Global environmental changes, such as rising atmospheric CO2 concentrations, have a wide range of direct effects on plant physiology, growth, and fecundity. These environmental changes also can affect plants indirectly by altering interactions with other species. Therefore, the effects of global changes on a particular species may depend on the presence and abundance of other community members. We experimentally manipulated atmospheric CO2 concentration and amounts of herbivore damage (natural insect folivory and clipping to simulate browsing) to examine: (1) how herbivores mediate the effects of elevated CO2 (eCO2) on the growth and fitness of Arabidopsis thaliana; and (2) how predicted changes in CO2 concentration affect plant resistance to herbivores, which influences the amount of damage plants receive, and plant tolerance of herbivory, or the fitness consequences of damage. We found no evidence that CO2 altered resistance, but plants grown in eCO2 were less tolerant of herbivory-clipping reduced aboveground biomass and fruit production by 13 and 22%, respectively, when plants were reared under eCO2, but plants fully compensated for clipping in ambient CO2 (aCO2) environments. Costs of tolerance in the form of reduced fitness of undamaged plants were detected in eCO2 but not aCO2 environments. Increased costs could reduce selection on tolerance in eCO2 environments, potentially resulting in even larger fitness effects of clipping in predicted future eCO2 conditions. Thus, environmental perturbations can indirectly affect both the ecology and evolution of plant populations by altering both the intensity of species interactions as well as the fitness consequences of those interactions.
Bibliographical noteFunding Information:
Acknowledgments We thank A. Mueller for Weld and laboratory assistance, P. Reich for allowing us to use the BioCON experiment at Cedar Creek Natural History Area, and J. Conner for providing helpful comments on an earlier draft of this manuscript. This project was funded primarily by NSF IOB 0417094 to P. TiYn, R. Shaw, and P. Reich and secondarily by NSF LTER (DEB 0080382) and Biocomplexity (0322057) programs. This is W. K. Kellogg Biological Station contribution no. 1,465. The experiments described herein comply with current laws of the United States of America.
- Carbon dioxide
- Global change