Temporal dynamics of bark and wood functional traits in determining invertebrate communities during coarse and fine woody debris decomposition

Plant functional traits act as environmental filters, influencing invertebrate community assembly during decomposition processes and thus biogeochemical cycling. Within a plant, bark and wood exhibit distinct functional trait characteristics, and these traits further vary among different sizes of deadwood, such as coarse woody debris (CWD) and fine woody debris (FWD), as well as different decomposition stages. Despite this, studies on deadwood biodiversity and decomposition often ignore differences between bark and wood. Using a 42-month experiment with 41 woody species in subtropical forests, we examined how bark and wood functional traits structure invertebrate communities during deadwood decomposition. We hypothesized that (i) invertebrate abundance and diversity are higher for resource-acquisitive traits than for resource-conservative traits; (ii) bark traits are more important for FWD and wood traits are more important for CWD in determining invertebrate communities; and (iii) the effect of bark traits on invertebrate communities dominates during the early decomposition stage, while the effect of wood traits dominates during later decay stages. Our results demonstrated size- and stage-dependent trait effects on invertebrate communities. The bark economics spectrum was positively related to invertebrate abundance and richness during early decomposition (18 months), with stronger effects for FWD than for CWD. In contrast, the wood economics spectrum (WES) influenced invertebrate diversity only in CWD but not in FWD. Effects of WES persisted through both early and later decomposition stages (42 months), but the effect strength and direction showed strong site dependency. Synthesis. We found that bark traits are important drivers of invertebrate diversity in deadwood during early decomposition for both FWD and CWD, whereas the effects of wood traits are longer lasting but restricted to CWD. These findings expand our understanding of the afterlife effect of plant traits by demonstrating that bark and wood traits play distinct roles for invertebrate community assembly, while their relative importance shifts during deadwood decay. Studies of deadwood-decomposer succession and plant–invertebrate interactions should therefore consider bark and wood traits.