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Ellison Abstract- 2000 LaDeau and Ellison

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LaDeau, S. L., & A. M. Ellison. 1999. Seed bank composition of a northeastern U.S. tussock swamp. Wetlands 19: 255-261.


A seedling and sporeling emergence assay was conducted on 50 soil cores taken from within Carex stricta tussocks (intra-tussock) and from paired, adjacent inter-tussock areas in the Hawkins Conservation Area, South Hadley, Massachusetts, USA, to test the hypothesis that local heterogeneity in water levels alters seed bank composition and subsequent seedling emergence patterns. Soil cores were sliced into 2.5-cm-thick sections and split into flooded and drawn-down treatments. Germination of buried seeds and spores was assessed in these treatments under greenhouse conditions for 6 months. Eighteen species emerged from both treatments combined: 17 from inter-tussock samples and 12 from intra-tussock samples. Pooled across sample depths and watering treatments, more species of grasses, forbs (exclusive of Impatiens capensis), and woody plants germinated from intra-tussock samples, while more pteridophytes germinated from the inter-tussock samples. Emergence of pteridophytes, grasses, and forbs was associated significantly with sample depth. More pteridophytes germinated from samples close to the swamp surface, while grasses and forbs were most abundant in samples 10-20 cm below the surface. In the drawn-down treatment, pteridophyte and forb seedlings were more plentiful from inter-tussock samples. In contrast, more forb seedlings emerged from intra-tussock samples in the flooded treatment. This variation in forb emergence seems to reflect differences in species composition within and between tussocks. Twenty-two species occurred in the standing vegetation of the study area, but only nine of these also occurred in the seed bank. The composition of standing vegetation atop and between tussocks did not differ significantly. Grasses, which dominated the seed bank, were absent from standing vegetation. Grasses clearly represent a persistent population of seeds in the seed bank, while forbs are more transient within the seed bank. The depth-stratified species composition of the seed bank also suggests patterns of temporal succession in the aboveground vegetation of this New England tussock swamp.

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