The effects of elevated CO2 atmospheres on the nutritional quality of Eucalyptus foliage and its interaction with soil nutrient and light availability

Oecologia - Tập 109 - Trang 59-68 - 1996
I. R. Lawler1, W. J. Foley1, I. E. Woodrow2, S. J. Cork3
1Department of Zoology James Cook University of North Queensland Townsville, 4811 Queensland, Australia fax: +61 77 251570 e-mail:[email protected]., , AU
2Department of Botany, James Cook University Townsville, Qld. 4811, Australia, , AU
3CSIRO Division of Wildlife and Ecology, Lyneham, ACT 2602, Australia, , AU

Tóm tắt

 Seedlings of Eucalyptus tereticornis (Smith) were grown under two levels of availability each of CO2 (352 and 793 µmol mol−1), soil nutrients (1/24 and 1/4 Hoagland’s solution) and light (full and 30% sunlight). Low soil nutrient availability or high light increased the C:N ratio of leaves, leading to lower leaf nitrogen concentrations, higher leaf specific weights and higher levels of both total phenolics and condensed tannins. These results were consistent with other studies of the effect of environmental resource availability on foliage composition. Similar results were observed when the C:N ratio of leaves was increased under elevated CO2. The changes in leaf chemistry induced by the treatments affected the performance of 4th-instar larvae of Chrysophtharta flaveola (Chapuis) fed on the leaves. Increased C:N ratios of leaves reduced digestive efficiencies and pupal body sizes and increased mortality. Below a threshold nitrogen concentration of approximately 1% dry mass, severe reductions in the performance of larvae were recorded. Such changes may have significant consequences for herbivores of Eucalyptus, particularly in view of projected increases in atmospheric CO2.