No abstract

The goal of this study was to compare the vegetation structure of macrophytes in an anabranch-lake system. Sampling was carried out at flood in three types of aquatic vegetation, (wild-rice, floating meadow and Polygonum bank) in anabranch Bonfim (lotic) and in lake Mandioré (lentic) in plots along transects, to estimate the percent coverage and record life forms of species. We collected 59 species in 50 genera and 28 families. Fabaceae and Poaceae were the most representative and emergent plants predominated (62%). In the anabranch, with 48 species, Polygonum acuminatum and Paspalum repens (7%) were more frequent (8%); in the lake, with 39 species, the most frequent were Polygonum ferrugineum (7%) and Hymenachne amplexicaulis (9%). Both evaluated ecosystems have low floristic similarity (66.6%), which was repeated among the communities analyzed by environment: wild-rice (0.33%), Polygonum banks (0.37%); floating meadows (0.32%). The anabranch was richer and more diverse than the lake; wild-rice community was the most diverse compared to other ones in anabranch, while in the lake the Polygonum bank community was the most diverse. The life forms of species varied in relation to the environments (lotic and lentic) studied.

O objetivo deste trabalho foi avaliar o potencial de utilização de lâminas foliares da gramí­nea tropical Paspalum spp. para o consumo animal por meio das características morfofisiológicas, da anatomia quantitativa e das características químicas. O experimento foi realizado no período de agosto de 2009 a junho de 2010, no município de Dourados -MS. Foram avaliadas oito espécies de Paspalum spp., sendo as sementes cedidas pela Embrapa Pecuária Sudeste. O delineamento experimental utiliza­do foi o de blocos ao acaso, com quatro repetições. As médias das características foram agrupadas pelo teste Scott-Knott. Foram evidenciados genótipos com potencial para forrageamento. Paspalum mala­cophyllum destacou-se em relação às características morfofisiológicas, químicas e anatômicas. Para as características anatômicas com proporções de tecidos de maior qualidade, o genótipo Paspalum glau­cescens também se destacou, apresentando altas proporções de mesofilo e bainha parenquimática dos feixes. As avaliações anatômicas de lâminas foliares de Paspalum spp. indicaram importantes diferenças entre os genótipos quanto à proporção e à composição de tecidos.

Nymphaea has seven species already catalogued in the flood prone areas of the Brazilian Pantanal. However, some species remain difficult to identify and descriptions of the anatomy of vegetative organs are an important tool for infrageneric separation to aid in group taxonomy. The species collected in the Pantanal and prepared according to the usual techniques for anatomical studies showed similar structural characteristics, and data on the arrangement of vascular bundles in the midrib and petiole, as well as the form and distribution of sclereids, were consistent. Nymphaea oxypetala stands out from the other evaluated species for having a greater number of differential characters, including angular collenchyma and the absence of bicollateral bundles in the petiole. Nymphaea lingulata stands out as the only species to feature bicollateral bundles in the leaf blade. The results, summarised in the dichotomous key, facilitate the identification of species that use the flower as the main differentiation, but are in a vegetative stage.

The phenology of macrophytes in response to environmental stressing factors is easily evidenced in wetlands under seasonal floods, such as the Pantanal. In these environments, the survival and establishment of seedlings of aquatic plants are restricted, limited to episodes with the presence of water, resulting in posterior sexual propagation for dispersal of seeds adapted to hydrochory, overcoming the dry period dormant in the sediment. We described the reproductive phenology of the macrophyte community in relation to the phases of flooding and between the species life forms. We sampled monthly the phenology of the macrophyte community of twenty ponds in the Pantanal, during two years, during the four phases of the flood pulse: 'drought', 'rising', 'flood' and 'receding'. The peak of flowering and fruiting in species of community occurred at the begin of rising, under the influence of the water depth variation on flowering. The species with different life forms develop flowers and fruits in the phases with water (flooded). Amphibious species present wider phenological amplitude, flowering also in the drought phase. There is a correlation between the species flowering in the community and the water depth in the ponds, not observed when considering the life forms of the species. There is a correlation between flowering of amphibious plants and temperature, and rainfall; and a correlation between flowering rooted floating plants and temperature. The macrophyte community presents phenology associated to seasonal alterations of the flooding cycle, such as the presence and depth of water, by means of the diversified life histories and life forms, determining the dynamics, resistance and resilience of this flora in the Pantanal.