Effects of leaf litter on the growth of an invasive annual grass

An important component of the understory that may influence the success of invasion in intact forests is the surface leaf litter. The type and quantity of leaf litter covering the forest floor may affect the ability of an invasive annual grass, Microstegium vimineum, to spread. I hypothesized that different types of leaf litter will differentially affect the germination and growth of M. vimineum in a greenhouse experiment. I used field soil from a maple/sweetgum dominated forest and soil from an oak/hickory dominated community both previously uninvaded by M. vimineum to fill 100 trays. I sowed approximately 600 M. vimineum seeds in each tray. Four litter treatments of different species (maple, oak, M. vimineum, and woodchip mulch) were spread on the surface of the trays to mimic field depths and one no litter treatment served as control. Plants were destructively sampled after four months. Although M. vimineum germinated in all litter treatments, trays receiving oak litter and mulch had significantly less germination. Overall aboveground biomass was not affected by litter treatments compared to the control, but belowground biomass was decreased in trays with M. vimineum litter. When considering the control of M. vimineum in forested systems, native species with recalcitrant litter quality should be considered in restoration plans.