Restoration of a disturbed semi-arid grassland using priority effects and soil amendments to promote native plant communities and prevent invasion by exotic species

As an ecosystem, grasslands in British Columbia are home to a third of the province's endangered and threatened species but make up less than 1% of the total land coverage in the province. Grasslands provide numerous important ecosystem services such as carbon sequestration, hydrology control, and maintaining species diversity. Anthropogenic disturbances threaten grasslands and once disturbed are challenging to restore or reclaim. My project tests successional theory and priority effects to restore native grassland plants with different soil amendments (straw matting and biochar). Priority effects entail different seeding orders of arrival of successional plant species and may be used to determine the best combination that promotes the establishment and growth of native plant communities and prevents invasion of exotic species in grassland restoration. Combinations of four different planting orders of native early and late successional grasses and forbs, and four different soil treatments were applied at three different sites in Kenna Cartwright Nature Park in Kamloops, British Columbia, Canada. In addition, a greenhouse study was conducted using three different planting orders and two fertilizer levels to test priority effects and the resilience of a native grassland community against invasion. Results show early successional plants exhibit stronger priority effects in the greenhouse but in the field the results of priority effects are site specific. Plots in the field that received both biochar and straw matting as amendment treatments experienced higher soil moisture and less exotic invasion. These findings provide insight into the benefits of using priority effects and amendments in a restoration setting in the interior grassland of British Columbia, giving restoration managers more tools to help restore land as anthropogenic disturbance becomes increasingly more common.