不同土地利用方式对岩溶山区旱坡地土壤水分时空分异的影响

通过对岩溶山区贵州修文县2年的土壤水分定点观测,系统分析了研究区不同坡度下土地利用方式对土壤水分的影响.分析结果表明,在不同坡度之间,土壤水分的变化差异极为显著;在不同的土地利用方式条件下,蔬菜地的土壤水分变化与其他两种用地的差异极为显著,而裸地与小麦-玉米轮作地之间却没有显著差异.同一时间径流深虽然16°坡地＞9.5°坡地＞6.5°坡地,但土壤水分却存在9.5°坡地＞16°坡地＞6.5°坡地的关系,初步分析这是由土壤剖面质地差异所致,从剖面分布来看,土壤水分含量都随着深度的增加而增大.坡度和土地利用方式对土壤水分的影响主要集中在BC层以上,而在C层这种影响较弱,坡度因素的影响深度比土地利用方式小.

IMPACT OF LAND USE ON SPATIO-TEMPORAL VARIATION OF SOIL MOISTURE OF SLOPING UPLAND IN KARST MOUNTAINOUS AREA

Stationary soil-moisture-observation was carried out in Xiuwen County, Guizhou Province, which lies in the karst mountainous area of Southwest China.Based on the two year observation from June 13, 2001 to July 23, 2003, impacts of gradient and land use on soil moisture are analyzed systemically.The result shows that gradient and land use have a marked effect on soil moisture.Comparison of change in soil moisture between soils under three different kinds of land uses shows that it is the most remarkable in soil under vegetable, and there is no significant difference between bared soil and soil under wheat or corn.But in terms of effect of slope on soil moisture, surface runoff shows a decreasing order of 16°>9.5°>6.5° in gradient field while soil moisture has a decreasing order of 9.5°>16°>6.5° in gradient field.According to a preliminary analysis, the difference in soil profile structure is the potential cause.Soil profile soil moisture increases with the depth in the soil profile.In conclusion, the impact of gradient and land use on soil moisture is mostly effect ive in the soil layers above the BC layer, and is quite weak in the C layer.And the impact of gradient on moisture distribution in depth is lower than that of land use.