The impact of decomposer size classes and litter quality on litter decomposition in food forests

Urban Farm DB summary

This study examined litter decomposition dynamics in food forests, perennial multi-layered food production systems gaining popularity as alternatives to intensive, input-dependent agriculture that rely on nutrient recycling via litter decomposition. Litter from Alnus glutinosa (black alder), Corylus avellana (common hazel), and Castanea sativa (sweet chestnut), ranging from high to low litter quality, was decomposed in food forests planted on former grasslands and compared with neighboring grasslands. Litter bags of varying mesh size were used to assess the relative contribution of microbes and micro-, meso-, and macrofauna to short-term litter mass loss, and abundance and biomass of key decomposer groups were quantified. Decomposer communities differed between land use types: food forests harbored a higher abundance of oribatid mites but a lower abundance and biomass of earthworms and lower arbuscular mycorrhizal fungi biomass than grasslands. Overall litter mass loss differed little between the systems, except that high-quality litter accessible to the full decomposer community lost more mass in grasslands. The lowest-quality litter (sweet chestnut) decomposed slowest, with its rate unaffected by mesh size or land use. High-quality leaf litter generally decomposed faster in grasslands than in food forests, and the distinct decomposer communities in young food forests did not favor breakdown of recalcitrant litter.