作 者 ：兰再平 苏显峰 吴金坤
期 刊 ：林业科学 1999年 35卷 zk期 页码：2-12
关键词：速生丰产林；水土流失定位观测；地表径流量；土壤流失量；土壤养分流失量；
Keywords:High-yielding timber plantations, Long term fixed soil erosion monitoring, Runoff, Soil loss, Soil nutrient loss,
摘 要 ：本文对设置在世界银行贷款“国家造林项目”12个项目省(区)的7个主要造林树种新造丰产林地上的18个水土流失定位观测点连续5年的观测数据进行了综合分析。结果表明,造林施工会导致造林地不同程度的水土流失,在全部18个观测点中,在发生水土流失相对最严重的造林后当年或次年,84%的点只发生了微度或轻度土壤侵蚀,11%的点发生了中重度土壤侵蚀,只有1个点发生了重度土壤侵蚀。水土流失主要发生在造林当年和次年,从造林后第3年(或第2年)起,地表径流量降低到一定水平,以后历年随降雨量波动,而土壤流失量则迅速减少,以后逐渐消失。高强度的整地作业是造成水土流失的重要原因,全垦整地与穴垦整地相比可使土壤流失量增加100%。造林地土壤养分流失量年变化与水土流失年变化同步,在流失的养分总量中,土体有机质>土体全N、P、K>水体N、P、K>土体速效N、P、K。建议改变大强度造林清场、整地和幼林抚育作业方式,以减少或消除造林地的水土流失。
Abstract:A comprehensive analysis was made on the 5 year‘s successive monitoring findings from the 18 fixed soil erosion monitoring sites of newly established high yielding timber plantations of 7 main species, such as Larix kaempferi, Cunninghamia lanceolata, Pinus elliottii, Pinus massoniana, Eucalyptus globulus, Pinus caribaea and Eucalyptus urophylla, for the National Afforestation Project loaned by the World Bank, which distributed in 12 provinces or autonomous regions in China. The study showed following conclusions: (1)The afforestation operation would result in soil erosion of the planting site in varing degrees e.g. most(84%) of the 18 soil erosion monitoring sites showed extremely slight or slight soil erosion, few (11%) sites showed middle soil erosion and only one site showed severe soil erosion after the plantation establishment. (2)The site slashing, especially the slash burning, and site preparation, especially the intensive site preparation were the main causes of soil erosion when forest plantation was established. Hence, the runoff and soil loss mainly occurred in the first and second year when planting operation was made. (3)Since the third year (or second year) after the plantation establishment, the soil erosion was significantly reduced to a low level. The runoff decreased to a certain low level and fluctuated in small range with rainfall over years, while the soil loss decreased to an extremely low level and disappeared gradually in the future years. (4)Different site preparation methods would result in soil erosion in different degrees, e.g. the soil erosion occurred at the plantation sites with different site preparation methods varied in the order of overall >strip hole preparation in the first two years after the plantation establishment, with the difference range up to 100% between overall and strip preparation as well as between strip preparation and hole preparation. (5)The changing pattern of nutrient loss from the plantation land was the same as the soil erosion, i.e. it also occurred mainly in the first and second year after plantation and then decreased or disappeared. Of the total amount of lost nutrients, the loss of soil organic mater and soil total N+P+K took the majority, which were ordered by their lost amount as soil organic mater>soil total N+P+Kliquid N+P+K>soil available N+P+K. The total available nutrients carried by the runoff and lost soil, including liquid N, P and K as well as soil available N, P and K. were ordered by their lost amount as total available K>total available N>total available P. However, the total amount of total available nutrient loss was relatively small. It was suggested that site slashing and site preparation methods for plantation establishment should be further improved, such as giving up site slash burning and overall ploughing for site preparation etc., in order to minimize the soil erosion when afforestation operation is conducted. In regard to the lost nutriments caused by soil erosion, a fertilization scheme should be made to replenish the lost available N, P and K to the plantation land.
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