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Abstract
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Identifying changes in soil organic carbon stocks (SOCS) is essential for determining appropriate ways to deal with land degradation, understand soil and crop management and for gathering useful information for a range of environmental studies. The aim of this study was to predict SOC stocks, including topsoil (0-30 cm) and subsurface (30-60 cm), and compare under current (i.e. forest, wetland, cropland, urban) and potential future land uses. Soil organic carbon (SOC) and bulk density ( - g/cm3) were measured at 137 locations across the Marivan, Kurdistan Province, Iran and soil SOCS was computed from the SOC and . To improve estimates based on the limited number of soil samples, particularly in locations where no samples had been collected, auxiliary data including, terrain attributes and Landsat 8 ETM+ data were acquired. Random Forest (RF) models were used to relate the SOCS to the auxiliary data. Current and potential future land use maps were made and carbon sequestration was calculated. Based on validation statistics, the RF model predicted SOCS best at a depth of 0-30 cm. Results also suggested that the mean SOCS in the topsoil and subsurface in croplands were lower than forestland and wetland, although not significantly so. In the area, approximately 18.48% of forestland and 17.39% of wetland have been brought into cultivation. We estimate that this has led to a loss of SOCS from forestland topsoil of 22,860 Mg C and subsurface of 15,685 Mg C. The SOCS loss from wetland topsoil and subsurface were not as great at 4,193 and 2,680 Mg C, respectively, but this was due to the size of the area not being as large.
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