为了揭示青藏高原高寒地区土壤冻融过程对地表植被大气三者之间能量水分循环的影响, 在青藏高原风火山左冒孔流域(长江源)开展了不同植被盖度条件下冻土活动层水热状态的野外观测(在30%、 60%、 90%的草甸盖度下观测分层土壤水分及温度)和相关试验. 选取考虑了积雪、植被覆盖及枯枝落叶层对土壤冻融影响的水热盐分耦合模型SHAW为动力学约束模型, 进行参数率定及其模拟计算. 结果表明: 青藏高原地气间的能量交换主要受冻土、植被生长和地表土壤含水量的影响, 并且呈明显的季节性变化;未退化高寒草甸草地对青藏高原冻土具有明显的隔热保温作用, 可以降低冻土对气候变化的响应. 在土壤活动层冻结过程期间, 土壤水分具有向表层和深层两向分流汇聚的特征, 植被覆盖变化对水分运移通量有明显影响.

In order to reveal the influence of freezing-thawing processes to surface-vegetation-atmosphere in the cold regions of the Tibetan Plateau,in-situ observation of water-energy state for different meadow coverage at frozen soil areas in the Fenghuoshan Zuomaokong Basin was developed.Water-heat coupling model SHAW was selected as dynamics restraint frame,in which the influences of snow cover,vegetation coverage and the forest flooring on the soil freezing and thawing are considered.The results,which were obtained by calibrating parameters,indicate:(1) Energy exchange of meadow ecosystem in the Tibetan Plateau are influenced mainly by the frozen soil state,vegetation and surface soil moisture content,with an obvious seasonal change;(2) Non-degenerated meadow in the cold regions have an obvious heat insulation and temperature preservation function to the plateau frozen soil,and may reduce the influence of frozen soil on the response to climate change;(3) In the processes of freezing-thawing of dynamic frozen zone,the soil water has divergence gathering characteristic to the surface layer and the in-depth,the vegetation coverage change has an obvious influence on the moisture content migration.