It has been suggested that higher nitrogen levels in the soil may lead to a positive feedback loop involving production of litter with higher nitrogen content, faster decay rates, and even higher nitrogen availability. Studies of belowground processes along a natural nitrogen gradient from old to young dunes on Hog Island provide an opportunity to examine root responses in the context of this idea. There was little variation in fine root biomass (FRB) on dunes along the gradient, but FRB decreased from low to higher soil nitrogen in the interdunal swales. The fine roots on the higher nitrogen sites did have higher nitrogen content than those on the low nitrogen sites (0.81 % to 0.59 % on the dunes; 1.33 % to 0.91 % in the swales). Decomposition rates of fine roots were faster on the higher nitrogen dune sites as predicted but varied little along the gradient in the swales. These results suggest that other factors, such as freshwater availability and flooding, may prevent the establishment of a positive feedback loop in the nitrogen cycle.

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