وصف الكتاب | Mountains, deserts and grassland systems, each characterized by climate and vegetation, and certain animals, yet these systems are closely related. Mountains are often red borders. The Mei grasslands are made up of mountain ranges; mountains therefore affect the climate of the desert and adjacent grasslands. Human activities have upset the balance between these ecosystems. For example, in some areas trees have cut down land development for agriculture, housing or recreation. Most scientists believe that global warming caused by human activities is the main threat to these systems. |