Arthur H. Johnson
Alain F. Plante
David R. Vann
The study program in terrestrial biogeochemistry examines elemental cycling in ecosystems and its relation to local and global environmental change. These research activities are focused on A) an improved understanding of nutrient availability and cycling in tropical and temperate forests; B) organic matter and carbon biogeochemistry in soils and sediments, and C) long-term variations in nutrient cycles after natural and anthropogenic disturbances. This research is field-based and experimental and uses traditional mass-balance approaches as well as stable-isotope techniques and laboratory experiments. Many of our studies are collaborative and have involved researchers from other Departments at UPENN, the Long-Term Ecological Research Network, the USDA Forest Service, the Stroud Water Resource Center, and various U.S. and international universities.
To accomplish this research, we have a broad range of both field and laboratory equipment. Our long-term field sites include permanent plots in the Canadian Artic, the Adirondacks, the Green Mountains, New England, the Mid-Atlantic States, Puerto Rico, and Chile. In addition to the equipment in the research facilities of the University of Pennsylvania, the laboratory equipment within the Department includes a Carlo Erba elemental analyzer, Technicon autoanalyzer, Spectro Genesis ion-coupled plasma spectrograph, x-ray diffractometer, Delta mass spectrometer, Netzsch simultaneous thermal analyzer, automated grain size analyzers, gas chromatographs, and an infra-red gas analyzer for CO2 measurement.
Ongoing Research Projects:
While EES Faculty and research staff work on a variety of projects at any given time, and graduate students are encouraged to develop their own projects, the Department has several of areas of ongoing research, including:
1. Temperate Ecosystem Carbon Accumulation and Storage. In cooperation with the USDA Forest Service Global Change program and a network of Universities we are conducting field and modeling studies of the accumulation and storage of aboveground and soil carbon in New England, the Great Lake States, and the Mid-Atlantic region of the United States. Research involves the quantitative sampling and modeling of both chrono-sequences and unique longitudinal studies that span multiple decades.
2. Nutrient Dynamics of Tropical Watersheds. A 20 -year record of watershed scale forest structure, litterfall, soil chemistry, and aquatic nutrient fluxes is being maintained in the Luquillo Mountains of Puerto Rico with the help of the USDA Forest Service International Institute of Forestry and the Luquillo Long-Term Ecological Research program. This record, one of the most detailed available for any ecosystem, is being analyzed and modeled to evaluate the influence of natural disturbances and environmental change on watershed productivity, biodiversity, and nutrient stoichiometry.
3. Characterization of organic matter dynamics and mechanisms of stabilization: A suite of biological, chemical, thermal, and physical fractionation techniques are being used to characterize soil organic matter and explain the mechanisms that stabilize organic residues in soils. The overall focus of the research is to understand the mechanisms responsible for the long-term sequestration of carbon in soils and to help predict soil organic matter dynamics in response to global and environmental change. Contact A. Plante for additional details.
4. Nutrient dynamics of Montane Cloud Forests: The Department has a long history of studies on the biogeochemistry of both tropical and temperate cloud forests. Permanent research sites exist in the Tropical Cloud Forests of Puerto Rico, the Chioli region of Chile, (a location of one of the world’s only non-polluted, old growth cool-temperate forests), the Green Mountains of Vermont, and the Adirondacks Mountains of New York.