美国新墨西哥州中部的Sevilleta荒漠-草原生态交错区是监测全球气候变化和人类活动对生物影响的重要区域之一。本文以Sevilleta荒漠-草原生态交错区为例,利用气象资料和物候观测数据,通过回归和相关分析,研究在当前全球气候变暖的条件下,温度变化对交错群落的影响。研究结果表明,最近10年（1989¹998）该区域的温度变化具有反向不对称性:夏秋季节最高气温升高很明显,冬春季节最低气温降低较明显,而年平均最高气温升高较明显,平均最低气温和平均气温变化不明显。本区荒漠/草原过渡群落的两种优势物种Bouteloua eripoda和Bouteloua gracili对温度的变化表现出不同的动态响应。第二优势种Bouteloua gracilis的盖度随着冬春最低气温的降低呈现明显的下降趋势。第一优势种Boutel-oua eripoda的盖度与冬春最低气温之间没有明显的相关性。温度的变化对群落的结构目前还没有产生明显的影响。

Because temperature is a key factor that controls the growth and distribution of vegetation,and there is no apriori reason to assume that ecosystems will respond similarly to changes in the minimum and the maximum temperatures,it is very important to explore the ecological consequences of global warming,especially the changes of the maximum and the minimum temperatures in different seasons,on terrestrial communities. Arid/semiarid biome transitional zones or ecotones are considered to be particularly sensitive areas to directional changes in climate.The desert/grassland biome transitional zone of Sevilleta in central New Mexico,U.S.provides an important region for testing species' different responses to global warming.Based on the data of climate and two dominant plants,Bouteloua eripoda and Bouteloua gracilis,which are collected from the Deep Well station in Sevilleta,this paper studies the effects of global warming on the vegetation at arid/semiarid biome transitional zone with methods of regression and correlation.The results show that the maximum and the minimum temperatures at this zone changed to different directions,that is,the increase of the maximum temperature in the summer and the fall went faster than the decrease of the minimum temperature in the winter and the spring during the study period from 1989 to 1998,which was different from the trend of climate changes that showed the minimum temperature in the winter increased faster than the maximum temperature in summer in other places(such as in North China).There were on significant changes for annual mean temperature. Responses of the two dominant plants(Bouteloua eripoda & Bouteloua gracilis)of this area to temperature changes were different due to their ecological characteristics.The cover of Bouteloua gracilis,the second dominant plant,decreased significantly,with stronger relationship to the minimum temperature of the winter and the spring than Bouteloua eripoda,the first dominant plant.The structure of biome has no significant changes.The author suggests that the structure and function of the transitional zone could be altered if the temperature changes further.So,the identification of key elements of temperature change is very important for understanding and predicting the impacts of global warming on ecosystem.