HR: 1340h
AN: B43D-1586    [Abstracts]
TI: Contributions of Deciduous and Evergreen Trees to the Seasonal Dynamics of CO₂ and Water Vapor Exchange Over Developed Land in the Midcontinental United States
AU: * Peters, E B
EM: pete1679@umn.edu
AF: University of Minnesota, Department of Ecology, Evolution and Behavior, 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, MN 55108,
AU: Montgomery, R
AF: University of Minnesota, Department of Forest Resources, 115 Green Hall, 1530 Cleveland Ave. N., Saint Paul, MN 55108,
AU: McFadden, J P
AF: University of Minnesota, Department of Ecology, Evolution and Behavior, 100 Ecology Building, 1987 Upper Buford Circle, Saint Paul, MN 55108,
AB: Half the world's population currently lives in urbanized areas, a proportion expected to increase to 60% by 2030. The clearing of agricultural and natural ecosystems for urban and suburban development is consequently one of the fastest rates of land use change around the world. Although developed land areas represent major sources of CO₂ and alter hydrology, they are also ecosystems with significant vegetation cover that takes up CO₂ and humidifies the atmospheric boundary layer. Direct measurements are needed to develop a mechanistic understanding of how vegetation contributes to the land-based CO₂ sinks and evapotranspiration in developed areas, especially residential developed land which accounts for most of the land-use change in the United States. We quantified whole-tree transpiration, and modeled canopy conductance and canopy photosynthesis using thermal dissipation sap flow and leaf-level gas exchange measurements on stands of deciduous and evergreen trees in a suburban residential neighborhood of Minneapolis-St. Paul, Minnesota. A suite of environmental variables was continuously monitored at each site. During the 2007 growing season, seasonal drought and synoptic and diurnal variations of vapor pressure deficit (VPD) strongly controlled transpiration and photosynthesis in both the deciduous and the evergreen stands. The results are analyzed against a phenology data set (including leaf area index (LAI), and plant and soil biophysical properties) measured at a larger number of stands within a suburban region during the 2006 growing season. These results will allow us to determine the relative contributions of different tree plant functional types to the seasonal dynamics of CO₂ exchange and evapotranspiration in developed land, and to scale up the effect of these land cover types on regional carbon and water budgets. This study is a contribution to the North American Carbon Program (NACP) Mid-Continent Intensive Field Campaign.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0476 Plant ecology (1851)
DE: 0493 Urban systems
SC: Biogeosciences [B]
MN: 2007 Fall Meeting