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Remote sensing techniques and fixed-site observations were used to evaluate vegetation, habitat and physiographic characteristics of coastal fore dunes in southern Brazil during the last 50 years. The results demonstrated a gradual increase of edaphic stability and biological diversity in fore dunes during several decades, followed by a rapidand profound attenuation of these attributes. The changes in regional hydrology, as a result of long-term and large-scale impoundment andmore recent and localized drainage activities, are appointed as the major cause for foredune modifications in this part of the southwestern Atlantic. [ABSTRACT FROM AUTHOR]

The investigation reported here is concerned with the use of plant diversity measures for coastal dune monitoring. The original set of recorded plant species on dune systems was broken into 3 functionally homogeneous groups, which allow ecological comparisons among fore dunevegetation on a much wider sense than traditional taxonomic approaches. Plant diversity was measured both, as species richness and as therate of species number increase with area. Plant diversity values were tested as a dependent variable of a coastal dune vulnerability Index. Increasing coastal dunes vulnerability, caused by natural or human events, lowered the rate of species increase with area within the plant functional type associated to prograding fore dunes. Results suggest that plant diversity within this functional type, measured as the slope of the species-area curve, may be used as a management tool for predicting coastal dune vulnerability. [ABSTRACT FROM AUTHOR]

Santa Rosa Island, a barrier island located in the panhandle of Florida, was severely impacted by hurricane Opal's 3-4 m tidal surge in October 1995. Rapid reestablishment of the fragmented dune system through sand accumulation and stabilization is essential for many wildlife and plant species and protection of coastal structures against storm surge. Comparisons of sand accumulation rates for two biodegradablematerials, three-fence orientations and non-fenced controls were assessed in a secondary dune position. Effect of winter and spring planting without supplemental water on survival and growth of nursery-grown sea oats and bitter panicum was also evaluated. Wood and Geojute material sand fences in three orientations were installed at six sites.Sand accumulation associated with these fence material/orientation combinations and non-fenced controls was measured twice a year (1996-99). There were no significant differences in sand accumulation between Geojute and wood fences at most positions for the first eight months. Following this, Geojute degraded and its accumulated sand was no more than that of the controls 18 months after installation. Sand accumulation did not differ significantly among wood fence configurationsat most distances from the fence. Through time the straight-conventional wood and perpendicular-wood fence treatments had consistently higher sand accumulation values compared to unfenced controls. While survival of transplanted sea oats and bitter panicum was not effected by season of planting, growth varied with planting season. [ABSTRACT FROM AUTHOR]

Palynological analyses of 20 surface sediment samples collected fromLong Island Sound show a pollen assemblage dominated by Carya, Betula, Pinus, Quercus, Tsuga, and Ambrosia, as is consistent with the regional vegetation. No trends in relative abundance of these pollen types occur either from west to east or associated with modern riverine inputs throughout the basin. Despite the large-scale, long-term removal of fine-grained sediment from winnowed portions of the eastern Sound, the composition of the pollen and spore component of the sedimentary matrix conforms to a basin-wide homogeneous signal. These resultsstrongly support the use of select regional palynological boundariesas chronostratigraphic tools to provide a framework for interpretation of the late glacial and Holocene history of the Long Island Sound basin sediments. [ABSTRACT FROM AUTHOR]

Above ground primary production and above ground and below ground decomposition of several wetland species were studied in seven wetland sites in the Rhone delta from October 1992 to October 1993. The siteswere located in three characteristic zones of the delta: a low salinity area close to the river mouth, a marine site near the Mediterranean Sea and managed, impounded areas. These areas are vegetated by helopytes and glassworts (family Chenopodiaceae). Wetland production wasaffected by salinity, cattle and horse grazing and water levels. In a grazed freshwater wetland dominated by Scirpus maritimus, production was 452 g m2 yr1, while in an adjacent ungrazed site dominated by Typha angustifolia production was 2989 g m2 yr1. The most productive glasswort marshes were dominated by Arthrocnemum fruticosum, one near the river mouth (1123 g m2 yr1), and a second with a free connection to the sea (1262 g m2 yr1). The least productive glasswort marshes were dominated by Arthrocnemum glaucum. The lowest production (244 g m2 yr1) was in a grazed, semi-impounded marsh with high soil salinity and high ground water levels,while a second area in the central part of the delta with high soil salinity and grazing had a production of 294 g m2 yr1. In the non-grazed brackish Phragmites australis-Scirpus maritimus marsh at the river mouth, production was 824 g m2 yr1, whereas in an unprotected site nearby, grazing was so intense that above ground vegetation was eliminated. Decomposition rates were significantly different among species and plant parts but not among sites when the same species were used. Root decomposition was not significantly different with depth. Shoots had the highest decomposition rates with mean K values of 0.033 wk1 for Arthrocnemum fruticosum, 0.024 wk1 for Phragmites australis and 0.019 [ABSTRACT FROM AUTHOR]