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Pest management is the application of approved strategies to maintain a pest's population within tolerable levels. Improved pest management may prevent damage and tree mortality in forests and thus increase carbon stocks. Processes related to tree health are well known, whereas the reasons pests occur and how they can be prevented are less well known. Interactions between climate change, pest populations, and wildfire (see Fact Sheet 4.14) are likely to become more important in affecting forest carbon stocks in managed and unmanaged forests in the next century.
Use and Potential
Nabuurs et al. (1999) (based on Kurz et al., 1992; Townsend et
al., 1996; Gillies and Leckie, 1996) estimate the area affected by insect
attacks in Canada to be roughly equivalent to the area burned. They assume that
reducing the area affected by insect attacks by 50 percent would save the same
amount of carbon as fire protection (about 2.3 Gt C yr-1). These phenomena are
not disconnected, however. Large insect epidemics can create areas of dead and
dying trees that provide a fuel source for very large wildfires in the right
ignition and weather conditions. As a result, pest management may be one important
parameter of fire management and long-term forest ecosystem health.
Methods and Scientific Uncertainties
This activity is very uncertain. Even in areas where access is possible, effective
methods of predicting and preventing pest outbreaks may be lacking. In remote
areas, mitigation or treatment may be impractical or impossible. Few empirical
studies exist to help managers affect why and how pest populations move from
endemic to epidemic.
Time Scale, Monitoring, Variability, and Transparency
There seem to be few practical ways in which this activity, by itself, could
be linked directly to changes in carbon stocks. As part of a broad forest management
activity, it could contribute to measured changes in carbon stocks achieved
by land-based methods. Separating the carbon impacts of this single activity
would seem to be difficult or impossible.
Associated Impacts
Where biocides are used to control pests, this activity may result in reduced
biodiversity and lower landscape/recreational benefits. On the other hand, where
it prevents large-scale forest die-off, it may dramatically increase landscape,
recreational, watershed, and other benefits. High costs and uncertainty about
the effectiveness of various mitigation measures are among the reasons that
this activity is limited in many areas.
Relationship to IPCC Guidelines
See Fact Sheet 4.12.
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