Upper Hudson (green) and Upper Delaware watersheds (blue), and the streams of the Upper Delaware watershed found within Pennsylvania.
Plant community ecology
The lab's primary research is in plant community ecology, focused on the diversity and species composition of the riparian zones of small streams. Study regions include the Delaware watershed (Pennsylvania) and other waterways of eastern Pennsylvania, as well as the Upper Hudson watershed (New York). We integrate field observational studies and greenhouse experimental approaches to understand what factors govern the organization of riparian plant communities and how they differ from nearby upland communities. We also use plant functional traits to help explain the composition of riparian plant communities and biological invasions in those communities.
River corridors may contribute to the spread of introduced species across the broader landscape, and invaders are often very common in riparian zones. The lab's research examines why introduced species are successful in these habitats, and how common invasive riparian plants like Japanese knotweed (Fallopia japonica (Houtt.) Ronse Decr.) can affect the health of stream macroinvertebrate communities.
We have developed several research projects surrounding the ecology of common milkweed (Asclepias syriaca) and other Asclepias species. These include work on the effect of oleander aphids (Aphis nerii) on the relationship between milkweeds and monarch butterflies (Danaus plexippus), and interactions between milkweed and firefly species.
Disturbance is a fundamental concept in ecology, but also an extremely broad one. In the context of riparian zones, for instance, the term disturbance could be used both to describe a natural flood event and to describe the complete loss of a flood regime following the construction of a dam upstream. We study role of multiple types of disturbances, particularly distinct aspects of flood events, in the success of riparian species and in structuring riparian plant communities.
Our conservation-related research addresses a variety of questions in applied conservation ecology, from both biological and policy perspectives.
With Susan Tsang, we are working to bridge theoretical and applied conservation biology in the islands of southeast Asia. We are developing models to more effectively designate currently occupied area by endangered flying foxes (Pteropus). Species ranges are often defined simply as the entire area of any islands on which these species are found, but in reality, many occupy very restricted habitats. We are working to identify more accurate ranges for these species. We are also using this group as a case study to incorporate strict habitat requirements into species-area relationship models.
Other recent projects
In collaboration with Dana Opulente and the Hittinger lab (UW Madison), we examined assemblages of yeast species found in different environments, correlations between metabolic traits and those environments, and trade-offs between metabolic traits.