The wood economics spectrum modulates the positive effects of termite foraging intensity on deadwood invertebrate diversity

How populations of ecosystem engineers are both driven by and drive biodiversity is poorly known, even less so in detrital subsystems. Deadwood plays a key role in maintaining biodiversity and ecosystem functions. The wood economics spectrum (WES), which represents the initial wood quality through a suite of wood traits and adheres to economic trade-offs, might affect termite populations and deadwood invertebrate community structure via afterlife effects. Termites, as ecosystem engineers, exert a significant impact on other invertebrate diversity. However, how the WES modulates the effects of termite foraging intensity on deadwood invertebrates is unclear. We hypothesized that the WES had significant effects on termite foraging intensity and deadwood invertebrate abundance and richness. Moreover, the WES was hypothesized to modulate the effects of termite foraging intensity on deadwood invertebrate diversity. We conducted a wood decomposition experiment to test our hypotheses in two subtropical forests of China. Logs of 22 tree species with distinct functional traits were incubated for 30 months to assess termites' foraging intensity (relative termite feeding area and the mass of soil materials imported by termites) and the associated deadwood invertebrate abundance and richness. We found that, from the resource conservative (low wood quality) to the acquisitive (high wood quality) end of the WES, termite foraging intensity increased. As termite foraging activity intensified, the deadwood invertebrate abundance and richness increased correspondingly. Moreover, there were significant positive relationships between termite foraging intensity and the abundance of dominant detritivore groups (Acari, Collembola and Opisthopora). In contrast, the position along the WES had no direct effect on the abundance and richness of deadwood invertebrates besides via termite foraging intensity. Synthesis. Our findings showed the pathway of how the WES affects deadwood invertebrate diversity. They supported the hypothesis that the WES plays a crucial role in shaping the effects of termites as ecosystem engineers on the broader invertebrate community. Future studies should focus more broadly on whether and how plant traits, via afterlife effects on ecosystem engineers, influence invertebrate community composition and structure. Such studies will promote our understanding of the importance of both plant traits and ecosystem engineer traits for ecosystem carbon and nutrient cycling and biodiversity.