Monday, November 13, 2006
89-9
Characterization of Changes in Soil Structure along an Urban-Rural CO2 / Temperature Gradient.
Hyen Chung Chun1, Daniel Gimenez1, Lewis Ziska2, Kate George3, and Richard Heck4. (1) Rutgers, The State University of New Jersey, 14 College Farm Rd, New Brunswick, NJ 08901-8551, (2) Crop Systems & Global Change , Agricultural Research Service, USDA, Building 1, Room 342, 10300 Baltimore Ave., Beltsville, MD 20705, (3) Crop Systems & Global Change, Agricultural Research Service, USDA, Building 1, Room 342, 10300 Baltimore Ave., Beltsville, MD 20705, (4) Land Resource Science, University of Guelph, Guelph, ON N1G 2W1, CANADA
Soils are an important component of terrestrial ecosystems. Soil carbon affects soil formation and soil structure, which in turn leads to changes in biota and nutrient cycling. Changes in soil biota and nutrient cycling caused by elevated atmospheric carbon dioxide have been documented, but there is no report on its potential effects on the morphology (heterogeneity) of soil structure. The objective of this work was to measure changes in soil structure using three dimensional images of soil sampled from sites located along a natural gradient of CO2 and temperature. Plots located in urban, suburban, and rural areas in Maryland were excavated and filled with the same fallow agricultural soils in 2002. The maximum differences in temperature and carbon dioxide between the urban and the rural plots was about 3° C and 20%, respectively. On May 2006, undisturbed samples were taken in triplicate from selected plots at each site and scanned with a computer tomography to obtain 3-D images. Soil structure was quantified with a normalized entropy applied to 3-D images. Preliminary results of this study showed that soil heterogeneity increases with increases in CO2 and temperature (urban > suburban > rural soil). Other measures of soil structure such as pore size distribution and pore connectivity will be discussed. Alteration of soil structure during climate change is likely to impact the ecology of soils.