Use of Simulation Models to Evaluate the Alteration of Ecotones by Global Carbon Dioxide Increases

Abstract

There is increasing potential for shifts in ecosystem boundaries in the face of widespread climate changes, stemming from increases in carbon dioxide levels. Initial attempts at predicting these shifts have assumed that biomes will reestablish boundaries in accordance with the governs of precipitation, temperature, and evapotranspiration (Emanuel et al. 1985). Such work has been based on the associations between the present distribution of natural vegetation zones and climatic regions (Holdridge 1964; Trewartha 1968). These models update the world map of average annual precipitation and temperature, using predictions from global climate models, and then remap vegetation zones, assuming that the correlation between vegetation zones and climate will remain intact. While this seems like a tenuous assumption at best, evidence from paleoecological studies in the eastern United States suggests that ecosystem distribution may maintain a relationship with climatic variables when quantified at time scales of thousands of years (Delcourt and Delcourt 1987).