摘要
利用EOF (经验正交函数 )方法对河北坝上和内蒙古后山地区近 4 0年降水、年风速、大风日数、气候因子、牲畜头数和气候产量等 6个沙漠化波动因子主分量进行了计算 ,表明沙漠化诸因子尽管受降水的影响有同步波动的一面 ,但又可分解为风、畜、水三个相对独立变化的系列。由此将年大风日数、气候因子、牲畜头数和气候产量确定为影响沙漠化的主要波动因子 ,并以生物学年度将其按牧区和农牧交错区两类进行等权重耦合。结果表明 ,近 4 0年全区沙漠化因子主分量的耦合度经 3年滑动平均后 ,在 2 5 %～ 10 0 %间变化 ,196 5年至今一直维持在 75 %上下波动 ,196 7～ 1977年为耦合度最高的阶段。 80年代中期多雨段沙漠化的持续蔓延 ,充分证明了人类不合理活动在坝上后山地区沙漠化发展中的主导作用。
Based on the EOF, the paper takes 6 factors such as precipitation, climatic output of grain, the relative change of livestock, wind speed, days of yearly gale and climatic wind erosive force as fluctuating factors of desertification to analyze their principal components since 1950 in rear hills of Bashang. The result shows that despite their synchronization in fluctuation for the dominance of rainfall, they can be decomposed into three relative independent series of wind, cattle and rainfall according to the REOF. Hereby, we choose four factors of climatic output of grain(O), the number of livestocks(A), days of yearly gale(G) and climatic wind erosive force(C′) as the ones which mainly influence desertification, and calculate them in the same weight coupling(C) in biological year by two different types of pastoral area and interlock area of farming and pasturing(IAFP) In pastoral areaC(%)=(G+C′+A)*3 -1 in IAFPC(%)=(G+C′+A+O)*4 -1 The coupling(C) in the 3 year smoothed average among the principal components of desertification factors fluctuated between 25%～100% since 1950, and maintained the level of 75% after 1965, but it reached the highest period during 1967～1977. The conflict between pasture and livestock mostly took place in the two periods of 1965～1975 and 1986～1990, in which there was deficient rainfall in the study area. As the resonance of the higher annual wind speed, much more days of yearly gale and less rainfall during 1965～1975, soil erosion experienced higher risk. Compared with the human contribution to the development of desertification, natural environment just forms a background, it is the irrational reclamation that plays the leading role, and the sustainable development of desertification in the mid 1980s with much more rain fall speaks well for the leading role of human played in this region. Nothing but the coupling between irrational land use and strong wind erosion during 1965～1975 greatly promotes the overspreading of desertification. Two different fluctuating types of Hebei province and Inner Mongolia are identified in the study area.
出处
《地理研究》
CSCD
北大核心
2002年第3期391-398,共8页
Geographical Research
基金
中科院资源与环境研究重点项目 (KZ95 2 jl 2 10 )
关键词
沙漠化因子
主分量
耦合度
desertification factors
principal components
coupling
