Soil-vegetation relationship in savanic formations of the Jalapão, Brazil.

Understanding the influence of fine-scale abiotic filters on plant communities can provide important insights into floristic patterns of the Brazilian Cerrado. We aimed to evaluate the interactions of the soil and the plant community composition with their distribution in different sandy environments of Brazilian Cerrado, the Jalapão region. Eight environments were sampled, each with ten plots of 20 × 50 m. All woody individuals presenting circumference at soil height ≥ 10 cm were sampled. Subplots of 5 × 15 m were demarcated, where woody individuals with a circumference at soil height ≥ 5 and < 10 cm were sampled. Subplots of 2 × 2 m were also demarcated to sample herbaceous individuals. Soil samples varying from 0 to 20 cm of depth were collected for each plot (20 × 50 m). Overall, 20000 individuals that belong to 338 species and 76 families were sampled. The dominant family was Fabaceae. There were significant differences among the environments regarding species richness and soil. The analyzed soils are extremely poor and with a tendency to sandy texture, small chemical and/or physical variations imply differences in the distribution of vegetation. Our study revealed abiotic filters exerted crucial fine-scale effects on plant community in the Jalapão region.

Phytosociology in areas of the Brazilian Cerrado: Cerrado stricto sensu, municipality of Porto Nacional, State of Tocantins

Phytosociological studies are essential for the elaboration of conservation strategies for the Cerrado. The goal of this study was to survey two areas of cerrado stricto sensu: Fazenda Canaã and Fazenda Providência, located in the Municipality of Porto Nacional, State of Tocantins. There were 10 plots of 100 m2 allocated in each area. All individuals with circumference equal to or greater than 10 cm, at ground height ≥10 cm were sampled, soil samples were taken for physical-chemical analysis. Sampling in Canaã resulted in 379 individuals belonging to 28 families and 50 species. In Providência, there were 300 individuals from 27 families and 49 species. The Shannon-Wiener Index for the Canaã was 3.48 and for Providência, 3.45. The studied areas presented a large number of small sized individuals, presenting a reverse J-shaped diameter structure. The Canonical Correspondence Analysis showed significant scores for the first axes (p < 0.05) according to the Monte Carlo test, which explained 70% total variability of the data. The variables with the highest structure coefficient in axis 1 were clay (0.94), pH (0.62) and magnesium (-0.32). On axis 2, the most important variables were aluminum (0.29), silt (0.25) and potassium (-0.078). These soil variables show a differentiation of the study areas.

The anti-ulcerogenic effects of Curatella americana L.

ETHNOPHARMACOLOGICAL RELEVANCE: Curatella americana L. (Dilleneaceae) is a medicinal plant very frequently cited as acting against gastrointestinal disorders in ethnopharmacological inventories of the Cerrado region of Brazil. AIM OF THE STUDY: The ethanolic extract (CEB) and infusion (BI) of Curatella americana bark were investigated for their ability to prevent and heal ulceration of the gastric mucosa. MATERIALS AND METHODS: The preventive and healing actions of Curatella americana were evaluated in experimental in vivo models in rodents that simulated this disease in human gastric mucosa. RESULTS: CEB significantly decreased the severity of gastric damage formation induced by the combination of several gastroprotective models (HCl/ethanol, indomethacin/bethanecol, absolute ethanol, stress and pylorus ligature). But, unlike CEB, the BI did not exert gastroprotective effect. The gastroprotective action of CEB involved antisecretory action, augmentation of gastric mucus (48%) and participation of endogenous sulfhydryl compounds that increase efficacy of barrier mucosa against injurious agents. CEB also presents effective healing action in chronic gastric disease (1.90+/-0.55 vs. 6.86+/-0.46 mm2)in the control) and its action mechanisms consisted of increasing the PGE2 (40%) and somatostatin levels (269%) while decreasing the gastrin level in rat plasma (79%). CONCLUSIONS: The gastroprotective effect and healing action of Curatella americana involved modulation of PGE2, somatostatin and gastrin levels, probably due to the presence of oligomeric and polymeric proanthocyanidins in the bark.