苏尼特右旗荒漠草原三种放牧方式下群落斑块特征

利用景观指数、分形模型以及稳定性指数、单变量点格局方法，对内蒙古苏尼特右旗荒漠草原不同放牧方式下群落微斑块特征、形状分形及稳定性、分布格局进行探究，以期揭示荒漠草原微斑块自身特征及其与环境的关系。结果表明：1）3种放牧方式下群落斑块特征差异明显。休牧状态下芨芨草斑块面积占景观整体面积的91.15%，蔓延度指数（CONTAG）为77.92，连接性较好，为优势斑块，分形维数为1.43，稳定性较差；自由放牧状态下银灰旋花斑块空间分布最为密集；轮牧状态下锦鸡儿数量最多，分离度指数（SPLIT）为46.99，破碎化程度较高，分形维数为1.88，形状最不规则。2）3种放牧方式下各斑块类型在样地尺度范围（120 m×120 m）内主要呈聚集分布，且自由放牧状态下各斑块类型的聚集规模均较大，表明其资源分布不均匀。

Characteristics of community patches under three grazing modes in Sunite Desert-steppe

This research investigated the characteristics of vegetation micro-patches in the desert steppe and their relationship with environmental conditions.The landscape index,fractal model,stability index and univariate point pattern methods were used to explore the characteristics,shape fractal,stability and distribution pattern of plant community micropatches under different grazing modes(rested from grazing:It refers to the short-term prohibition of grazing;free grazing:It is a kind of grazing way to drive the herd to swim and feed in a large range;and rotational grazing:It is a kind of grazing way of reincarnation or circular grazing according to season grassland and grazing plot)in Sunite Desert-steppe,Inner Mongolia.It was found that:1)The patch characteristics of the three grazing methods varied significantly.The area of Achnatherum splendens patches in the area rested from grazing accounted for 91.15%of the overall landscape area.For this community the contat degree index was 77.92,indicating good connectivity and the fractal dimension was 1.43,indicating poor stability.The spatial distribution of Convolvulus ammannii patches was the densest under free grazing.The number of Caragana rosea patches in the rotational grazing area was the largest.For these patches the SPLIT index was 46.99,indicating a high degree of fragmentation.The highest fractal dimension was 1.88,indicating the most irregular shape.2)Under all three grazing methods,the patch types were mainly distributed in clusters in the scale range of the sampling plots,with random and uniform distributions appearing occasionally.The aggregation scale of each patch type was large in the free grazing state,indicating that the resource distribution was uneven.