Mine restoration of a native grassland plant community in the British Columbia interior: The use of biochar, hydroseeding and raking

The extraction of non-renewable resources results in disturbances which alter ecosystems and change landscapes. Semi-arid ecosystems create a unique challenge in the restoration of disturbed ecosystems, as they are water limited. To protect topsoil for future use, mines often strip and stockpile topsoil during the building of infrastructure. Soil amendments and site preparation have been shown to have positive effects in restoration efforts of these disturbed ecosystems. As well, soil preparation, such as tilling, imprinting, use of litter, and hydro-seeding have been used to increase germination and establishment in restoration. In a greenhouse study, I looked at the effects of biochar as a soil amendment for improving growth of native species indigenous to the semi-arid grasslands of the BC interior. Biochar was mixed at 15% volume by weight to a mixture of 50/50 sand and stockpiled topsoil. Thirty grassland species were studied. Plants were grown in a temperature and humidity controlled greenhouse and harvested after 89 days of growth. Results indicated biochar had no effect on the above or below ground biomass of the native species studied. My field study looked at the effects of raking and hydro-seeding on the establishment of native species on stockpiled topsoil. The field study was set up and seeded in the fall of 2012. The study consisted of sites raked, hydro-seeded and raked x hydro-seeded. Each factor was either seeded or not seeded with a native seed mixture of 12 forbs and 12 graminoids (200 seeds each) at a seeding density of 1200 seeds/m2. Seeding natives was found to significantly increase species richness and diversity. For native species overall as well as for the native forb and graminoid functional groups, the use of hydro-seeding showed no significant difference compared to the seeded control. Raking x seed increased establishment rates for native species overall as well as for the two native functional groups. In conclusion, biochar did not have the intended effect of increased growth on the species studied from the BC interior semi-arid grasslands. However, further research should be conducted using larger pots, increased time, and biochar from different feedstocks. My field study demonstrated seeding of desirable species and site preparation are important aspects of restoration and can influence the direction of succession. However, hydro-seeding was found to have little benefit in the seeding of natives and is not recommended for use in the restoration of semi-arid grasslands. Management should include soil preparation by way of loosening and roughening the soil before seeding. Further techniques in soil preparation and landscaping should be explored to further increase germination and establishment success