Odum School Faculty
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Population Ecology
Plant-Herbivore Interactions
Ecosystem Processes
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Welcome to our web page. Here you'll find information about current research in the lab and what we've done before.
Background
The common theme running through the various projects in the lab is attempting to understand the causes and consequences of variation in plant quality in ecological systems. We know, for example, that plants as sources of food and shelter are extremely heterogeneous in space and time. From where does this heterogeneity arise? What are the consequences of such variability for population dynamics, trophic interactions, community dynamics, and ecosystem processes?
To answer these questions, we divide our time roughly among four pursuits:
- Documenting spatial and temporal variation in the quality of primary production
- Investigating the biotic and abiotic factors that generate that variation
- Exploring the consequences of variation in plant quality for herbivores and their natural enemies, and
- Trying to understand the role of plant-animal interactions in ecosystem processes such as decomposition and the cycling of nutrients
What Systems Do We Study?
If you look at what we've done in the past, you can see that we've concentrated on studying forest trees, particularly oaks, and the insects that feed upon oak foliage. However, the kinds of questions that we have asked using the oak/insect system are broadly applicable to many kinds of trophic interactions. For example, Sandy Helms is looking at a tri-trophic interaction between milkweed, Asclepias sp., aphids and predators. She is focusing on the effects of temporal and spatial variation in plant quality on insect herbivore population dynamics. Caralyn Zehnder is also studying milkweeds, herbivores, and parasitoids. She is studying the impact of maternal effects on animal-plant interactions and population dynamics. Carmen Hall is studying the effects of increased carbon dioxide on plant quality, insect herbivores, and decomposition in a scrub oak community in south Florida. Chris Frost is examining the effects of herbivory on soil nutrients through frass deposition. He is using a model system of red oak, Quercus rubra, and tussock moths in a controlled microcosm experiment. Kyle Wickings studies the effects of transgenic plants on invertebrate biodiversity. His work will establish whether the products of transgenes are more or less important than other environmental forces in determining above- and below-ground biodiversity. Becky Ball is studying biodiversity at a different scale. She is interested in whether the diversity of leaf litter on the forest floor influences rates of decomposition and nutrient cycling. She is part of a team investigating the role of litter diversity in terrestrial and aquatic systems. Finally, Tom Greenstone is exploring the effects of Hemlock Woolly Adelgid on ecosystem structure and function. The adelgid is slowly killing hemlock trees throughout eastern North America, and Tom is studying the changes in nutrient dynamics and biodiversity that result. Keeping everybody in order is Star Scott, who manages the labs and provides logistical support for all of our ongoing projects
Former students, such as Mike Madritch focused on the role of litter quality in nutrient dynamics and decomposition. He studied the degree to which genetic biodiversity influences ecosystem function in a turkey oak system. Rebecca Forkner studied the relative impact of resource availability to oaks and predation pressure on the population dynamics of oak herbivores. Rebecca Klaper studied the relative contributions of genotypic and environmental variation to the expression of phenolic defenses in turkey oak, Quercus laevis. Kitti Reynolds had a more ecosystem-oriented project, studying the effects of insect defoliation in the canopy on forest floor processes such as decomposition and nutrient cycling. Katie Kearns took some of the concepts developed from studies of chemical induction in oaks and applied them to her work on interactions among cyanobacteria and green algae. Alissa Salmore focused on tradeoffs in the allocation of resources to defense and reproduction in the perennial herb Sanguinaria canadensis.
Last Updated: August 23, 2004
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