祁连山海北地区两种高寒草甸植被类型的土壤热通量比较

Comparative Analysis of Soil Heat Flux between Two Alpine Meadow Vegetation Types at Haibei Station,Qilian Mountains

对祁连山海北地区矮嵩草(Kobresia humilis)草甸和金露梅(Potentilla fruticosa)灌丛草甸两种植被类型土壤热通量观测和比较分析发现:晴天两种植被类型区土壤热通量日变化均表现为单峰型,夜间低午后高;阴雨天土壤热通量变化复杂,随降水或云层厚薄波动剧烈。金露梅灌丛草甸土壤热通量的日变化较矮嵩草草甸更为平稳。两种草甸土壤热通量的月际变化同样表现为单峰型,12月最低(矮嵩草草甸和金露梅灌丛草甸分别为-40.27MJ/m2和-16.85MJ/m2)、6月最高(矮嵩草草甸和金露梅灌丛草甸分别为20.47MJ/m2和18.98MJ/m2)。矮嵩草草甸与金露梅灌丛草甸土壤热通量的年总量差异明显,分别为-24.72MJ/m2和48.10MJ/m2。表现出前者由土壤深层向地表散热,而后者由地表向土壤深层输送热量。两种植被类型区不同时间尺度上的土壤热通量与冠层净辐射均有显著的线性相关关系。由于冠层厚度的影响,金露梅灌丛草甸土壤热通量所占净辐射的比例较小,同步性较差,反馈延时约2.5h,而矮嵩草草甸的土壤热通量与净辐射的相关性更加密切。

Based on the measurement station,Qilian Mountains, the results of soil heat flux of Kobresia humilis indicated that the diurnal change of clear days was lower at night and higher in the afternoon, representing a si and Potentilla fruticosa meadows at Haibei soil heat flux for both types of meadows in ngle-peak distribution. And it was complex in rainy days, with drastic fluctuation caused by rain and cloud. Whether it was sunny or not, the diurnal change of soil heat flux for Potentilla fruticosa meadow was more stable and its extent was smaller for high canopy height and much soil water content in Potentilla fruticosa meadow, with respecting to Koresia humilis. The monthly change of soil heat flux which was lowest in December （Kobresia humilis and Potentilla fruticosa meadows were -40. 27MJ/m2, -16. 85MJ/m2 respectively）and highest in June（Kobresia humilis and Potentilla fruticosa meadows were 20. 47MJ/m：, 18.98MJ/m2 re- spectively）, appearing a single-peak distribution. The annual total soil heat flux for Kobresia humilis and Potentillafruti- cosa meadows was significantly different and was - 24. 72MJ/m2 and 48. 10MJ/m2 respectively. Both of the annual change of soil heat flux was relevant to the variations of plant growth,soil water,seasonal frozen soil,especially net radia- tion. Due to the difference of vegetation types and environment factors,Potentilla fruticosa meadows＇ soil heat flux was a smaller consumer of net radiation than that of Kobresia humili. However,the synchronicity between soil heat flux and net radiation was worse for Potentilla fruticosa,whose delay feedback was 2. 5 hours,longer than that of Kobresia humilis.