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.

City collembolan, country collembolan: A tale of lawn and garden landscape ecology.

Byrne, Loren^*,1, ¹ Pennsylvania State University, University Park, PA, USA

ABSTRACT- Landscape ecology is the study of the causes and consequences of spatial heterogeneity. Because urban ecosystems have highly heterogeneous distributions of habitat and resources, they are ideal for examining the creation and ecological effects of spatial patterns. To elucidate the importance of human activities on landscape patterns and processes, I developed a conceptual framework using habitat structure to link human habitat management, abiota, biota and ecosystem functions. To test this framework, a field experiment was initiated in which soil variables and arthropods were measured in four urban habitat structures: lawn, unmowed vegetation and two mulched garden habitats. Soil variables (bulk density, pH, nitrate) and microclimates differed significantly among the habitats. Soil moisture was upwards of 20% greater and ground temperatures were 10 to 20 °C warmer in the mulch habitats than in lawn and unmowed habitats. These abiotic conditions, in addition to carbon availability, likely influenced arthropod abundances which also differed among the habitats. For example, in June 2003 entomobryomorpha collembolans tended to be more abundant in bark mulch while sminthurid collembolans were more numerous in unmowed habitats. In July, sminthurid numbers were significantly greater in lawns and entomobryomorphan numbers did not differ among the habitats. Such trends suggest that arthropod population fluctuations in urban landscapes may be novel and unpredictable due to high heterogeneity of resources and microclimates. Data collection will continue in 2004 for arthropods and carbon and nitrogen cycling. However, it is clear from this experiment and other research that microclimate and soil physiochemical variables are critical to measure in urban ecology investigations because of their potential to interact and generate feedback loops with biodiversity and ecosystem functions in unpredictable ways. Habitat structure provides a conceptual link to integrate studies on the ecological effects of landscape heterogeneity with urban, community and ecosystem ecology.

Key words: collembola, habitat structure, urban ecology, soil ecology