Effects of moss patch size on nematodes distributions on tree bark in a coniferous plantation

To maintain biodiversity, understanding how small organisms assemble in fragmented microhabitats is central topic to community ecology. Moss patches on trees act as resource-rich habitats that are ideal for testing island biogeography theory on animals inhabiting canopy habitats. Among these animals, nematodes are particularly suitable for examining colonization processes due to their ubiquity, rapid turnover, and sensitivity to microhabitats. Although the theory has been applied to nematodes, few studies have explicitly addressed the underlying processes involved. We aimed to clarify the effect of moss habitat areas on the nematode communities associated with the tree bark. We expected greater nematode richness in larger moss patches. To achieve this, moss patches of varying sizes (from 0.0625 cm2 to 64 cm2) were attached to Japanese cedar (Cryptomeria japonica D.Don) barks in a plantation site. After five, seven, and ten months, the mosses were retrieved, and the nematodes were morphologically identified. Nematode richness were significantly and positively affected by moss size. Breakpoint analysis revealed that a single breakpoint was consistently identified at a moss size of 16 cm2 for both nematode richness. Overall, our results suggest that moss patches on tree barks are regarded as discreate microhabitats for nematodes, with larger patches being more favorable for nematodes.