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11.
Addressing the need for reference sites that permit wetland managers to evaluate the relative success of wetland restoration
efforts, this project examines the early successional properties of a chronosequence of 17 forested wetlands that have been
clear-cut and allowed to naturally revegetate. Ordinations performed on the data using CANOCO software indicated three general
types of communities—one dominated by bald cypress (Taxodium distichum) and water tupelo (Nyssa aquatica), one dominated by black willow (Salix nigra), and one with a species composition similar to that of a mature stand of bottomland hardwoods. These divisions were correlated
with the percentage of stems originating as coppice on stumps leftover from the clear-cut. In particular, the bottomland hardwood
stands were regenerating predominantly as coppice, while the cypress/tupelo and black willow stands were regenerating primarily
as seedlings. As indicated by the earlier development of overstory basal area, coppice sites were also regenerating much faster.
The hydrology of a site also exhibited a strong impact on the rate of regeneration, with the semipermanently to permanently
flooded portions of sites often exhibiting little or no regeneration. The results indicate that, because of the overwhelming
reliance on coppice sprouts as the main source of stems and the concomitant enhanced rates of regeneration, certain vegetative
parameters of clear-cut bottomland hardwood stands would not be effective benchmarks by which to judge the relative success
of creation and restoration efforts. 相似文献