Effects of Plant Functional Identity on Ecosystem Nitrogen Retention Following Fire

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Effects of plant functional identity on ecosystem nitrogen retention following fireRecent warming trends and increased human activities have led to documented increases in fire occurrence in North American boreal forests. Forest productivity in the boreal biome is generally limited by the availability of nitrogen (N), and increased fire frequency causes increased opportunity for N to be lost from the ecosystem via combustion and post-fire losses to the atmosphere and water. Understanding controls over these N losses following fire is important for predicting the long-term consequences of increased fire frequency for forest productivity and carbon cycling. In this proposal, the investigators hypothesize that the functional traits of the plant species that initially colonize burned ecosystems will control the ability of the ecosystem to accumulate carbon and thus retain N following fire. The researchers will test this hypothesis with a study of N loss in a boreal black spruce forest that burned in June 1999. The research approach will entail an ecosystem-scale addition of a stable N isotope that can be tracked, combined with experimental manipulation of plant colonization.