SOIL NUTRIENT CONCENTRATIONS AND STOICHIOMETRY IN RESPONSE TO LAND-USE TYPES IN A TYPICAL SUBTROPICAL MOUNTAINOUS AREA OF SOUTHWEST CHINA

The effects of land use change on soil texture and nutrient have been widely documented; however, knowledge of the imbalances in soil nutrient stoichiometry remains limited, particularly with respect to the relationship with land-use type and soil nutrient limitation under 'Grain for Green' project(GGP) in subtropical mountainous ecosystems. Here, we assessed the soil nutrient concentrations and stoichiometry in afforestation land (FL) abandoned land (SL), native grassland (GL) and cultivated land (CL) under GGP in a typical subtropical mountainous region from Yunnan-Guizhou Plateau of southwest China. Soil organic carbon (SOC), total nitrogen (STN), and total phosphorus (STP) concentrations were significantly lower in SL than in FL, GL and CL. The lower SOC, STN, STP concentrations, and consequently lower SOC, STN, STP storages (0-30 cm) in SL resulted in significant differences of SOC:STN and SOC:STP ratios between SL and other study sites. Compared with Chinese and global scales, the higher average STN:STP ratio and lower average STP concentration in our study sites suggest P limitation. Our results demonstrate that considerable human activities affect the soil nutrient concentrations and stoichiometry, and more available P inputs should be applied and the vegetation of abandoned land should be reconstructed rather than natural restoration under GGP in the typical subtropical mountainous area of southwest China.