Global environmental changes are redistributing both native and exotic plant species ranges, and innovative management strategies that allow us to react quickly and optimally are necessary to confront these looming changes. Developing a framework for understanding plant population responses to environmental changes will require bringing ecological theory and data together to harness the power of logic. My research integrates theoretical plant ecology and quantitative global change biology, with a focus on plants with changing ranges. I develop mathematical models, use simulations, conduct controlled field experiments, and incorporate ecological data to uncover the causes and consequences of the spatial spread of plants in a world with increasing anthropogenically-driven environmental change. My research is structured by the following overarching questions:
- How will plant distributions shift in response to climate change?
- How does climate change alter the mechanisms that affect invasive species spread and the response of native plant communities to invasive species?
- What mechanisms provide the opportunity for plant species to coexist, and how will changing environmental conditions alter patterns of plant coexistence?
- How can we use models and theory to understand how plant populations will respond to future unexpected and rapid environmental changes?
Past Projects
Trailing-edge zombie forests can increase population persistence in the face of climate change
As ranges shift, individuals at the trailing range edge may be some of the oldest, most reproductive individuals, left behind in an environment that is no longer climatically optimal. These mature trees form “zombie forests”, which may persist for decades after the climate has shifted, still dispersing seeds, many of which will likely have limited recruitment success in the suboptimal environmental conditions of the trailing edge. Are these zombie forests simply the remnants of ecosystems past, or do they play an ecological role in supporting population persistence in the face of climate change? I developed a data-driven mathematical model that shows that populations with remnant individuals at the trailing range edge can withstand faster speeds of climate change than those without. These findings suggest that conservation strategies that preserve zombie forests could improve tree population persistence in the face of climate change.
Sea-level rise can reverse the conditions that promote the spread of ecosystem engineers
Plant-environment feedbacks can influence the spread of invasions. Some invasive plants are ecosystem engineers, capable of modifying their local environment. For example, salt marsh grasses accumulate sediment that raises the height of the population relative to sea-level. Low levels of sediment accumulation are optimal for population spread. I developed a spatial model that shows that sea-level rise can reverse the conditions that drive high rates of spatial spread. The model demonstrates that with sea-level rise, high rates of ecosystem engineering will be necessary for population persistence. This suggests that controlling invasive marsh populations may become more difficult with increasing sea-level rise. Moreover, ecosystem engineering can serve as a mechanism for adaptation to climate-driven changes in environmental gradients. Ecosystem engineering has the potential to rescue both exotic and native plant populations from climate-driven decreases in habitat suitability.
This work is published in Theoretical Ecology: https://link.springer.com/article/10.1007/s12080-022-00548-8 (or free to view version here rdcu.be/c0626)
Post-invader-removal community recovery is resilient to major climate perturbations
Climate change can play a critical role not only during a biological invasion, but also after the invasion, during native community recovery. Extreme climatic events have become more frequent and intense with global climate change. How will projected extreme climate perturbations affect the already dubious benefits of exotic species removal for native community recovery? I used a carefully controlled exotic species removal field experiment, fortuitously followed by a natural drought-fire-deluge sequence, to assess the success of exotic species removal at restoring a native Californian grassland. I found that the benefits of an intensive invasive species removal program can persist even through a series of major climatic perturbations.