Seed dispersal is a limiting factor in the maintenance and distribution of plant communities, especially in rainforest ecosystems where a major proportion of plant species are dispersed by animals. Knowledge of seed removal by terrestrial mammals (particularly small mammals) in
forest patches scattered in Campos grassland is relatively sparse. In this study, we assessed: (1) whether the removal rate of
seeds differs in different successional stages of
forest advancing over grassland, and (2) the importance of small mammals and others vertebrates for seed removal rates in each environment type. We used seed removal experiments and camera trapping to answer these questions. Our results showed that seed removal was higher in more-forested sites than in open ones and in control treatment in 2006, we found an interaction between successional stage and treatment in 2007 and, in 2008, only treatments differed significantly. Our photographic records were mostly of small cricetid rodents. Seed-removal increment as a function of forested area suggests increased use of these sites by terrestrial mammals as patches develop in grassland. The use of large patches by mammals may increase the probability of mammal-dispersed plants colonizing patches as they attain a given structural development, which might determine to some degree the future patch nucleation dynamics.
Authors:M. Carlucci, F. Teixeira, F. Brum, and L. Duarte
The vegetation in the southern Brazilian highlands is characterized by Araucaria forest and Campos grassland. Evidences indicate that Araucaria forest is currently expanding over grassland and that this expansion may occur by nucleation or edge dynamics. Nucleation mechanisms of Araucaria forest expansion are well documented, whereas mechanisms of expansion starting from the forest edge are not. In this study, we aimed (1) to assess how prominent is Araucaria forest expansion over Campos grassland starting from the forest edge, and (2) to discuss about the possible mechanisms underlying sapling community colonization in grassland. We conducted our sampling in 11 transects disposed from the forest edge towards the grassland. The transects were distributed in four study sites. Each transect was 50 m long and was divided into 25 plots with area of 8 m2. All forest woody sapling individuals were identified and registered. We considered distance from forest edge, presence of dead shrubs, Baccharis uncinella cover, nurse tree cover and rock cover as predictors of forest plant abundance and composition. Niche and distance contribution on the explanation of sapling composition and abundance were partitioned using, respectively, canonical correspondence analysis and multiple regressions. Cover of nurse trees explained almost 31% of total variation in sapling abundance, followed by the distance from the forest edge that explained 6.9%. Site explained 7.6% of total variation in sapling species composition, followed by distance from the forest edge, which explained 2.3%, whereas niche had a minor (2.1%) and non-significant proportion of variation explanation. Our findings show that Araucaria forest expansion over native grasslands in southern Brazil relies deeply on the nurse plant effect. Previous studies have demonstrated that Araucaria forest forms nuclei scattered in the grassland where nurse plants or nurse rocks are established. Here, we bring evidences that nurse plants are important also to the tree encroachment starting closer to the forest edge. This study provides new information on the mechanisms involved in the forest expansion over native grasslands.
Authors:L. Duarte, M. Carlucci, C. Fontana, S. Hartz, and V. Pillar
We evaluated the functional relevance of diaspore traits related to disperser attraction (DAT) of woody plants as indicators of plant-disperser mutualisms in the colonization of Araucaria forest patches in southern Brazil. Diaspores of colonizer plant genera were characterized in relation to DAT (diaspore type, size and color). We discriminated the influences of phylogenetic relationships among plant genera, forest patch size and interaction records with frugivorous birds on DAT by using variation partitioning based on Redundancy Analysis (RDA). DAT variation was poorly explained by each factor separately. Nonetheless, variation explanation shared between phylogeny and interactions was considerably high, indicating that the influence of interactions with frugivorous birds on DAT tended to be phylogenetically conserved. Furthermore, the variation related to patch size was high only when shared with phylogeny and interactions. Large, red, orange or brown diaspores, mainly berries and figs were related to more developed patches, while small to medium, violet or black drupes were related to small patches. Patch colonization is likely to result from a balance between plant responses to habitat conditions and plant diaspore traits, which is expected to influence seed deposition patterns depending on habitat use and diaspore handling by dispersers. Although phylogenetic habitat filtering is commonly thought to reflect ecophysiological plant traits, our results suggest that interactions with dispersers could also explain phylogenetic habitat filtering in plants.
Authors:K. C. S. Almeida, H. Oikawa, J. Oliveira, and C. L. Duarte
A major concern with leaking petroleum is the environmental contamination by the toxic and water-soluble components such as
benzene, toluene and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant
toxicity. All BTX compounds are depressants to the central nervous system. Consequently, BTX are priority pollutants and their
occurrence has led to the development of several physical, chemical and biological methods for their removal. The use of nuclear
technology for protection and conservation of the environment, by the destruction of toxic organic compounds present in the
environmental, drinking water, soils and industrial sewage has been the object of study of several authors in Brazil and in
the world. The objective of this paper is to present the preliminary results of the study of contamination of the seawater
by the main pollutants of the output and transport of petroleum, such as benzene, toluene and xylene, and their removal by
the exposure to the ionizing radiation.
Authors:M. N. Mori, H. Oikawa, M. H. O. Sampa, and C. L. Duarte
Chlorpyrifos is an organophosphate pesticide commercialized since 1965 and it is now one of the top five commercial insecticides.
It is registered for use in over 900 different pesticide formulations in the world. Chlorpyrifos poisoning usually affects
many organs of the body, such as the central and peripheral nervous system, eyes, respiratory system, and the digestive tract.
Depending on the pesticide formulation and type of application, chlorpyrifos residues may be detectable in water, soil, and
on the surfaces from months to years. This paper presents preliminary studies of the removal of chlorpyrifos by exposition
to ionizing radiation, to be applied in pesticide container decontamination. Samples containing various concentrations of
chlorpyrifos in acetonitrile were irradiated with absorbed doses varying from 5 to 50 kGy, using a 60Co gamma-source with 5,000 Ci activity (Gamma cell type). The chemical analysis of the chlorpyrifos and the by-products resulted
from the radiolitic degradation were made using a gas chromatography associated to mass spectrometry (GC-MS) and gas chromatography
with flame ionization detector (GC-FID).
Authors:A Barros, J Santos, S Prasad, V Leite, A Souza, L Soledade, M Duarte, and V dos Santos
The conventional treatments
of effluents containing heavy metals produce significant quantities of byproducts
with recalcitrant characteristics, making necessary looking after alternative
techniques in order to avoid the production of new contaminated residues.
Sorption process of chromium and zinc in vertical columns loaded with sewage
sludge and organic solid waste has been studied in this work. The data from
the TG curves of the two sorbents presented significant differences when they
were submitted to the metal uptake, being noticed the displacement of the
thermal events towards lower temperatures for both types of sorbents studied.
As it was expected, for both sorbents, an increase in the mass of samples
has been observed at the completion of the thermal tests upon metal uptake.
Therefore, these facts demonstrate that during the biosorption process a physico-chemical
interaction took place between sorbents and metals, as it was evidenced by
the more than 100 K increase in the decomposition temperatures as well as
the variation of the ΔH values of the
Authors:V. J. Debastiani, S. C. Muller, J. M. Oliveira, F. S. Rocha, M. C. Sestren-Bastos, and L. D. S. Duarte
The phylogenetic relationship among species may influence the mechanisms controlling local community assembly in ecological time. We analyzed the degree of recurrence of phylogenetic structure patterns in woody plant communities distributed along grassland-forest ecotones, across different vegetation types in southern Brazil, and the effect of phylogenetic pool size used to assess such patterns. Species frequency in quadrats distributed along grassland-forest ecotones was surveyed in different phytogeographic regions, where forests tend to expand over grasslands. We used principal coordinates of phylogenetic structure (PCPS) to evaluate the structure within vegetation quadrats divided into three habitat categories: grassland, forest edge and forest interior. Furthermore, phylogenetic structure measures were computed using different phylogenetic pool sizes. Our analyses showed consistent patterns in relation to habitat categories and to different phylogenetic pool sizes. Basal clades of angiosperms were associated with forest areas, while late-divergence clades were associated with grasslands. These results suggest that grasslands act as phylogenetic habitat filters to forest woody species, independently of species composition at each site and the phylogenetic pool. Rosanae and Asteranae act as vanguards of forest expansion over grasslands, while Magnolianae species tend to be restricted to forest. Our results shed light on the organization of ecological systems, providing evidence of recurrent phylogenetic structure patterns in ecotone plant communities at regional scale.
Authors:J.P. Duarte, Manuel Coelho-e-Silva, V. Severino, D. Martinho, L. Luz, J.R. Pereira, R. Baptista, J. Valente-dos-Santos, A.M. Machado-Rodrigues, V. Vaz, A. Cupido-dos-Santos, J. Martín-Hernández, S.P. Cumming, and R.M. Malina
The study was aimed to investigate the reproducibility of performance parameters obtained from 10-s maximal cycling effort against different braking forces in young adult athletes. The sample (n = 48) included male athletes aged 18.9–29.9 years (175.5 ± 6.9 cm, 76.2 ± 10.1 kg). The exercise protocol was performed in a cycle-ergometer against a random braking force (4% to 11% of body mass). Intra-individual variation was examined from repeated tests within one week. Descriptive statistics were computed and differences between sessions were tested using paired t-test. The coefficient of correlation between repeated measures, technical error of measurement (TEM), coefficient of variation and ICC were calculated. Agreement between trials was examined using the Bland-Altman procedure. Mean values of peak power were relatively stable when obtained from sampling rates of 50 Hz and ranged between 1068 watt and 1082 watt (t(47) = 1.149, p = 0.256, ES-r = 0.165) or while corresponding to a sampling rate of 1 Hz (t(47) = 0.742, p = 0.462, ES-r = 0.107). Correlations between repeated measures were high (+0.907, 95% CI: +0.839 to +0.947) and TEM about 59.3 watt (%CV = 5.52%; ICC = 0.951, 95% CI: 0.912 to 0.972). The present study suggests that reproducibility of peak power in male adult athletes tended to be acceptable and within individual error appeared unrelated to braking force.