Impacts of land cover changes on soil chemical properties in Taihang Mountain, China

The original forest in Taihang Mountain of China has been destroyed by converting to cropland, cutting wood for fuel demand and cattle grazing before 1970s. During the past two decades, great efforts have been made to restore the local vegetation, such as conversion of cropland to forest or pastureland in the area with slope gradient higher than 25 and banning of cattle grazing in forest land. The objective of this research is to investigate whether these vegetation recovery efforts had resulted in positive impacts on soil chemistry by comparing the measured data between 1986 and 2008. The measured soil chemical variables included soil organic matter (SOM), total nitrogen (N), total phosphorus (P), total potassium (K), total iron (Fe), total sodium (Na), total calcium (Ca), total magnesium (Mg), total manganese (Mn) and total zinc (Zn). The results indicated that the vegetation community height and biomass have been significantly increased. The SOM content has stopped decreasing. The collected N in B horizon, K, Na, Fe, Mg and Zn in both A and B horizons showed significantly higher level in 2008 compared with 1986. This might be due to the increased soil nutrient pool from the decomposition of the litter and decrease in nutrient loss from soil and wind erosion. In both A and B horizons, measured Ca in 2008 were significantly lower than 1986, which might be due to the long-term impacts of clearing of historical forest. The collected 2008 data indicated that slope aspect had no impacts on all the soil chemical variables in both A and B horizons. At earlier stage of the recovery of forest ecosystem, the impacts of slope aspect might be limited.