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Elevated CO2 reduces leaf damage by insect herbivores in a forest community
Rachel G Knepp1, Jason G Hamilton, Jacqueline E Mohan
1Department of Plant Biology, University of Illinois, Urbana, IL 61820, USA.
The New Phytologist
|June 14, 2005
Summary
Elevated atmospheric carbon dioxide (CO2) levels may reduce insect herbivore damage to hardwood trees by altering leaf chemistry. This finding suggests potential shifts in forest ecosystem dynamics as CO2 concentrations rise.
Area of Science:
- Plant ecology
- Forest science
- Environmental science
Background:
- Atmospheric carbon dioxide (CO2) levels are rising globally.
- Elevated CO2 can alter plant physiology and foliage quality.
- Plant responses to elevated CO2 can influence herbivore interactions.
Purpose of the Study:
- To investigate the impact of elevated CO2 on the foliage quality of hardwood trees.
- To quantify the resulting changes in insect herbivore damage.
- To explore potential mechanisms linking CO2-induced foliar changes to herbivory.
Main Methods:
- Studied 12 hardwood tree species over 3 years using free-air CO2 enrichment (FACE).
- Measured foliar carbon (C), nitrogen (N), C:N ratio, phenolic content, and specific leaf area (SLA).
- Quantified leaf damage caused by chewing insects.
Main Results:
- Effects of elevated CO2 varied significantly by year and tree species.
- Elevated CO2 decreased herbivore damage in one year but not others.
- Observed changes in foliage included lower N and SLA, and higher C:N ratio and phenolics in some species under elevated CO2.
Conclusions:
- Elevated CO2 may reduce hardwood tree defoliation by insects, though effects are species and year-dependent.
- Changes in foliar C, N, SLA, and phenolics may mediate the observed reductions in herbivory.
- Future increases in atmospheric CO2 could alter forest trophic structures due to reduced herbivore damage.