Linking Insect Communities to Ecosystem Function: Litter Decomposition in a Forest Diversity Experiment

 
Biotic communities impact ecosystem function through a number of direct and indirect pathways. Decomposition is one of many important ecosystem processes driven by abiotic factors, like temperature and precipitation, but also by plant and arthropod communities. Here we examined the role of tree species identity, locational and origin diversity, and decomposer access on the leaf litter decay of five tree species. A large-scale litterbag experiment was deployed at BiodiversiTREE, a forest diversity experiment in Edgewater, Maryland. Litterbag data was supplemented with nutrient analysis and green leaf traits. In the first two litterbag collections, litter decay varied by tree species, with sweetgum and tulip poplar litter experiencing the fastest decay rates. Decomposer access was correlated with faster decomposition at the second collection point, suggesting that macro-arthropod decomposers are important drivers of decomposition, particularly in the spring months. Leaf nutrients are good indicators of decomposition in some species, but physical traits are determining decomposition trajectory in others. With two more litterbag collections forthcoming, we expect increasing important of diversity at the plant and decomposer levels.