Assessment of agricultural ecological security of the Zhifanggou Valley in the Loess Hilly Region over 70 years Evaluation of adaptability of conservation tillage in Loess Plateau semi-arid areas Quantitative study on ecological suitability of Chinese herbal medicine based on GIS Environmental Suitability for Camping Tourism in Langxiang Nature Reserve Based on Analytic Hierarchy Process Evaluation on ecosystem management capacity dynamic of Jiajiyu catchment in upper reaches of the Yellow River