晋西黄土区不同密度刺槐林地土壤水分补偿特征

为研究晋西黄土区不同密度刺槐人工林对土壤水分的影响,分别选取2 400株/hm2与1 300株/hm2刺槐人工林代表研究区高、低密度刺槐林分,以裸地为对照,分别利用Enviro-SMART土壤水分定位监测系统和翻斗式自记雨量计对0—150cm深度范围内各土层体积含水量与林外降雨进行定位观测。结果表明:(1)从不同降水年份来看,在干旱年和平水年,低密度刺槐生长季平均土壤储水量高于高密度刺槐,在研究年份中,低密度刺槐多年平均土壤储水量比高密度刺槐多年平均土壤储水量高6.80 mm。(2)在土壤剖面垂直方向,干旱年、平水年高密度刺槐对0—30cm土层土壤水分的消耗高于低密度刺槐,丰水年0—30cm土层土壤水分消耗各刺槐林间差异不显著(P0.05)。(3)综合分析降雨入渗深度、入渗量及雨季土壤水分补偿度等指标,研究区天然降雨可对低密度刺槐林分生长所消耗的土壤水分进行有效补充,不会出现人们所担心的黄土高原在植被恢复过程中会造成水分的不足而导致新的生态退化。但考虑到高密度刺槐林对土壤水分的消耗,建议在研究区进行刺槐林植被建设过程中多考虑采用低密度刺槐林的配置方式。

Soil Water Compensation Characteristics of Robinia pseudoacacia Forestlands with Different Densities in the Loess Region of Western Shanxi Province

In order to study the effects of Robinia pseudoacacia forestlands with different densities on soil moisture in the loess region of Western Shanxi Province, the R. pseudoacacia forestlands with densities of 2 400 per hacter and 1 300 per hacter were selected to represent the high and low density R. pseudoacacia forestlands in the study area respectively, and the bare land as a control. The soil water content in 0-150 cm range and precipitation outside the forest were carried out by using Enviro-SMART soil moisture positioning monitoring system and self-recording dump rain gauge. The results showed that:(1) In different precipitation years, the average soil water storage of low-density R. pseudoacacia forestland was higher than that of high-density R. pseudoacacia forestland in drought and normal years. In these years, the absolute value of annual average soil water storage of low-density R. pseudoacacia forestland was 6.80 mm higher than that of high-density R. pseudoacacia forestland. (2) In the vertical direction of soil profile, the water consumption of 0-30 cm soil layer by high-density R. pseudoacacia forestland was higher than that of low-density R. pseudoacacia forestland in drought and normal years, and there was no significant difference in soil moisture consumption between these two kinds of R. pseudoacacia forestlands in wet years(P>0.05). (3) Comprehensive analysis of rainfall infiltration depth, infiltration amount and compensation degree of soil moisture in rainy season, natural rainfall in the study area could effectively supplement the soil moisture consumed by low-density R. pseudoacacia stand growth, and there was no new ecological degradation caused by water shortage in the process of vegetation restoration in the Loess Plateau. However, considering the consumption of soil moisture by high density R. pseudoacacia forestland, it was suggested that low density R. pseudoacacia forestland should be popularized in vegetation construction in the study area.