PARENT SESSION
Symposium 11: Digging Deeper or Scratching the Surface? Exploring Ecological Theories in Urban Soils.
Organized by: M Pavao-Zuckerman and L Byrne
Wednesday, August 4, 8:00 AM to 10:30 AM, Oregon Ballroom 203.
Anthro-soils: Urban effects on soil carbon pools and fluxes±.
Pouyat, Richard1, 1 USDA Forest Service, Baltimore, MD
ABSTRACT- Urban land-use change can potentially affect biogeochemical cycles through altered disturbance regimes, landscape management practices (e.g., irrigation and fertilization), built structures, and changes in environmental factors (heat island effect, pollution, introduction of non-native species, loss of native species). These changes have created novel ecosystems, which have the potential to significantly affect carbon pools and fluxes. For urban ecosystems, very little data exists to assess whether urbanization leads to an increase or decrease in soil C pools. I will present two data sets to assess the potential for urbanization to affect soil organic C. These included surface (0-10 cm) soil C data from unmanged forests along urban-rural gradients, and data from made soils (1 m depth) from several different cities, including New York City and Baltimore, MD. Along the New York City urban-rural gradient, soil organic matter concentration and organic C densities in the surface 10 cm varied significantly among land-use types(P = 0.001 and 0.02). These results suggest that urban environmental changes can affect soil C pools even in forests that are not directly or physically disturbed by urban development. Our analysis of pedon data of made soils showed that the highest soil organic C densities occurred in recently formed dredge fill (28.5 kg m-2) with the lowest occurring in clean fill and old dredge materials (1.4 and 6.9 kg m-2, respectively). Soil organic C densities for residential areas (15.5 ± 1.2 kg m-2) were consistent across cities. These data suggest that soil C storage in urban ecosystems is highly variable with very high and low C densities (kg m-2 to a 1 m depth) present in the landscape at any one time. For those soils with low SOC densities, there is potential to increase C sequestration through management, but specific urban related management techniques need to be evaluated.
Key words: urban soil, urban ecosystems, soil carbon