藏北燕麦草地持续利用与撂荒对高寒草甸土壤特征的影响

为研究不同利用方式对藏北高寒草甸建植一年生燕麦（Avena sativa Linn.）人工草地的土壤理化性质及土壤细菌群落的影响，本试验于8月份植物生长旺季，在持续利用人工草地（AG）、撂荒人工草地（AC）和对照天然草地（NG）采集土壤样品，分析了土壤理化性质、土壤细菌群落组成和结构特征变化。结果表明，AG样地土壤有机质、全钾含量和pH与NG样地相比无显著性变化，土壤全氮、速效氮和速效钾含量显著降低；AC样地与NG样地相比土壤pH显著升高，土壤有机质、全氮、速效氮和速效钾含量显著降低。AG样地土壤细菌群落Chao1，Shannon和Pielou均匀度指数显著高于NG样地，AC样地酸杆菌门和变形菌门丰度显著升高。土壤理化性质是土壤细菌群落结构组成门、属相对丰度变化主要影响因子。综上所述，高寒草甸一年生燕麦人工草地长期利用应科学补充肥料，保持土壤肥力；草地撂荒需谨慎，应及时采取恢复措施避免草地发生退化。

Effects of Continuous Utilization and Abandonment of Oat Grassland on Soil Characteristics of Alpine Grassland in Northern Tibet

The effects of continuous utilization and abandonment of oat (Avena sativa Linn.) grassland on the soil physicochemical properties and soil bacterial community were studied in an alpine meadow in northern Tibet. Soil samples were collected from sustained artificial grassland (AG), abandoned artificial grassland (AC) and control natural grassland (NG) in August, the peak season for plant growth. The changes of soil physical and chemical properties, soil bacterial community composition and structure characteristics were ananlyzed. Results showed that no significant difference existed in soil OM, TK and pH between AG plot and natural grassland, but the contents of soil TN, AN and AK decreased significantly. Soil pH of AC sample plots increased significantly, and soil OM, TN, AN and AK contents decreased significantly. The Chao1, Shannon and Pielou indexes of soil bacterial community in the AG plot were significantly higher than those in the NG plot, the abundance of soil Acidobacteria and Proteobacteria in AC plots increased significantly. Soil physical and chemical properties were the main factors that affected the relative abundance of phyla and genera in the soil bacterial community structure. In view of this situation, the long-term utilization of annual oat artificial grassland in alpine meadow should be supplemented with fertilizer to maintain soil fertility. The abandonment of grassland should be cautious and restoration measures should be taken timely to avoid grassland degradation.