Effects of Climate Change and a Doubling of CO²on Vegetation Diversity

A model is presented for predicting the response of global family diversity to global environmental change. The model assumes that three primary mechanisms determine diversity: the capacity to survive the absolute minimum temperature of a site, the ability to complete the life cycle in a given length and warmth of the growing season, and the capacity to expand leaves in a defined regime of precipitation and vegetation transpiration. The direct effects of CO2 on vegetation transpiration are also included. About one-third of the floristic regions of the world exhibit increased diversity with a 3°C increase in temperature, a 10% increase in precipitation, and a doubling of the CO2 concentration. The addition of CO2 offsets the increased rates of transpiration, caused by global warming through its capacity to reduce transpiration. As a consequence, the diversity of dry regions displayed the greatest increase in diversity due to increased CO2.