Chemical and Biological Characteristics of Remnant Soils Along Urbanization Gradients.

The study of forest ecosystems in urban areas is important, not only because of the spatial extent of urbanization, but because such areas provide an excellent opportunity to study how changes in temperature, atmospheric chemistry, and species composition interact to affect soil chemical and biological characteristics.  For example, older cities generally have had a history of heavy industrial activity and are often characterized by having higher deposition of heavy metals and warmer temperatures than surrounding areas.  Newer, less industrialized cities, while having warmer temperatures than surrounding areas, may not experience the deposition levels of an older industrial city.  These contrasts provide an opportunity to compare environmental factors that can affect soil characteristics.  In this presentation, I consider the unique abiotic and biotic aspects of forest ecosystems embedded within urban, suburban, and rural areas (i.e., urbanization gradients) and describe how urban environments can be used as study subjects of multiple anthropogenic impacts on soils, including potentially climate change.  I then present case studies to describe the use of urbanizing gradients to make these investigations.  Results thus far suggest that soils of remnant forests embedded within urban or suburban areas are altered by environmental changes occurring along the gradient.  For instance, forest soils within or near urban areas often receive high amounts of heavy metals, organic compounds, and acidic compounds in atmospheric deposition, while the soil invertebrate community is often dominated by introduced species.  These changes in turn have an effect on carbon and nitrogen dynamics.   Finally, I compare the results of several urbanizing gradients across different metropolitan areas to see if a generalized pattern exists.