青藏高原多年冻土区高寒草地生物量与环境因子关系的初步分析

A Preliminary Study of the Relationships between Alpine Grassland Biomass and Environmental Factors in the PermafrostRegions of the Tibetan Plateau

以青藏高原多年冻土区3种高寒草地植被为研究对象,设置6个样地,并结合附近活动层观测场环境因子数据,定量分析生物量与环境因子的关系.结果表明,各高寒草地地下生物量对总生物量的贡献率最大,而地下生物量在0～10cm集中分布;对于总生物量和地下生物量,各因子影响程度大小次序为:土壤盐分>土壤含水量>空气温度,而对地上生物量,依次为土壤含水量>土壤盐分>空气温度;土壤温度同生物量存在负相关关系.同时,伴随多年冻土退化,活动层表层不同深度(10～50cm)土壤温度明显升高,含水量逐渐降低,土壤盐分不断增加,从而使高寒草地植被类型出现由高寒沼泽草甸、高寒草甸至高寒草原的逆向演替过程,群落总盖度及生物量均表现出明显降低的趋势.

In order to quantitatively analyze the relationships between the biomass and the environmental factors for the three types of alpine grasslands （alpine marsh meadow,alpine meadow and alpine steppe） in the permafrost regions of Tibetan Plateau,six active layer plots in the plateau were selected. The results show that the underground biomass contributes a large percentage of the total biomass in the alpine grasslands,which concentrates in the depth range from 0 to 10 cm. The factors affecting total biomass and underground biomass rank in the order：soil salinity,soil moisture content and air temperature. However,the factors affecting the aboveground biomass rank in the order：soil moisture content,soil salinity and air temperature. It is also observed that the soil temperature has a negative correlation with biomass. Furthermore,with permafrost degradation,the soil temperature significantly increases,the soil moisture content decreases gradually and the soil salinity continuously increases throughout different soil depths of the active layer （10~50 cm）; As a result,a retrograde succession from alpine marsh meadow,alpine meadow to alpine steppe occurs in the alpine grasslands vegetation,and then a obvious decreasing trend will occur for the total coverage and biomass.