An analysis was made of the floristic composition of 98 areas of cerrado and Amazonian savanna, encompassing most of the area of such vegetation in Brazil. A total of 534 species of trees and large shrubs were recorded for these areas, of which 158 (30%) occurred at a single site only. Such unicates and taxa without determinations to specific level were excluded from the study since they provide no basis for comparison. The data were analysed by three techniques of multivariate analysis: (a) a divisive hierarchical classification by Two-way Indicator Species Analysis (TWINSPAN). (b) an agglomerative hierarchical classification by UPGMA (Unweighted Pair-Groups Method using Arithmetic Averages) using the Sørensen Coefficient of Community (CC) as a measure of similarity, and (c) an ordination by Detrended Correspondence Analysis (DCA). The results from all three methods showed great similarity, demonstrating a strong geographic pattern in the distribution of the flora of the cerrado biome and allowing the recognition of southern (Sâo Paulo and S Minas Gerais), southeastern (largely Minas Gerais), central (Federal District, Goiás and parts of Minas Gerais), central-western (largely Mato Grosso, Goiás and Mato Grosso do Sul) and northern groups (principally Maranhão, Tocantins and Pará), as well as a disjunct group of Amazonian savannas. Soil type (mesotrophic or dystrophic) is an important factor in determining floristic composition. The study demonstrated that cerrado vegetation is extremely heterogeneous: none of the 534 species occurred at all sites and only 28 species were present at 50% or more.

Forested wetland creation for compliance with Section 404 of the Clean Water Act is increasing dramatically throughout the Mid-Atlantic region of the United States. However, no quantitative data are available regarding the effectiveness of past forested wetland creation efforts in this region, and no quantitative assessment techniques fdr evaluating success have been developed. Created wetlands may lack sufficient time for soil formation; however, colonizing vegetation and hydrology may be considered indicators of existing conditions. Hydrology monitoring is expensive, time-consuming, and highly variable over short time periods. This study was designed to test the hypothesis that one parameter (vegetation) could be used to evaluate early site conditions following wetland creation. We attempt to show the advantages and disadvantages of using vegetation to calculate percentage "wetland" and "upland" as an early monitoring tool. Calculations were made using the 1989 Federal Manual for Identification and Delineation of Jurisdictional Wetlands, colonizing vegetation weighted average, site moisture estimates, and comparisons with an adjacent reference wetland. Percentage "wetland" and "upland" estimates were similar whether vegetation alone or vegetation in combination with hydrology was used in calculations. Vegetation colonizing the site may respond to both soil and hydrology and may provide an early indication of conditions within created wetlands. The findings of this study suggest that calculating plot-weighted averages and comparison with pre-impact wetland vegetation (or an adjacent reference wetland) may be a useful component of a monitoring scheme for certain created wetlands.

No abstract

No abstract

Many studies have chronicled the early development of vegetation in wetlands created as mitigation for wetland impacts; however, very few studies have followed the floristics of wetlands that are more than 10 years post-creation. This article reports the results of vegetation composition and structural analysis within eleven 20-yr-old created non-tidal, emergent wetlands. Vegetation and inundation were sampled in 173 plots within 11 wetlands during the 1992 and 1994 growing seasons. A drought occurred in 1993, thus analyses characterized vegetative response and included weighted average (weighted by the tolerance of the species to excess soil moisture), species richness, species composition, and life history strategy. Weighted average and species richness increased in 7 and 10 of the 11 sites, respectively. There was little change among most species including Typha latifolia and Scirpus cyperinus, the two species with highest impor