青海湖流域典型生态系统土壤水分对降水脉动的响应

土壤水分是影响干旱半干旱地区植物生长与空间分布的关键因素,对维持整个生态系统的稳定具有重要作用.通过对青海湖流域3种典型生态系统(草地、灌丛、农田)降水过程和土壤水分的连续动态观测,分析了不同时间尺度(逐月、逐日、10min)土壤水分对降水脉动的响应.结果表明:草地、灌丛和农田深层(60、90cm)土壤水分对降水的响应均比浅层土壤(10、30cm)滞后1个月左右;灌丛土壤水分对降水的响应集中在60cm以上,深层土壤水分主要受地下水影响,由于冠层截留损耗,单次小降水事件对灌丛土壤水分的补给作用较为有限;草地土壤水分对降水的响应集中在10和30cm,而农田降水补给的有效深度小于30cm,响应时间也明显滞后于草地.

Response of soil moisture to precipitation pulse in typical ecosystems in Qinghai Lake Watershed

Soil moisture is a key factor affecting growth and spatial distribution of vegetation in arid and semi-arid regions,and it determines stability of entire ecosystems.Continuous measurements of precipitation and soil moisture in three typical ecosystems (grassland,shrub,and farmland)in Qinghai Lake Watershed were used to analyze response of soil moisture to precipitation pulse on different temporal scales (monthly, daily,10 minute).It was found that response of deeper soil moisture (60,90 cm)to precipitation was about one month later than shallower layer (10,30 cm).The responding depth of soil moisture to precipitation for shrub was concentrated above 60 cm,while change of deeper soil moisture was mainly affected by groundwater. Due to canopy interception,replenishment of a single small precipitation to soil moisture was very limited.The responding depth of soil moisture to precipitation for grassland was concentrated from 10 cm and 30 cm.The effected depth of farmland by precipitation pulse was less than 30 cm,responding time of grassland is significantly later than that of grassland.