A Study of Soil Characteristics across an Arid, Urban Landscape and their Relationship with Greenhouse Gas Emissions

The heterogeneous nature of urban systems is a documented phenomenon that can potentially cause widespread changes in soil characteristics across urban habitat type. These differences in soil characteristics may be linked to hot spots within the city of greenhouse gas (N2O, CO2, CH4) emissions, which have the potential to affect global climate. The purpose of this study was to take an in depth look at how soil characteristics (i.e. soil moisture, organic matter, and inorganic nitrogen) vary across the urban Phoenix landscape and how these differing landscape characteristics can potentially create hot spots of greenhouse gas emissions. We measured greenhouse gas emissions and soil characteristics from ten different landscape types during the summer and fall of 2013 and included a wetting experiment to simulate flooding events in the desert. Using statistical analyses we found that all soil characteristics varied significantly based on both season and land-use type. In addition, land-use types could be clustered into recognizable groups based on their soil characteristics, with the presence of irrigation being a strong deciding factor in how the groups were arranged. However, N2O emissions did not vary significantly based on season, land-use type, or the presence of a wetting experiment. Patterns reinforce the heterogeneous nature of the Phoenix urban area and suggest that N2O emissions may not relate to soil characteristics and habitat designations (i.e. human land use) in the way that we originally predicted.