Changes in the structure due to strong winds in forest areas in the Pantanal, Brazil.

The Pantanal climate presents marked seasonality and eventually strong winds occur, especially in the beginning of the rainy season, which may last from September or October until April. A phytosociological study was conducted to evaluate the effects of a strong wind on the composition and structure of two forest formations in Pantanal wetland, a semideciduous forest (19º 15’ 32’’S and 55º 45’ 23.7’’W) and a forested savanna - “cerradão” (19° 17’ 21’’S and 55º 45’ 8.9’’W), with trees with diameter at breast height (DBH) ? 5 cm. After the strong wind, a reduction of 6% of the basal area and volume in the semideciduous forest was observed, mainly due to the uprooting of Xylopia aromatica trees. In the forested savanna, the basal area and volume reduction was even higher; an estimated 10%, representing 69 uprooted trees per hectare, mainly of Copaifera martii trees. In both areas it was observed that the uprooted trees presented an average height and diameter bigger than the trees that remained intact. Usually, the trees that were uprooted presented higher wood density and the species that had broken branches had a lower density

Ecological aspects of Langsdorffia hypogaea (Balanophoraceae) parasitism in the Pantanal wetlands.

Most studies on holoparasitic plants have focused on taxonomic or systematic issues. The objective of this study was to examine the ecological aspects of parasitism of Langsdorffia hypogaea (Balanophoraceae) in the Pantanal wetlands. Individuals of L. hypogaea were dug out by hand and the host trees were identified. Eighty-eight percent of host trees exhibited zoochory dispersal syndrome. Protium heptaphyllum and Cordiera sessilis represented 50% of the sampled trees. Both species are evergreen and are preferentially shade-tolerant species growing under the canopy of other trees. Fecal sample of collared peccaries (Pecari tajacu) had seeds from both the host tree (Protium sp.) and the parasite L. hypogaea. We therefore propose the hypothesis that P. tajacu play a role as a seed disperser and may affect root parasitism

Estrutura e distribuição espacial de Trichilia elegans A. Juss. (Meliaceae) em uma Floresta Semidecídua no Pantanal da Nhecolândia, Mato Grosso do Sul, Brasil.

Trichilia elegans A. Juss. é uma espécie com ampla distribuição, que ocorre desde a Venezuela até o Uruguai, e constitui componente comum no sub-bosque de formações estacionais. Mesmo que os primeiros estudos sobre a flora pantaneira datem de mais de um século, trabalhos voltados para a estrutura e a distribuição espacial de espécies arbóreas ocorrentes na região são ainda raros. Os objetivos do presente estudo foram identificar o padrão de distribuição espacial e a distribuição diamétrica de T. elegans e verificar se existe correlação entre o número de indivíduos jovens e o número de indivíduos adultos em uma floresta semidecídua no Pantanal da Nhecolândia. Para o levantamento, foram amostradas 50 parcelas de 200 m2 cada e inventariados os indivíduos jovens e adultos em cada uma delas. Com o intuito de identificar o padrão de distribuição espacial, foram utilizados o Índice de Morisita (IM) e a razão de variância/média (R). Foram encontrados 218 indivíduos jovens e 78 adultos. Indivíduos jovens e adultos apresentaram distribuição espacial agrupada, estando os jovens (IM = 2,32; R = 5,49) mais agrupados que os adultos (IM = 1,88; R = 2,05). O coeficiente de correlação linear encontrado (r = 0,60) demonstrou que a densidade de indivíduos jovens está altamente correlacionada com a densidade de indivíduos adultos

First results of material charging in the space environment

A satellite experiment, designed to measure potential charging of typical thermal control materials at near geosynchronous altitude, was flown as part of the SCATHA program. Direct observations of charging of typical satellite materials in a natural charging event ( 5 keV) are presented. The results show some features which differ significantly from previous laboratory simulations of the environment

Root behavior of savanna species in Brazil's Pantanal wetland.

The objective of this study was to determine the maximum depth, structure, diameter and biomass of the roots of common woody species in two savanna physiognomies (savanna woodland and open woody savanna) in Brazil's Pantanal wetland. The root systems of 37 trees and 34 shrubs of 15 savanna species were excavated to measure their length and depth and estimate the total root biomass through allometric relationships with stem diameter at ground level. In general, statistical regression models between root weight and stem diameter at ground level showed a significance of P < 0.05 and R2 values close to or above 0.8. The average depths of the root system in wetland savanna woodland and open woody savanna are 0.8 ± 0.3 m and 0.7 ± 0.2 m, respectively, and differ from the root systems of savanna woody species in non-flooding areas, whose depth usually ranges from 3 to 19 m.Weattribute this difference to the adaptation of woody plant to the shallow water table, particularly during the wet season. This singularity of woody species in wetland savannas is important when considering biomass and carbon stocks for national and global carbon inventories

Oscillatory Shear Flow-Induced Alignment of Lamellar Melts of Hydrogen-Bonded Comb Copolymer Supramolecules

In this work we present the orientational behavior of comb copolymer-like supramolecules P4VP(PDP)1.0, obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol, during large-amplitude oscillatory shear flow experiments over a broad range of frequencies (0.001-10 Hz). The alignment diagram, presenting the macroscopic alignment in T/TODT vs ω/ωc, contains three regions of parallel alignment separated by a region of perpendicular alignment. For our material, the order-disorder temperature TODT = 67 °C and ωc, the frequency above which the distortion of the chain conformation dominates the materials’ viscoelasticity, is around 0.1 Hz at 61 °C. For the first time flipping from a pure transverse alignment via biaxial transverse/perpendicular alignment to a perpendicular alignment as a function of the strain amplitude was found.