不同地形部位土壤水分的年变化分析

Study on Annual Variation of Soil Moisture in Different Positions of Topography

通过测定飞马河流域阴坡、阳坡、半阴半阳坡、川地不同部位0-180 cm土壤的储水量,分析土壤水分空间、时间变异性,以及不同植被在不同部位土壤水分亏缺程度。结果表明:梯田宽度不同,土壤水分分布不同,在0-180 cm土层,窄式梯田水分分布较均匀,宽式梯田土壤水分由内侧向外侧递减;坡向、坡位不同,土壤水分变异很大,阴坡土壤年平均储水量远比阳坡高111.9mm;在坡地上修建水平阶后,沿坡长土壤水分趋于均匀。土壤水分年变化总体看来,可分3个阶段:11月初至翌年6月底,土壤水分变化很缓慢;7月初至8月底,急剧变化;9-10月缓慢变化,阴坡土壤水分变化比阳坡缓慢。在不同立地条件上生长的作物,水分满足程度差异很大,阴坡生长的次生林,坡中部和坡下部水分基本不亏缺,坡上部水分亏缺较严重,玉米地和果园,自5月开始水分出现亏缺,玉米地4-10月平均水分满足程度为74.4％,果园4-10月平均水分满足程度为83％。

By measuring soil moisture in depth 0 - 180 cm on shaded hillside, sunny hillside, semi - shaded hillside and plain land in Feimahe valley, the about time, space of soil moisture and shortage degrees of various site was analyzed . The result indicated that the distribution of soil moisture varied from terrace widthes. The soil moisture of narrow terrace was well distributed in depth 0 - 180 cm, but that of the wide terrace was decreased from inside to outside. It was different from aspect of slope and seat of slop. The soil moisture of shaded hillside was 111.9 mm more than that on sunny hillside in the annual average value. The soil moisture along slope was well distributed after constructing horizontal stage. The variation of soil moisture in a year could be divided into three stages, namely very slow variation stage from the beginning of December to the end of June of next year, very fast variation stage from the beginning of July to the end of August and slow variation stage from September to the end of October. The variation of shaded hillside was slower than sunny hillside. On the other hand, difference of satisfied degrees of soil moisture on plant was very large in various standing conditions. Secondary forestry on middle and lower part of shaded hillside was not lack of water basically but upper part was lack of water. The corn and fruit tree were deficient in water since the May and the satisfied degrees were 74.4% and 83% respectively from April to October.