Effects of utilization types on soil properties of forest-grassland in Lanzhou South Region

Characteristics of plant species and coverage, soil chemical properties (soil organic matter, total nitrogen, available nitrogen and available potassium etc.)and microbial biomass of different utilization types including sloping farmland (SF), abandoned (1, 5 and 10 year) and 30- year-abandoned with forestation (30AF) were invested in Forest-grassland of Lanzhou South Region. The results showed that plant species and coverage had great difference for different utilization types. Utilization type of 30AF had the highest plant abundance and coverage, followed by 10 year abandoned (10AF) and 1-year abandoned (1AF) had least plant abundance and coverage and formed an unstable artemisia dominated community. Soil organic matter, total nitrogen, available nitrogen and available potassium contents decreased with the following orders: 30AF＞SF＞10AF＞5AF＞1AF, however, available phosphorus, pH and CaCO3 contents decreased with the following orders: SF＞1AF＞5AF＞10AF＞30AF. SMBC and SMBN decreased in following orders: 30AF＞10AF＞5AF＞1AF＞SF. Soil microbial biomass phosphorus (SMBP) decreased with the following orders: 30AF＞SF＞10AF＞1AF＞5AF. The Pearson correlation analysis indicated that SMBC and SMBN presented significant positive relationship(P0.01) with organic matter, total nitrogen, available nitrogen and remarkable negative relationship with available P and CaCO3(P0.05). There was a significantly negative relationship between SMBP and CaCO3(P0.05).