Land use transformation is a significant driver of habitat degradation across diverse ecosystems, leading to biodiversity loss and disrupting essential ecological processes. This study is a part of the global LandComp initiative, which investigates how changing land use impacts biological communities and processes in freshwater ecosystems worldwide through modifying flow patterns, temperature regimes, and sediment dynamics. Furthermore, LandComp aims to determine whether shifts in leaf litter breakdown vary with the quality of the litter and the exclusion of consumers.
This work specifically examines the relationship between leaf litter breakdown in freshwater streams, surrounding land use patterns, and macroinvertebrate community composition. Using the standardized leaf litter bag methodology, we measured breakdown rates in representative streams within three distinct landscape categories (urban, forested, and agricultural) in central Maryland, USA. Three leaf types with distinct foliar chemistries (Quercus rubra, Acer rubrum, and Alnus spp.) were used, and consumer exclusion bags were also utilized. The instream breakdown of senesced leaves—a process mediated by foliar chemistry, consumers, and environmental conditions—serves as a sensitive indicator of ecosystem condition.
Preliminary results from global LandComp collaborator locations running the same study design have revealed that both agricultural and urban land cover types significantly reduce breakdown rates compared with forested sites. This aligns with our work at our Baltimore, USA location, which shows similar trends. These findings provide valuable insight into the cascading effects of land use change on critical ecosystem processes and biodiversity maintenance in freshwater environments.