Environmental Factors Relating to Landscape Variation in Soil Carbon Fractions in Florida, USA.

Carbon (C) is a spatially and chemically dynamic component in the soil landscape. Environmental information correlated to soil C can help explain the dynamic processes controlling the spatial variability of C fractions. Geospatial models that quantify total soil C and chemical C fractions are needed to elucidate on processes and dynamics of the C cycle. We developed geospatial models of soil C fractions as a function of environmental variables for a large region in the southeastern U.S. (Florida). A regional dataset was collected with 1014 site observations from the top 20 cm of Florida soils (~150,000 km²). Measurements included total C (TC), inorganic C (IC), soil organic C (SOC), hot-water extractable C (HC), and recalcitrant C (RC). A database of environmental covariates such as digital elevation models, satellite imagery, soil map-units and map-unit attributes, land cover/land use, canopy density, and biomass were collected in a geographic information system. Several data mining approaches were tested and compared for modeling of soil C fractions across the whole State using calibration/validation split. We examine the performance of individual covariates to model C fractions. This research provides estimates of TC and several C fractions across a large subtropical region composed of diverse soil-hydrology and land uses.