Effect of Nutrient Content on Leaf Decomposition in a Coastal Plain Stream: A Comparison of Green and Senescent Leaves

The decomposition of fresh-green and autumn-shed (senescent) red maple leaves (Acer rubrum) were compared in a low-gradient blackwater stream. When the two types of leaves were incubated in the stream during the fall, there was no significant difference in processing rate. The invertebrate fauna was similar on the two leaf types and did not appear to affect decomposition. However, higher densities of invertebrates were found on green leaves during the final stage of decomposition. Bacterial densities were higher on senescent leaves than on green leaves during the initial phase of decomposition, although green leaves were richer in nutrients. Toxic or inhibitory compounds in the green leaves may override effects of nutrient enhancement on bacterial growth and leaf decomposition.