Potential of forest fertilization to alleviate effects of climate change-induced insect infestation

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Due to the massive, climate-induced outbreak of the Mountain and Western Pine Beetles, the pine forests on which much of the forest industry in interior BC is based will largely disappear by 2013. This will devastate the economies of many forestry-supported towns and cities. As an intervention strategy to increase timber supply, the BC Ministry of Forests and Range has proposed widespread use of fertilization to accelerate the development of already-existing stands. Given that 17,000 ha were operationally fertilized in BC last year, and that a further 9 million ha have already been killed by pine beetles, the potential area for fertilization is extremely large. Earlier research in Europe, the NE USA, and Alaska has demonstrated that addition of high levels of nitrogen to forests can reduce root growth, disrupt microbially-driven nutrient cycles, and increase leaching, but that effects vary by ecosystem and are not predicted by current theory. Our study would make use. of an existing long-term fertilization experiment in interior pine and spruce forests to test whether belowground microbial communities and the ecosystem services they provide are disrupted by stand-level fertilization. We | will use cutting-edge approaches to determine the effect of fertilization on (i) nutrient supply rates of N, P, K, S, and B and (ii) chemical composition of litter and soil organic matter. We will then use biochemical, isotopic, and molecular methods to determine whether the microbial community has 'adapted' to these new conditions or whether the ability of soil bacteria and fungi to cycle the altered nutrients has been compromised. This will be the first time in Canada that fertilizer-induced changes in the chemistry of soil organic matter will be linked to corresponding changes in nutrient cycling in forest soils. The results will allow forest licensees and government regulators to identify fertilizer regimes that allow the best combination of growth enhancement and ecosystem resilience.