Effects of Land Use and Vegetation Cover on Soil Temperature in an Urban Ecosystem

Human activity has changed land surfaces by converting native ecosystems to urban and agricultural land uses. This conversion has caused increases in air and soil temperatures that influence soil C and N cycling. Efforts to model changes in soil temperature resulting from urban land use change have not accounted for changes in both plant cover and land use and thus fail to produce accurate predictions at high-resolution spatial and temporal scales. We measured average daily soil temperature at a 10-cm depth at urban and rural forest and grassland sites for 8 yr in the Baltimore, MD, metropolitan area and developed a model of the average daily soil temperature that accounts for two vegetation and two land use types. Average annual soil temperature was higher in urban than rural sites under both turfgrass (15.0 degrees C vs. C vs. 13.5 degrees C) and forest (12.6 degrees C vs. 12.2 degrees C). The application of climate-change scenarios predicted by general circulation models to our soil temperature model suggested that the highest increases in mean soil temperatures will occur in August, September, February, and March, and will range from 1.2 to 2.0 degrees C, while air temperature is predicted to change from 3.4 to 5.6 degrees C between 2070 and 2099. The model can be used to predict the average daily soil temperature in the Baltimore area for sites with similar hydrologic and soil conditions, i.e., remote from the shoreline and characterized by loamy soils.