Management Intensity and Litter Chemistry Interact to Determine Microarthropod Succession Patterns during Decomposition

Microarthropods play an important role in plant litter decomposition, and variation in the structure of their communities may lead to considerable variation in decomposition dynamics.  As a result, it is critical that we understand the factors that drive differences in the density and composition of microarthropod communities.  In decomposing litter, factors such as initial litter quality and agricultural management intensity can alter the density and complexity of microarthropod communities, but it is unclear how these communities vary over time in relation to litter chemistry.   We conducted a 730 day litter decomposition study to characterize temporal changes in litter-colonizing microarthropod communities in two qualitatively different litter types decomposing in three agricultural ecosystems (no-till and conventional till corn-soybean-wheat rotations and an old-field).  We examined changes in litter chemistry using pyrolysis-gas chromatography and mass spectrometry during decomposition and correlated these changes with shifts in microarthropod density and community composition.  The effects of management intensity on microarthropod densities varied considerably over time, and the magnitude of management effects was significantly related to precipitation rates.  Microarthropod communities were also influenced by plant litter type, and temporal variation in the densities of many taxa correlated with shifts in litter lignin, protein, polysaccharide and phenol content during decomposition.  Our data demonstrate that precipitation facilitates colonization of surface litter by microarthropods in intensively managed ecosystems and that management intensity interacts with litter chemistry over the course decomposition to determine both the size and composition of microarthropod communities inhabiting litter at the soil surface.