Community Structure and Species Diversity in Liangucheng Nature Reserve of Minqin County Research Progress in Relationship Between Shrub Invasion and Soil Heterogeneity in a Natural Semi-Arid Grassland A review of mountain grazing-paths and vegetation spatial heterogeneity Response of root systems to soil heterogeneity and interspecific competition in Alhagi sparsifolia Plant traits and soil properties in pasture mini-patches in an alpine meadow