Can elevated CO₂ and ozone shift the genetic composition of aspen (Populus tremuloides) stands? New Phytologist

Abstract

The world's forests are currently exposed to increasing concentrations of carbon dioxide (CO₂) and ozone (O₃). Both pollutants can potentially exert a selective effect on plant populations. This, in turn, may lead to changes in ecosystem properties, such as carbon sequestration. Here, we report how elevated CO₂ and O₃ affect the genetic composition of a woody plant population via altered survival. Using data from the Aspen free-air CO₂ enrichment (FACE) experiment (in which aspen clones were grown in factorial combinations of CO₂ and O₃), we develop a hierarchical Bayesian model of survival. We also examine how survival differences between clones could affect pollutant responses in the next generation. Our model predicts that the relative abundance of the tested clones, given equal initial abundance, would shift under either elevated CO₂ or O₃ as a result of changing survival rates. Survival was strongly affected by between-clone differences in growth responses. Selection could noticeably decrease O₃ sensitivity in the next generation, depending on the heritability of growth responses and the distribution of seed production. The response to selection by CO₂, however, is likely to be small. Our results suggest that the changing atmospheric composition could shift the genotypic composition and average pollutant responses of tree populations over moderate timescales.

Keywords

Bayesian, CO2, FACE, growth, mortality, ozone, Populus tremuloides (aspen), selection

Citation

Moran, Emily V.; Kubiske, Mark E. 2013. Can elevated CO2 and ozone shift the genetic composition of aspen (Populus tremuloides) stands New Phytologist. doi: 10.1111/nph.12153.