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Forest defoliator pests alter carbon and nitrogen cycles
Anne L-M-Arnold1, Maren Grüning1, Judy Simon2
1Institute of Soil Science of Temperate and Boreal Ecosystems , Büsgen-Institute, Georg-August-University , Büsgenweg 2, 37077 Göttingen , Germany.
Royal Society Open Science
|November 18, 2016
Summary
Climate change can increase forest pest outbreaks, significantly raising carbon and nitrogen fluxes from insect frass and leaf litter. This stimulates soil microbial activity, potentially creating a carbon cycle feedback loop.
Area of Science:
- Forest ecology
- Biogeochemistry
- Climate change impacts
Background:
- Climate change is linked to increased forest pest outbreaks.
- These outbreaks can alter ecosystem functioning through changes in element fluxes.
- Understanding these impacts is crucial for predicting forest ecosystem responses.
Purpose of the Study:
- To investigate the impact of forest pest outbreaks on carbon (C) and nitrogen (N) fluxes in oak forests.
- To quantify the contribution of insect frass, leaf litter, and throughfall to canopy-to-soil element transfer.
- To assess the effect of insect frass on soil microbial activity and carbon cycling.
Main Methods:
- Field study in deciduous oak forests (Quercus petraea) comparing infested and uninfested sites.
- Analysis of C and N compounds in insect faeces, leaf litter, throughfall, and soil solutions.
- Microcosm incubation experiment to measure soil respiration and dissolved organic carbon (DOC) fluxes.
Main Results:
- Canopy-to-soil fluxes of C and N were 30- and 18-fold higher, respectively, in infested forests during a 3-year pest outbreak.
- Infested forests showed elevated soil solution C and N levels and reduced C/N ratios in humus.
- Insect faeces in microcosms increased carbon dioxide and DOC fluxes by 16- and 10-fold, respectively.
Conclusions:
- Forest pest epidemics significantly enhance canopy-to-soil element fluxes.
- The deposition of nitrogen and labile carbon compounds stimulates soil microbial respiration.
- This process represents a potential carbon cycle feedback mechanism driven by climate change.
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