1) Large-scale spatiotemporal population dynamics of forest-defoliating insects
I am interested in why population abundance tends to fluctuate synchronously across space and why the populations of many species exhibit cyclical "boom-or-bust" dynamics. I have been working on these questions by studying spatial and temporal patterns in the outbreaks of forest-defoliating insects and using these patterns to inform mechanistic simulation models that allow me to study the roles of underlying biotic (e.g., natural enemies) and abiotic (e.g., Moran effects induced by weather) processes. My primary study subject is the gypsy moth, one of the most damaging forest pests in North America.
2) Effects of climate change on forest-defoliating insect populations and forest dynamics
Many studies predicted that climate warming would increase the frequency and severity of outbreaks of forest-defoliating insects. Though some species show these responses, the few studies that have examined the outbreak histories of defoliator species, have revealed few generalities in their responses to climate change. Interestingly, one of the more common effects seems to be collapsing of population cycles. To date, my main approach has been use of a variety of time-series analysis techniques to study temporal variation in population dynamics and to uncover the underlying climatic drivers.
I am also studying the effects of climate changes on aspects of forest health, such as the growth and mortality of trees. Rising temperatures, increasing frequency of summertime drought, and increased susceptibility of trees to herbivorous insects resulting from these climate changes are expected to cause widespread tree mortality and shifts in forest composition. I am currently working with several colleagues on developing methods for quantifying the effects of such threats through time and over large spatial extents.
3) Light pollution: ecological impacts
I examine the ecological impacts of light pollution (artificial light at night) through collaborations with graduate students and undergraduate participants in the NSF-funded Research Experiences for Undergraduates (REU) program. Currently, Ph.D. student Melissa Hey is examing effects of light pollution on ecosystem processes including primary production and decomposition. Ariel Firebaugh recently earned her Ph.D. studying how light pollution impacts the demography (dispersal and mating success) of bioluminescent fireflies. Undergraduate (REU) students are examining the effects of light pollution on plant-herbivore interactions.