Assessing the Recovery Trajectory of Restored Plant Communities
thesisposted on 06.08.2019, 00:00 authored by Brook D Herman
A primary goal of this research was to explore the recovery of restoration projects over time, compared to a range of reference and unrestored conditions. This study used multi-year monitoring data to track the recovery of restored native plant communities, measured with species composition and functional groups, and compared their recovery to reference and unrestored conditions. Restorations from 3 habitat types were assessed, including emergent marsh, mesic prairie and oak savanna. Recovery of species composition and functional groups were also compared to plant community qualitative indices (FQAI) to assess if metrics were related to their recovery. Plant community data was collected with 2 different methodologies (quantitative (plots/transects) and qualitative (meander survey)) that may change the way restoration success is assessed. Species composition exhibited low to no recovery of similarity with reference conditions and little change from unrestored conditions. Functional groups exhibited greater increase in similarity to reference and greater decrease in similarity to unrestored conditions. Overall, success metrics had a positive relationship with recovering species composition and functional groups, although, they were inconsistent among habitats. This could mean that increases in success metrics over time may not necessarily be indicative of similarity to reference conditions. Success metrics may be overestimating restoration success. Between the two data collection techniques compared, the qualitatively collected data showed a greater recovery than the quantitatively collected data. The cost of restoration activities exhibited an inverse relationship to recovery of species composition and functional groups. This could indicate that sites that require higher levels of effort to restore will result in the least recovery. Lastly, the use of multiple reference and unrestored areas was useful in comparison to recovery of restorations. Long-term monitoring (~10-15 years) is needed to better understand the overall shape and rate of recovery. More research should be directed at developing methods to establish and recover common species. Practitioners should assess multiple lines of evidence when assessing restorations. Recovery may vary between data (species composition vs. functional groups) and data types (quantitative vs. qualitative). Be aware of the limitations of using indices that offer generalized assessments of community condition (e.g., Floristic Quality Assessment Index). Standard monitoring protocols should be developed so more confident comparisons can be made among sites that will facilitate a deeper understanding of and lead to better prediction of restorations outcomes. Future research should be focused on developing guidelines on how to appropriately identify and select reference sites for assessing restoration success.