SUBSTRATE HETEROGENEITY AND REGENERATION OF A SWAMP TREE, NYSSA-AQUATICA

In a South Carolina riverine swamp forest, water tupelo substrates were categorized as emergent (surfaces of trees, living cypress knees, stumps, or logs), protected (submerged sediment adjacent to an emergent object), or open (sediment >50 cm from any emergent object and fully submerged during the growing season). Seeds germinated best (>25% in 16 days) on emergent substrates, but seed predation was extremely high on these same substrates. Substrate types differed significantly in permanence and in rates of sediment loss or deposition. Growth rates of transplanted seedlings did not differ among substrate types. Mortality due to erosional scour or impermanent rooting zones, superimposed on germination patterns is apparently responsible for observed non-random distribution of woody plant seedlings among substrate types. -from Authors