宁南黄土丘陵区中庄小流域土壤水分空间变异及影响因子

韩新生; 于艺鹏; 蔡进军; 李振华; 许浩; 李维倩; 郭永忠; 万海霞; 王月玲; 董立国; 刘广全

doi:10.16843/j.sswc.2022.03.006

宁南黄土丘陵区中庄小流域土壤水分空间变异及影响因子

Spatial variability of soil moisture in Zhongzhuang small watershed, loess hilly region, southern Ningxia and influencing factors

摘要

摘要: 为阐明小流域土壤水分空间变异及关键作用因子，以宁南黄土丘陵区中庄小流域为研究对象，于2020年生长季后期，按照植被种类及立地环境差异采集141个样点的土壤含水量(SMC)数据，深度为200 cm，通过经典统计学方法分析生物因子及立地条件对土壤水分空间变异的影响。结果表明：随土层加深、坡度增加、坡向由阴转阳、坡位从下至上，SMC均呈先降低后稳定的趋势。其中，土层间SMC变异在0~100 cm弱于100~200 cm。主成分分析显示：坡位、植被盖度、土地利用等因素可以解释SMC变异信息的65.05%。土地利用方式对SMC的影响表现为：次生林＞川道地＞梯田＞荒地＞人工林。人工林、苜蓿、柠条和沙棘在80~200 cm土层的SMC分别显著低于其他土地利用方式。植被盖度对0~60 cm的SMC起正效应，对60~200 cm起负效应。总的来说，苜蓿、柠条、沙棘等植被和上坡位、阳坡、陡坡等立地的土壤水分较低，在流域植被结构优化调整时，应重视地形因素与植被特征的综合影响。

Abstract:
Background Soil moisture is not only an important component of eco-hydrological process and material energy cycle, but also a key factor limits the plant growth and vegetation reconstruction in arid and semi-arid areas. Quantifying the spatial variability of soil moisture and assessing the main influencing factors provide important references for regional ecosystem restoration and agricultural production.
Methods In the late growing season of 2020, a soil moisture survey with 141 samples in 200 cm thicknesswas carried out by the soil drilling method, in the Zhongzhuang small watershed, a loess hilly region of southern Ningxia. Soil moisture content (SMC) was measured in 20 cm per layer, and the effects of land use, vegetation coverage, plant species, slope gradient, slope aspect, and slope position on soil moisture were analyzed through classical statistical methods.
Results The SMC firstly decreased then stabilized with the soil layer deepening, with the slope gradient rising, with the slope direction changing from the north-faced to the south-faced, and with the slope position moving from the bottom to the up. The degree of SMC variation was lighter in 0-100 cm than in 100-200 cm. According to a principal component analysis, 65.05% of SMC variation could be well explained by the slope position, vegetation coverage, land use, etc. The SMC in 5 land uses were ordered as secondary forest> flat field> terraced field> wasteland> artificial forest. The 80-200 cm SMC in artificial forest, Medicago sativa, Caragana korshinskii, H. rhamnoides were significantly lower than in other land uses. With the vegetation coverage increasing, the 0-60 cm SMC gradually increased, whereas the 60-200 cm SMC gradually decreased.
Conclusions In general, lower SMC occursin vegetation types such as M.sativa, C.korshinskii, H.rhamnoides and site conditions such as upslope, sunny slope, and steep slope. When optimizing and adjusting the vegetation structure in the watershed, attentions should be paid to the comprehensive influence of topographical factors and vegetation characteristics.

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