including its rivers， and sites (from ponds to dry ridges) to forested landscapes. ， lakes， soils， and oceans. Large amounts of earth and organic materials enter streams as sediment as a result of this landslide and erosion activity， Landslides affect the following elements of the environment: (1) the topography of the earth’s surface; (2) the character and quality of rivers and streams and groundwater flow; (3) the forests that cover much of the earth’s surface; and (4) the habitats of natural wildlife that exist on the earth’s surface， thus reducing the potability of the water and quality of habitat for fish and wildlife. Biotic destruction by landslides is also common; widespread stripping of forest cover by mass movements has been noted in many parts of the world. Removal of forest cover impacts wildlife habitat. The ecological role that landslides play is often overlooked. Landslides contribute to aquatic and terrestrial biodiversity. Debris flows and other mass movement play an important role in supplying sediment and coarse woody debris to maintain pool/riffle habitat in streams. As disturbance agents landslides engender a mosaic of seral stages，。