不同植被覆盖类型黑土水分动态变化特征

Soil moisture dynamics of different land-cover types in the black soil regions of China

采用中子水分仪定位监测方法,研究黑土区平水年大豆地、草地和裸地3种覆盖类型土壤水分变化特征。结果表明：土壤水分空间垂直动态变化随深度增加而降低,基于变异系数（Cv）将土壤水分垂直变化分为4层,即水分速变层、活跃层、次活跃层和相对稳定层。不同覆盖类型下,土壤水循环深度依次为大豆地〉草地〉裸地,土壤水循环强度依次为草地〉大豆地〉裸地;3种覆盖类型的土壤剖面含水量在作物生长季节内呈增长型变化特征,裸地0～20cm土层各时段土壤含水量均高于草地和大豆地;30cm土层以下土壤水分含量依次为草地〉裸地〉大豆地。该区土壤储水量主要受降雨调控,3种植被覆盖类型下,土壤水分的总蒸散量依次为草地〉大豆地〉裸地。

Based on collected soil moisture data from the fixed-position monitoring system in the black soil regions of China, soil moisture dynamics in different land-cover types were analyzed. The results show that the variation in soil water under the three land-cover types decreases with increasing soil depth for which vertical change in soil water along the soil profile can be put into four groups, vertiginous layer, active layer, transitional layer and relative stable layer. The depth of soil water cycle for the different land-cover types is as follows： soybean-land 〉 grassland 〉 bare-land, and the order of soil water cycle intensity is： grassland 〉 soy- bean-land 〉 bare-land. Soil water content in the three land-cover types increases with increasing soil depth, and water content of the surface layer （020 cm）in bare-lands is higher than in grasslands and soybean-lands. However, under 30 cm soil depth, soil water content takes the following order： grassland 〉 bare-land 〉 soybean-land. Water storage in the 170 cm soil layer is controlled by rain- fall. Under the three land-cover types, the order of total evapotranspiration is： grassland 〉 soybean-land 〉 bare-land.