祁连山排露沟流域典型植被类型的水源涵养功能差异

土壤水分是"绿水"重要的储存,连接植被与水文系统的纽带。水源涵养功能是山地生态系统重要的生态系统服务,这种功能主要体现是生态系统将水分保持在系统内的过程和能力,并受多种因素的影响(如植被类型、土壤类型和地形)。通过对祁连山排露沟流域的土壤属性、土壤温湿度和降雨2个生长季的野外调查与观测,以及计算水源涵养功能指标来评估3种典型植被类型土壤水分涵养能力的差异。研究结果:(1)灌丛和青海云杉林下有机质、粉粒和砂粒含量、田间持水量、饱和持水量和孔隙度等土壤属性值高于草地,而土壤容重和粘粒含量低于草地;(2)青海云杉林的根区土壤累计入渗量高于灌丛和草地,草地土壤水分损失较灌丛和青海云杉林更快;(3)整个生长季内青海云杉林和灌丛土壤湿度明显高于草地湿度,青海云杉林的水源涵养功能指标值多大于1。这些结果表明青海云杉林较灌丛和草地具有更强的水源涵养能力。因此,研究结果能为国内干旱区山地生态系统的流域生态系统管理与可持续发展提供科学参考。

The differences of water conservation function under typical vegetation types in the Pailugou catchment, Qilian Mountain, northwest China

Soil water is an important element of "green water" that constitutes the physical linkage between vegetation and hydrological system. Water retention function represents the process and ability of retaining water in the ecosystem and is an essential ecosystem service in the mountainous ecosystems. Due to the soil heterogeneity, vegetation and topography, water retention function is variable in space and time. This study aimed to characterize the differences of water retention function of three typical vegetation types in the Pailugou catchment, Qilian Mountain, northwest China. The abilities of different vegetation types are evaluated by the water conservation function index, which portrayed as the integrated effect of soil properties, soil moisture, precipitation and temperature during the growing season. The results indicated that 1) the value of soil organic matter, sand and silt content, field capacity, saturation moisture capacity and porosity were considerably higher in the shrubland and Qinhai spruce (Picea crassifolia) forest than that in the grassland. By contrast, the value of the bulk density and clay content in the grassland was higher in comparison to that of shrubland and forestland; 2) The cumulative water infiltration of the root zone in the Qinhai spruce forest was higher than that in the shrubland and grassland, and the rate of soil water loss at the grassland reached the highest level among the different vegetation types; 3) Soil moisture in the Qinhai spruce forest and shrubland was higher than that in the grassland during the whole growing season, and the water conservation function index were mostly larger than 1. In conclusion, the Qinhai spruce forest had a higher soil water holding capacity in comparison to the shrubland and grassland. Thus, the results of this study can provide scientific guidelines for the management and sustainable development of the mountainous ecosystems in the semi-arid region of China.