Effects of altered precipitation and increased warming on a restored southern California salt marsh

Background/Question/Methods

Salt marshes provide several critical ecosystem functions, i.e. nutrient cycling, faunal biodiversity support, and filtration. These functions have been threatened by human activities such as urban development, pollutants, and climate change. One strategy to deal with loss and deterioration of salt marsh ecosystems is restoration. We know current methods, e.g. actively planting native plants, are effective under known climate conditions. Yet the success of restorations under altered climate regimes is unknown. Southern California has a Mediterranean climate characterized by rain in the winter and dry conditions in the summer. Climate change projections for this region include increased frequency of severe storms, longer periods of drought, and increases in temperature (2-10°C). In order to understand these effects I am evaluating how altered precipitation and increases in temperature will affect a restored high marsh berm in southern California salt marsh. Structures made of PVC pipe and greenhouse plastic mimic these environmental changes and have been placed along the berm in a randomized block design. I am measuring changes in the invertebrate community, plant height, algal biomass, and nutrient availability. The project will run for 15 months with the last sampling point in September 2012.

Results/Conclusions

Pre-treatment invertebrate counts demonstrated no difference among blocks with an overall low total abundance (0-2 organisms/18.1m²). Continuous data loggers placed within each experimental plot indicate treatments are effective in raising the temperature on average (+2 in the IT treatments) and reducing precipitation by 50% in DP treatments. Four month sampling indicates an increase in plant height and algal biomass from time 0 across all treatments, but later sampling points (post-rainy season) are predicted to reflect changes in invertebrate community by treatment. Our final results can provide managers of future restorations information to assist in design and budgets by understanding the success of restoration under different climate change scenarios.