人工柠条林生物土壤结皮地表水文效应的季节转换

Seasonal Conversion of the Effects of Biological Soil Crusts on Surface Hydrology in the Artificial Caragana intermedia Shrublands

人工柠条林地表广泛分布的土壤结皮对地表水文过程有重要的影响。该研究以荒漠草原人工柠条林生物土壤结皮为研究对象,通过有无结皮处理下旱季和雨季表层土壤水文过程的监测以及土壤水文物理特性的分析,进一步在季节尺度上揭示生物土壤结皮地表水文效应的形成及其影响因素。结果表明:(1)人工柠条林表层土壤结皮层水分含量动态在旱季和雨季表现出了截然相反的格局,其持水效应在以小降水为主,土壤蒸发强烈的夏季体现最为典型,但是进入雨季结皮的相对持水效应弱化甚至丧失。(2)由于生物结皮活性的季节转换,人工柠条林表层土壤容重、饱和含水率、总孔隙度在季节尺度上发生了不同程度的变化。(3)无论是旱季还是雨季,生物结皮的存在都会降低土壤水分入渗性能,而无论有无结皮覆盖,雨季土壤水分入渗速率都低于旱季。

Distributed extensively in the artificial Caragana intermedia shrublands,soil crusts play key roles in the hydrological process of earth surface.Taking the biological soil crusts of artificial C.intermedia forests in desert steppe as the research object,this paper studies the form and influencing factors of the surface soil hydrological effects of biological soil crust from the seasonal scale through the analysis of the monitor of the hydrological and physical characteristics of the soil in dry season and rainy season with or without crust processing.Several key results are shown as follows.(1)The dynamics of soil water content in the surface soil of the artificial C.intermedia stands in distinct patterns in the dry season and the rainy season.The water-holding effect is mainly manifested in small rainfall among which the most typical one is in summer with strong soil evaporation,but the relative water-holding capacity of the crust is weakened or even lost when in rainy season.(2)Due to the seasonal conversion of biological crusts activity,the physical indexes such as soil capacity,saturated moisture content and total porosity on the surface layer of C.intermedia plantation have changed different degrees on the seasonal scale.(3)Whether in the dry season or the rainy season,the existence of biological crusts will reduce soil moisture infiltration performance,regardless of whether there is crust coverage,the soil moisture infiltration rate in the rainy season is lower than that in the dry season.