黄土高原水蚀风蚀交错带坡耕地土壤风蚀速率空间分布  

Spatial distribution pattern of soil-wind erosion on slope farmlands in the wind-water erosion crisscross region of the Loess Plateau,China

作　　者：刘章[1] 杨明义[1,2] 张加琼[1,2] 

机构地区：[1]西北农林科技大学水土保持研究所,黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100 [2]中国科学院水利部水土保持研究所,杨凌712100

出　　处：《科学通报》2016年第4期511-517,共7页Chinese Science Bulletin

基　　金：国家自然科学基金(41401314,41171228)资助

摘　　要：受水蚀和风蚀的交错作用,黄土高原水蚀风蚀交错带的土壤风蚀速率难以从总侵蚀中提取出,更难以描绘其坡面分布特征.本研究运用~7Be示踪技术,在神木县六道沟流域选择方向偏北的砂壤土和黏壤土坡耕地,沿与坡面走向大致平行的方向布设采样线,采集0~30 mm土壤样品,估算土壤风蚀速率,探究风蚀速率的坡面分布特征及其所指示的风况和微地貌特征.结果表明:经过风季后,表层土壤颗粒变粗,比表面积变小,有机质含量降低,这些土壤理化性质变化表明两坡面均发生风蚀.砂壤土坡面A的平均风蚀速率为1560.81 t/(km^2 a),黏壤土坡面B的平均风蚀速率为694.26 t/(km^2 a),风蚀速率在两坡面均呈现从坡顶到坡脚逐渐减小的空间分布特征.两坡面风蚀速率等值线分布不仅指示了土壤风蚀的坡面分布特征,还揭示了造成该分布的有效合成风向为北风.风蚀速率等值线的局部形状变异显示了坡面微地貌形态,等值线的变异程度显现了微地貌对风蚀速率的影响程度和范围.Wind erosion is difficult to separate from the total erosion in the wind-water erosion crisscross region of the Loess Plateau, regardless of its spatial distribution. Water erosion also contributes to the total erosion. Water and wind erosions affect each other. The methods and techniques used in current research present the most significant limitation. Therefore, the methods and techniques of the field must be improved. A short-lived radionuclide 7Be--was used to trace wind erosion in this study. Surface soil samples （0-30 mm） were collected from two north-faced farmland slopes with sandy loam and clay loam using the transect approach in the Liudaogou Watershed. This study estimated the rates of soil-wind erosion, analyzed the spatial distribution pattern of soil-wind erosion, and discussed its implication to wind conditions and local microreliefs. Results showed that the average rate of wind erosion was 1560.81 t/（km2 a） on sandy loam slope A and 694.26 t/（km2 a） on clay loam slope B. The wind erosion rate decreased from top to bottom for both slopes. Soil particles were coarser, specific surface areas were smaller, and organic matter contents were lower in the surface layer （0-30 mm） after wind erosion than those before wind erosion. The isolines of the wind erosion rate visually showed the wind erosion distribution and indicated that the north wind was the effective resultant wind direction that caused soil loss. The variation in the shape of the isolines reflected the microreliefs of the slopes, and their variation degree denoted the influence degree and scope of microreliefs on wind erosion.

关 键 词：水蚀风蚀交错带 风蚀速率 ^7Be示踪技术 空间分布 

分 类 号：S157[农业科学—土壤学]