晋西黄土区不同立地刺槐林土壤水分动态特征

Dynamics of Soil Moisture in Different Stand Sites of Robinia Pseudoacacia Forestlands in Loess Region of Western Shanxi Province

选择晋西黄土区蔡家川流域4块不同坡向(阴坡、阳坡)、不同密度(1 450,2 150,2 525株/hm^2)刺槐样地作为研究对象,在每块样地的中心位置布设一个观测点,采用TRIME-TDR土壤水分测定仪定位观测2016年1—12月的土壤体积含水量,每月上、中、下旬分别对各样地0—200cm土层的土壤水分进行分层观测(每个测层20cm),研究4块刺槐样地的土壤水分季节变化规律、垂直剖面变化规律以及坡向和密度对土壤水分的影响。结果表明:(1)研究区土壤水分季节变化分为平稳期、消耗期、波动期和恢复期4个时期,年最大土壤水分与年最大降水量所在月份相同,降水季节分配对土壤水分有影响。(2)研究区土壤水分垂直变化土层分为剧烈变化层、弱变化层和相对稳定层3个土层,土壤水分随土层深度表现为先增加后减少最后趋于稳定的趋势。(3)坡向和密度对研究区刺槐林的土壤水分具有显著性影响,阴坡的土壤水分显著高于阳坡(P<0.01),低密度的土壤水分显著高于高密度(P<0.01)。

In this paper,four sampling plots with different slope directions and different densities were selected as the research object in the Caijiachuan watershed of the loess area in western Shanxi Province.An observation point was placed at the center of each plot,and the soil volumetric water content from January 2016 to December 2016 were determined by the TRIME-TDR soil moisture analyzer.The soil moisture in each 0-200 cm soil layer was determined stratified with every 20 cm respectively in the early,middle and late of each month.Four sampling plots were studied about the seasonal variation of soil moisture,the vertical variation in soil profiles,and the effects of slope directions and densities on soil moisture.The results showed that:(1)Seasonal changes of soil moisture could be divided into four periods including stationary period,consumption period,fluctuation period and recovery period,the annual maximum soil moisture was in the same month of the maximum rainfall in the year,and the seasonal distribution of precipitation had effect on soil moisture.(2)Soil layers could be divided vertically into three layers,including severe-changing layer,weak-changing layer and relatively stable layer.With the increasing soil depth,soil moisture increased first,decreased next,and then leveled off.(3)The slope directions and densities had significant effects on soil moisture.Soil moisture on shady slopes was significantly higher than that on sunny slopes(P<0.01).Low-density soil moisture was significantly higher than the high-density(P<0.01).