Leaf decomposition of three species of native Ozark vegetation was compared to that of one nonnative invasive species. Leaves were placed in an urban gravel-bed stream for 23 days. Changes in mass and condition of the leaves were assessed along with stream temperature, flow, width, depth and discharge. Species native to Eastern North American forests were sycamore (Platanus occidentalis), dogwood (Cornus florida), and redbud (Cercis canadensis). The nonnative species, Japanese (Amur) honeysuckle (Lonicera maackii) comprised approximately 80% of the understory vegetation within the riparian zone of the study reach. After 23 days, Sycamore lost 24.6% mass, dogwood lost 30%, redbud lost 37.5%, and honeysuckle lost 38.3%. Sycamore leaves retained their relative structures the most (ranked 9 on a scale of 1 to 10, with 10 being the most sclerophyllous), and honeysuckle the least (ranked 2 on a scale of 1 to 10). As a result of this study, we suggest that the fast decomposition of leaves at southern latitudes may contribute to the low percentage of detritivores in streams, and that Japanese honeysuckle exacerbates this situation as a result of its more rapid rate of decomposition, therefore potentially depriving univoltine detritivores of nutrients later in their life cycles.

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