Investigating Sub-Tropical Community Resistance and Resilience to Climate Disturbance
Changes in global climate will likely increase climate variability. In turn, changes in climate variability have begun to alter the frequency, intensity, and timing of climate disturbances. Continued changes in the climate disturbance regime experienced by natural systems will undoubtedly affect ecological processes at every hierarchical scale. Thus, in order to predict the dynamics of ecological systems in the future, we must develop a more mechanistic understanding of how and in what ways climate disturbance affects natural systems. In South Florida, two climate disturbances recently affected the region, a severe cold spell in 2010, and a drought in 2011. Importantly, these disturbances affected an ecosystem of long-term, comprehensive, and persistent ecological study in the Shark River estuary in the Everglades National Park. The aims of my dissertation were to (1) assess the relative severity of these two climate disturbances, (2) identify effects of these disturbances on community structuring, (3) compare community change from the 2010 cold spell with community change from another extreme cold spell that affected sub-tropical China in 2008, (4) assess the effects of the drought on predator prey interactions in the Shark River and (5) apply a spatial approach to predicting population resistance to these events. My results show that the 2010 cold spell was the most severe cold event to affect the Shark River in the last 80 years, while the drought was the worst drought to occur in the last 10 years. The cold spell drove community change that was predictable based on the traits of component species, whereas community change was less predictable using trait-based approaches. When comparing community change from the extreme 2010 event in Florida with the event in China, I identified three consistencies related to community change from extreme cold events that occurred across both events that will help build generalized understanding of community resistance to increasingly extreme climate events in the future. From the trophic study, I found that the drought reduced prey for estuarine piscivores. Not only was prey biomass reduced, the drought drove a compositional shift in prey communities from fish to invertebrates, which are lower in calories. Last, I found that animal movement may create temporally dynamic resistance scenarios that should be accounted for when developing predictive models.