Over the past 60 years, great changes have taken place in the ecology of Nan mang county. The ecosystem of Nan mang county takes the forest as the core, and the change of forest ecology has caused a series of ecological consequences. It should be noted that ecology in this book mainly refers to ecosystems, that is, natural systems in which biological communities and their physical environments interact. It consists mainly of four components: inorganic environment, producers (green plants), consumers (herbivores and carnivores) and decomposers (saprophytic microorganisms). In the history of 60 years, ecological change in Nan mang County, there are different characteristics in different periods. According to the manifestations and causes of ecological changes, it can be roughly divided into three periods: before the 1950s, during the period of the people's commune, and after the "contracted production to the household". <<