Community characteristics of macroinvertebrates in woody debris in a subtropical forest in Badagongshan, China: A case study on three tree species and two debris diameter classes

Aims: Woody debris provides essential habitat and food resources for macroinvertebrate communities and greatly impacts soil macrofauna biodiversity. Little is known about how features of woody debris are associated with soil macroinvertebrate communities, especially for subtropical forests. This study aims to investigate the effects of tree species, diameter classes, and decomposition stages of woody debris on the composition and structure of macroinvertebrate communities. Method: We sampled the woody debris of three tree species (Sassafras tzumu, Fagus lucida, and Cryptomeria fortunei), crossed with two size classes (10 ± 2 cm and 4 ± 2 cm in diameter) at different decomposition stages in the subtropical forests of the Badagongshan National Nature Reserve, Hunan, China, from October to November 2020. Then, macroinvertebrates in the sampled woody debris (i.e., taxonomical groups and number of individual) were inventoried for community feature characterization. Results: (1) A total number of 2,558 individuals belonging to 4 phyla, 10 classes, and 23 orders were found throughout the study. The dominant groups, common groups, and rare groups of macroinvertebrates differed in preferred tree species. (2) The individual density of macroinvertebrates in the woody debris of F. lucida was significantly higher than that in C. fortunei and S. tzumu. For F. lucida and S. tzumu, the Shannon-Wiener diversity index of macroinvertebrates was significantly higher in large-diameter woody debris than that in small-diameter debris. The number of total groups and specialist groups of invertebrates in large-diameter wood debris were more than those in small-diameter woody debris. The Shannon-Wiener diversity index, Simpson index, and Pielou index of macroinvertebrates in woody debris were significantly and negatively correlated with wood density, indicating shifted macroinvertebrates communities in woody debris with the progress of decomposition. (3) The physical and chemical properties of woody debris (e.g., relative moisture content, total nitrogen, total carbon, and carbon nitrogen ratio), soil temperature and soil humidity were significantly correlated with the characteristics of macroinvertebrate communities in woody debris. Conclusion: Our results highlight that the characteristics of macroinvertebrate community are different depending on the effect of tree species, diameter classes, and decomposition stages of woody debris. Preserving woody debris of both large and small