16 - Interactive Effects of Carbon Dioxide and Environmental Stress on Plants and Ecosystems: A Synthesis

Abstract

This chapter summarizes the interactive effects of rising atmospheric CO2 and environmental stress. Research on CO2 and stress interactions is needed to address one question in two ways. One is whether or not elevated CO2 ameliorates or exacerbates environmental stresses. The other is how environmental stress moderates the direct effect of elevated CO2 on plants and ecosystems. Results from plant-level studies have suggested that elevated CO2 is likely to ameliorate mild drought, salinity, UV-B, and ozone stresses, to exacerbate nutrient stress, and to interact with temperature in a complex fashion. Accordingly, direct effects of elevated CO2 on plants are likely to be amplified under mild drought and salinity stresses but dampened by nutrient stress. At the ecosystem scale, there is very limited evidence to suggest one way or another on impacts of CO2 and stress interactions because major feedback mechanisms have not been evaluated using multifactorial experiments. Global change is a multifactorial process, involving not only rising atmospheric CO2 concentration but also increases in nitrogen deposition, global warming, ozone, UV-B radiation, and salinity in association with variations in precipitation.