Grant: Advancing Climate Change Science in Canada

Forests play an important role in removing carbon dioxide from the atmosphere and storing it in soil - thus countering the tendency for atmospheric carbon dioxide to warm our climate. We will ask how outbreaks of spruce budworm, a major forest pest that defoliates and kills conifers over millions of hectares, alter this process. In defoliated forests, dead needles and budworm feces likely provide a short-term boost in carbon flow to soils. However, in the longer term, defoliated forests are less able to remove carbon dioxide from the atmosphere, and the thinner tree canopy means warmer soils and therefore, potentially, more release of stored carbon from the soil. We will study these effects and their interactions by comparing forest plots that have been defoliated by budworm with similar, nearby plots that have been protected from budworm damage by aerial spray with a biological insecticide, Btk. We will measure the fall of needles and caterpillar feces from the canopy to the ground, measure carbon content in soil cores, and measure the emission of carbon dioxide from microbes in the soil. We will also measure the abundance of "mycorrhizal" fungi - fungi that form partnerships with tree roots and which receive carbon-containing sugars from the tree and move them into soil. Together, these measurements will help us understand how budworm outbreaks change the carbon cycle in forests, and how we can use Btk treatments to intervene to protect the carbon-storage role of the forest. This research will involve both established scientists and students in training from the University of New Brunswick, the Canadian Forest Service, and Agriculture and Agri-Food Canada.