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Litter decomposition in invaded and uninvaded forest communities.
Ashton, Isabel*,1, Hyatt, Laura1, Lerdau, Manuel1, Gurevitch, Jessica1, 1 State University of New York at Stony Brook, Stony Brook, NY
ABSTRACT- Leaf litter in forested communities constitutes a major pool of both carbon and nitrogen (N). The rate of nutrient release from leaf litter back to the ecosystem is regulated by climate, the composition and activity of the decomposer community, and quality of the litter. Alterations in decomposition rates can have cascading effects on primary production and community structure. The litter from exotic species, when introduced to native communities, has the potential to alter nutrient cycles in such a way that makes those communities more amenable to further colonization by exotics. We conducted experiments to explore the differences in decomposition between pine barren communities, which remain relatively uninvaded by exotic species, and both invaded and uninvaded mesic hardwood communities on Long Island. We evaluated the mass and nutrient decomposition rates of 12 species, representing both common native and exotic species, in two replicate communities of each type. Analyses of the most common natives (Quercus velutina and Sassafras albidum) and exotic species (Acer platanoides and Celastrus orbiculatus) reveal that mass decay and N release rates are significantly faster in mesic uninvaded habitats. There is a significant interaction between species and site for net mineralization and mobilization of N. The results show that A. platanoides has a high N mineralization rate across all site types, yet N from Q. velutina litter is immobilized in one pine barren site and mineralized in the replicate site. These results provide evidence that there may be a link between invasion history and current litter dynamics.
KEY WORDS: Litter decomposition, Exotic species