Abstract
The “Home Field Advantage” (HFA) hypothesis posits that plant litter decomposes more rapidly in its native environment because local soil microbiomes are functionally adapted to the biochemical and structural properties of local litter inputs. However, the mechanisms driving HFA responses, and their sensitivity to climate change, remain unclear. Here, we conducted a 24-month reciprocal litter-soil transplant experiment between temperate and subtropical forests to evaluate how climate, litter quality, and microbial community composition interactively shaped HFA effects. We observed clear HFA effects for both litter types, but underlying mechanisms diverged. Temperate litter was associated with greater fungal diversity, including a higher relative abundance of Mortierellomycota and Ascomycota phyla, than subtropical litter. Conversely, high-nitrogen, low-phosphorus subtropical litter suppressed fungal activity in temperate soils, despite only modest changes in bacterial community composition. Different litter–decomposer affinity relationships may arise from site-associated differences in soil properties and climate. Consistent with this interpretation, our reciprocal soil transplantation experiment showed that altering the recipient environmental context weakened HFA. Soil transplantation into novel climates caused dominant fungal taxa to be progressively replaced by locally adapted fungal assemblages, and several climate-associated fungal classes (e.g., Rhizophydiomycetes, Dothideomycetes, and Leotiomycetes) were strongly correlated with litter mass loss. Our findings highlight the central role of fungi in mediating HFA effects, suggesting that site-associated factors (e.g., climate, vegetation, and soil type) shape microbial turnover and decomposition trajectories. As climate change alters plant species distributions and restructures soil microbiomes, these interactions may become increasingly decoupled, with significant implications for ecosystem carbon dynamics.