No abstract

No abstract

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 bottomiand hardwood stands would not be effective benchmarks by which to judge the relative success of creation and restoration efforts.

No abstract

The production of reproductive shoots, vegetative shoots, and seeds was characterized for Ruppia maritima populations in the Virginia portion of Chesapeake Bay in 1988 and 1989. The study locations included two previously unvegetated sites recently colonized by R. maritima in the Rappahannock River and an established site and an in'egularly flooded marsh panue site, both in the York River. A corer was used to collect plant material, which was then separated into reproductive shoots, vegetalive shoots, and seeds. Sampling took place at approximately 2-week intervals from the time of first observation of flowering shoots until reproductive senescence. Reproductive shoot and seed production were high for all sites, particularly the previously unvegetated sites. The percent of reproductive shoots ranged from less than one percent to 52 percent. One previously unvegetated site produced 23,390 seeds m--" in 1988, the highest level of seed production measured during this study. Dramatic decreases in production from 1988 to 1989 at two of the study locations, the salt pannc and one previously unvegetated site, are attributable to the effects of drought and cownose ray (Rhinoptera bonasus) activity, respectively. High levels of seed production, frequently above 20,000 seeds m ~' , and their eventual dispersal may account for the rapid colonization in cerlain areas of Chesapeake Bay by R. mar#ima.