关键词: 羊草草原, 优势物种, 地上初级生产力, 动态模拟, 内蒙古

Abstract: Global warming affects productivities of plants, and then, the structure and evolution of community. Located in the Xilin River basin in eastern part of Inner Mongolia Highland in North China, the typical primary Leymus chinensis grassland impacted by the global warming has shown depletion to some extent. In order to probe the relationship between global warming and botanic community changes, based on the multi-species competition models given by Tilman and others, this paper puts forward a dynamical model, which is focused on multi-species competition under the condition of disturbances caused by global warming, to simulate evolution of first four dominant species in Leymus chinensis grassland in Inner Mongolia Highland for several score years, which are Leymus chinensis,Stipa grandi,Artemisia commutate and Achnatberum sibiricum. The model considers the proportion of the aboveground net primary productivities (ANPP) of the four species as variables in place of the proportion of sites occupied by species in Tilman's model. The simulated results show: (1) The order of dominant species from the strongest one to the weaker ones would not change if the rate of temperature rise is less than 0.06℃ a^-1 in Inner Mongolia Leymus chinensis grassland, China, during the given period of 60 years; otherwise, the original odd dominant species of the first one and the third one will retreat to the second one and the fourth one, and the original even dominant species, the second one and the fourth one, will evolve to become the first one and the third one. The new order is Stipa grandi,Leymus chinensis,Achnatberum sibiricum and Artemisia commutate. (2) The time of rank exchange for the former two dominant species precedes the latter ones. (3) If the rate of temperature rising is more than 0.17℃ · a^-1, the new order will be Stipa grand, Achnatberum sibiricum, Leymus chinensis and Artemisia commutate.The simulated results of the order of the first four dominant species' aboveground net productivity are approximately in accordance with field investigation data under the condition of annual temperature arising by 0.086 during 1980-1994 in this area, although there is disagreement with time scale. Results of this research would provide useful enlightenment for predicting Leymus chinensis grassland evolution and helping people to manage it.

Key words: Leymus chinensis grassland, dominant species, ANPP, dynamic simulation, Inner Mongolia