Termites amplify the effects of wood traits on decomposition rates among multiple bamboo and dicot woody species

Abstract

Summary Wood decomposition is a key process in the terrestrial carbon cycle, controlling carbon storage with feedback to climate. In (sub) tropical forest, termites are major players in wood decomposition, but their role relative to that of microbial decomposers and wood traits of different tree species is poorly understood. The current literature also has strong bias towards dicot tree decomposition, while abundant woody monocots, particularly bamboos, also contribute greatly to (sub) tropical carbon cycling. Here, we present the first experiment to disentangle effects of dead wood traits and termite activity on decomposition of 66 angiosperm species of wide‐ranging phylogenetic position: 31 bamboos, eight non‐bamboo Poaceae, 18 eudicots and nine magnoliids. We incubated dead stems of up to 4 size classes per species in a ‘common garden’ in tropical S China. We tested the hypotheses that (i) dead wood of bamboo (monocots) is less decomposable than dead wood of eudicots or magnoliids; (ii) both microbial‐ and termite‐driven decomposition show negative relationships with initial wood density and with dry matter content. Bamboo wood generally decomposed more slowly than dicot wood but only slightly slower at given wood density or diameter. Wood decomposition in both bamboo and dicot clades decreased with wood density or dry matter content. Termites contributed greatly to this pattern, explaining 53.4% of the variance in wood decomposition and preferentially attacking dead wood of lower initial density, which corresponded with thicker outer culm walls in the case of bamboo species. Thus, termites strongly strengthen the relationship between species' wood traits and litter decomposition as driven by microbial activity. Synthesis. These previously unknown relationships among dead wood quality, diameter, termites and decomposing microbes of both woody monocots and dicots will advance our understanding of the driving mechanisms of (sub) tropical wood decomposition and its contribution to the global carbon cycle.