Effects of elevated atmospheric CO2 concentration on insect herbivory and nutrientfluxes in a mature temperate forest

Aradhana J. Roberts*, Liam M. Crowley, Jon P. Sadler, Tien T.T. Nguyen, Scott A.L. Hayward, Daniel B. Metcalfe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Insect herbivory is one of the most important ecological processes affecting plant–soil feedbacks and overall forest ecosystem health. In this study, we assess how elevated carbon dioxide (eCO2) impacts (i) leaf level insect herbivory and (ii) the stand-level herbivore-mediated transfer of carbon (C) and nitrogen (N) from the canopy to the ground in a natural mature oak temperate forest community in central England at the Birmingham Institute of Forest Research Free Air CO2 Enrichment (BIFoR FACE) site. Recently abscised leaves were collected every two weeks through the growing season in August to December from 2017–2019, with the identification of four dominant species: Quercus robur (pedunculate oak), Acer pseudoplatanus (sycamore), Crataegus monogyna (com-mon hawthorn) and Corylus avellana (hazel). The selected leaves were scanned and visually analyzed to quantify the leaf area loss from folivory monthly. Additionally, the herbivore-mediated transfer of C and N fluxes from the dominant tree species Q. robur was calculated from these leaf-level folivory estimates, the total foliar production and the foliar C and N contents. This study finds that the leaf-level herbivory at the BIFoR FACE has not changed significantly across the first 3 years of eCO2 treatment when assessed across all dominant tree species, although we detected significant changes under the eCO2 treatment for individual tree species and years. Despite the lack of any strong leaf-level herbivory response, the estimated stand-level foliar C and N transferred to the ground via herbivory was substantially higher under eCO2, mainly because there was a ~50% increase in the foliar production of Q. robur under eCO2. This result cautions against concluding much from either the presence or absence of leaf-level herbivory responses to any environmental effect, because their actual ecosystem effects are filtered through so many (usually unmeasured) factors.

Original languageEnglish
Article number998
Number of pages10
Issue number7
Publication statusPublished - 24 Jun 2022

Bibliographical note

Funding Information:
Funding: This research was funded by the European Research Council (ERC) under the European Union’s ECOHERB-682707.

Acknowledgments: We thank all our collaborators for making this research possible, especially the BIFoR technical team for enabling and supporting research at the facility as well as Rob Mackenzie, Giulio Curioni and Deanne Brettle for all the data collection and advice on the site work. We thank Anna Gardner for the oak nutrient data and analysis. This research utilized BIFoR FACE data supported by the JABBS foundation and the University of Birmingham.

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • carbon
  • free-air CO enrichment (FACE)
  • leaf area loss
  • nitrogen
  • nutrient transfer

ASJC Scopus subject areas

  • Forestry


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