Abstract: Destruction of an ecosystem means destruction of the environment that is mostly caused by human activities. In fact, the so-called environmental science is actually a human ecosystem science consisting of many branches of natural sicence and social science related. In a natural ecosystem without human interruption, organisms operate the whole process of material exchange and energy flow of the system. Once human activites are involved, the sequence of the process changes greatly.In the system, the human being assumes a specific position and plays a double role, biologically and sociologically. Just like other organisms, he is a component of the system and links himself to the complicated food web. In the meantime, he is also a dynamic in exploiting, utilizing, modifying and even destrovying the ecosystem. Thus, in addition to the atmosphere, hydrosphere, lithosphere and biosphere, intelecto-sphere should logically be included in a humanly disturbed ecosystem.In view of environmental protection, it is very important to understand the operating patterns and dynamic mechanisms of an ecosystem in which normal material exchange and energy flow occur. An ideal situation can be achieved in which natural resources are fully utilized for the benefit of the human being without any damage to the environment and the ecosystem can simultaneously be maintained in its normal structure and function, if he behaves well in right conscience of his future.A forest ecosystem is an ecosystem with dominance of forest trees, occupies a huge ecosphere in the terrestrial area of the earth and is a most productive and valuable part of human ecosystem. It provides not only abundantly renewable resources but also effective protection against the deterioration of natural environment. In planning industry, agriculture, landuse and city development, it is necessary to regard forests as an indispensable component of the environment. Recently more attention has been paid to environmental protection and research of forest ecosystem has achieved some advances.