Soil fauna explain the plant apparency effect on litter decomposition in tropical rainforests

The home-field advantage hypothesis predicts that litter decomposes more rapidly at its origin (‘home’) than at other locations. However, it often fails to explain site-specific variations, particularly in hyper-diverse forests, suggesting alternative mechanisms. To address these limitations, the plant apparency hypothesis that originated from plant-herbivore interactions studies was considered. Plant apparency hypothesis in the context of decomposition posits that litter of dominant species decomposes more rapidly than that of rare species. This study conducted reciprocal litter transplant experiments in three tropical rainforests in Southwest China. Within each forest, three canopy tree species were selected and categorized as dominant, common, and rare species according to their basal area in the plot. Leaf litter from these species was decomposed using two mesh sizes (0.15 mm and 2 mm) to manipulate decomposer access. This study found that in the coarse mesh, litter beneath dominant species (k = 2.98) decomposed faster than litter beneath rare species (k = 2.23), regardless of the litter source. Moreover, the litter of dominant species (k = 3.04) decomposed faster than the litter of rare species (k = 2.05). Thus, this study reject the home-field advantage hypothesis and support the plant apparency hypothesis. The plant apparency effect was likely driven by soil fauna community adaptations to dominant litter, regardless of litter quality or soil nutrient. This study highlights the ecological significance of dominant tree species in shaping soil fauna composition and nutrient cycling. Further research on decomposition within complex communities should consider how litter characteristics, such as abundance and distribution, impact the decomposition process.