.9 17.7calc - 2548 2215 8.4 17.9calc - 6500 7800 39.7calc 50 - calc T16 T17 Elaeocarpus sp. Eschweilera spp. 6500 2622 7800 2672 3.2 0.1 9 - - T18 Eucalyptus melanophloia 718 - 0.8 - - T19 Eucalyptus mixed cross 1502 - 1.6 - - T20 Eucommia ulmoides 1347.2 2086.1 7.6 - - T21 Evergreen montane forest 2048 2504 1.0 - T22 T23 Gliricidia sepium Guazuma ulmifolia 2127 2127 T24 Large timber extraction forest 2437 - 3424 T25 T26 T27 Lowland dipterocarp forest Lowland evergreen rain forest Lowland tropical forest 255.1 264.2 220 185 259 1.5 ± 0.21 2.3 ± 0.28 0.7 0.7 0.6 74.8 at 18.3 mm 29.7 105.1 at 18.8 mm 37.7calc 1.7calc 1.3calc 1.7calc 2030 - 3050 2381 0.6 - SF (L/100 sq.m) = 0.008 P (x102 L/100 sq.m) - 2.6797 3625 ± 560 2995 0.2 - SF (ml/mm) = 4.2 BDH (cm) - 32.2 2862 2199 3563 Logged: 1.4 Unlogged: 0.3 - SF (m3) = 0.008 + 0.019BA (m2)a SF (m3) = 0.002 + 0.019BA (m2) 3.5 2.8 3.0 T28 Lowland tropical forest 2740.5 Yr 1: 2292 Yr 2: 2439 Yr 3: 2668 T29 Mixed pine broadleaf Monsoon evergreen broadleaf 1900 - 6.5 8.7 at 22 mmcalc Year 1: 8.1calc Year 2: 6.5calc Year 3: 6.9calc - 1900 - 8.3 - T30 calc - SF (mm) = 0.046 P (mm) - 0.18 SF (ml/mm) = -11.6 + 122.4 log10(DBH (cm)) - 59 T31 Monsoon pine forest 1900 T32 Natural montane forest 2437 - 3424 T33 Nectandra sp. 1300 T34 Nectandra sp. 130 215 165 148 32 16 16 1.9 0.6 0.3 0.5 0.9calc 0.6calc 1.0calc - - Event high: 111.9 - - Event high: 135.3 - calc T35 Ochroma pyramidale 2127 269.6 0.9 ± 0.6 29.9 at 14.8 mm 10.3 T36 T37 T38 T39 Oenocarpus bacaba Pachira quinata Pinus canariensis Pinus massoniana 2622 2127 2672 232.6 29.8 at 26.8 mm 12.2calc 1347.2 2086.1 0.7 1.3 ± 0.3 0.03 - 13 2.4 T40 Prestoea montana 3000 - 4000 2246 2.7 T41 T42 T43 T44 Quercus copeyensis Quercus copeyensis Quercus copeyensis Rain forest Rain forest with high abundance of ectomycorrhizal trees 2830 2900 2900 - 3627 5011 T45 - 2.2 16.1 16.6 1.9 206.9 at 10 mmcalc 214.0calc 132.5 at 14 mmcalc 133.9calc 63.3 at 15 mmcalc 63.2calc 115.3 at 19 mmcalc 110.7calc 11.2 at 23 mmcalc 10.3calc 73.5 at 6 mmcalc 76.0calc 272.8 at 2 mmcalc 275.7calc 53.1 at 7 mmcalc 55.1calc - SF (mm) = 0.03P (mm) - 0.508con SF (L) = 4.05P (mm) - 3.94 SF (L) = 3.03P (mm) - 5.11 SF (L) = 1.47P (mm) - 2.95 SF (L) = 2.41P (mm) - 7.09 SF (L) = 0.35P (mm) - 1.49 SF (L) = 1.76P (mm) - 0.55 SF (L) = 4.87P (mm) - 0.10 SF (L) = 1.30P (mm) - 0.67 - 5370 2.2 - - T46 Rain forest with low abundance of ectomycorrhizal trees 5011 5370 1.5 - - T47 Semi-deciduous monsoon forests 1650 - 2650 - 3.0 - - 60 T48 Sloanea berteriana 3000 - 4000 2246 0.6 T49 Sloanea berteriana - T50 Small timber extraction forest 2437 - 3424 480 315 300 1.0 0.7 0.9 0.6 9.7 at 33 mmcalc 7.7calc 6.3 at 35 mmcalc 4.7calc 14.4 at 27 mmcalc 12.6calc 2.1 at 36 mmcalc 1.6calc 1.3calc 1.3calc 1.4calc T51 Stunted heath forest 3625 ± 560 2995 0.4 - SF (ml/mm) = 3.2DBH (cm) - 10.0 T52 Stunted heath forest 3625 ± 560 2995 1.0 - SF (ml/mm) = 49.0DBH (cm) + 2.6 T53 Tall heath forest 3625 ± 560 2995 0.8 - SF (ml/mm) = 1.1DBH (cm) + 6.53 SF (ml/mm) = 3.3DBH (cm) + 13.74 T54 Terra firme rainforest 2442 3064.2 0.7 3.1 at 24 mmcalc SF (mm) = 0.013P (mm)- 0.06 T55 Tristania sp. 3625 ± 560 2995 0.6 - SF (ml/mm) = 35.4DBH (cm) - 27.6 T56 Tropical dry forest Tropical montane rainforest Tropical rain forest Tropical rain forest (228 species) Tropical rain forest (100 species) 1300 304 0.7 - - - - < 0.1 - - 2442 2721 1.8 ± 1 - - - 2861 7.1 - - - 3087 1.8 - - 0.9 0.9 1.5 1.1 - T57 T58 T59 T60 SF (L) = 0.29P (mm) - 2.31 SF (L) = 0.27P (mm) - 2.48 SF (L) = 0.28P (mm) - 1.57 SF (L) = 0.13P (mm) - 1.25 - T61 Tropical rainforest 3100 3273.8 3293.0 3158.4 3120.9 T62 Vernicia fordii 1347.2 2086.1 3.6 - Plot 1 - SF = 0.0015P1.53 Plot 2 - SF = 0.0020P1.467 Plot 3 - SF = 0.0029P1.423 Plot 4 - SF = 0.0031P1.325 Units: SF(mm) P(mm) - T63 Vismia guianensis, Myrcia sp. and Clusia sp. 2548 2215 2.0 50.0calc - T64 Vismia spp. 2622 2672 20.3 - SF (L/mm) = 0.026DBH (cm) - 0.03 61 a BA = Basal area Table 2.9. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for Mediterranean studies. Code Species Location Tarragona, Spain Density (Trees/ha) BA (m2/ha) Author Lone trees - Bellot and Escarré (1998) 67 - 13.5 1792 25 12.7 1760 24.6 Ferreira (1992) 7.3 1664 17.3 Ferreira (1992) 14.2 1010 - Valente et al. (1997) Diam. (cm) 2.8 3.2 5.4 7.0 10.5 41.2 39.2 M01 Arbutus unedo M02 Castanea sativa M03 Eucalyptus globulus M04 Eucalyptus globulus M05 Eucalyptus globulus M06 Eucalyptus globulus M07 Eucalyptus macrorhyncha Canberra, Austalia 23 292 7.3 Crockford et al. (1996) M08 Eucalyptus mannifera Canberra, Austalia 23 433 10.8 Crockford et al. (1996) M09 Eucalyptus melliodora Canberra, Austalia 15 100 1.4 Crockford et al. (1996) M10 Eucalyptus nitens Collipulli, Chile - 1560 29.6 Huber and Iroumé (2001) M11 Eucalyptus nitens Collipulli, Chile - 850 19.5 Huber and Iroumé (2001) M12 Eucalyptus nitens Collipulli, Chile - 633 15.9 Huber and Iroumé (2001) M13 Eucalyptus rossii Canberra, Austalia 21 700 14.6 M14 Fagus moesiaca Pindous MTS, Greece - - - Crockford et al. (1996) Michopoulos et al. (2001) (Llorens and Domingo, 2007) Argemil, Tras-osMontes, Portugal Pousadas, Agueda basin, Portugal Cabeço Cão, Agueda basin, Portugal Serra de Cima, Agueda basin, Portugal Herdade da Espira, Portugal Portela and Pires (1995) (Llorens and Domingo, 2007) Ferreira (1992, 1996) (Llorens and Domingo, 2007) 62 M15 Fagus sylvatica Mont Lozère, Lozère, France 10.2 4270 52.2 Didon-Lescot (1996, 1998) (Llorens and Domingo, 2007) M16 Fagus sylvatica Toscana, Italy 28.5 28.5 - - Giacomin and Trucchi (1992) M17 Fagus sylvatica 24.3 889 41.2 M18 Fagus sylvatica 39.7 327 40.3 M19 Fagus sylvatica 10.3 4356 35.15 M20 Fagus sylvatica 36.2 345 35.46 M21 Fagus sylvatica Selva Piana, Abruzo, Italy Piano Nuda, Campanioa, Italy Brasimone, EmiliaRomagna, Italy Pian Cansiglio, Veneto, Italy Burgos-Logroño, Spain 4 - 20 526 - Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo Moreno et al. (2001) (Llorens and Domingo Moreno et al. (2001) (Llorens and Domingo Tarazona et al. (1996) M22 Fitzroya cupressoides Fraxinus ornus Quercus pubescentis Hueicolla, Chile Istrian Peninsula, Slovenia - 1100 58 Huber and Iroumé (2001) - 3100 - Šraj et al. (2008) M24 Holm-oak forest Tarragona, Spain - 9178 37.9 M25 Juniperus oxycedrus El Ardal, Murcia, Spain - Lone - M26 Laurel forest >6 1693 33.7 M27 Mixed broadleaved Agua Garcia Mountains, Tenerife Hueicolla, Chile - 530 99.6 Bellot and Escarré (1998); Bellot et al. (1999) Belmonte (1997); Belmonte and Romero (1998) (Llorens and Domingo, 2007) Aboal et al. (1999); Aboal et al. (2002) Huber and Iroumé (2001) M28 Mixed broadleaved Mariquina, Chile - 335 - Huber and Iroumé (2001) M29 Mixed broadleaved Malalcahuello, Chile - 367 47 M30 Nothofagus dombeyi Chile - - - M31 Nothofagus obliqua Nothofagus alpina Nothofagus dombeyi Nacimiento, Chile 37.6 43.4 26 26 26 3500 133 200 14.8 29.6 Huber and Iroumé (2001) Uyttendaele and Iroumé (2002) (Johnson and Lehmann, 2006) Huber and Iroumé (2001) Lone trees - M23 M32 M33 Olea europaea Malalcahuello, Chile Coraba, Spain Iroumé and Huber (2002) Gomez et al. (2002) 63 M34 Phyllirea media Tarragona, Spain 3.2 3.8 6.5 7.0 13.7 M35 Picea abies Lozère, France 27 395 22 M36 Pinus hapepensis El Ardal, Murcia, Spain - Lone - M37 Pinus nigra L. 23.1 25.7 1533 867 64.5 44.9 M38 Pinus pinaster M39 Pinus pinaster M40 Pinus pinaster M41 Pinus pinea M42 Lone trees - Bellot and Escarré (1998) Don Bruno, Sila Greca, Italy Barrosa, Agudea Basin, Portugal Bordeaux, France Herdade da Espira, Portugal Petit-Saint-Jean, Delta Rhone, France 32.1 400 32.8 9 - 15 800 - Didon-Lescot (1996); DidonLescot (1998) (Llorens and Domingo, 2007) Belmonte (1997); Belmonte and Romero (1998) (Llorens and Domingo, 2007) Iovino et al. (1998) (Llorens and Domingo, 2007) Ferreira (1992, 1996) (Llorens and Domingo, 2007) Loustau et al. (1992) 33.7 312 - Valente et al. (1997) - 800 - Pinus pinea Languedoc, France 20.2 800 33.9 M43 Pinus radiata Valdivia, Chile - 733 60 Ibrahim et al. (1982) (Llorens and Domingo, 2007) Rapp and Ibrahim (1978) (Llorens and Domingo, 2007) Huber and Iroumé (2001) M44 Pinus radiata Valdivia, Chile - 973 65.9 Huber and Iroumé (2001) M45 Pinus radiata Valdivia, Chile - 467 51.6 Huber and Iroumé (2001) M46 Pinus radiata Valdivia, Chile - 194 34.9 Huber and Iroumé (2001) M47 Pinus radiata Nacimiento, Chile - 2000 - Huber and Iroumé (2001) M48 Pinus radiata Nacimiento, Chile - 443 - Huber and Iroumé (2001) M49 Pinus radiata Collipulli, Chile - 460 19.5 Huber and Iroumé (2001) M50 Pinus radiata Collipulli, Chile - 220 12 Huber and Iroumé (2001) M51 Pinus radiata Collipulli, Chile - 833 13.4 Huber and Iroumé (2001) M52 Pinus radiata Collipulli, Chile - 395 6.8 Huber and Iroumé (2001) M53 Pinus radiata San Ignacio, Chile - 1206 27.1 Huber and Iroumé (2001) 64 M54 Pinus radiata San Ignacio, Chile - 549 13.7 Huber and Iroumé (2001) M55 Pinus radiata San Ignacio, Chile - 1143 22.1 Huber and Iroumé (2001) M56 Pinus radiata San Ignacio, Chile - 417 8.8 Huber and Iroumé (2001) M57 Pinus radiata Laja, Chile - 926 11 Huber and Iroumé (2001) M58 Pinus radiata Laja, Chile - 1087 16.5 Huber and Iroumé (2001) M59 Pinus radiata Canberra, Australia 18 1708 35.1 M60 Pinus radiata Chile - - - M61 Pinus sylvestris S.J. Pena, Aragón, Spain 18.6 1080 52.3 M62 Pinus sylvestris Mediterranean - 2400 39 Crockford et al. (1996) Uyttendaele and Iroumé (2002) (Johnson andLehmann, 2006) Alvera (1976) (Llorens and Domingo, 2007) Llorens (1997) (Llorens and Domingo, 2007) M63 Pinus sylvestris Sierra de la Demanda, Spain - 581 29.6 M64 Pinus sylvestris Salamanca, Spain 19.8 1700 - M65 Pinus sylvestris Burgos-Logroño, Spain 30 - 40 581 - M66 Pseudotsuga menziesii - 1143 97 M67 Quercus cerris 12.5 2131 25.9 M68 Quercus cerris 14.1 1623 25.3 M69 Quercus cerris Malalcahuello, Chile Carrega, EmigiaRomagna, Italy Monte Rufeno, Lazio, Italy Monteromano, Lazio, Italy - 2375 - 1.9 4.1 4.6 6.0 6.2 11.7 12.6 15.1 19.1 23.4 Lone trees - M70 Quercus ilex Tarragona, Spain Santa Regina and Tarazona (2001) Santa Regina (1995) (Llorens and Domingo, 2007) Tarazona et al. (1996) Huber and Iroumé (2001) Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Bellot and Escarré (1998) 65 M71 Quercus ilex Montpellier, France Colognole, Toscana, Italy La Castanya, Montseny Range, Spain St Pere Vilamajor, Montseny Range, Spain 4 - 12 6885 M72 Quercus ilex M73 Quercus ilex M74 Quercus ilex M75 12.7 2366 30.2 11.3 2127 26.5 Rodrigo and Avila (2001) 12 1753 22.3 Rodrigo and Avila (2001) Quercus ilex rotundifolia Évora, Portugal 0.5 ± 0.11 35 - 45 - David et al. (2006) M76 Quercus ilex rotundifolia Munovela, Salamanca, Spain 24.9 Lone - M77 Quercus ilex rotundifolia Guadalperón, Cáceres, Spain 25.5 Lone - M78 Quercus petraea Carrega, EmigiaRomagna, Italy 12.5 2131 25.9 M79 Quercus pubescens Settimo, Crati, Italy 2.2 3250 1.8 M80 Quercus pubescentis Carpinus orientalis croaticus Istrian Peninsula, Slovenia - 900 - M81 Quercus pyrenaica 15.2 820 14.9 M82 Quercus pyrenaica 25.4 406 20.6 M83 Quercus pyrenaica 16.5 738 15.8 M84 Quercus pyrenaica 11 1043 9.9 M85 Quercus suber Odemira, Portugal 15.8 - - M86 Rosmarinus officinalis El Ardal, Murcia, Spain - Lone - Navasfrias, Salamanca, Spain El Payo, Salamanca, Spain Fuenteginaldo, Salamanca, Spain Villasrubias, Salamanca, Spain Limousin et al. (2008) Moreno et al. (2001) (Llorens and Domingo, 2007) Calabuig et al. (1978) (Llorens and Domingo, 2007) Mateos (2001); Mateos and Schnabel (1998) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Iovino et al. (1998) (Llorens and Domingo, 2007) Šraj et al. (2008) Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Moreno et al. (2001) (Llorens and Domingo, 2007) Pereira de Almeida and Riekerk (1990) Belmonte (1997); Belmonte and Romero (1998) (Llorens and Domingo, 2007) 66 M87 El Ardal, Murcia, Spain Thymus vulgaris - Lone - Belmonte (1997); Belmonte and Romero (1998) (Llorens and Domingo, 2007) Table 2.10. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for Mediterranean studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) M01 Arbutus unedo 570 1296.26 3.8 72.3 at 23 mmcalc 79.9 at 29 mmcalc 137.9 at 17 mmcalc M02 Castanea sativa 1133 2490 0.2 - SF (L) = 0.096P (mm) + 0.060 SF (L) = 0.072P (mm) - 0.318 SF (L) = 0.234P (mm) - 1.480 SF (L) = 0.625P (mm) - 1.603 SF (L) = 0.425P (mm) + 2.276 - M03 Eucalyptus globulus 1600 156.8 2.9 11.6calc - M04 Eucalyptus globulus 1600 223.4 2.9 11.8calc - calc - M05 Eucalyptus globulus 1600 335.7 2.9 16.8 M06 Eucalyptus globulus Eucalyptus macrorhyncha Eucalyptus mannifera 600 1545.80 1.7 - - 679 805 0.3calc 4 - 805 1.1 calc 10.6 - calc 18.6 - M07 M08 679 M09 Eucalyptus melliodora 679 805 0.2 M10 Eucalyptus nitens 1540 1996/97: 1039 1997/98: 1858 1998/99: 734 4 4 4 13.5calc SF (mm) = 0.014P (mm) + 20.65 M11 Eucalyptus nitens 1540 1996/97: 1039 1997/98: 1858 1998/99: 735 3 3 3 15.4calc SF (mm) = 0.014P (mm) + 20.65 M12 Eucalyptus nitens 1540 1996/97: 1039 2.0 12.6calc SF (mm) = 0.014P (mm) + 20.65 67 M13 Eucalyptus rossii 679 805 3.1calc 21 - M14 Fagus moesiaca - - 8.0 - - M15 Fagus sylvatica 1900 1537.5 M16 Fagus sylvatica 2027 - M17 Fagus sylvatica 1300 - M18 Fagus sylvatica 1500 1552.5 20.4 13.8 15.0 4.1 1.1 39.1 calc - - - - - 2.7 calc - calc - M19 Fagus sylvatica 1800 1139 6.4 18.2 M20 Fagus sylvatica 1900 - Fagus sylvatica 895 2.0 6.0 5.6 8.3 5.6calc M21 1366.5 1986: 812.8 1987: 1669.8 1988: 1911 - - M22 Fitzroya cupressoides 3500 1982/83: 4603 9.0 15.5calc - M23 Fraxinus ornus Quercus pubescentis 1000 1300 1318 4.5 ± 0.8 - - M24 Holm-oak forest 570 1296.26 12.1 M25 Juniperus oxycedrus 228 89.7 22.0 M26 Laurel forest 733 626 6.9 M27 Mixed broadleaved 2500 1982/83: 3563 4.0 4.0calc SF (mm) = 0.014P (mm) + 20.65 2 1 1 7 1 1 1 1 - SF (mm) = 0.014P (mm) + 20.65 8.0 17.0calc SF (mm) = 0.014P (mm) + 20.65 M28 Mixed broadleaved 2400 1986: 2973 1987: 2268 1988: 1538 1989: 1643 1990: 2287 1991: 2355 1993/94: 2690 1994/95: 2066 M29 Mixed broadleaved 2350 1998/99: 1347 30.4 at 16 mmcalc 31.9calc 19.2 at 11 mmcalc 20.5calc SF (mm) = 0.133P (mm) - 0.285 SF (mm) = 0.0719P (mm) – 0.0805 68 M30 Nothofagus dombeyi 1982 - 2.0 - M31 Nothofagus obliqua 1200 1991/92: 1973 3.0 - M32 Nothofagus alpina Nothofagus dombeyi SF (mm) = 0.014P (mm) + 20.65 calc 2341 3805 7.0 16.0 at 19 mm 15.8calc 51 85 60 77.6 at 39 mmcalc 117.1 at 33 mmcalc 118.1 at 9 mmcalc 47.9 at 30 mmcalc 19.9 at 22 mmcalc 3.2calc SF (mm) = 0.0509P (mm) - 0.1814calc SF (mm) = 0.1055P (mm) - 0.3962calc SF (mm) = 0.0606P (mm) - 0.1012calc SF (L) = 0.087P (mm) - 0.958 SF (L) = 0.175P (mm) - 1.393 SF (L) = 0.428P (mm) - 0.324 SF (L) = 0.239P (mm) - 1.643 SF (L) = 0.361P (mm) - 1.477 - - - - - 3.4calc - - - - - SF (mm) = 0.085P (mm) - 0.263 M33 Olea europaea 606 180.17 3.9 7.9 5.4 M34 Phyllirea media 570 1296.26 1.6 M35 Picea abies 1900 1537.5 0.7 M36 Pinus hapepensis 228 217.8 M37 Pinus nigra L. 1179 M38 Pinus pinaster 1600 M39 Pinus pinaster 920 M40 Pinus pinaster 600 990.1 1987: 139.4 1988: 97.5 1988: 190.3 1989: 82.5 1366.20 1.7 0.7 0.8 1.1 3.4 4.9 2.7 4.2 0.3 M41 Pinus pinea 494 - 2.3 - - 769 1982: 2389 1983: 1628 1984: 2059 1985: 2295 1986: 2341 1987: 1841 2.3 13 12 12 11 10 9 calc 6.8 21.7calc 20.0calc 20.0calc 18.3calc 16.8calc 15.0calc - 1992/93: 2925 1993/94: 2075 10 9 15.2calc 13.7calc M42 Pinus pinea 648 M43 Pinus radiata 2150 M44 Pinus radiata 2150 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 69 M45 Pinus radiata 2150 1992/93: 2925 1993/94: 2075 1994/95: 2394 1996/97: 2574 1997/98: 1676 1992/93: 2925 1993/94: 2075 1994/95: 2394 1996/97: 2574 1997/98: 1676 8 8 8 8 8 6 5 5 5 6 15.5calc SF (mm) = 0.106P (mm) - 72.29 17.2calc 14.3calc 14.3calc 14.3calc 17.2calc SF (mm) = 0.106P (mm) - 72.29 M46 Pinus radiata 2150 M47 Pinus radiata 1200 1991/92: 1971 5.0 - SF (mm) = 0.106P (mm) - 72.29 M48 Pinus radiata 1200 1991/92: 1972 3.0 - SF (mm) = 0.106P (mm) - 72.29 M49 Pinus radiata 1540 SF (mm) = 0.106P (mm) - 72.29 Pinus radiata 1540 8.3calc 16.7calc SF (mm) = 0.106P (mm) - 72.29 M51 Pinus radiata 1540 14.9calc SF (mm) = 0.106P (mm) - 72.29 M52 M53 M54 M55 M56 M57 M58 M59 Pinus radiata Pinus radiata Pinus radiata Pinus radiata Pinus radiata Pinus radiata Pinus radiata Pinus radiata 1540 1000 1000 1000 1000 1000 1000 679 3 3 1 2 2 2 2 1.0 5.0 4.0 6.0 2.0 1.0 3.0 11.2calc 15.4calc M50 1996/97: 1039 1997/98: 1858 1996/97: 1039 1997/98: 1858 1996/97: 1039 1997/98: 1858 1998/99: 734 1996/97: 1039 1998/99: 1005 1998/99: 1005 1998/99: 1005 1998/99: 1005 1998/99: 1038 1998/99: 1038 824 14.7calc 18.5calc 29.2calc 27.1calc 22.7calc 9.1calc 18.2calc 32 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 SF (mm) = 0.106P (mm) - 72.29 - M60 Pinus radiate 1982 - 22.0 - - M61 Pinus sylvestris 931 858 0.8 - - M62 Pinus sylvestris 850 - 1.3 - - calc - M63 Pinus sylvestris 886 1254 0.5 1.7 M64 Pinus sylvestris 985 1021 10.8 - 70 M65 Pinus sylvestris 895 1986: 600.7 1987: 1281.4 1988: 1678.7 0.35 0.5 0.4 - M66 Pseudotsuga menziesii 2350 1998/99: 1346 6.0 6.2calc 3.1 12.0 calc - calc - M67 Quercus cerris 1200 748 SF (mm) = 0.106P (mm) - 72.29 M68 Quercus cerris 1000 991.5 10.4 41.1 M69 Quercus cerris - - 6.3 M70 Quercus ilex 570 1296.3 6.6 M71 Quercus ilex 908 1605 12.5 62.8 at 35 mmcalc 60.9 37.9 at 34 mmcalc 32.0 46.8 at 36 mmcalc 44.8 34.0 129.6 at 9 mmcalc 137.0 20.7 at 24 mmcalc 21.6 21.5 at 29 mmcalc 21.8 27.9 at 25 mmcalc 29.0 16.4 at 29 mmcalc 16.7 26.2 at 25 mmcalc 27.2 - SF (L) = 0.024P (mm) - 0.217 SF (L) = 0.072P (mm) - 0.944 SF (L) = 0.106P (mm) - 1.015 SF (L) = 0.069P (mm) + 0.899 SF (L) = 0.430P (mm) - 0.349 SF (L) = 0.273P (mm) - 1.218 SF (L) = 0.347P (mm) - 2.305 SF (L) = 0.619P (mm) - 2.977 SF (L) = 0.603P (mm) - 3.825 SF (L) = 1.393P (mm) - 6.703 SF (mm) = 0.16P (mm) - 0.98 M72 Quercus ilex 900 861.5 3.4 11.3calc - calc - M73 Quercus ilex 876 1275.2 2.7 10.2 M74 Quercus ilex 876 1048.2 5.3 23.8calc - M75 Quercus ilex rotundifolia 665 1736.4 0.3 - - M76 Quercus ilex rotundifolia 432 - 0.6 - - M77 Quercus ilex rotundifolia 516 755 0.7 - - M78 Quercus petraea 1200 748 4.7 18.1calc - M79 Quercus pubescens Quercus pubescentis Carpinus orientalis croaticus Quercus pyrenaica 1021 1000 1300 1580 - 0.3 - - 1318 2.9 ± 0.6 - - 1056.7 0.9 6.0calc - M80 M81 71 M82 M83 Quercus pyrenaica Quercus pyrenaica 1245 720 933.3 0.64 3.1calc - 0.8 5.1 calc - calc - 624.7 M84 Quercus pyrenaica 872 825 0.6 6.1 M85 Quercus suber - - 1.3 - - M86 Rosmarinus officinalis 228 181.3 42.5 - - M87 Thymus vulgaris 228 181.3 31.2 - - Table 2.11. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for arid and semi-arid studies. Code Species Location Diam. (cm) Density (Trees/ha) BA (m2/ha) Author S01 Acacia aneura South-Western Queensland, Australia - - - Pressland (1973) S02 Acacia farnesiana Nuevo Leon, Mexico 12.75 Lone shrubs - Návar (1993); Návar and Bryan (1990) S03 Acacia rigidula Adenocarpus decorticans Nuevo Leon, Mexico - - - Filabres, Almeria, Spain 12.4 Lone - Almería, Spain - Lone - Návar et al. (1999) Domingo et al. (1994); Llorens and Domingo (2007) Domingo et al. (1998); Llorens and Domingo (2007) S04 S05 Anthyllis cytisoides Mu Us, China - - - Yang et al. (2008) S07 Artemisia sphaerocephala Bumelia celastrina Nuevo Leon, Mexico - - - Návar et al. (1999) S08 Caragana korshinskii Gaolan, China - - - S09 Cistus laurifolius Filabres, Almeria, Spain 8.3 Lone - S10 Condalia hookeri Nuevo Leon, Mexico - - - Li et al. (2008) Domingo et al. (1994); Llorens and Domingo (2007) Návar et al. (1999) S11 Cordia boissieri Nuevo Leon, Mexico - - - Návar et al. (1999) S12 Diospyros palmeri Nuevo Leon, Mexico - - - Návar et al. (1999) S06 72 S13 Diospyros texana Nuevo Leon, Mexico 9.22 Lone shrubs - Návar (1993); Návar and Bryan (1990) S14 Ficus benjamina Queretaro City, Mexico 22.4 Lone - Guevara-Escobar et al. (2007) S15 Flourensia cernua New Mexico, USA - - - Martínez-Meza and Whitford (1996) S16 Grevillea robusta Machakos, Kenya - - - Jackson (2000) S17 Hedysarum scoparium Shaanxi, China - - - Li et al. (2009) S18 Larrea divaricata Viedma, Argentina - - - Cecchi et al. (2006) S19 Larrea tridentata Las Cruces, New Mexico - - - Abrahams et al. (2003) S20 Larrea tridentata New Mexico, USA - - - Martínez-Meza and Whitford (1996) S21 Larrea tridentata - Lone shrubs - Whitford et al. (1997) S22 Matorral community - - 16.2 Carlyle-Moses (2004) S23 Pinus halepensis Las Cruces, New Mexico Santa Rosa de Iturbide, Mexico Yatir forest, Israel - 360 - S24 Pinus nigra Filabres, Almeria, Spain 5.8 Lone - S25 Pinus pinaster Filabres, Almeria, Spain 12.8 - - S26 Pithecellobium pallens Nuevo Leon, Mexico - - - Shachnovich et al. (2008) Domingo et al. (1994); Llorens and Domingo (2007) Domingo et al. (1994); Llorens and Domingo (2007) Návar et al. (1999) S27 Prosopis glandulosa New Mexico, USA - - - Martínez-Meza and Whitford (1996) S28 Prosopis laevigata Nuevo Leon, Mexico 10.6 Lone shrubs - Návar (1993); Návar and Bryan (1990) S29 Prosopis laevigata Nuevo Leon, Mexico - - - Návar et al. (1999) S30 Quercus emoryi Arizona, USA 11.7 - 45.9 - - Haworth and McPherson (1995) S31 Reaumuria soongorica Gaolan, China - - - S32 Retama sphaerocarpa Almería, Spain 1.7 Lone - S33 Salix psammophila Shaanxi, China - - - Li et al. (2008) Domingo et al. (1994); Llorens and Domingo (2007) Li et al. (2009) S34 Salix psammophila Mu Us, China - - - Yang et al. (2008) S35 Tamarix ramosissima Gaolan, China - - - Li et al. (2008) 73 S36 S37 Tamaulipan thornscrub Zanthoxylum fragara Nuevo Leon, Mexico 2.3 - 3.9 - - Návar et al. (1999) Nuevo Leon, Mexico - - - Návar et al. (1999) Table 2.12. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for arid and semi-arid studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) S01 Acacia aneura - 618.55 18.0 - S02 Acacia farnesiana - 230 0.6 11.7 BA(0-0.01): SF = 1.446P - 0.026P2 - 2.235 BA(0.01-0.03): SF = 2.198P + 0.191 BA(0.03-0.065): SF = 6.047P - 6.842 BA(>0.065): SF = 8.085P - 5.128 P(0-6.25): SF = 0.026BA + 1.631 P(6.25-12.5): SF = 0.076BA + 7.751 P(12.5-25): SF = 0.162BA + 0.369 P(>25): SF = 0.280BA + 13.810 Units: P (mm) SF (L) BA (cm2) - S03 Acacia rigidula Adenocarpus decorticans Anthyllis cytisoides Artemisia sphaerocephala Bumelia celastrina 805 489.1 - - SF (mm) = 0.038P (mm) - 0.085 395 650 4.4 - - 300 - 20.0 - - 395 173 2.7 41.5 SF (mm) = 0.024P (mm) + 0.015 805 489.1 - - SF (mm) = 0.014P(mm) - 0.019 S04 S05 S06 S07 S08 Caragana korshinskii 263 - 7.2 153.5 ± 66.2 Event high: 292 SF (mm) = 0.079P (mm) - 0.028 SF (mm) = 0.107P (mm) - 0.036I (mm/h) - 0.056 S09 Cistus laurifolius 395 650 7.2 - - 74 S10 Condalia hookeri 805 489.1 - - SF (mm) = 0.013P (mm) - 0.040 S11 Cordia boissieri 805 489.1 - - SF (mm) = 0.027P (mm) - 0.066 S12 Diospyros palmeri 805 489.1 - - SF (mm) = 0.034P (mm) - 0.080 S13 Diospyros texana - 230 5.6 - S14 Ficus benjamina 548 152 2.4 57.7 16.8 at 5 mmcalc 17.2calc S15 Flourensia cernua 230 - Summer: 10.6 Winter: 10.5 S16 Grevillea robusta Hedysarum scoparium 782 1583.00 0.7 395 - 3.4 S18 Larrea divaricata 350 - Disturbed: 3.6 Intact: 7.2 - S19 Larrea tridentata 245 - 6.7 - SF = 0.0361P - 0.1512 SF = 0.0722P - 0.3483 All units in mm SF (cm/h) = 0.16A (cm2) P (cm/h) S20 Larrea tridentata 230 - 10 - SF (L) = 17·0 + 20·5V (m3)b S21 Larrea tridentata Matorral community 235 635 ± 145 - 16.8 ± 1.9 - - 8.5 ± 1.9 21.1 SF = [21.13(P x BA)]nstemc Units: SF (L) P (mm) BA (m2) S23 Pinus halepensis 280 2000/01: 306 2001/02: 307 2002/03: 341.5 2.1 1.4 1.5 - SF (mm) = 0.02P (mm) - 0.06 S24 Pinus nigra Ar. 395 650 12.3 - - S25 395 650 1.5 - - 805 489.1 - - SF (mm) = 0.037P (mm) - 0.068 SF (L) = 10·3A (m2) + 7.6 230 Summer: 5.4 Winter: 5.3 0.6 - S28 Pinus pinaster Pithecellobium pallens Prosopis glandulosa Prosopis laevigata 11.1 - S29 Prosopis laevigata 805 489.1 - - SF (mm) = 0.005P (mm) - 0.012 S17 S22 S26 S27 230 SF (mm) = 0.0248P (mm) – 0.007calc - SF (L) = 3·9A (m2) + 4.8a 77.8 Event high: 203 SF (mm) = 0.034P (mm) - 0.046 75 S30 Quercus emoryi 600 - - - ln(SF) = 8.65 + 0.036(A) - 11e-1.36(P) Units: SF(ml) CA(m2) P(mm) S31 Reaumuria soongorica 263 - 3.7 53.2 ± 25.7 Event high: 97 SF (mm) = 0.065P (mm) - 0.13 SF (mm) = -0.103 + 0.066P (mm) - 0.019I (mm/h) 300 - 7.0 - - 395 - 6.3 48.7 Event high: 117 SF (mm) = 0.063P (mm) - 0.139 395 173 7.6 69.4 SF (mm) = 0.057P (mm) + 0.136 263 - 2.2 24.8 ± 15.3 Event high: 54 SF (mm) = 0.039P (mm) - 0.083 SF (mm) = 0.041P (mm) - 0.001I (mm/h) - 0.070 805 489.1 3.0 ± 1.9 - - 805 489.1 - - SF (mm) = 0.007P (mm) - 0.012 S32 S33 S34 S35 Retama sphaerocarpa Salix psammophila Salix psammophila Tamarix ramosissima Tamaulipan thornscrub Zanthoxylum S37 fragara a A = Canopy area S36 b V = Canopy volume c nstems = Number of stems Table 2.13. Species, location, stand information (diameter: Diam, tree density: Density, stand basal area: BA), author(s), and alphanumeric code for agroforestry studies. Density (Trees/ha) BA (m2/ha) Author 8.6 23.7 26.5 Dietz et al. (2006) 16.5 <8 1706 2705 2612 625 1875 - 2500 - Code Species Location Diam. (cm) A01 Agroforest Central Sulawesi, Indonesia - A02 Bactris gasipaes Manaus, Brazil A03 Bactris gasipaes Manaus, Brazil - Schroth et al. (1999); Schroth et al. (2001) Schroth et al. (1999); Schroth et al. (2001) 76 Schroth et al. (1999); Schroth et al. (2001) Schroth et al. (1999); Schroth et al. (2001) Opakunle (1989) (Levia and Frost, 2003) A04 Bertholletia excelsa Manaus, Brazil 8.4 93 - A05 Bixa orellana Manaus, Brazil - 156 - A06 Cacao plantation - - - - A07 Manihot esculenta Zea mays Oryza sativa West Java, Indonesia - - - van Dijk et al. (2001) A08 Musa sp. - - - Cattan et al. (2007) A09 Musa sp. Capesterre-BelleEau, Guadeloupe Roseau, St Lucia - - Harris (1997) A10 Phyllostachys pubescens Munakata, Japan 12.4 13.4 13.7 6800 - Onozawa et al. (2009) A11 Theobroma grandiflorum Manaus, Brazil 5.5 93 - Schroth et al. (1999); Schroth et al. (2001) A12 Zea mays Grevillea robusta Machakos, Kenya - - - Jackson (2000) Table 2.14. Species, meteorological data (annual rainfall: PA, and study period rainfall: PS), stemflow production information (funnelling ratio(s): F, and percentage of gross rainfall diverted to stemflow: SF), and stemflow formulae for agroforestry studies. Code Species PA (mm) PS (mm) SF (%) F Formula(s) calc 2622 293 172 214 2672 0.7 0.9 1.0 24.7 8.1 3.8calc 3.8calc - SF (L/mm) = 5.32 - 0.224 DBH (cm) Bactris gasipaes 2622 2672 20.6 - SF (L/mm) = 0.114DBH (cm) - 0.09 Bertholletia excelsa 2622 2672 0.8 - SF (L/mm) = 0.303DBH (cm) - 2.59 A01 Agroforest 2437 3424 A02 Bactris gasipaes A03 A04 - 77 A05 Bixa orellana 2622 2672 0.1 - - A06 Cacao plantation Manihot esculenta Zea mays Oryza sativa - - 2.0 - - 2600 1995: 1577 1999: 1642 2.4 3.9 - SF (L/m2)= 0.054TF (mm)a A07 A08 Musa sp. 3850 Vegetative: 164 Flowering: 158 Bunch: 151 25.6 24.1 17.9 Ve: 20 Fl: 28 Bu: 28 F = 11.2LAIb c A09 Musa sp. - - 10.0 13 - A10 Phyllostachys pubescens 1697 2105 15.3 - - A11 Theobroma grandiflorum 2622 2672 0.1 - - 782 1583.00 0.6 - - Zea mays Grevillea robusta a TF = Throughfall A12 b F = Funnelling ratio c LAI = Leaf area index 78 CHAPTER 3 MODELLING STEMFLOW PRODUCTION BY JUVENILE LODGEPOLE PINE (PINUS CONTORTA VAR. LATIFOLIA) TREES IN SOUTHERN BRITISH COLUMBIA, CANADA INTRODUCTION Stemflow is rainfall that has been intercepted by vegetation cover and subsequently directed down the stem or trunk of the plant or tree to its base. The ability of vegetation to produce stemflow can be described quantitatively using the stemflow funnelling ratio (Herwitz, 1986), which represents the ratio between the stemflow volume collected at the base of the plant’s stem or tree’s bole to the volume of rainfall that would have been collected by a rain gauge having an area equal to that of the base of the plant stem / tree bole in the absence of vegetation cover. The stemflow funnelling ratio is calculated as (Herwitz, 1986): F= SF/(Pg ∙BA) (3.1) where F is the funnelling ratio (dimensionless), SF is stemflow volume (L), Pg is rainfall depth (mm), and BA is the basal area of the plant’s stem or tree’s bole (m2). Stemflow has received relatively little attention in the hydrologic literature due to its volumetric insignificance at the plot-scale and beyond when compared to throughfall and canopy interception loss (Levia and Frost, 2003). However, stemflow may still be of hydrological and biogeochemical importance since it is a focused point source of water at the base of a plant or tree (Herwitz, 1986; Levia and Frost, 2003). The importance of stemflow as a source of soil moisture has been highlighted by a number of studies (Voigt, 1960; Tanaka et al., 1996; Taniguchi et al., 1996; Whitford et al., 1997). Taniguchi et al. (1996) found that 20 % of groundwater recharge within a red pine forest in Japan originated as stemflow, while in a rainforest in Queensland, Australia, Herwitz (1986) showed that large concentrations of stemflow can exceed the infiltration capacity of soil and result in Hortonian overland flow subsequently causing erosion. Stemflow has also been found to be a concentrated source of nutrients and, in some cases, pollutants 79 (Brinson et al., 1980; Chang and Matzner, 2000; Schroth et al., 2001; Johnson and Lehmann, 2006). Only two studies have examined stemflow production by tree species in the Interior of British Columbia, with both of these studies being conducted within mature coniferous stands. Spittlehouse (1998) reported a stemflow fraction of < 0.5 % of a 454 mm May – October study period rainfall record for both a mature Pinus contorta var. latifolia (lodgepole pine) stand, and a mature Picea glauca x engelmannii (hybrid white spruce) - Abies lasiocarpa (subalpine fir) forest, while Moore et al. (2008) reported that stemflow comprised 0.2 % of the rainfall over two growing seasons within a mature lodgepole pine – hybrid white spruce – subalpine fir stand. The results of these studies suggest that stemflow is a minor component of the canopy water balances of mature coniferous forests in the Interior of British Columbia. British Columbia is currently undergoing a Dendroctonus ponderosae (mountain pine beetle – MPB) epidemic which has been forecast to kill ~ 77 % of all merchantable pine in the province by 2014 (Walton et al., 2007). In addition, the frequency of wildfires in British Columbia is projected to increase as a consequence of global climatic change (BC Ministry of Water, Land and Air Protection, 2004). Due to these disturbances, many of the province’s interior watersheds will see a shift in land-cover dominated by mature conifers to stands at various stages of juvenile re-growth. This shift in stand composition brings with it many uncertainties, including the impacts on site hydrology. One aspect of the forest water balance that may be altered is the quantitative importance of stemflow. McKee and Carlyle-Moses (2010) found that juvenile lodgepole pine trees produced more stemflow compared to mature trees; however, no studies to date have examined factors influencing stemflow production from juvenile lodgepole pine. Despite studies that have highlighted the influence of a multitude of variables on stemflow production (Levia and Frost, 2003), the majority of stemflow simulation models produced to date only utilize one independent variable, normally rainfall depth or plant / tree diameter. However, other variables have also been shown to exert a control on the quantity of stemflow produced, including, branching angle (Herwitz, 1987; Návar, 80 1993; Martínez-Meza and Whitford, 1996), number of branches (Návar, 1993), tree height (Brown and Baker, 1970), storm duration and intensity (Brown and Baker, 1970; Crockford and Richardson, 2000), crown projection area (Brown and Baker, 1970; Pressland 1973; Aboal et al., 1999; Park and Hattori, 2001), and bark roughness (Horton, 1919; Aboal et al., 1999). Logistically, it would be difficult to collect sufficient data to include all of the potential factors influencing stemflow production; however, the inclusion of more than one predictive variable would lead to more accurate modelling (Levia and Frost, 2003) and improve our understanding of how tree architecture and meteorological conditions influence stemflow production. The objective of this research was threefold: (1) to identify the abiotic and biotic factors that influence stemflow production by lodgepole pine, (2) to incorporate the most influential of these factors into a predictive model of stemflow yield from this forest type, and (3) to evaluate the spatial transferability of the developed model. MATERIALS AND METHODS Site description Measurements of incident rainfall and stemflow were made from 1 June, 2009 to 31 October, 2009 at the Mayson Lake Hydrological Processes Study Area (MLk) located approximately 60 km NNW of Kamloops, British Columbia on the Thompson-Bonaparte Plateau at 51o 13’ N, 120o 24’ W. The MLk, located at an elevation of ~1260 m a.m.s.l., is situated within the Montane Spruce Biogeoclimatic Zone (MSdm2), a zone typified by cold winters and moderately short, warm summers (Lloyd et al., 1990). The nearest longterm meteorological station with a comparable elevation to the study site, 1155 m a.m.s.l, is Bridge Lake 2 (Meteorological Service of Canada Climate Station ID = 1160986). This station, located approximately 41 km NNW of the study area, has a mean annual rainfall depth of approximately 600 mm (1980 – 2000) with approximately half falling during the growing-season (mid-May to September, inclusive) in the form of rain. Snow is the dominant form of precipitation during the dormant season. Mean annual temperature at 81 the Bridge Lake 2 station is 3.7 oC with mean monthly values ranging from -7.8 oC in December to 14.2 oC in July and August. Data were largely collected from two plots situated within juvenile lodgepole pine dominated stands. These two juvenile stands, designated Plots E and D (Figures 3.1 and 3.2, respectively), were replanted after commercial harvesting. Detailed tree and stand characteristics for Plots E and D can be found in Table 3.1. Stemflow was also measured in three additional plots: Plot A – a mature pine-spruce-fir stand of ~ 125 years of age with most pine at the MPB grey attack stage, Plot B – a pine dominated stand of ~ 27 years of age at the red / grey MPB attack stage, and Plot C – a stand of ~ 16 years of age largely comprised of healthy pine, although a few individuals were at the green or red MPB attack stage. Plots A, B, C, and E measured 72 m by 40 m in size, while Plot D measured 160 m by 24 m. Table 3.1. Stand characteristics for Plots E and D. Stand Age (yrs) Avg. Tree Diameter (cm) Avg. Tree Height (m) Avg. Tree CPA (m2) Tree density (trees ha-1) BA (m2 ha-1) Avg. Number of branches per tree Pine Composition (%) Subalpine Fir Relative Dominance of Pine (%) Plot E ~7 2.7 1.42 0.43 8476 Plot D ~9 3.5 2.01 0.63 7974 7.4 23 86 14 94 10.9 32 79 21 89 Meteorological data The meteorological station used for this study was situated in the centre of Plot E and was equipped with an Onset® Wind Speed and Direction Smart Sensor (product # SWCA-M003) and an Onset® Temperature / Relative Humidity Smart Sensor (product # S-THA-M002). Measurements of wind speed, temperature and relative humidity were taken 2 m above the principal tree canopy on a 30 second time-step and averaged and 82 Figure 3.1. View of Plot E from the northwest corner of the plot. Figure 3.2. View of Plot D from the centre looking south. 83 logged on 10 minute time-step using a Hobo® Micro Station data logger (product # H21002). Rainfall depth and intensity measurements were taken in locations closest to each plot that allowed for unobstructed measurement. At each location rainfall was measured using an Onset ® Data Logging Rain Gauge (product # RG-3-M) with an orifice diameter of 15.4 cm and a resolution of 0.2 mm tip-1 as well as a cylindrical polyethylene gauge having a diameter of 29.0 cm in which the volume of collected rainfall was measured using a graduated cylinder. Rainfall measurements for Plots A, B, and C were taken in a fire break located ~ 630 m from the geographic centre of Plot A and ~ 560 and 310 m from the centres of Plots B and C, respectively. Rainfall measurements for Plots D and E were taken with both an Onset® rain gauge and a cylindrical polyethylene gauge situated in clearings no further than ~ 90 m from the centres of each of the two plots. A rain event was defined for this study as a period of rainfall bounded by periods of eight hours with no measurable rainfall, as this was the observed maximum time required for the juvenile pine canopies and boles to dry completely. Stemflow collection Stemflow was sampled from lodgepole pine trees only. Plots A, B, and C contained seven, seven, and five stemflow collection systems, respectively. Stemflow in these three plots was collected using stemflow collars constructed from 2.5 cm diameter corrugated flexible tubing that was cut in half lengthwise, then wrapped 360o around the tree on a downward angle and secured with nails and silicone sealant (Levia, 2004). An uncut piece of corrugated tubing running from the stemflow collar diverted the intercepted stemflow to a collection container at the base of the tree. Stemflow collection containers in these three plots ranged in capacity from 4 to 20 L depending on the expected stemflow production of each tree. Stemflow in Plots D and E was sampled more intensely than the other plots because previous research showed that juvenile lodgepole pine trees were more efficient stemflow producers when compared to mature pine trees (McKee and Carlyle-Moses, 2010). Thirty-six and thirty-seven trees were sampled for stemflow in plots D and E, 84 respectively. Twelve relatively small, 12 medium, and 12 large trees were sampled in Plot D in order to achieve a representative sample. The same sampling method was used in Plot E with the addition of one medium tree. Adjacent to Plot E, one small, one medium, and one large tree had their branches and trunk needles removed. Stemflow collars were attached to these trees in an attempt to further understand the influence of abiotic factors by eliminating tree architecture completely. Sample trees were located outside of Plot E on the northeast edge to insure that experiments inside the plot were not influenced by anthropogenic damage to these trees. Each stemflow collar in these two plots was constructed using fabricated plastic funnels that were cut vertically, then wrapped and sealed to the tree near the base of the bole using silicone sealant (Figure 3.3). A plastic tube with a diameter of ~ 1.0 cm connected the inner portion of the stemflow collar to a 4 L collection container for subsequent measurement. All stemflow collars in the five plots were tested weekly to determine if any leakage may have occurred due to tree growth and/or animal disturbance. If a stemflow collar had a leak it was noted and promptly repaired and any data collected since the prior test was discarded. Collected stemflow was measured after each rainfall event using a graduated cylinder. Figure 3.3. Stemflow collar and collection container used in Plots E and D. 85 Tree characteristics Stand level characteristics were recorded along with individual tree characteristics for trees associated with stemflow collection. The point-quarter method (Mueller et al., 1974) was used to determine tree density, species frequency, and basal area information required to determine stand scale stemflow production for Plots D and E. In order to relate stemflow production to tree architecture, tree characteristics were recorded for each plot. In Plots A, B, and C, tree diameter and height were recorded for all trees being sampled for stemflow. As the focus of this research was on juvenile trees, more detailed tree characteristics were recorded in Plots D and E. In these two plots, tree height, number of branches, canopy width, branching angle, and tree diameter (at the base just under the first branch) were recorded for each tree sampled for stemflow. North, south, east, and west facing branches were selected at the base and top of the tree, as well as at one-third and two-thirds the tree height. Branching angle where the branch met the tree bole was recorded for each of these branches, measured from the horizontal yielding a positive or negative angle. Canopy width was also derived for the four sampled levels for each tree by taking the average horizontal distance from the outermost extent of the branch projecting in a northerly direction to that projecting in a southerly direction and the outermost extent of the easterly branch to that of the branch extending westward. A proximity metric was developed for Plots D and E to determine if sheltering by neighbouring trees had an influence on stemflow production. All trees whose canopies extended to within a 45o cone of the base of a stemflow tree were recorded. The distance of each of the neighbouring trees from the tree sampled for stemflow, as well as the height of those trees, were recorded. The proximity statistic was then calculated for each stemflow tree as: ̅ /𝐷 ̅ 𝑀 = 𝑛 ∙𝐻 (3.2) where M is the proximity metric (dimensionless), n is the number of trees whose heights’ extended to within a 45o cone centred on the base of the tree sampled for stemflow, while ̅ and 𝐷 ̅ are the average height (m) and average horizontal distance (m) from the tree 𝐻 sampled for stemflow of the n trees. 86 Statistical analysis Statistical analysis and modelling was performed using Microsoft® Office Excel 2010 (Microsoft Corporation, Redmond, WA, USA) spreadsheet application and Minitab® 15 (Minitab Inc., State College, PA, USA) statistical software. Excel 2010 was used for data organization and graphing, while Minitab 15 was used to perform stepwise multiple regression analysis. Levels of statistical significance reported in this study were at the p < 0.05 level. Modelling procedure Park and Hattori (2002) suggested that the slope, a, and the intercept, b, associated with the linear relationship between stemflow depth (mm) and rainfall depth (mm) [i.e., Stemflow = a · Rainfall + b] for a single tree or an entire stand may be related to the tree / stand diameter at breast height (DBH) in the form of power relationships: a = A(DBH)β1 (3.3) b = B(DBH)β2 (3.4) where A, B, β1, and β2 are regression coefficients, while DBH is diameter at breast height. In contrast to Park and Hattori (2002), the slope (a) and intercept (b) values in this study were compared against a number of different abiotic and biotic factors to determine which factor(s) had a statistically significant influence on stemflow production. Biotic factors were analysed on the event basis and abiotic factors were analysed on a per tree basis. The analysis was conducted in this manner because a multiple regression could not be conducted with all independent variables versus stemflow volume due to some variables changing from tree to tree, while others only changed from event to event. This resulted in linear equations replacing Eqs. 3.3 and 3.4 containing one or more variables. Regression between event rainfall depth (mm) and associated stemflow volume (L) was conducted for each tree in order to produce a and b values. Stepwise multiple regression was then conducted to determine which variables explained variations in a and b for Plot E and for Plot D. The candidate biotic predictor variables were: total number of branches, 87 tree height (m), tree diameter (cm), the proximity metric (dimensionless), canopy width (m) and branching angle (o), at the top, two-thirds of the height, one-third of the height, and at the bottom of the tree. The candidate abiotic predictor variables were rainfall depth (mm), intensity (mm h-1), storm duration (h), maximum wind gust speed (m s-1), as well as storm duration (h), wind speed (m s-1), and vapour pressure deficit (kPa) when rainfall intensity ≥ 0.4 mm h-1. Once Plot E and Plot D models have been produced, they will be examined to determine if common variables exist between the two, and if they do, simplified models will be produced using those variable(s). Data sets used to produce simplified models will then be combined if their slopes and intercepts are not significantly different. The regression process employing common variable(s) will then be repeated using the combined dataset to produce a generic model of stemflow prediction for these stands. RESULTS Funnelling ratios for lodgepole pine For the research period, cumulative rainfall for 22 events ranged from 126.0 mm in Plot E to 135.6 mm in Plot D, with individual events ranging in size from 0.5 to 41.3 mm. Plots E and D produced a total of 102.5 and 77.1 L of stemflow, respectively, from 20 of the sampled trees in each plot whose stemflow collection systems were operational throughout the study period (~ 5.1 L tree-1 in Plot E and 3.9 L tree-1 in Plot D). Plot-scale stemflow for Plots E and D were estimated at 1.8 % of rainfall for both stands, assuming that the juvenile sub-alpine fir trees had similar stemflow production abilities to that of the juvenile pine. Given that crown projection area (CPA) represented ~ 3750 m2 ha-1 in Plot E and ~ 5200 m2 ha-1 in Plot D, a total of 5.1 and 3.7 % of rain falling within the crown areas was portioned into stemflow, respectively. The season-long funnelling ratio for pines within Plot E averaged 24.3, while individual trees had season-long funnelling ratios up to 69.3, with a single event maximum of 95.9 (tree diameter = 1.6 cm, rainfall = 7.0 mm). The season-long funnelling-ratio for Plot D averaged 22.2, while individual 88 trees in this plot had season-long funnelling ratios as great as 60.4, with a single event maximum of 111.7 (tree diameter = 3.3 cm, rainfall = 17.4 mm). The exponential decay relationship between season-long funnelling ratios and tree diameter (cm) is shown in Figure 3.4. Figure 3.4 contains only data for healthy lodgepole pine trees from which stemflow was collected over the entire study period. The largest healthy lodgepole pine sampled was 18.1 cm in diameter; however, pine at various stages of MPB attack, nine in total, ranged in size from 8.6 to 39.5 cm in diameter. These dead pine trees had an average season-long funnelling ratio of 2.3, ranging from 0.01 to 17.6, with the latter value being derived from the smallest dead tree. Season-Long Stemflow Funnelling Ratio 75 60 45 F = 93.0 D-1.14 R² = 0.46 30 15 0 0 5 10 Tree Diameter (cm) 15 20 Figure 3.4. Season-long stemflow funnelling ratios versus tree diameter for all healthy lodgepole pine trees in Plots E, D, C, and B. Abiotic and biotic influences on stemflow and the simulation of stemflow production Multiple regression analysis, which included the linear transformations of some of the data, revealed that each of the biotic predictor variables used in this study, with the exception of proximity, had a statistically significant influence (p < 0.05) on stemflow volume at the individual rainfall event scale for at least one event. However, canopy 89 width at various levels, branching angle at various levels, and diameter at the base were the most prominent. Since a multitude of variables were shown to have a statistically significant influence on stemflow production for different rainfall events, it was decided that all biotic variables, with the exception of proximity, would be included in the multiple regression for predicting the values of a and b in Eqs. 3.3 and 3.4, respectively. When examining abiotic variables, it was found that only one variable, rainfall depth (p < 0.001), was consistently statistically significant throughout. Rainfall depth explained over 80 % of the variation in stemflow production for 31 of the 34 trees tested in Plot E. Trees that were influenced by a variable aside from rainfall are listed in Table 3.1. Storm duration was statistically significant for nine trees, maximum gust during the storm was significant for two trees, and duration of the storm when rainfall intensity was greater than 0.4 mm hr-1 was significant for one tree. Only duration explained between 5 % and 11 % of the variation in stemflow for three trees, while for the remaining trees, duration, maximum gust speed, and duration when rainfall intensity ≥ 0.4 mm hr-1 explained less than 3 % of the stemflow variation. Due to these findings, rainfall depth was the only abiotic variable selected for inclusion in the final model. Table 3.2. Coefficient of determination (R2) and p-values associated with statistically significant abiotic predictor variables of stemflow production for individual study trees. Tree 1 4 12 16 18 20 24 26 28 34 Rainfall Depth (mm) 0.96 (p < 0.001) 0.91 (p < 0.001) 0.80 (p < 0.001) 0.97 (p < 0.001) 0.92 (p < 0.001) 0.77 (p < 0.001) 0.94 (p < 0.001) 0.93 (p < 0.001) 0.97 (p < 0.001) 0.97 (p < 0.001) Duration (h) 0.03 (p = 0.001) 0.03 (p = 0.004) 0.11 (p = 0.001) 0.03 (p = 0.001) 0.09 (p = 0.007) 0.02 (p < 0.001) 0.05 (p < 0.001) 0.01 (p = 0.008) Max. Gust (m s-1) 0.01 (p = 0.048) 0.01 (p = 0.003) - Duration while intensity ≥ 0.4 mm h-1 (h) 0.01 (p = 0.016) - 90 Linear regression equations were developed between stemflow volume (L) and rainfall depth (mm) for individual trees in Plot E. The derived slope (a) and intercept (b) values were then plotted against the diameter of the individual trees sampled for stemflow. According to Park and Hattori (2002) a versus DBH and b versus DBH should produce power relationships. Although a versus tree diameter (cm) was found to follow a power relationship, b versus tree diameter (cm) did not (Figures 3.5 and 3.6, respectively). In this study, since all of the biotic variables with the exception of proximity, and not just diameter, had a statistically significant influence on stemflow production for at least one event, and because the relationship between plotted b values and diameter was found to be weak, stepwise multiple regression using a and b as dependent variables was conducted to determine which biotic factors best explained variation in slope and intercept values. 0.14 0.12 Slope (a) 0.1 a = 0.004 DBH1.671 R² = 0.79 0.08 0.06 0.04 0.02 0 0 1 2 3 4 5 6 7 8 Diameter (cm) Figure 3.5. Power relationship between slope values and tree diameter for healthy lodgepole pine trees. 91 0.1 Y-Intercept (b) 0.05 0 -0.05 -0.1 b = -0.018 DBH + 0.020 R² = 0.35 -0.15 -0.2 0 1 2 3 4 5 6 7 8 Diameter (cm) Figure 3.6. Intercept values versus diameter showing a weak linear relationship and not the power relationship shown by Park and Hattori (2002). Upon performing the regression analysis multicollinearity was observed. Tree diameter at the base, height, number of branches, and canopy width at differing levels were highly correlated, resulting in the removal of diameter when performing analyses on slope and intercept values. The result passed the multicollinearity test, however correlation between independent variables remained fairly high. This was resolved by replacing the four separate canopy width measurements with one variable, CPA. Crown projection area solved all multicollinearity problems and also increased the accuracy of the model. Crown projection area (p < 0.001) and branching angle at two-thirds the height of the tree (Angle2/3) (p = 0.001) explained 76.8 % of the variation in a. Branching angle at the bottom of the tree (Anglebottom) (p = 0.004) and CPA (p < 0.001) explained 55.2 % of the variation in b. Following are the two equations that were used in conjunction with Eq. 3.7 to produce a predictor model of stemflow volume as a function of biotic and abiotic factors in Plot E: a = 0.04 CPA + 0.001 Angle2/3 - 0.008 (3.5) 92 b = - 0.06 CPA + 0.003 Anglebottom - 0.0007 (3.6) SF = a Pg + b (3.7) where SF is stemflow volume (L) and Pg is rainfall depth (mm). The next stage of the analysis was to determine the performance of the stemflow model in simulating observed versus predicted stemflow volumes within Plot E, the plot in which the model was developed (Piñeiro et al., 2008). The model was successful in predicting 83.0 % of the variation in stemflow production for Plot E (Figure 3.7). Total predicted stemflow volume was 147.3 L and observed stemflow volume totalled 144.0 L, an overprediction of only 2.3 %. Analysis of the slope and intercept associated with the linear equation of observed versus predicted values found that they did not differ significantly from one and zero, respectively. In order to assess the spatial transferability of the Plot E model, it was applied to Plot D data. The above procedure was repeated to determine the performance of the model when applied to a different plot. The model was found to explain 74.1 % of the variations in observed data; however, for large rainfall events the model greatly overestimated the amount of stemflow produced (Figure 3.8). Although the intercept of predicted versus observed stemflow (L) was not significantly different from zero, the slope was found to be significantly different from one. In an attempt to understand why the Plot E model greatly overestimated stemflow production when applied to Plot D, Plot D stemflow was modeled in the same manner as Plot E using stepwise multiple regression. This was to determine if other variables aside from the ones highlighted during the Plot E analysis were important for predicting stemflow production in Plot D. Crown projection area (p = 0.006), number of branches (#Brch) (p = 0.038), and branching angle at the bottom of the tree (p = 0.036) explained 46.6 % of the variation in a. Number of branches (p = 0.013) explained 17.4 % of the variation in b. Following are the two equations that were used in conjunction with Eq. 3.7 for Plot D: a = 0.02 CPA + 0.001 Anglebottom + 0.001 #Brch + 0.006 (3.8) b = - 0.002 #Brch - 0.008 (3.9) 93 5 Observed Stemflow (L) 4.5 4 3.5 3 2.5 2 1.5 Observed SF = 1.03 Predicted SF - 0.01 R² = 0.83 1 0.5 0 0 1 2 3 4 5 Predicted Stemflow (L) Figure 3.7. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot E ( ) and the 1:1 line (------). 8 Observed Stemflow (L) 7 Observed SF = 0.65 Predicted SF - 0.012 R² = 0.74 6 5 4 3 2 1 0 0 1 2 3 4 5 Predicted stemflow (L) 6 7 8 Figure 3.8. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D employing the Plot E model ( ) and the 1:1 line (------). 94 The process used in Plot E to test the performance of the model was repeated for Plot D. The resulting Plot D model predicted 78.1 % of the variation in stemflow production (Figure 3.9). 5 Observed Stemflow (L) 4.5 4 3.5 3 2.5 2 1.5 1 Observed SF = 0.98 Predicted SF - 0.009 R² = 0.78 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Predicted Stemflow (L) Figure 3.9. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D ( ) and the 1:1 line (------). Total predicted stemflow volume was 127.9 L and observed stemflow volume totalled 119.6 L, an overprediction of 6.9 %. Analysis of the slope and intercept found that they did not differ significantly from one and zero, respectively. Both the Plot E and Plot D models successfully modelled stemflow production, however for the most part they employed different variables to do so. Due to the variety of variables used in each model, a simplified model was also developed. In an attempt to produce a generic model, stemflow was re-modelled for both plots using only CPA, which was the most influential variable common to both of the more complex models. Crown projection area explained 65.8 % of the variation in a (p < 0.001) for Plot E and 31.8 % for Plot D (p < 0.001), along with 40.5 % of the variation in b (p < 0.001) for 95 Plot E and 16.7 % for Plot D (p = 0.015). Equations 3.10 and 3.11 were used in conjunction with Eq. 3.7 to produce the simplified Plot E model (Figure 3.10): a = 0.05 CPA + 0.003 (3.10) b = -0.07 CPA – 0.005 (3.11) 5 Observed Stemflow (L) 4.5 4 3.5 3 2.5 2 1.5 Observed SF = 1.03 Predicted SF - 0.005 R² = 0.77 1 0.5 0 0 1 2 3 4 5 Predicted Stemflow (L) Figure 3.10. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot E employing the simplified model ( ) and the 1:1 line (------). Equations 3.12 and 3.13 were used in conjunction with Eq. 3.7 to produce the simplified Plot D model (Figure 3.11): a = 0.02 CPA + 0.019 (3.12) b = -0.04 CPA – 0.038 (3.13) The process previously used to access model performance was repeated for both the simplified Plot E and Plot D models. The Plot E model explained 77.3 % of the variation in cumulative stemflow production by individual trees, while predicting an all sample tree production of 143.5 L compared to the observed 144.0 L, an underprediction of 0.3 %. The Plot D model explained 74.3 % of the variation in cumulative stemflow 96 production by individual trees, while predicting an all-sample tree production of 130.0 L compared to 119.6 L, an overprediction of 8.7 %. 5 Observed Stemflow (L) 4.5 4 3.5 3 2.5 2 1.5 1 Observed SF = 0.96 Predicted SF - 0.007 R² = 0.74 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Predicted Stemflow (L) Figure 3.11. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for Plot D employing the simplified model ( ) and the 1:1 line (------). The culmination of the modelling process was the production of a generic model that could be used to determine stemflow production for both Plot E and Plot D. Slope (a) and intercept (b) values were produced in the same manner as the previous models. Slope and intercept values for Plot E and Plot D did not differ significantly and were combined for the regression analysis culminating in one model which was applicable to both stands, resulting in Eqs. 3.14 (p < 0.001) and 3.15 (p < 0.001). This model applies to individual trees or stands with trees having CPAs in the range of 0.01 to 3.5 m3. Trees with this CPA range had associated diameters ranging from 1.6 cm to 8.8 cm (CPA = 0.078 D1.55, R2 = 0.81) and tree heights (H) ranging from 0.85 m to 4.89 m (CPA = 0.201 H1.58, R2 = 0.77). The model can be seen in Figure 3.12 and was produced using Eqs. 3.14 and 3.15, in conjunction with Eq. 3.7: 97 a = 0.03 CPA + 0.015 (3.14) b = - 0.05 CPA – 0.023 (3.15) 6 Observed Stemflow (L) 5 4 3 2 1 Observed SF = 0.99 Predicted SF - 0.006 R² = 0.71 0 0 1 2 3 4 5 6 Predicted Stemflow (L) Figure 3.12. Observed stemflow volume versus predicted stemflow volume derived from Eq. 3.7 for lodgepole pines in Plots E and D employing the generic model ( ) and the 1:1 line (------). The generic model explained 71.3 % of the variation in stemflow production for juvenile lodgepole pine stands, while predicting an all sample tree production of 274 L compared to the observed 264 L, an over prediction of 3.8 %. The slope did not differ significantly from one nor did the intercept differ significantly from zero. Equations 3.14 and 3.15 were used in conjunction with the relationship between CPA and D and applied to tree frequency data for each stand to generate stand scale estimates of stemflow volume and percentage of rainfall portioned into stemflow (Figure 3.13). The relationship between the percentage of rainfall that became stemflow and rainfall depth also highlights the point at which stemflow production commences: 1.6 mm of rainfall for both Plots E and D. 98 3 Stemflow (% of rainfall) 2.5 2 1.5 1 0.5 0 0 5 10 15 20 25 30 35 40 Rainfall Depth (mm) Figure 3.13. The percentage of rainfall that became stemflow versus rainfall depth at the stand scale for Plot E ( ) and Plot D (------), highlighting the rainfall depth required for the commencement of stemflow production (1.6 mm). Stemflow produced by a branchless tree Three branchless trees were sampled for stemflow in an attempt to further understand the influence of abiotic factors on stemflow production. However, these trees suffered very high data loss due to leaking stemflow collars. As a result, only the large tree had a complete dataset and the incomplete data sets of the small and medium trees were discarded. Stepwise multiple regression was conducted using stemflow volume as the dependent variable and only meteorological conditions as independent variables. The result of the analysis was Eq. 3.16 which explained 94.8 % of the variation in stemflow production. Stemflow production for a tree with no canopy was influenced by the amount of rainfall and the duration of the storm. Stemflow increased as the amount of rainfall increased but decreased as the duration of a storm increased. The decrease due to increased storm length is most likely due to evaporation from the trunk, including evaporation during breaks in the storm. SF = 37.9 Pg – 5.2 Dur – 63.8 (3.16) 99 A tree lacking a canopy was expected to have minimal stemflow production and be an inefficient stemflow producer. However, this was not the case for this lone branchless tree, as it had an average season-long funnelling ratio of 10.9 and an event high funnelling ratio of 19.8. DISCUSSION The results show that juvenile lodgepole pine trees are far more efficient stemflow producers than their mature counterparts due to differences in tree morphology. It is therefore not surprising that in comparison to other canopy water balance studies, with a sampling emphasis on mature lodgepole pine, we have observed much higher stemflow production. Juvenile lodgepole pine dominated stands partitioned up to ~ 2 % of incoming rainfall into stemflow and individual trees are highly efficient producers, with event funnelling ratios as high as 111.7. In contrast to our findings, Moore et al. (2008) in a mature pine – hybrid white spruce – subalpine fir stand at the Mayson Lake study site, found that stemflow represented ~ 0.2 % of season-long rainfall, while Spittlehouse (1998) calculated that < 0.5 % of rainfall became stemflow for a mature lodgepole pine stand in Penticton, BC. A comparison between the results of this present study and those presented by Moore et al. (2008) suggest that within the study area, juvenile lodgepole pine stands divert ~ 10 times more rainfall to stemflow than do mature coniferous stands. Dunford and Niederhof (1944), however, reported higher values of 1.5 % of rainfall becoming stemflow for a lodgepole pine stand in Colorado. Unfortunately, very few stand characteristics necessary for accurate comparisons were provided by these authors. Dunford and Niederhof (1944) provided the average canopy area (3.25 m2), which is just over four times larger than the average canopy area observed in Plot E. Thus, although it is evident that the Dunford and Niederhof (1994) study took place in an older stand, it is not clear if it was a mature stand or one at the pole-stage. Spittlehouse (1998) listed tree heights ranging from 22 – 26 m, much taller than the 0.85 – 3.48 m observed in Plot E. As one can see, these studies both examine trees that are considerably larger than those 100 examined in this study, highlighting the lack of attention juvenile lodgepole pine canopy water balances have received in the hydrologic literature. Lodgepole pine stemflow production The stand-scale funnelling ratios for Plots E and D were 24.3 and 22.2, respectively, while the highest observed season-long funnelling ratio for an individual tree was 69.3, and the single event lone tree maximum was 111.7. These findings suggest that during the study period the base of these trees received an average stemflow input having an equivalent depth of 3060 and 3010 mm, respectively – some 5 times the average annual precipitation depth. Unfortunately, no other studies have provided funnelling ratios for pine, let alone lodgepole pine, making comparisons with other pine stands impossible. Only one other study has derived funnelling ratios for a coniferous species. Murakami (2009) derived funnelling ratios for Chamaecyparis obtuse (Japanese cypress) over a four year period, and found that funnelling ratios decreased from 81.3 to 29 with increasing stand age (9 – 12 yrs of age). The funnelling ratios derived in this study compare well with findings in other forest environments. Herwitz (1987), for example, observed a maximum season-long funnelling ratio from a lone Balanops australiana of 112 in a tropical rainforest, while Van Stan and Levia (2010) found that season-long funnelling ratios varied from 3.1 to 19.2 and 26.9 to 47.2 for lone Liriodendron tulipifera (yellow poplar) and Fagus grandifolia (American beech) trees, respectively. Návar (1993) recorded a season-long high funnelling ratio of 128 for a single Diospyros texana; however, he also recorded a large variation in season-long funnelling ratios ranging from 13 to 128 over 15 sampled shrubs. Season-long funnelling ratios in this present study also varied by an order of magnitude (6.9 to 69.3). Juvenile lodgepole pines are efficient stemflow producers, however, the large variation observed at the individual tree scale highlights the impact tree characteristics can have on the amount of rainfall partitioned into stemflow. 101 Model assessment In addition to rainfall depth, a number of tree characteristics allowed for the accurate modelling of stemflow production from juvenile lodgepole pine. The identification of rainfall depth as the only prominent abiotic factor that influenced stemflow production is in keeping with the findings of Cape et al. (1991). Tree characteristics were used to explain variation in the slope and intercept values of the regression between stemflow volume and rainfall depth. The slope of the regression represents stemflow production and the intercept value represents the storage capacity of the tree. The use of multiple predictor variables resulted in increased model accuracy when compared to using only one variable like tree diameter (Park and Hattori, 2002). It is important to note that the usefulness of adding additional variables to increase model accuracy will vary depending on the species of study. Comparing our findings with those of Park and Hattori (2002) is a perfect example of the differences that occur when modelling species or specimens with differing morphology. Stemflow production for the Plot E model increased as crown projection area and the branching angle at two-thirds the tree height increased. A tree with a wider canopy will produce more stemflow as it is able to capture more rainfall, while increasing the upward branch inclination will result in more efficient flow along those branches (Herwitz, 1987). However, a tree with a wider canopy will have a larger storage capacity, and as the angle of the lower branches of the tree becomes more negative, more water will drip from that canopy, contributing to throughfall rather than stemflow. The model incorrectly assumed that canopy drip was becoming storage and thus the intercept of the model should be viewed as representing both canopy + trunk storage and throughfall in the form of canopy drip. The application of the Plot E model (Eqs. 3.5 and 3.6) to Plot D resulted in a gross overestimate of the amount of stemflow produced. The poor performance of Eqs. 3.5 and 3.6 when applied to Plot D was believed to be the result of a variable that was highly influential in Plot E but not in Plot D. In an attempt to identify this variable, a new stemflow model was produced for Plot D using the same methodology as Plot E. The Plot D model (Eqs. 3.8 and 3.9) identified that stemflow 102 production increased as crown projection area and number of branches increased, but decreased as the inclination of the bottom branches of the tree became more negative. The storage capacity of trees in Plot D was dependent upon the number of branches: as the number of branches increased, the storage capacity of the tree increased. Both Plot E and Plot D models identified CPA as the prominent variable; however, both models also contained other variables not common to both. The Plot D model included number of branches, highlighting that more rainfall will be intercepted by a denser canopy. Upon analysis of the variables contained in the Plot E and Plot D models, it was found that Angle2/3 and #Brch were statistically different between the two plots, p = 0.035 and p = 0.056, respectively. Therefore, this was the likely cause of the overestimation of stemflow production observed when applying the Plot E model to Plot D resulted in an incorrect estimation of stemflow production. Our findings that branching angle (Herwitz, 1987; Návar, 1993; Martínez-Meza and Whitford, 1996; Aboal et al., 1999), canopy area (Ford and Deans, 1978; Martínez-Meza and Whitford, 1996), and number of branches or canopy density (Martínez-Meza and Whitford, 1996) have a significant influence on stemflow production for trees sampled in this study are consistent with past studies. As CPA was the only common and most influential variable between the models produced for each plot, new simplified models were produced using only CPA as a predictor of stemflow production and storage capacity. Our finding that CPA was the most influential biotic predictor of stemflow production for both plots is in keeping with the findings of Davie and Durocher (1997) and Aboal et al. (1999). The simplified models for Plot E (Eqs.3.10 and 3.11) and Plot D (Eqs. 3.12 and 3.13) explained only 5.5 % and 3.8 % less variation in stemflow production, respectively. This is most likely due to an overall decrease in the importance of canopy architecture for a lodgepole pine stand as it matures, and more of a reliance on total rainfall. The final modelling stage involved combining Plot E and D data to produce a generic equation for juvenile pine stands using CPA. This model explained 71.3 % of the variation in stemflow production for individual lodgepole pines or entire stands using CPA and gross rainfall. The model is applicable to individual trees or stands that contain trees with CPAs ranging from ~ 0.1 to 3.5 m3. 103 The finding that a lone branchless tree had a season-long funnelling ratio of 10.9 suggests that meteorological conditions influence stemflow production for a tree lacking a canopy. If rain was to fall vertically then the funnelling ratio of a branchless tree would be less than one due to trunk storage. Therefore, rain must be falling on an angle and stemflow production is therefore dependent on rainfall intensity and wind speed (Herwitz and Slye, 1995; Xiao et al., 2000). CONCLUSION Field research conducted during the 2008 growing season showed that healthy juvenile lodgepole pine trees are far more efficient stemflow producers than mature individuals. Due to these findings, two stands of juvenile lodgepole pine were heavily sampled for stemflow during the 2009 growing season. Stemflow production for both juvenile stands was successfully modelled using two predictor variables: rainfall depth and crown projected area. Additional variables could be added to the individual models for each plot; however, the increase in accuracy for the sampled stands was insignificant when compared to the variation in stemflow production explained by the aforementioned variables. However, it is important to note that the identification of different biotic variables at the plot scale highlights the fact that as trees age, the biotic factors that influence stemflow production change. Therefore, modelling stemflow production is more accurate when more than one variable is employed, in contrast to using only one as the majority of studies have done to-date. However, gathering the data required for the inclusion of additional variables in one’s model is no small task. If a researcher is restrained by resources or time, crown projected area can be used in conjunction with rainfall depth to produce a generic model for juvenile lodgepole pine that, at least in this study, accurately predicted stemflow volumes. The inclusion of detailed stand characteristics in one’s methodology is paramount for comparison with other studies. It is therefore important that future publications include detailed stand characteristics for ease of intra- and interspecific stemflow production comparisons. Due to the findings that juvenile lodgepole pine are efficient 104 stemflow producers, further research into the hydrologic importance of the stemflow produced by these trees, including the potential impact on soil moisture and groundwater recharge, is merited. LITERATURE CITED Aboal JR, Morales D, Hernández JM, Jiménez MS. 1999. The measurement and modelling of the variation of stemflow in a laurel forest in Tenerife, Canary Islands. Journal of Hydrology 221: 161-175. BC Ministry of Water, Land and Air Protection. 2004. Weather, Climate and the Future: BC’s Plan. http://www.env.gov.bc.ca/air/climate/index.html#1 Brinson MM, Bradshaw HD, Holmes RN, Elkins JB Jr. 1980. Litterfall, stemflow, and throughfall nutrient fluxes in an alluvial swamp forest. Ecology 61(4): 827-835. Brown JH Jr., Barker AC Jr. 1970. 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Ecoscience 13(3): 324-333. Levia DF Jr., Frost EE. 2003. A review and evaluation of stemflow literature in the hydrologic and biogeochemical cycles of forest and agricultural ecosystems. Journal of Hydrology 274: 1-29. Levia DF Jr. 2004. Differential winter stemflow generation under contrasting storm conditions in a southern New England broad-leaved deciduous forest. Hydrological Processes 18: 1105-1112. Lloyd D, Angove K, Hope G, Thompson C. 1990. A Guide to Site Identification and Interpretation for the Kamloops Forest Region. B.C. Min. For., Res. Br., Victoria, B.C., Land Manage. Handbook No. 23. Martínez-Meza E, Whitford WG. 1996. Stemflow, throughfall and channelization of stemflow by roots in three Chihuahuan desert shrubs. Journal of Arid Environments 32: 271-287. McKee AJ, Carlyle-Moses DE. 2010. Stemflow: A potentially important point source of water for growth. Linking Innovations and Networking Knowledge 11(2): 11-12. Moore RD, Winkler R, Carlyle-Moses D, Spittlehouse D, Giles T, Phillips J, Leach J, Eaton B, Owens P, Petticrew E, Blake W, Heise B, Redding T. 2008. Watershed response to the McLure forest fire: Presentation summaries from the Fishtrap Creek workshop. Streamline Watershed Management Bulletin 12(1): 1–11. Mueller Dombois D, Ellenberg H, 1974. Aims and Methods of Vegetation Ecology. John Wiley, New York. 106 Murakami S. 2009. Abrupt change in annual stemflow with growth in a young stand of Japanese cypress. Hydrological Research Letters 3: 32-35. Návar J. 1993. The causes of stemflow variation in three semi-arid growing species of northeastern Mexico. Journal of Hydrology 145: 175-190. Park H, Hattori S. 2002. Applicability of stand structural characteristics to stemflow modelling. Journal of Forest Research 7: 91-98. Piñeiro G, Perelman S, Guerschman JP, Paruelo JM. 2008. How to evaluated models: Observed vs. predicted or predicted vs. observed? Ecological Modelling 216(3-4): 316-322. Pressland AJ. 1973. Rainfall portioning by an arid woodland in South-Western Queensland. Australian Journal of Botany 21: 235-245. Schroth G, Elias MEA, Uguen K, Seixas R, Zech W. 2001. Nutrient fluxes in rainfall, throughfall and stemflow in tree-based land use systems and spontaneous tree vegetation of central Amazonia. Agriculture, Ecosystems and Environment 87: 3749. Spittlehouse D. 1998. Rainfall interception in young and mature conifer forests in British Columbia. Proceedings 23rd Conference on Agricultural and Forest Meteorology. Spittlehouse D. 2008. Annual water balance of forest and burnt stands. Streamline Watershed Management Bulletin 12(1): 3-4. Tanaka T, Taniguchi M, Tsujimura M. 1996. Significance of stemflow in groundwater recharge. 2: A cylindrical infiltration model for evaluating the stemflow contribution to groundwater recharge. Hydrological Processes 10: 81-88. Taniguchi M, Tsujimura M, Tanaka T. 1996. Significance of stemflow in groundwater recharge. 1: Evaluation of this stemflow contribution to recharge using a mass balance approach. Hydrological Processes 10: 71-80. Van Stan JT II, Levia DF Jr. 2010. Inter- and intraspecific variation of stemflow production from Fagus grandifolia Ehrh. (American beech) and Liriodendron tulipifera L. (yellow poplar) in relation to bark microrelief in the eastern United States. Ecohydrology 3: 11-19. Voigt GK. 1960. Distribution of rainfall under forest stands. Forest Science 6(1): 2-10. 107 Walton A, Hughes J, Eng M, Fall A, Shore T, Riel B, Hall P. 2007. Provincial-level projection of the current Mountain Pine Beetle outbreak: Update of the infestation projection based on the 2006 provincial aerial overview of forest health and revisions to the “model” (BCMPB.v4).http://www.for.gov.bc.ca/hre/bcmpb/BCMPB.v4.BeetleProjection. Update.pdf Whitford WH, Anderson J, Rice PM. 1997. Stemflow contribution to the ‘fertile island’ effect in creosotebush, Larrea tridentate. Journal of Arid Environments 35: 451457. Xiao, Q, McPherson EG, Ustin SL, Grismer ME, Simpson JR. 2000. Winter rainfall interception by two mature open-grown trees in Davis, California. Hydrological Processes 14: 763-784. 108 CHAPTER 4 CONCLUSION In comparison to other components of the vegetation canopy water balance, stemflow has received the least attention in the hydrologic literature (Levia and Frost, 2003). Despite being volumetrically insignificant at the plot scale and beyond when compared to throughfall and interception loss, stemflow is hydrologically important because it is a focused input of precipitation at the base of a tree or plant (Herwitz, 1986). Over the course of a century of study, the important impact stemflow can have on site hydrology has been highlighted time and time again. Stemflow can have implications for groundwater recharge, erosion, and vegetation growth (Voigt 1960; Brinson et al., 1980; Herwitz, 1986; Tanaka et al., 1996; Taniguchi et al., 1996; Whitford et al., 1997; Chang and Matzner, 2000; Schroth et al., 2001; Johnson and Lehmann, 2006). Due to the importance of stemflow as highlighted by prior studies, it is imperative that we strive to increase our knowledge by studying different vegetation species under differing geographic and climatic conditions, as well as under different age and condition (e.g., disturbance, planting arrangement, etc.) scenarios. Stemflow production data was compiled for studies published prior to June 30, 2010, which contained one or more of the following: a stemflow equation, percentage of rainfall that became stemflow, or stemflow funnelling ratios. The information was organized by species and partitioned into seven climate and vegetation classifications. Once organized, stemflow funnelling ratios and plateau funnelling ratios were calculated for studies that provided the necessary information. Upon table completion, the data was examined to identify inter-climatic, intra-climatic, and inter-genera relationships. Plateau funnelling ratios were used to estimate the amount of rainfall required to satisfy the storage capacity of a tree or bush. When compared to the values used in current canopy water balance models, rainfall amounts found using the plateau funnelling ratio method were much greater, highlighting a large underestimation in current models. Finally, the data contained within the reference tables was used to highlight areas where knowledge 109 remains fairly weak, and to identify particular genera which have received the most attention to date. After examination of the stemflow literature it was noted that stemflow knowledge for species found in the Interior of British Columbia was lacking. Due to the changes in the landscape that will occur as a result of the Mountain Pine Beetle epidemic, an examination of stemflow production for lodgepole pine was undertaken. Spittlehouse (1998) showed that stemflow production was fairly low for mature lodgepole pine, however, no studies to-date had examined juvenile lodgepole pine. Field research conducted for the 2008 growing season showed that juvenile lodgepole pine were much more efficient stemflow producers when compared to mature trees (McKee and CarlyleMoses, 2010). Due to these findings, two stands of juvenile lodgepole pine were heavily sampled over the 2009 growing season with the goal of identifying the meteorological conditions and tree characteristics that influence stemflow production. The dataset gathered for this thesis further supports the findings of McKee and Carlyle-Moses (2010) that juvenile lodgepole pine produce significant volumes of stemflow. Analysis of the dataset resulted in the successful production of three stemflow models, one for each individual research plot, and a comprehensive model encompassing the entire dataset. These models employed multiple variables, highlighting the importance of considering a wide array of variables when modelling stemflow production. Reviewing the quantitative importance of stemflow not only produced a reference guide for future researchers, it also highlighted the shortcomings of current canopy water balance models. Calculated plateau funnelling ratios were used to estimate the amount of rainfall required to satisfy the storage capacity of a tree or plant. The rainfall depths associated with the calculated plateau funnelling ratios suggest that current methods of estimating the required rainfall depth to saturate a vegetation canopy (e.g. Valente et al., 1997) may be erroneous. Examination of the review tables also highlighted the importance of including detailed stand characteristics which aid in inter-study comparisons. 110 With regards to the field study, logistics limited the number of plots used to produce the dataset required for developing the stemflow models to two. Plots E and D contained 37 and 36 samples, respectively, that were representative of their respective stands. The inclusion of more samples from other locations with differing tree architecture would have resulted in a more comprehensive model, or multiple models categorized by tree size. Despite the limitations due to sampling logistics, the final model explained 71.3 % of the variation in stemflow production for both juvenile stands. This model provides the basis for the development of a broadly applicable model that would allow hydrologists to calculate stemflow production for individual juvenile lodgepole pine or for lodgepole pine stands outside the geographic area of this study. Based on the findings that plateau funnelling ratios can be used to estimate the amount of rainfall required to satisfy the storage capacity of a tree, and that current models greatly underestimate the storage capacity, new canopy water balance models must be produced that accurately estimate canopy storage. The use of the stemflow funnelling ratio in the stemflow literature should be expanded because it is an effective way of explaining a tree’s or stand’s ability to produce stemflow. The inclusion of detailed stand characteristics is paramount for comparison with other studies. It is therefore important that future studies include detailed stand characteristics for ease of inter- and intra-specific stemflow production comparisons. Juvenile lodgepole pine trees are efficient stemflow producers and are capable of producing large volumes of stemflow, up to 10 times more than their mature counterparts. Based on that finding alone, more research is required to determine the hydrological and ecological implications of stemflow production from juvenile lodgepole pine. What are the implications for site hydrology? Specifically, is stemflow from juvenile lodgepole pine important for soil moisture and groundwater recharge? Is this water flux also an important source of nutrients for growth for this tree species? Further investigation into the hydrological and biogeochemical importance of stemflow from juvenile lodgepole pine is paramount due to the uncertainties surrounding the potential 111 impacts of mountain pine beetle, wildfire, and climate change on the hydrology and ecology of British Columbia’s Interior. LITERATURE CITED Brinson MM, Bradshaw HD, Holmes RN, Elkins JB Jr. 1980. Litterfall, stemflow, and throughfall nutrient fluxes in an alluvial swamp forest. Ecology 61(4): 827-835. Chang S, Matzner E. 2000. 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