高寒沼泽化草甸群落常见种对土壤水分条件的响应 研究.

Plant species in alpine swamp meadow which is a successional stage of dried alpine wetland, is sensitive to changes in soil water content, and thus it is important to understand the responses of common species of alpine swamp meadow to changed soil water condition. In order to determine the effects of different soil water content on plants of alpine swamp meadow, we transplanted 17 common species from an alpine swamp meadow to a manipulated environment located in Maqu county of Gansu Province, eastern Qinghai-Tibetan Plateau. These plants were then subjected to three soil moisture regimes: flooding (FD), control treatment (CK), and slightly drought (SD). The net photosynthesis （A）, stomatal conductance (g) and leaf dry mass per unit area (LMA) were measured for leaves from 6 plants each species per treatment. We calculated the difference of A, g and LMA between FD or SD and CK for each species, and the relationships between A and g or LMA was analyzed. Results are as follows. (1) The LMA of alpine swamp meadow common species was significantly affected by soil water condition, and there were different responses among different species. (2) Significant habitat-specific responses of gas exchange to water condition were found among the species. (3) There were significant correlations between A and g under both treatments, but it was not for A and LMA. As a conclusion, the common species of alpine swamp meadow was strongly influenced by soil water content, in additional; there was significant habitat-specific responses of the morphological traits or physiological taints to different soil water condition. Our findings suggested that the species composition of alpine swamp meadow was very sensitive to change in soil water condition. In the context of global climate change, which is predicted to alter the precipitation regime of alpine area, will be significantly influence the composition and structure of alpine swamp meadow community in the future. This should be considered carefully for protection and restoration of alpine grassland. [ABSTRACT FROM AUTHOR]