高寒草地土壤保持功能的风洞模拟及其定量评估

青藏高原高寒草地的土壤保持功能对于保护生态环境具有重要的作用。为了研究人类活动不同干扰方式对高寒草地土壤保持功能的影响,利用大型风洞,对不同干扰方式下高寒草甸、草原化草甸和高寒草原3个类型的土壤保持功能定量评估,以侵蚀率作为土壤保持功能的测度指标。实验结果表明,随着风速的增大,3个样品的土壤侵蚀率均呈现增大趋势,但不同处理下侵蚀率的增幅不同。当植被根系破坏后,土壤侵蚀率大小为高寒草甸<草原化草甸<高寒草原,说明,高寒草甸土壤的可蚀性低,高寒草原土壤的可蚀性高,极易遭到破坏。从总体来看,土壤保持功能的强弱依次为高寒草甸>草原化草甸>高寒草原。风蚀前后土壤中有机质和养分含量的变化分析表明,土壤有机质和养分含量显著下降,其中速效K2O的养分含量下降幅度最大。对3个草地类型单位面积土壤保持经济价值进行计算,计算主要包括保持有机碳、保持养分和减少土壤流失对河流湖泊淤积3个方面的价值。结果表明,高寒草原化草甸单位面积的土壤保持价值最高,其次为高寒草甸,高寒草原单位面积土壤保持价值最低。

Wind Tunnel Simulation and Assessment of Soil Conservation of Alpine Grassland in Qinghai-Tibet Plateau

The soil conservation of alpine grassland is one of the important functions for environ,mental protection in Qinghai,Tibet Plateau.Aimed to study on impact of human activities on services of soil conservation,this paper simulated soil erosion changes under different disturbed patterns of human activities by using the wind tunnel laboratory.Three types of grassland were selected which included alpine meadow,alpine steppe meadow and alpine steppe and the erosion rate as indicator measure function of soil conservation.In general,the greater the soil erosion is,the lower the soil conservation function is.The results showed that the soil erosion rate of three grassland samples increased with wind velocity under different treatments but the increment of erosion rate varied greatly.The erosion rate change of the alpine meadow was the same as that of the alpine steppe when the surface vegetation was cut,and compared with the original status both of them changed a little.And when the root system was broken the erosion rate ranged from high to low in turn of alpine meadow,alpine steppe meadow and alpine steppe.So the data suggested that the function of soil conservation for three types of grassland should be alpine meadow>alpine steppe meadow>alpine steppe.The organic matter and nutrient content were analyzed before and after the aeolian erosion simulation and the decrease of all nutrients were obvious in particular the K2O.The economic values of soil conservation were estimated that included the values of organic carbon fixation,nutrient detention and decrease of soil deposits.The results indicated that the value of nutrient detention is the highest and the economic value of soil deposits decrease is the lowest.The total economic value per unit area varied in turn of alpine steppe meadow,alpine meadow and alpine steppe.