Invasive species accelerate decomposition and litter nitrogen loss in a mixed deciduous forest

Invasive species can change decomposition rates within an ecosystem by changing the quality of the litter entering a system. It is not known, however, whether or not invasions can also change rates of decomposition irrespective of litter quality. We conducted an experiment to explore the differences in decomposition between leaf litter of native and exotic invasive woody plants and between invaded and uninvaded mesic hardwood forests on Long Island, New York, USA. We evaluated the mass and nitrogen loss rates from leaf litter of four pairs of native and exotic woody species. Litter from the exotic species decomposed and released nitrogen significantly faster than litter from the native species. The largest differences in decomposition and nitrogen loss occurred between the invaded and uninvaded sites rather than between native and exotic species, with litter of all species types decomposing substantially faster in invaded sites. These results suggest that the invasion of exotic species into hardwood forests alters decomposition and nutrient cycling, irrespective of species-specific litter quality differences between natives and exotics.