Moran, Emily V , Kubiske, Mark E .
Selective impacts of CO2 and ozone on aspen (Populus tremuloides).
Genetic variation in plants influences many community and ecosystem properties. If global change factors cause shifts in the genetic composition of plant populations, this could have cascading effects on processes such as herbivore community assembly, nutrient cycling, and carbon storage. While a number of studies have examined adaptive responses to CO2 and O3 in herbaceous plants, few have examined the potential for adaptive responses in trees. Making use of data from the AspenFACE experiment, we ask: Can these atmospheric pollutants exert a measurable selective effect on a woody plant over short timescales? To address this question, we developed a hierarchical Bayesian model to test whether genotype x environment interactions are necessary to explain patterns of tree mortality. We hypothesized that fast-growing clones would tend to have an advantage, particularly in the more competitive high [CO2] environment, but that factors other than growth (such as stress tolerance) would also be important for survival. We find that G x E interactions in mortality lead to altered dominance hierarchies and decreased evenness under elevated CO2 and O3. These responses are largely due to differences in growth responses between clones. While one might have expected a tradeoff between growth and stress tolerance, this was not observed. These results support the hypothesis that elevated [CO2] favors fast-growing genotypes and those with a higher-than average growth response to CO2, while high [O3] selects for genotypes that can maintain their growth despite exposure to this leaf-damaging pollutant. This suggests that managers might be able to increase carbon sequestration in temperate forests by selectively planting genotypes with these traits, which are identifiable in young saplings; however, because of possible tradeoffs between growth and tolerance of drought and or frost, further study is needed.
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1 - NIMBioS, 1534 White Avenue, University of Tennessee, Knoxville, TN, 37996, USA
2 - USDA Forest Service, Northern Research Station, Rhinelander, WI, 54501, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Portland Room/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 2:45 PM