Available water capacity and organic carbon storage profiles in soils developed from dark brown soil to boggy soil in Changbai Mountains, China

The available water capacity (AWC) is the most commonly used parameter for quantifying the amount of soil water that is readily available to plants. Specific AWC and soil organic carbon storage (SOCS) profiles are consequences of the soil development process. Understanding the distributions of AWC and SOCS in soil profiles is crucial for modelling the coupling between carbon and water cycle processes, and for predicting the consequences of global change. In this study, we determined the variations in the AWC and SOCS from the surface to a depth of 100 cm in soils developed from dark brown soil, skeletal dark brown soil, meadow dark brown soil, white starched dark brown soil, meadow soil, and boggy soil in the Changbai Mountains area of China. The AWC and SOCS profiles were calculated for each main soil group/subgroup using only the readily available variables for the soil texture and organic matter with the soil water characteristic equations. The results showed the following. (1) The AWC and SOCS decreased initially and then increased, before decreasing again in soils developed from dark brown soil to boggy soil, where the maximum SOCS occurred in the white starched dark brown soil, and the maximum AWC in the dark brown soil. (2) The SOCS was decreased by deforestation and concomitant soil erosion, but the negative impact of this decrease in the SOCS in the Changbai Mountains area was not caused completely by reductions in AWC. (3) In the soil development process from dark brown soil to boggy soil in response to deforestation, the AWC distribution differed in the profile and even among individual layers, whereas the SOCS was mainly present in the upper layer.