Plant species diversity in a Neotropical wetland: patterns of similarity, effects of distance, and altitude

Cerrado physiognomies in Chapada das Mesas National Park (Maranhão, Brazil) revealed by patterns of floristic similarity and relationships in a transition zone

The Chapada das Mesas National Park is a federal reserve located in the State of Maranhão, in an ecotonal region of the Brazilian Northeast Cerrado. Aiming to assess the influence of biogeographic patterns and support restoration actions for regions where information is scarce, we analyzed the floristic composition of savanna and forest Cerrado physiognomies, the floristic relationships with other Brazilian Cerrado areas and investigated the floristic relationships between the Cerrado and the Amazon, and the Caatinga and Atlantic Forest biomes. A total of 242 species in 181 genera and 64 families are recorded in our study. Fabaceae was the most representative family. We report 50 new records of species for Maranhão, four new records for the Cerrado biome and one vulnerable species. The separation of the gallery forest from cerradão and typical cerrado by ordination shows the influence of water availability and soil characteristics on floristic composition. In Cerrado ecotonal regions, such as Mato Grosso and Maranhão, the presence of species shared with the Amazon is expressive. In addition to the Amazon, physiognomies had greater floristic connection with the Caatinga flora. Our data demonstrates that the marginal areas of the Brazilian Cerrado may present high species diversity.

Flood and fire affect the soil seed bank of riparian forest in the Pantanal wetland

Abstract Flood and fire can harm plants but they can have survival strategies, such as the seed bank. We aimed to determine the influence of fire and flood on the richness, abundance and diversity of the seed bank. Sampling was carried out in October/2013, year of prolonged drought, and October/2014, year of a heavy flood, in ten areas along the Paraguay River. The areas were selected in satellite images, five with old burn (2010, three years before sampling) and five with recent burn (2013, three months before sampling). In each area, we marked a 20 m long transect with ten 20 × 20 cm quadrats where we collected 5 cm deep topsoil samples, five with and five without litter. Seed bank richness and abundance were determined by seedling emergence. Old burn areas presented greater abundance than recent burn. The drier year presented greater abundance, richness and diversity than flood year. Removal of litter reduced the richness only in the wetter year. There was no difference in richness in the drier year. The removal of the litter did not affect the abundance and diversity. Interaction between fire and flood did not affect richness, abundance and diversity of the seed bank.

Conservation priorities and distribution patterns of vascular plant species along environmental gradients in Aberdare ranges forest

Distribution patterns of biodiversity and the factors influencing them are important in conservation and management strategies of natural resources. With impending threats from increased human population and global climatic changes, there is an urgent need for a comprehensive understanding of these patterns, more so in species-rich tropical montane ecosystems where little is known about plant diversity and distribution. Vascular species richness along elevation and climatic gradients of Aberdare ranges forest were explored. A total of 1337 species in 137 families, 606 genera, 82 subspecies and 80 varieties were recorded. Correlations, simple linear regression and Partial least square regression analysis were used to assess richness and diversity patterns of total plants, herbs, shrubs, climbers, arboreal and endemic species from 2000-4000 m above sea level. Total plant species richness showed a monotonic declining relationship with elevation with richness maxima at 2000-2100 m a.s.l., while endemic species richness had a positive unimodal increase along elevation with peaks at 3600-3700 m a.s.l. Herbs, shrubs, climbers and arboreal had significant negative relationships with altitude, excluding endemism which showed positive relations. In contrast, both air and soil temperatures had positive relationships with taxa richness groups and negative relations with endemic species. Elevation was found to have higher relative influence on plant richness and distribution in Aberdare ranges forest. For effective conservation and management of biodiversity in Aberdare, localized dynamic conservation interventions are recommended in contrast to broad and static strategies. Establishment of conservation zones and migration corridors are necessary to safeguard biodiversity in line with envisaged global climatic vicissitudes.