LB 17-151 - Restoration of ecosystem services in post-fire chaparral landscapes.

Fire in chaparral shrublands has a major impact on native vegetation and the ecosystem services that it provides, consequently post-fire restoration is sometimes implemented to promote chaparral integrity. However, restoration is expensive and time intensive and, to date, there are no data to indicate the impacts of restoration on the recovery of shrubland ecosystem services and function. In this study, we assess restoration on the Piru Fire (2003) on the Los Padres National Forest, with two over-arching questions relating: how do ecosystem services recover with restoration and how do they differ between low quality (degraded) and high quality (intact) chaparral shrubland? We applied the Postfire Restoration Prioritization Tool to the Piru Fire to identify areas with low natural regeneration capacity and established 16 plots (4m x 4m) for restoration; 16 adjacent controls; and 8 reference plots in high quality shrubland. We planted 837 plants using a palette of 15 native species from chaparral and coastal sage scrub communities (January 2022) and recorded: monthly data on mortality; plant height, canopy cover, presence of non-native species, and bare ground (in April 2022); invertebrates using pitfall traps and sweep nets (May 2022); extracted soil cores to assess N, C, and microbial biomass (October 2022); and buried tea bags at three time periods during the year to assess decomposition rates in the soil. Restored plots were watered (2 gallons per plot/month) from June to October 2022 during the summer drought. After six months, results showed the majority of plant species had over 70% survivorship with Artemisia californica and Elymus condensatus at 99% and 98% respectively, while Quercus berberidifolia had the lowest survivorship (7%). Mortality in chaparral species started in July, but coastal sage scrub species showed a delay by one month. Non-native grass frequency was significant lower in restored plots versus control, and lowest in intact reference plots. We found the biomass of restored plots quadrupled from year 1 to year 2, especially of A. californica and Encelia californica. For invertebrates, species richness of Coleoptera and Hymentoptera was higher in restored versus control plots (but no difference detected in insect abundance). Finally, we recorded similar decomposition rates in restored and control plots over one year, with an increase in decomposition with wetter conditions moving from summer, fall to winter. Our findings will support USDA Forest Service resource managers involved in shrubland restoration including the selection of species to use and whether to irrigate.