The spatial distribution of soil carbon and nitrogen in a regional matrix of urban, agricultural, and desert ecosystems.
Kaye, Jason*,1, Majumdar, Anandamayee2, Gries, Corinna2, Hope, Diane2, Zhu, Weixing3, Grimm, Nancy2, Jenerette, Darrel4, Baker, Larry5, 1 Pennsylvania State University, University Park, PA2 Arizona State University, Tempe, AZ3 Binghamton University - SUNY, Binghamton, NY4 Ohio State University5 University of Minnesota
ABSTRACT- Accurate predictions of regional C and N pools are important to global change research but urban ecosystems are typically excluded from both small and large scale estimates of soil C and N storage. We analyzed the regional distribution of surface soil C and N in urban, agricultural, and desert land-use types in a 6400 km2 study region near Phoenix, AZ. At 200 points within the study region, we measured surface soil C and N and 13 geomorphic, ecological, and socioeconomic independent variables. A hierarchical Bayesian regression analysis showed that a relatively small number of independent variables (2 to 4) explained more than 70 % of the variance in region-wide soil C and N and that about half of the residual variance was attributable to spatial autocorrelation. Both geomorphic (elevation, slope) and socioeconomic (per capita income, landscape design) factors were important predictors of soil C and N pools. Soils from mesic lawns contained the most organic C, inorganic C, and total N, while desert soils contained the least. These results suggest that both biological processes (for organic C) and irrigation (for inorganic C) are causing C accumulation in urban ecosystems. Previous analysis found that this region was accumulating N and our results suggest that some of this N is accumulating in urban mesic lawns.
Key words: land use change, soil carbon storage, soil nitrogen storage, urban ecosystems
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