Potential effects of global climate change on the biodiversity of plants

Abstract

Climate models of doubled atmospheric CO2 predict that mean temperatures will increase between 1.5 and 4.5°C globally; these temperature changes will be greater at high latitudes. Mid-continental regions will experience lower rainfall. Predictions of species northward range shifts in response to climate change vary from 100 km to >500 km. Historical evidence of species range movements following the Pleistocene indicate that tree species typically migrated at rates of 10-40 km per century. A simulation model that predicts the migration response of trees through modern fragmented landscapes predicts migration rates much lower than Pleistocene observations. Thus migration response is likely to lag far behind rates of climate change, potentially threatening narrowly distributed species whose predicted future ranges do not overlap with their current range. Insect pests and microbial pathogens should respond to climatic warming faster than long-lived trees. Predicted increased drought frequency may increase plant stress and thereby increase the frequency of insect outbreaks and disease. Predictions of species responses are complicated by direct effects of increased CO2, such as increased water-use efficiency. However, response to elevated CO2 varies among species. Thus, shifts in composition within plant communities are also likely but are, as yet, unpredictable. -from Author