I do experimental field research in community ecology. My research interests are fairly broad but center around the ecology of species diversity. In particular, my research addresses four key questions:
1. How is ecosystem function related to trophic and species diversity?
The Earth is currently losing species at a higher rate than that any other time in the last million years. What effect will this loss in species diversity have on vital ecosystem functions, such as carbon fixation and decomposition? This is a large question, but we can begin to get an idea of the answers by using small-scale communities, such as the detritivorous insects in bromeliads (see below) and enclosures in streams. I have been involved in a number of research syntheses in this field.
2. How important is the regional species pool for maintenance of local species richness?
If local species richness depends heavily on regional processes (long-range dispersal, species invasions and evolutionary events), then conservation needs to focus more on the preservation of large regions and dispersal corridors than on the preservation of isolated habitats. This question can be addressed by comparing species richness in similar habitats around the world; we are carrying out such comparisons with bromeliad insects, treeholes insects and bracken herbivores. We are also directly testing this idea by using mites in moss patches.
3. How does habitat affect local species diversity?
I use aquatic insects in Costa Rican bromeliads to examine how habitat geometry and size affects insect communities. Bromeliad complexity appears to provide a stochastic refuge for prey species, but also reduces their searching efficiency for resources. Bromeliad size is linked to drought risk, especially important for the top predator in bromeliads, a long-lived damselfly larva. This may explain why large bromeliads have more trophic levels than small bromeliads.
Our research on mites in moss patches indicates that habitat connectivity is especially important for recovery of communities from catastrophic disturbance. We have also used mites in moss patches as a model system to study the effects of no-take reserves on harvest sustainability.
4. How do human activities affect species diversity?
New research in Costa Rica explores the effects of landscape changes, such as forest fragmentation, on decomposer food webs and processes.
Previous research in Cameroon showed that logging affects the diversity of different taxa in very different ways. Earlier research examined effects of goose management on arctic marshes, and effects of eutrophication on lake vegetation.