Causes and consequences of exotic plant invasions
Why are some exotic plant species able to become dominant in a local plant community while others remain minor constituents? This is an important but difficult area of research in ecology. To date, research presents mixed and contradictory results of the relationship between phylogenetic novelty and invasiveness. We hope to resolve some of this variation with a synthetic approach that considers the spatial scale of the analysis and the stage of invasion.
How do biotic resistance (competition), enemy release and habitat disturbances influence the success of exotic plant species? We address this by conducting field experiments that examine multiple mechanisms of invasion and their interactions on exotic plant population dynamics. In addition, we are synthesizing the effects that natural enemy introductions have on the fitness and population dynamics of exotic weeds.
What determines the commonness and rarity of plants in island ecosystems? We address this question with a detailed case study in Hawaii on the functional traits and community composition of plants at multiple spatial scales and with a global analysis on the relative abundances of plants at local scales in island ecosystems.
Role of human perturbations on plant-pollinator interactions and pollen limitation
Pollen limitation occurs when plants produce fewer fruits and/or seeds than they would with an adequate receipt of pollen. Our research aims to understand the drivers of pollen limitation on a global scale by correlating the results of pollen supplementation experiments with plant traits, pollination syndromes and environmental factors. In addition, our research will address the likely consequences for pollen limitation for plant population and community dynamics and for mating system evolution.
How have human changes to the environment influenced the stability of plant-pollinator networks? Our research addresses this by examining how exotic plant introductions influence network structure. Further, we examine how climate and land use change influence plant-pollinator networks over long time periods by using historic data collected by naturalists in the late 1800s.
Restoration of degraded habitats
How can we optimize our restoration efforts to increase the abundance and diversity of native species? Our research in restoration involves 1) two long-term experiments on community assembly of prairie and glade ecosystems in St. Louis, Missouri, 2) examining the effects of large-scale habitat restoration on the endangered plant, Lupinus tidestromii, in California, 3) synthesizing the effects of coastal sand dune restoration projects on the population dynamics of rare plant species and the composition of plant communities, and 4) quantifying at the optimal timing of reintroducing fire to fire-suppressed ecosystems.
Forest community dynamics
Forest ecosystems have economic and cultural value, and provide vital ecosystem services. We contribute to global efforts to understand the macroecological patterns of tree species, and assess the threat to these species, in collaboration with Botanical Garden Conservation International and the Chicago Botanic Garden. Our first site for this research is a case study in the diverse country of Fiji.