荒漠-草原生态交错区植物对温度变化的动态响应——以美国新墨西哥州Sevilleta生态交错区为例

Abstract

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 gracilic, 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.