Decomposition and Nutrient Exchange of Litter in an Alluvial Swamp Forest

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Abstract
Weight loss from cellulose sheets was measured monthly at three sites (river, swamp floor, natural levee) of a North Caroline swamp forest dominated by Nyssa aquatica. Rates of loss were significantly different seasonally and between sites. Both temperature and moisture appeared to be important in controlling decomposition rates. For Nyssa leaves, dry weight decreased to 25% of original after 48 wk while twigs fell to 80% of original after 56 wk. Three modes of nutrient exchange were found: (1) accumulation of N, Ca, and Fe by both leaves and twigs, with stronger leaf accumulation of these elements; (2) strong leaf accumulation with rapid twig loss of P; and (3) losses by both leaves and twigs of K and Mg. Final atomic ratios of C:N and C:P were about 15:1 and 500:1, respectively, suggesting that P may be in short supply. The significance of nutrient accumulation is that there was little or not net release of P, N, Ca, and Fe from autumn leaf fall until tree growth in the spring. Conservation and recycling of nutrients appear to be tight even in swamps open to flooding during tree dormancy.