希拉穆仁草原根层土壤水分变化特征

Soil moisture characteristics of root zone on Xilamuren grassland

为了探明阴山北麓希拉穆仁草原土壤水分的自然变化规律,采用AZ-DT自动水分监测仪长期定位监测天然草地根层土壤水分,结合降水量观测和植被调查,分析该区域土壤水分的变化特征及其对植被的影响。结果表明,1)降水是坡面土壤水分的主要来源,由于该地区降水稀少,导致坡面土壤水分经常处于体积含水量15%以下的较低水平;坡底土壤水分除降水以外还有径流来源,径流形成地面积水,使坡底土壤水分较高甚至经常处于过饱和状态。2)生长季降水量对坡面植被高度、盖度和生物量影响明显,但对坡底植物生长影响很小。坡底土壤通气不良并且盐碱化,致使植株低矮、细弱,但株丛数较多。3)由于冻融和积雪融化的影响,春季土壤水分较高且波动剧烈,这有利于牧草返青期的水分供应。

In order to explore the natural variation laws of soil moisture in Xilamuren grassland,north Yinshan Mountains,AZ-DT automatic soil moisture monitor was used to monitor the soil moisture of root zonewith long-term period.Soil moisture,in combination with rainfall observation and vegetation survey,was applied to analyze local soil moisture variation characteristics and its impact on vegetation.The results of this study showed rainfall was the only source of soil moisture of the slope soil and was often below 15% due to rare rainfall.However,soil moisture at slope bottom come from runoff resources and rainfall,and was higher than that of slope soil,which led the soil moisture to be saturation condition.Rainfall significantly affected the height,coverage and biomass of plant community in slope soil,however,did not affect on those of plant community in slope bottom.The plant community in slope bottom is low and thin but large number because poor ventilation and salinization of slope bottom soil was not beneficial to plants growth.The soil moisture of the slope and the bottom was higher and the fluctuation was severe in spring season every year due to freezing thawing and snow melting,which was helpful to grassland regreen with enough water supply.