Collembola (Isotomidae) and mowing management practices control distinct aspects of thatch decomposition in a lawn mesocosm experiment

Soil mesofauna, such as Collembola and mites, are important decomposers in many ecosystems. In lawns, soil mesofauna have been implicated in the decomposition of thatch, an unsightly and problematic by-product of management found in many urban grasslands. In this study, we utilized a model lawn mesocosm experiment and ubiquitous soil mesofauna (Collembola: Isotomidae) to understand their role in thatch decomposition under a variety of simulated lawn management conditions. Our results showed that Collembola enhanced thatch decomposition by 6–8% over Collembola-absent treatments, with clipping additions moderating, and in some cases diminishing the role of Collembola in thatch decomposition. This finding was likely caused by substrate switching in the presence of clippings, and Collembola and clipping additions favoring unique aspects of microbial decomposition: Collembola enhanced oxidative enzymes, enhanced microbial biomass carbon, and marginally reduced microbial respiration, which are associated with oligotrophic microbes. Clipping additions generally increased hydrolytic enzymes, had little effect on microbial biomass, and enhanced respiration, which are associated with copiotrophic microbes. These contrasting results highlight the nuanced effects of soil mesofauna in enhancing thatch decomposition and suggest that management decisions related to lawn mowing may be equally important in mitigating thatch in lawns.