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大多数国家林区土壤肥力下降,林木生长量减少。其原因:①土壤中氮多数不能被林木吸收,氮碳比率高,②在高山多雨林区因雨水冲刷,氮流失严重,土壤贫瘠;③森林采伐后林地气候因子发生变化,特别是湿度变小,土壤微生物活动受到抑制,枯枝落叶分解慢,土壤养分缺少而不能满足林木正常生长的需要,为此要提高林地土壤肥力,施肥是补充林地养分主要技术措施。同时施肥对提高林地生产力,加快林木生长,扩大根系幅度,缩短林木采
In most countries, the soil fertility of forest areas decreased and the quantity of tree growth decreased. The reasons are as follows: (1) Most of the soil nitrogen can not be absorbed by forest trees, and the ratio of nitrogen and carbon is high. (2) In the mountainous rainforest area, due to rain erosion, the nitrogen loss is serious and the soil is poor. (3) The forest climate factors change after the forest harvesting, , Soil microbial activities are inhibited, litter decomposition slow, lack of soil nutrients and can not meet the needs of normal growth of forest, so to improve forest soil fertility, fertilization is the main technical measures to supplement woodland nutrients. At the same time, fertilization can improve the productivity of forestland, accelerate the growth of trees, increase the amplitude of root system and shorten the forestation