Oral Abstract Details

Author(s):
John Hom1, Nicanor Saliendra2, Kenneth Clark1, Matthew Patterson1, Nicolas Skowronski1, Ian Yesilonis1, and David Nowak1

Affiliation:
1US Forest Service Northern Research Station, 2University of Maryland, Baltimore County

Presentation Type:
Oral

Topic Area:
Evaluating changes to ecosystem goods and services along urban-rural gradients

Abstract Text:
Carbon flux measurements and carbon dioxide concentrations were taken along an urban to rural gradient from Baltimore, Maryland, to the New Jersey Pine Barrens. These gradients incorporate the effects of urban vegetation, CO2 emissions from energy use, the effects of land use, as well as natural disturbances and forest management in forested lands and in heavily vegetated non-forest lands. The urban tower in Baltimore is in a mixed deciduous forest, and monitors carbon flux dynamics and carbon dioxide concentrations in this urban/suburban environment. The three rural towers in the Pine Barrens have monitored carbon flux under management and disturbance. Results are presented showing the effects of anthropogenic cycles associated with the work week, land use, vegetation cover, prescribed burning, defoliation and inter-annual climate variability. Using an eddy-covariance system, we obtained net ecosystem exchange (NEE) values stratified according to wind direction from areas of different vegetation cover and land use composition. Both water flux and carbon flux estimates were closely correlated with the percent vegetation cover estimated from remote sensing. However, annual net CO2 exchange at the Baltimore LTER flux site indicated that this urban site was a net source from 2004-2008, with the largest losses occurring during the winter months, due to high CO2 emissions from fossil fuel energy use as well as leaf-off conditions of the deciduous tree cover. A seasonal comparison of the NEE estimates from the urban tower in Baltimore to similar rural forests in the NJ Pine Barrens, allowed us to estimate the amount contribution from fossil fuel emissions in comparison to apparent ecosystem respiration. Despite the large emissions signal, the urban tower showed high C uptake during the growing season due to the high percentage of vegetation cover surrounding the tower. This research shows the range of C losses that can be expected across an urban to rural gradient under the influence of anthropogenic emissions, land use, forest management and natural disturbances. Urban forest benefits and ecological services, primarily carbon sequestration and energy conservation are discussed.