Identifying effective restoration approaches to maximize plant establishment in California grasslands through a meta‐analysis

One reason restoration often fails is a lack of native plant establishment. Establishment failure can occur due to a lack of dispersal into the site, inappropriate abiotic conditions for plant survival, or biotic interactions that reduce germination rates or seedling survival. Understanding what is limiting establishment is critical for restoration success. Unfortunately, there has been little synthetic work to identify which restoration practices (e.g., direct seeding, weeding, irrigation) are most likely to improve plant establishment. Here we used a meta‐analytical approach to determine what practices are most likely to enhance establishment success in grassland communities in California. We explored the impact of these practices on whole communities as well as on different functional groups (grass and forb). We categorized techniques by the constraint they addressed (dispersal, abiotic, or biotic) to determine which restoration practices are more likely to improve plant establishment. We found that addressing the dispersal filter is the best way to improve plant establishment regardless of the functional group. This suggests that most native plants targeted in restoration are seed limited. While we were able to identify restoration techniques that improve plant establishment, our synthesis revealed that there were insufficient numbers of studies and a lack of uniformity between treatments that hampered efforts to make broad conclusions. If we can expand research to more ecosystems, and use standardized treatments within each ecosystem, the restoration community could synthesize research more efficiently, which would inform our ultimate goal of increasing the success of restoration.