Spatio-temporal trends for fine root biomass of alpine Rhododendron thymifolium and their significance for ecological adaptation in Qilian Mountain Analysis of the problem of food shortage in Southern China based on the study of two grassland ecological-economic regions The humidifying effect of riparian wetland park during autumn in Shijiazhuang City Plant Diversity and Disturbance on the Rhododendron Shrub Grassland of Eastern Qilian Mountains