Insect-mediated nitrogen dynamics in decomposing wood

Abstract. 1. Wood decomposition is characterised by complex and poorly understood nitrogen (N) dynamics with unclear implications for forest nutrient cycling and productivity. Wood-dwelling microbes have developed unique strategies for coping with the N limitations imposed by their substrate, including the translocation of N into wood by cord-forming fungi and the fixation of atmospheric nitrogen (N2) by bacteria and Archaea. 2. By accelerating the release of nutrients immobilised in fungal tissues and promoting N2 fixation by free-living and endosymbiotic prokaryotes, saproxylic insects have the potential to influence N dynamics in forests. 3. Prokaryotes capable of fixing N2 appear to be commonplace among wood-feeding insects, with published records from three orders (Blattodea, Coleoptera and Hymenoptera), 13 families, 33 genera and at least 60 species. These organisms appear to play a significant role in the N economies of their hosts and represent a widespread solution to surviving on a diet of wood. 4. While agricultural research has demonstrated the role that termites and other insects can play in enhancing crop yields, the importance of saproxylic insects to forest productivity remains unexplored.