Abstract
Shade trees are integral components of coffee agroforestry systems, contributing to microclimate regulation, biodiversity conservation, and nutrient cycling through litter decomposition. This study evaluated home-field advantage (HFA) in leaf litter decomposition under three coffee agroforestry shade systems in Gomma District, southwestern Ethiopia: diverse shade tree species systems, monoculture Albizia (Albizia gummifera) shade systems, and unshaded coffee systems. Laboratory incubation experiments were conducted using litter from each shade category under home- and away-field soil conditions, with phosphorus fertilization included as an explanatory factor. Soil physicochemical properties varied among systems, with diverse shade systems showing significantly lower bulk density, higher water-holding capacity, less acidic pH, and greater available phosphorus than unshaded coffee systems. Cumulative CO₂ respiration differed significantly among litter soil combinations (p < 0.05), indicating strong effects of litter type and soil origin on decomposition. Mixed-species litter under diverse shade systems exhibited the highest decomposition rates and positive home-field advantage, with additional decomposition at home (ADHₓ = 7.289%), demonstrating enhanced microbial adaptation to native litter inputs. In contrast, Albizia monoculture and unshaded coffee litter showed weaker and more variable HFA responses. Phosphorus fertilization enhanced decomposition trends, particularly under diverse shade and Albizia systems, although treatment differences among phosphorus levels were not consistently significant. The findings demonstrate that shade tree diversity strengthens litter decomposition efficiency and promotes stronger HFA by improving litter quality, soil nutrient status, and microbial specialization. Integrating Albizia gummifera within diverse multi-species shade systems is therefore more beneficial than maintaining Albizia monoculture shade systems for sustaining nutrient cycling in coffee agroforestry landscapes.
Keywords: Home-field advantage; Litter decomposition; Coffee agroforestry; Shade tree diversity; Phosphorus fertilization.
