Spatial Vegetation Patch Patterns and Their Relation to Environmental Factors in the Alpine Grasslands of the Qilian Mountains

Abstract

Globally, grasslands are affected by climate change and unsustainable management practices which usually leads to transitions from stable, degraded and then to desertification. Spatial vegetation patch configurations are regarded as key indicators of such transitions. Understanding the relationships between this grass-land vegetation and its environment is key to vegetation restoration projects. Spatial vegetation patch patterns were chosen across different soil and topographic conditions. Patch numbers, perimeter, and cover of each patch were measured along transects of each patch type. Using field surveys and multivariate statistical analysis, we investigated the differences in vegetation biomass and distribution and soil properties of four typical alpine plant species patches along with a range of environmental and topographic conditions. It was found that topographic conditions and soil properties, particularly soil moisture explained most of the variation in spatial patch vegetation characteristics and thus control vegetation restoration in the alpine grassland. The Kobresia humilis, Blysmus sinocompressus and Iris lactea patches under the drylands recorded small patch sizes, large patch numbers, low connectivity, and large total perimeter per unit area. Generally, species within the high moisture sites recorded small patch numbers, a large fraction of vegetation cover and a small total perimeter per m2. Patches in limited soil moisture areas recorded patch configurations indicating they are unstable and undergoing degradation and therefore need urgent restoration attention to forestall their further degradation and its resultant effect of desertification. These results would provide quantitative easy-to-use indicators for vegetation degradation and help in vegetation restoration projects.