94 resultados para transect


Relevância:

10.00% 10.00%

Publicador:

Resumo:

In Brazil, the degradation of soil and landscape by urban and agricultural frontiers expansion leads to the need for comprehensive studies and consider the diverse biological activities generated from different interventions in the landscape, becoming an instrument for assessing the impacts and the decision for its environmental management. The objective of this study was to evaluate the influence of different forms of occupation of the landscape, considering ecological elements and their interactions. The work was carried out on the Instituto Agronômico in the county of Jundiai, in the state of Sao Paulo, Brazil. The area under study has been subjected to different use and occupancy for a period of about 40 years. During this period the landscape has been transformed, with the current scenario can be classified as a degraded area mining; grassy area; Araucaria forest and pasture. These areas were evaluated by means of a transect, from which ten sampling sites were selected for the description of diverse biological activities, which included: evaluation and description of ground cover, identifying the presence of fungus and insect species. Furthermore, we evaluated in these points the pH, fertility and porosity of the topsoil (0-0.10 m). The results showed a variation of the elements analyzed and a relationship between the use and occupation of land in the different scenarios of the current landscape. The biological activity was more diverse in the Araucaria forest, reflected by the abundance of litter, higher content of organic matter and soil nutrients, demonstrating the effectiveness of the technique for assessing the level of degradation of the landscape used, which is expeditious and inexpensive.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The radioactivity due to 238U and 234U in three aquifer systems occurring within the Paraná sedimentary basin, South America, has been investigated. Uranium is much less dissolved from fractured igneous rocks than from the porous sedimentary rocks as indicated by the U-mobility coefficients between 7. 6 × 10-6 and 1. 2 × 10-3 g cm-3. These values are also compatible with the U preference ratios relative to Na, K, Ca, Mg and SiO2, which showed that U is never preferentially mobilized in the liquid phase during the flow occurring in cracks, fissures, fractures and faults of the igneous basaltic rocks. Experimental dissolution of diabase grains on a time-scale laboratory has demonstrated that the U dissolution appeared to be a two-stage process characterized by linear and second-order kinetics. The U dissolution rate was 8 × 10-16 mol m-2 s-1 that is within the range of 4 × 10-16-3 × 10-14 mol m-2 s-1 estimated for other rock types. The 234U/238U activity ratio of dissolved U in solutions was higher than unity, a typical result expected during the water-rock interactions when preferential 234U-leach from the rock surfaces takes place. Some U-isotopes data allowed estimating 320 ka for the groundwater residence time in a sector of a transect in São Paulo State. A modeling has been also realized considering all U-isotopes data obtained in Bauru (35 samples), Serra Geral (16 samples) and Guarani (29 samples) aquifers. The results indicated that the Bauru aquifer waters may result from the admixture of waters from Guarani (1. 5 %) and Serra Geral (98. 5 %) aquifers. © 2012 Springer-Verlag.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Soil attributes reflect influence of the geomorphic surfaces. Therefore, the objective of this work was to investigate the influence of the geomorphic surfaces on soil attributes in a topossequence from low lands to high lands in the Humaitá region, AM. A transect of 4.5 km, from the top of the slope towards the low lands was established and the geomorphic surfaces were identified and limited according to topographic and estratigraphic criteria, based on detailed field investigation. Twenty soil samples were collected in each one of the slope segments within the geomorphic surfaces (G.S.), at the following depths: G.S. I: LAa (0.0-0.16 and 0.48-0.79 m); G.S. II: Lad1 (0.0-0.13 and 0.44-0.70) and Lad2 (0.0-0.10 and 0.30-0.55 m); G.S. III: RYve1 (0.0-0.18 and 0.51-0.89) and RYve2 (0.0-0.23 and 0.58-0.91 m). The sampling depths were determined by the surface and subsurface horizon depths, defined during the soil morphological description. Physical analysis involved particle size distribution, disperse clay, soil and particle density and total porosity. The chemical analysis involved determinations of pH in water and KCl, exchangeable cations, exchangeable Al, total acidity (H+Al), available P, organic carbon. The relief variations contributed to the presence of dystrophic soils in the geomorphic surface I and eutrophic soils in the geomorphic surface III. The multivariate statistical techniques were able to separate three heterogeneous groups, equivalent to the mapped geomorphic surfaces.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Habitat fragmentation is the main cause of biodiversity loss, as remnant fragments are exposed to negative influences that include edge effects, prevention of migration, declines in effective population sizes, loss of genetic variability and invasion of exotic species. The Drosophilidae (Diptera), especially species of the genus Drosophila, which are highly sensitive to environmental variation, have been used as bioindicators. A twelve-month field study was conducted to evaluate the abundance and richness of drosophilids in an edge-interior transect in a fragment of semideciduous forest in São Paulo State, Brazil. One objective of the study was to evaluate the applied methodology with respect to its potential use in future studies addressing the monitoring and conservation of threatened areas. The species abundance along the transect showed a clear gradient, with species associated with disturbed environments, such as Drosophila simulans, Scaptodrosophila latifasciaeformis and Zaprionus indianus, being collected at the fragment edge and the species D. willistoni and D. mediostriata being found in the fragment's interior. Replacement of these species occurred at approximately 60 meters from the edge, which may be a reflection of edge effects on species abundance and richness because the species found within the habitat fragment are more sensitive to variations in temperature and humidity than those sampled near the edge. The results support the use of this methodology in studies on environmental impacts. © 2013 Penariol and Madi-Ravazzi; licensee Springer.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The reproductive biology of a species includes factors beyond its sexual maturity, fecundity and reproductive period, and may extend to the differential distribution of individuals. The reproductive dynamics of the blue crab Callinectes ornatus was investigated through monthly collections over the course of 2 years in three bays on the southeastern coast of Brazil. For each bay, six transects were established, four of them parallel to the beach line (at depths of 5, 10, 15, and 20 m), one transect exposed to wave action, and another sheltered from waves. Females and males were classified according to the gonadal maturation stage, and were grouped as individuals with reproductive potential (mature gonads or breeding females) or not (rudimentary gonads or in development). Analyses using ordination techniques (PCA) and gradient analysis (CCA) showed that 82.13 % of environmental variations were explained by the transect arrangement, and these characteristics explained 86.70 % of the differential distribution of female crabs and 96.57 % of the distribution of males. These results indicate that females with reproductive potential were more abundant in deeper regions, while females with rudimentary or developed gonads were abundant in shallower habitats and areas sheltered from wave action. Thus, the distribution of C. ornatus in these bays was linked to their reproductive state, as part of the reproductive strategy of the population. © 2013 Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Biologia Animal - IBILCE

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Produção Vegetal) - FCAV