Quantitative investigation of the interactive coupling relationship between urbanization and eco-environment The interactive mechanism between economy and environment in depressed area-A case study from Dingxi District,Gansu Province Coupling relationship of agricultural eco-economic system in Wuqi County based on structural equation model. Plant community characteristics and its coupling relationships with soil in depressions between karst hills, North Guangxi, China The coupling relationship and emergy analysis of farming and grazing ecosystems in Mu Us sandland