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日本防护林的面积约占森林总面积的1/3。凡是危害森林水流调节作用的采伐及土地利用的变更,都应加以限制。择伐对洪峰流量影响不大,而皆伐后增加1.4—1.8倍。森林采伐后,干旱季节的枯水流量会暂时大一些,但是,在植被恢复后,流量又回到采伐前的情况。日本禁止在有风害、冻害以及更新有困难的地区,特别是可能使土壤侵蚀严重发展的地区进行皆伐及择伐。在允许采伐的防护林其他部分,年采伐总面积可由下式决定:
Japan’s shelter area accounts for about 1/3 of the total forest area. Any change in the harvesting and land use that endangers the regulation of forest flow should be limited. Selective cutting had little effect on flood peak flow, but increased 1.4-1.8 times after clear cutting. After harvesting the forest, the dry flow of dry season will temporarily be larger, but the flow will return to the situation after harvesting after vegetation restoration. Japan prohibits clear-cut and selective cutting in areas where wind damage, frost damage and renewal are difficult, especially in areas that may cause serious soil erosion. In other parts of the shelter that are allowed to be harvested, the total annual area harvested may be determined as follows: