I am a plant ecologist studying biological invasions and their impacts on native plant communities and ecosystems. My research program seeks to understand the role of plant interactions in influencing plant community composition, shaping the links between plant community composition and the functions of invaded ecosystems, and predicting which nonnative, invasive species are likely to have the largest impact. Because invasive species are an environmental management concern, I design research that can inform invasive management policy and practice.
My research explores how interactions among invasive plants change the impacts that individual invaders have on plant communities and ecosystems. This line of research is novel and understudied, representing a theoretical gap in invasion biology and an applied challenge for managers. Studying invasive species provides opportunities to test fundamental questions in plant ecology, such as what factors drive plant community assembly processes and how changes in plant community composition affects ecosystem functions. I use observational studies, greenhouse and field manipulations, literature reviews and syntheses, and statistical and null modeling approaches in my research. Specifically, my research addresses the following questions:
1. How do interactions between co-occurring invasive plant species affect plant community structure and ecosystem function?
Most studies of invasive plants consider single species invasions even though many ecosystems contain multiple invasive plant species. My previous research has focused on understanding what types of interactions (negative, neutral, and positive) are most common between invaders, and how these interactions shape invader impacts and community composition. I have shown that co-occurring invaders can have non-additive impacts on soil properties, and that interactions between nonnative plants differ from interactions between native plants. Taken together, my research indicates that interactions between nonnative species can differ from interactions among closely related native species, and that these interactions can drive differences in plant community structure and function.
2. How do plant-soil interactions affect the presence, abundance and impact of nonnative plants?
Another potential driver of future plant community composition is the influence of nonnative species in communities they invade. Nonnative plants are associated with changes in soil biotic and abiotic properties, and I am particularly interested in understanding how these plant soil interactions influence community composition and nonnative plant impacts. Previously, I have used greenhouse and field experiments to test how co-occurring nonnative and native species influence soil properties and the future growth of other plant species. I have found that nonnative plants promote other nonnative species by altering soil biotic communities that favor the co-existence of co-occurring nonnatives as well as other nonnative plants, and that the biotic soil legacies of co-occurring nonnative shrubs can non-additively increase the growth of other nonnative species.
3. What abiotic and biotic factors influence plant community composition, patterns, and impacts of nonnative plants?
The composition of contemporary plant communities is a function of environmental variation and biotic interactions. My research seeks to understand the relative importance of abiotic and biotic drivers of plant community composition, and specifically to understand whether different mechanisms promote native and nonnative species recruitment into plant communities. My previous research has investigated how environmental conditions, co-occurring disturbances, or the presence of other invasive plants influence the presence, abundance, and impact of invasive plants.
4. What are the drivers of “invasion treadmills”, and how can conservation managers avoid them?
Because nonnative plants can have significant and long-lasting impacts, land managers spend substantial time and money managing nonnative invasive species. The reinvasion of sites managed for invasive species—either by the target nonnative or a secondary nonnative species—is an increasingly common impediment to achieving restoration goals. Researchers and practitioners have labeled this phenomenon an “invasion treadmill”, and successful invasive species management in conservation areas demands that researchers and practitioners develop a better understanding of the relative importance of the ecological mechanisms that promote invasion treadmills. I am interested in understanding the successional patterns of plant communities after management for nonnative species, and specifically how legacy effects of invaders may drive post-invasion succession.