Gelieke Steeghs

Food forests are perennial, multi-layered food production systems gaining popularity as alternatives to intensive, input-dependent agriculture. With limited use of external inputs, these systems rely on nutrient recycling via litter decomposition for plant nutrient supply. However, little is known about decomposition dynamics during food forest development. We studied how litter of Alnus glutinosa (L.) Gaertn. (black alder), Corylus avellana (L.) (common hazel) and Castanea sativa Mill. (sweet chestnut) (high to low litter quality) was decomposed in food forests planted on grasslands versus neighboring grasslands. Using litter bags with varying mesh sizes, we assessed the relative contribution of microbes, micro-, meso- and macrofauna on short-term litter mass loss. We also quantified abundance and/or biomass of key decomposer groups. Decomposer communities differed between the land use types, with food forests harboring a higher abundance of oribatid mites, but a lower abundance and biomass of earthworms and lower biomass of arbuscular mycorrhizal fungi than grasslands. We found little differences in litter mass loss between the systems, except for a higher mass loss of high-quality litter in grasslands when the litter was accessible to the entire decomposer community. The lowest-quality (sweet chestnut) litter decomposed slowest and decomposition rates were neither impacted by mesh size nor land use. Overall, high-quality leaf litter generally decomposed faster in grasslands than food forests and the different decomposer communities in young food forests did not favor the breakdown of (recalcitrant) litter. Future research could explore the potential implications of these findings for plant nutrient provisioning in self-sustaining agroecosystems.