古尔班通古特沙漠与绿洲交错带土地利用变化对土壤特性的影响

对比研究了古尔班通古特沙漠与绿洲交错带8种土地利用类型的土壤特性变化. 结果表明: 不同土地利用类型的土壤粉砂含量差异性显著(P<0.05). 人类活动干扰的时间越长、 强度越大, 粉砂和极细砂含量越高, 而细砂反之. 在人类活动干扰前期(≤5 a), 土壤养分与干扰时间成反比, 而后(＞5 a)与时间成正比. 不同土地利用类型的土壤养分分为4个等级: 1级为盐碱地, 为最高等级; 2级为生态防护林地、 荒草地和天然灌木林地; 3级为10 a农田地、 5 a菜园地和3 a农田地; 4级为5 a农田地, 为最低等级. 人类活动使得土壤盐分由原来的(盐碱土)上层高、 下层低转为上层低、 下层高. 而且盐分与干扰时间成反比. 土地利用变化的过程中, 土壤盐分与Cl^-、 SO₄^2-、 Ca²⁺、 Mg²⁺、 K⁺和Na⁺离子均成正比, 而与HCO₃^-离子成反比. 5 a农田地土壤退化指数(-30.58%)最高, 是其他土地利用类型的1.5~3.9倍.

The Effects of Land Use Change in Desert-Oasis Ecotones by the Gurbantunggut Desert on Soil Properties

In this paper, a comparative study is made on soil properties changes of eight land-use types in desert-oasis ecotone by the Gurbantunggut Desert. It is found that silt content has significant differentiations among various land use types (P<0.05). The longer time and greater intensity of cultivation are the higher silt and very find sand content are. On the contrary, fine sand content has a decreasing trend. During the early cultivation period (≤5 years), soil fertility is in inverse proportion to time. After then (＞5 years), it is proportional to time. Soil fertility of different land use types may be divided into the following four grades: 1) saline-alkali soil with the highest level, 2) ecological protection forest land, grassland and natural shrub land, 3) farmland of 10 years, farmland of 3 years and vegetable garden of 5 years, 4) farmland of 5 years at the lowest level. Human cultivation transforms soil salinity from the (saline-alkali soil) high salt in the upper layer and low salt in the lower layer into low salt in the upper layer and high salt in the lower layer. The saline matter is in inverse proportion to cultivated time. During the process of land use change, soil salinity is proportional to Cl^-, SO₄^2-4, Ca²⁺, Mg²⁺, K⁺ and Na⁺ concentrations and is in inverse proportion to HCO₃^- concentration. Soil degradation index of 5-year farming-land (-30.58%) is the highest, 1.5~3.9 times of other land-use types.