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Urban Soils and Nutrient Cycling

Urbanization contains many processes that directly and indirectly alter urban soil chemical, physical, and biological properties and processes.  As soil is a critical medium that directly affects the health and structure of trees growing in both woodland and managed urban landscapes, these alterations can have significant impacts on how to manage and sustain forest structure and health in urban and urbanizing landscapes.  However, due to complexities of the urban environment, little is known about the attributes and variation of urban biogeochemical processes, particularly the storage and fluxes of carbon and nitrogen. These chemicals impact climate change, tree health, and water quality. Urban environmental factors that can influence biogeochemical processes in urban and urbanizing landscapes include modified meso-climate (urban heat island), increased concentrations of atmospheric pollutants (nitrous oxides, sulfur oxides, ozone, heavy metals, organic chemicals, particulates), modified disturbance regimes, soil management practices (fertilization, irrigation), and compositional changes of plant and animal communities. 

Soil classification systems attempt to organize soil variability into useful groupings that are identifiable by field investigation and documented in soil survey activities to promote effective resource management and information transfer. Soils produce urban ecosystem services, e.g., water infiltration and purification, as the “brown infrastructure” of urban ecosystems, much in the same way urban vegetation, or green infrastructure, provides various ecosystem services.  An understanding of how urban land-use and environmental change affects soil ecosystem services is needed.

The purpose of our research is to 1) characterize soils in an urbanized watershed (Gwynns Falls, Maryland) which is being monitored and investigated in the Baltimore Ecosystem Study (BES); 2) identify key soil properties (chemical, physical, biological) and their spatial distribution and relationship with other factors (e.g., social, hydrologic, vegetation) in the watershed; 3) organize these properties as descriptors and diagnostic properties for the development of an urban soil classification system to aid urban managers; and 4) develop an urban soil quality index with respect to human and tree health. This research also addresses how soil carbon and nitrogen storage and fluxes vary across 1) different land-use types typically found in urban landscapes and 2) forest patches situated along an urbanization gradient. 

For more information please contact Ian Yesilonis, Soil Scientist.