中文摘要：

气候变暖影响植物生产力,进而影响群落的结构和演化。本文提出在不同的温度年变化率条件下内蒙古锡林郭勒盟锡林河流域羊草草原主要物种演化的动力学模型,模拟了近几十年来4个主要物种羊草、大针茅、变蒿和西伯利亚羽茅的地上初级生产力对气候变暖的响应过程。模拟和预测结果表明,在气温升高幅度不大的情况下,这4个物种的优势顺序不会发生改变,当温度年变化率高于0.06℃时,竞争能力相近物种的优势顺序发生了转换,即第一、三奇数优势物种羊草和变蒿退化为第二、四偶数优势物种,原来的偶数优势物种第二、四大针茅和西伯利亚羽茅进化为第一、第三奇数优势物种,出现的物种优势顺序为大针茅、羊草、西伯利亚羽茅和变蒿。如果温度年变化率达到0.17℃,物种的强弱顺序将重新组合,变为大针茅、西伯利亚羽茅、羊草和变蒿。现有的观测资料初步验证了这种变化的可能性。研究结果为该区羊草草原群落动态预测和草原管理提供依据。

英文摘要：

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 wit