生态学研究的是生命系统与环境之间相互作用的规律及其原理。生命系统主要指人类与环境的相互关系;环境系统指的是自然界的光、热、空气、水份以及各种有机和无机元素,彼此的相互作用所共同构成的空间。人类及一切动植物的生存和发展,是不能离开这个环境系统的。这已是人类长期生存实践共识和颠覆不破的真理。同样,今天人类进行的一系列生产发展及我国进行的社会主义现代化建设,也是离不开这个环境系统的。国家退耕还林政策的重大意 Ecology studies the laws and principles of the interaction between life systems and the environment. Life system mainly refers to the relationship between man and environment; environment system refers to the natural light, heat, air, water and a variety of organic and inorganic elements, the interaction of mutual common space. The survival and development of mankind and all animals and plants can not leave the environmental system. This is the consensus on the long-term survival of mankind and the truth that subversion is not broken. Likewise, the series of production and development conducted by mankind today and the socialist modernization drive carried out by our country are also inseparable from this environmental system. The Significant Significance of the Policy of Returning Farmland to Forest