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森林在地球大陆表面约占三分之一的面积,在生物圈内是一个重要组成单元。作为生态系统的森林如与其它的草原生态系统、农田生态系统等相比,是最大的生态系统。森林每公顷面积上的生物总产量可达100—400吨干重,约为农田或草本植物群落的20—100倍。而且林木的生产周期长,持续性强,有再生机能的特点,为人类提供生产建设原料,是取之不尽,用之不竭的自然资源。我国现有森林面积18亿亩,平均每人占有森林面积2亩,全国立木蓄积量95亿立方
About one third of the area of the Earth’s surface in the Earth’s continents is an important component within the biosphere. Forests as ecosystems are the largest ecosystems compared to other grassland ecosystems, farmland ecosystems, and others. The total biomass production per hectare of forest can reach 100-400 tons of dry weight, which is about 20-100 times of that of farmland or herbaceous plant. Moreover, the production cycle of trees is long, persistent and regenerative. It is an inexhaustible natural resource for mankind to provide raw materials for production and construction. China’s existing forest area of 1.8 billion mu, an average of 2 acres of forest area per share, the national stock volume 9.5 billion cubic meters