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Effects of Elevated Carbon Dioxide and Ozone on the Phytochemistry of Aspen and Performance of an Herbivore
Brian J. Kopper and Richard L. Lindroth
Vol. 134, No. 1 (Jan., 2003), pp. 95-103
Stable URL: http://www.jstor.org/stable/4223480
Page Count: 9
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The purpose of this study was to assess the independent and interactive effects of CO₂, O₃, and plant genotype on the foliar quality of a deciduous tree and the performance of a herbivorous insect. Two trembling aspen (Populus tremuloides Michaux) genotypes differing in response to CO₂ and O₃ were grown at the Aspen FACE (Free Air CO₂ Enrichment) site located in northern Wisconsin, USA. Trees were exposed to one of four atmospheric treatments: ambient air (control), elevated carbon dioxide (+CO₂; 560 μl/l), elevated ozone (+O₃; ambient ×1.5), and elevated CO₂+O₃. We measured the effects of CO₂ and O₃ on aspen phytochemistry and on performance of forest tent caterpillar (Malacosoma disstria Hübner) larvae. CO₂ and O₃ treatments influenced foliar quality for both genotypes, with the most notable effects being that elevated CO₂ reduced nitrogen and increased tremulacin levels, whereas elevated O₃ increased early season nitrogen and reduced tremulacin levels, relative to controls. With respect to insects, the +CO₂ treatment had little or no effect on larval performance. Larval performance improved in the +O₃ treatment, but this response was negated by the addition of elevated CO₂ (i.e., +CO₂+O₃ treatment). We conclude that tent caterpillars will have the greatest impact on aspen under current CO₂ and high O₃ levels, due to increases in insect performance and decreases in tree growth, whereas tent caterpillars will have the least impact on aspen under high CO₂ and low O₃ levels, due to moderate changes in insect performance and increases in tree growth.
Oecologia © 2003 Springer