Rethinking assumptions about plant litter decomposition

Abstract Plant litter decomposition is the breakdown of dead plant biomass by abiotic and biotic means. In terrestrial ecosystems, decomposition regulates the fate of fixed plant carbon, contributing both to its release into the atmosphere and its long-term storage in soil organic matter. In the present article, we revisit four assumptions about decomposition in light of advances in microbiology. First, we consider fungi as primary decomposers, noting bacterial contributions to breaking down lignin and cellulose and overcoming nitrogen limitation. Second, we discuss evidence of the role of microbial communities on litter decomposition, challenging assumptions of microbial redundancy. Third, given these functional consequences of their composition, we examine whether surface litter and bulk soil microbial communities are interchangeable. Finally, we reevaluate the idea that soil organic matter originates from plant litter, emphasizing the pivotal role of microbial necromass. We highlight the importance of integrating microbiological findings into ecosystem ecology to accelerate research on carbon cycling in terrestrial ecosystems.