The home-field advantage (HFA) hypothesis predicted that leaf litter decomposes fastest beneath its parent tree species, suggesting specialized decomposer communities adapted to "home" litter. However, this theory frequently failed to explain variations observed in species-rich forests.
In a study published in Catena, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences revealed that the dominance of tree species, not their specific location, is the key driver of how quickly leaf litter decomposes. The findings overturn the long-standing "home-field advantage" hypothesis and strongly support the alternative "plant apparency hypothesis" in the hyper-diverse ecosystems.
The researchers conducted meticulous reciprocal litter transplant experiments across three distinct tropical rainforest sites in Southwest China. Within each forest, they selected three canopy tree species classified as dominant, common, or rare based on their basal area (a measure of dominance). Leaf litter from these species was placed to decompose both beneath their own canopies and beneath other species' canopies.
They used litterbags with two mesh sizes: fine mesh (0.15 mm) to exclude most soil fauna, and coarse mesh (2 mm) to allow access by soil fauna like insects, mites, and earthworms.
They found that the decomposition rates were not consistently faster when the leaf litters were decomposing "at home" beneath its parent tree. However, the leaf litters decomposed significantly faster beneath dominant tree species than beneath rare species in the coarse mesh bags where soil fauna were present.
Moreover, when soil fauna were excluded using fine mesh bags, the plant apparency effects disappeared. It demonstrated that the faster decomposition linked to dominant species was driven by the soil fauna community.
The study underscored that characteristics like the abundance and distribution of litter are crucial factors, alongside chemical traits, influencing decomposition rates through their effect on soil fauna communities.
“Dominant tree species are pivotal in shaping soil decomposer communities and accelerating nutrient cycling processes. Further research on decomposition in naturally complex communities should consider the influence of litter characteristics, including abundance and distribution, on the decomposition process,”said YANG Xiaodong of XTBG.
Available online: 20 May 2025
