Description
The restoration of degraded ecosystems is becoming an increasingly important focus of natural resource management and environmental policy. However, despite many advances in the field of restoration ecology, little is known about the long-term effectiveness of restoration efforts. It is often assumed that restored habitats follow a reliable trajectory towards the desired ecological state, but very few studies have examined whether this is actually the case. This study begins to address this issue by examining the long-term effectiveness of habitat restoration efforts in upland and wetland habitats in San Diego County, California. I evaluated the current vegetation conditions of 11 upland restoration sites and 15 wetland restoration sites that had not been actively managed for at least 5 years. I compared the sites' current conditions to their conditions at the conclusion of active restoration (historic site conditions) and assigned synthetic measures of success to rate the overall restoration success and habitat quality of each site. I analyzed whether current vegetation conditions and/or the synthetic measures of success were related to historic site conditions. I also evaluated current environmental conditions on and immediately surrounding each site and analyzed the relationships between these environmental factors, the current vegetation conditions of the sites, and the synthetic measures of site success. The analyses found significant differences between upland and wetland restoration sites, both in the long-term sustainability of these restored habitats and in their current vegetation conditions. Upland restoration sites appear to be more variable in condition and less successful long-term, particularly if they were of lower habitat quality at the end of active restoration. Wetland restoration sites appear to be less variable in condition and more successful long-term, as long as the proper wetland hydrology is established. However, both upland and wetland restoration sites may be declining in habitat quality with time elapsed since the end of active restoration. The study provides several ways in which planning and implementation of upland and wetland restoration projects could be improved to better promote long-term restoration success. It also serves as a valuable baseline for future studies of restoration success in San Diego County.
