PARENT SESSION
Wednesday, August 9, 5:00-6:30 pm
Poster Session 17 - Community ecology: structure, composition, and dynamics
Exhibit Hall, Ballroom Level, Cook Convention Center
Community assembly models as predictive tools in restoration.
Aicher, Rebecca*,1, Suding, Katharine1, 1 University of California, Irvine, Irvine, CA, United States
ABSTRACT- In the context of community assembly and re-organization due to enhanced nitrogen (N) inputs, we tested three process-based community assembly models: neutral, deterministic, and stochastic-niche models. The deterministic trait model predicts that initial abundance would have little impact on the resulting community structure due to the importance of species traits. On the other hand, the neutral model predicts that initial abundance would be the primary factor in determining the resultant community structure. The stochastic-niche model predicts that species become established only if propagules can survive stochastic mortality while growing to maturity on the resources left unconsumed by established species. To test these models, we manipulated the relative abundance of twelve native and exotic annual grass, forb, and N-fixing species in a California annual grassland community at three levels of N availability. When a species' propagules were added at high abundance, the species was generally abundant in the community during the first year, regardless of the species' traits. This result supports the neutral model of assembly. However, some species had traits that enabled them to be disproportionately more abundant than predicted solely by the neutral model, thus partially supporting the deterministic model. In addition, community structure was predictably different in the three N environments, even with the same initial species abundances. These results indicate that a combination of neutral and trait deterministic processes affect the structure of California annual grassland communities. Restoration projects can effectively design seed mixtures for target communities based on these community assembly models.
Key words: community assembly, grasslands, restoration