Remote sensing identification of earthquake trigged landsides and their impacts on ecosystem services: a case study of Wenchuan County Spatial variability of surface soil nutrients in the landslide area of Beichuan County, Southwest China, after 5·12 Wenchuan Earthquake. Relationship between shallow landslide erosion and vegetation in the Ziwuling forest area: a case study of the “7·21” disaster in Fuxian County Impacts of Secondary Geological Disasters Induced by Wenchuan Earthquake on Soil Fauna Community