Patterns of persistence and spread: Tracking success of native prairie species 6 years after habitat restoration
Restoring degraded habitats with the goal of achieving long-term ecological complexity and stability is an essential component in combatting the worldwide decline of biotic diversity. The major goals of grassland restoration are to reduce the abundance of exotic species while maintaining or boosting native species richness and abundance, but it is often difficult to evaluate these goals far beyond project timelines. Understanding how initial trends play out over the long-term is essential for evaluating treatment efficacy. Additionally, observing how specific native species establish and spread following restoration treatments can inform further decisions regarding seeding practices and management timelines. To assess the degree to which initial treatment effects persist after project completion, we revisited prairie restoration sites 6 years after experimental treatments and supplemental seeding had ceased and evaluated composition and structure of the plant community. We tracked the persistence of seeded species across treatments and measured spread of populations as a metric to evaluate longer-term success, suitability of restoration species, and the ability of the habitat to support native plant populations.
We found that plots that received supplemental seeding of native species continued to exhibit higher native richness than those left unseeded, regardless of treatment, but that this did not necessarily translate to higher total cover of native species. Treatment was found to be a significant indicator in the persistence of 4 out of 8 of the seeded species. A case study of the seeded native species, Plectritis congesta, indicated that where persistence occurred, the population could achieve a level of spatial advance in agreement with theoretical predictions. Our results confirm that seeding native species plays a critical role in grassland restoration given that, once established, native species seem to have the ability to persist and perform in line with expectations even in exotic-dominated communities. Thus, our findings provide further support that seed limitation of native species continues to be one of the major concerns when conducting restoration in invaded grasslands.