PARENT SESSION
Oral Session #20: Urban Ecosystems: Comparisons Across Biomes, Patterns and process.
Presiding: M. Carreiro
Monday, August 5. 1:00 PM to 3:45 PM. Grand Ballroom West, Radisson.

Stable isotopes of trace gas fluxes as a tool in urban ecology.

Pataki, Diane^*,1, Ehleringer, James¹, ¹ Department of Biology, Salt Lake City, UT

ABSTRACT- Biogeochemical cycling and biosphere-atmosphere exchange can be complex to study in urban areas due to the large influence of anthropogenic disturbance and landscape heterogeneity. However, urban vegetation provides important services to cities, such as partially offsetting CO₂ emissions and mitigating urban heating effects. To incorporate an understanding of ecological processes in urban planning, we must better quantify urban vegetation structure and function in the heterogeneous, modified environment of human-dominated ecosystems. Here we describe the application of stable isotope ecology to quantifying the influence of vegetation on the exchange of CO₂ and water vapor with the urban airshed. We have established a pilot study in the Salt Lake Valley, Utah, to sample the isotopic composition of CO₂ in the atmosphere, vegetation, and soils in and surrounding Salt Lake City. We propose that urban isotope sampling can provide a means of 1) partitioning trace gas emissions into anthropogenic and biogenic components, and 2) studying the ecophysiology of the urban forest. We present preliminary results on the isotopic composition of CO₂ in the Salt Lake City atmosphere and biomass, and on the contributions of natural gas combustion, gasoline combustion, and urban forest respiration to the elevated CO₂ concentrations in Salt Lake City.

KEY WORDS: urban, isotopes, biosphere-atmosphere, fluxes