黄土丘陵区不同土地利用类型土壤水分时空变异特征

Spatio-temporal Varation Characteristics of Soil Moisture under Different Land Uses in the Loess Hilly Region

以黄土丘陵区的延河流域为研究区域,分析了3个时期(雨季前、雨季中、雨季后)不同土地利用类型对土壤水分动态的影响。结果表明:在水平层面、垂直剖面上土地利用类型对土壤水分动态有着显著的影响,农耕地土壤水分含量最高,并且对土壤水分含量影响最为明显,使其保持在一个较高的水平;其次是天然草地、撂荒地、乔木林地、果园用地和幼林地;含量最低的为灌木林地。在垂直剖面上,雨季前干旱期为递增型;雨季中湿润期为递减型和波动型;雨季后半湿润期为先减后增型。从总体趋势上来看,土壤水分的时空格局与降雨季节变化、植物蒸腾作用以及土地耕作利用方式密切相关。在延河流域,土地利用方式对土壤水分在不同的季节都具有显著性的影响。在该流域的管理中,应充分考虑不同土地利用类型对土壤水分的影响,优化土地利用结构,使流域的治理达到最优。

Effects of land use types on dynamic of soil moisture in three different periods（before the rainy season,at the rainy season,after the rainy season） in Yanhe basin were analyzed in this paper.The results show that the land use types have the significant influences on soil moisture on the horizontal and vertical scales,soil moisture of farm land is the highest and land use as farm land obviously influences soil moisture,which is followed by the natural grassland,bare land,woodland,orchard land and young forest land,and the soil moisture is the lowest in shrub land.In profile,the soil moisture increases along the depth of soil layer before the rainy season（drought period）,the soil moisture decreases or fluctuates in the middle period of rainy season（humid period）.The soil moisture declines firstly and then it increase in the late rainy season.It can be seen that the spatio-temporal pattern of soil moisture is closely related to rainfall distribution,plant transpiration and land use.In Yanhe River basin,land use types significantly influence soil moisture in different seasons.It is essential for management of this river basin and optimal basin administration that the effects of different land use types on soil moisture are paid attention and the land use structure is optimized.