Land Use and Climate Alter Carbon Dynamics in Watersheds of Chesapeake Bay

Sujay S. Kaushal, University of Maryland, skaushal@umd.edu (Presenter)
Michael Pennino, University of Maryland, michael.pennino@gmail.com
Bala Mathukumalli, University of Maryland, mbkp@umd.edu
Shuiwang Duan, University of Maryland, sduan@umd.edu
Melissa Grese, University of Maryland, mgrese@umd.edu
Kenneth Belt, U.S. Forest Service, belt@umbc.edu
Stuart Findlay, Cary Institute of Ecosystem Studies, findlays@ecostudies.org
Peter Groffman, Cary Institute of Ecosystem Studies, groffmanp@ecostudies.org
Raghu Murtugudde, University of Maryland, ragu@essic.umd.edu

There have been long-term changes in the quantity of organic carbon in streams and rivers globally. Shifts in the quality of organic carbon due to environmental changes may also impact downstream ecosystem metabolism and fate and transport of contaminants. We investigated long-term impacts of land use and hydrologic variability on organic carbon transport in watersheds of the Baltimore Long-Term Ecological Research (LTER) site. In small and medium-sized watersheds of the Baltimore LTER site, urban land use increased organic carbon concentrations in streams several-fold compared to forest and agricultural watersheds. Enzymatic activities of stream microbes were significantly altered across watershed land use during a record wet year. During the wet year, short-term bioassays showed that bioavailable dissolved organic carbon varied seasonally, but comprised a substantial proportion of the dissolved organic carbon pool. Similarly, measurements of biochemical oxygen demand across climate variability suggest that reactive organic carbon export from small and medium-sized urban watersheds during storms can be substantial. There were distinct isotopic values of d13C of particulate organic matter and fluorescence excitation emission matrices for streams influenced by different land uses. Stable isotopic values of d13C of particulate organic matter and fluorescence excitation emission matrices showed marked seasonal changes in organic matter quality during floods and dry periods. Across land use, there were differences in seasonal cycles of organic carbon quality and this may have been based on the degree of hydrologic connectivity between urbanized watersheds and streams. Our results suggest that land use and climate can alter quantity and quality of carbon delivered from coastal watersheds and this may have impacts on downstream coastal ecosystem processes.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Kaushal, Sujay: Understanding and Forecasting Impacts of Climate Change and Land Use on Terrestrial Carbon Fluxes in Coastal Watersheds ...details

Poster Location ID: 44