Soil Moisture’s Spatial Pattern Of Different Slope Positions In Alpine Grassland On North Slope Of Qilian Mountains

Soil moisture is a major factor in the formation and evolution of vegetation pattern of spatial heterogeneity of soil moisture understanding of grassland plants in arid area on the response mechanism of the environment is important, no matter in a larger scale or on a smaller scale, vegetation status, soil moisture spatial heterogeneity the main driving factor. Soil moisture in space there is generally a certain spatial autocorrelation, spatial autocorrelation contains some useful information.Soil moisture is an important part of vegetation growth and survival environment, directly affected the growth of vegetation, the structure characteristics and the stability of the community.Soil water spatial heterogeneity of vegetation condition is the main driving factors. In view of this, this paper, the traditional statistics, statistical methods, and Moran’s I coefficients of Northern of Qilian Mountains of Stipa krylovii shallow profile of a single dominant species patch(0-30) spatial heterogeneity of soil moisture from correlation between the spatial correlation scale, the results are as follows:(1) The results show: the distribution of surface soil moisture was normal distribution of Stipa krylovii in 0-30 cm depth, there was a high degree of spatial heterogeneity of soil moisture. Among them 74.07%-88.41% spatial heterogeneity was caused by the spatial autocorrelation part; Stipa krylovii’s soil moisture functions are nonlinear models, reflecting that the heterogeneity of soil moisture spatial distribution of resources as well as Stipa krylovii aggregated distribution features, layers of soil moisture has a strong spatial autocorrelation. Layers of soil moisture both showed patchy distribution pattern and there are a number of non-repeat center of high-value and low-value areas.(2) Soil moisture in the ground has good spatial continuity in top slope, while in middle slope and bottom slope there has a stronger fragmentation degree of soil moisture. This was due to soil evapotranspiration in study area of Stipa krylovii, which has a cluster-like distribution scale, the intensive plant plexus, the formation of dense grass carpet and litter composition effective surface cover, not only reduces the evaporation of soil moisture, and changes the spatial heterogeneity of soil moisture pattern. Soil moisture has a stronger fragmentation degree of soil moisture and have some center of high-value and low-value areas in top slope. The high spatial heterogeneity of soil moisture in top slope in 20-30 cm layer is mainly due to the Stipa krylovii patch are mainly concentrated in the 20-30 cm soil layer.(3) The distribution of surface soil moisture all displayed spatial autocorrelation characteristics and spatial agglomeration features. According to the results of Global Moran’s I indices, the spatial aggregation characteristics of top slope were higher than that of middle slope and bottom slope.This was due to the biological characteristics and the difference between the resource requirements of Stipa krylovii. According to the results of Local Moran’s I indices, soil moilsture of all the slopes showed significant local autocorrelation(P<0.05). Locally, formed “high-high” and “low-low” spatial aggregations; these “high-high” and “low-low” spatial aggregations persisted in the experiment plot.(4)On top slopes, the meadow community height is the major community characteristics of soil moisture, has significant influence on soil moisture; in middle slope positions, Stipa krylovii distribution was relatively concentrated in higher coverage patch, the underground root density is higher too, absorption of soil water utilization degree were stronger, Stipa krylovii’s coverage to the influence of soil moisture is a significant negative correlation; in lower slope, the Stipa krylovii’s coverage and community height has more significant effect on soil moisture.