All seminars are held Thursday afternoons in 147 Clark Hall at 4:00 PM. Reception at 3:30 PM in foyer in front of Clark 147.

23-Jan
Larry Band (University North Carolina) Host: Danny Welsch
Catchment Hydrologic and Biogeochemical Cycling along an Urban to Rural Gradient: The Baltimore Ecosystem Study

30-Jan
Scott Ollinger (University New Hampshire) Host: Jim Galloway
Predicting the Effects of Global Change on Temperate Forest Ecosystems: An Integrated Analysis of Multiple Environmental Stressors

ABSTRACT

Predicting the Effects of Global Change on Temperate Forest Ecosystems: An Integrated Analysis of Multiple Environmental Stressors.

Temperate forest ecosystems have undergone profound changes over the past several centuries as a result of human industrial and agricultural activities. In the eastern United States, important change agents include tropospheric ozone, acid rain and nitrogen deposition, elevated carbon dioxide and historical human land use. Although each of these has received considerable attention for its individual effect on ecosystem function, analyses that examine their combine or interactive effects are relatively rare. This seminar will examine an ecosystem modeling approach for conducting integrated analyses that has recently been applied across the northeastern U.S. in order to better understand the factors affecting present-day carbon and nitrogen cycles. Examples of questions to be addressed include: 1) how can ecosystem-level feedbacks offset or exacerbate multiple-stress interactions, 2) to what extent do present-day rates of net carbon exchange reflect atmospheric change versus prior disturbance, and 3) how can focused, multiple factor analyses help us understand the complex, nonlinear patterns that ecosystems often exhibit.

Finally, in addition to understanding the processes that affect forest biogeochemistry, we also face the question of how to detect present day C and N cycles across heterogeneous landscapes. In the White Mountains of New Hampshire, an ongoing study aimed at addressing this challenge involves the use of high spectral resolution remote sensing to detect nutrient levels in forest foliage. Results from this effort will be briefly reviewed, along with implications for future research activities

6-Feb
Rima Franklin (UVA, PhD seminar) Host: Aaron Mills
Measurements of Spatial and Temporal Heterogeneity in Bacterial Communities

13-Feb
Knute Nadelhoffer (NSF, Biological Sciences) Host: Jim Galloway
Tracing the Fate of N Additions to Temperate Forests on Decadal Time Scales: Implicatons for Carbon Sequestration

ABSTRACT:

"The fate of N inputs to temperate forests at decadal time scales: Implications for C sequestration"

by Knute Nadelhoffer

Some global scale analyses have suggested that human-derived nitrogen (N) deposition in temperate regions could contribute to carbon (C) storage by stimulating forest growth. Some have suggested that inadvertent "fertilization" of temperate forests resulting from N deposition might be removing about one-third of the fossil fuel CO2 released annually to the atmosphere. I have been working with teams of US and European investigators who are using 15N tracers to determine (1) how anthropogenic N inputs to forests might be altering forest N and C balances and (2) whether these inputs are stimulating forest growth and C uptake by forests. 15N is particularly suitable as a tracer for ecosystem-scale studies of N cycling because it is a stable (non-radioactive) isotope with a much lower abundance than the more common 14N. Nine European and North American forest sites were subject to 15N-labelled N additions in the early 1990s in order to determine how atmospheric N inputs cycle within forests and to quantify the effects of N additions on forest growth. Measurements of 15N distributions in forests made 1 to 3 years after N tracer additions showed minimal or no fertilization effect of N deposition. However, measurements being made in these same forests nearly 10 years after N tracers were added will allow for an improved assessments of how N deposition influences forest growth and carbon cycling at local and global scales.

20-Feb
Leonard McMaster (NASA) Host: Jose Fuentes
Aerosols and Radiative Transfer

27-Feb
Tony Wimmers (UVA, PhD seminar) Host: Jennie Moody
Image Processing of GOES Satellite Imagery: Tracer Determination, Boundary Detection and Morphing

6-Mar
SPRING BREAK - - -

13-Mar
Katie Ross (UVA, PhD seminar) Host: Alan Howard
Sediment Retention within Coastal Plain Bottomland Forested Wetlands

20-Mar
Gary Lovett (Institute of Ecosystem Studies) Host: Bruce Hayden
Nitrogen Retention in Forested Watersheds: Do Species Matter?

27-Mar
Dan Druckenbrod (UVA, PhD seminar) Host: Hank Shugart
Forest Dynamics in the Virginia Piedmont

3-Apr
Margaret Leinen (NSF, Geosciences) Host: Jim Galloway
21st Century Environmental Research: How can NSF help you make it happen?

10-Apr
Chuck Hopkinson (Marine Biological Laboratory) Host: Karen McGlathery
Patterns of Estuarine Ecosystem Metabolism

17-Apr
Jean Bahr (University of Wisconsin) Host: Janet Herman
Groundwater as an Ecosystem Resource

24-Apr
Danny Welsch (UVA, PhD seminar) Host: George Hornberger
Soil CO2 Production and Stream Alkalinity Simulations in a Small Mountain Catchment

Environmental Sciences Department 291 McCormick Rd Charlottesville, Virginia (434) 924-7761