Brazil plays an important role with regard to the emission of aerosols into the atmosphere. Ecosystems such as the Amazonian tropical forest and Brazilian Cerrado are undergoing sweeping changes. These human activities promote an increase in the levels of gases and particles emitted into the atmosphere. To determine how these activities have affected the emission of coarse and fine particulate matter (PM10 and PM2.5), atmospheric aerosol samples were collected continuously from June 2004 to April 2005 in the Cuiaba Basin of south-central Mato Grosso, Brazil. Aerosols were sampled using stacked filter units. Filters were analysed for particulate mass, black carbon and for concentrations of seventeen elements by Particle Induced X-Ray Emission. The results revealed that Mg, Al, Si, S, K, Ca, Ti and Fe were the major components detected in PM2.5 and PM10. The high enrichment factors observed in PM2.5 and PM10 suggest that anthropogenic activities were the predominant source for elements such as Cu, Zn and Pb. These data indicate that most of the aerosols measured in the Cuiaba Basin originate from land conversion and biomass burning. These patterns are similar to those observed in other Cerrado and Amazonian forest areas that are undergoing rapid and spatially extensive land-cover change.

A produtividade primária bruta (GPP) de ecossistemas é uma importante variável no estudo de mudanças climáticas globais. A GPP, geralmente, tem sido estimada por técnicas micrometeorológicas. No entanto, essas técnicas possuem elevado custo de implantação e manutenção, fazendo com que o uso de dados de sensores orbitais seja uma opção a ser avaliada. Sendo assim, o objetivo deste estudo foi avaliar a potencialidade do produto MODIS (Moderate Resolution Imaging Spectroradiometer) MOD17A2 e o modelo de fotossíntese da vegetação (VPM) para estimar a GPP de uma floresta de transição Amazônia-Cerrado. A GPP estimada pelo MOD17A2 (GPP MODIS) e pelo VPM (GPP VPM) foram validadas com a GPP estimada pelo método de correlação de vórtices turbulentos (GPP EC). A GPP MODIS, GPP VPM e GPP EC apresentaram sazonalidade similar, com maiores valores na estação chuvosa e menores na estação seca. No entanto, o VPM apresentou melhor desempenho do que o MOD17A2 em estimar a GPP, por utilizar dados climáticos locais para estimar a eficiência do uso da luz, enquanto que o produto MODIS utiliza um modelo de circulação global e uma tabela baseada no tipo de vegetação para estimar a eficiência do uso da luz.

The gross primary production (GPP) of ecosystems is an important variable in the study of global climate change. Generally, the GPP has been estimated by micrometeorological techniques. However, these techniques have a high cost of implantation and maintenance, making the use of orbital sensor data an option to be evaluated. Thus, the objective of this study was to evaluate the potential of the MODIS (Moderate Resolution Imaging Spectroradiometer) MOD17A2 product and the vegetation photosynthesis model (VPM) to predict the GPP of the Amazon-Cerrado transitional forest. The GPP predicted by MOD17A2 (GPP MODIS) and VPM (GPP VPM) were validated with the GPP estimated by eddy covariance (GPP EC). The GPP MODIS, GPP VPM and GPP EC have similar seasonality, with higher values in the wet season and lower in the dry season. However, the VPM performed was better than the MOD17A2 to estimate the GPP, due to use local climatic data for predict the light use efficiency, while the MOD17A2 use a global circulation model and the lookup table of each vegetation type to estimate the light use efficiency.

Vochysia divergens Pohl (commonly known as cambara) is a pioneer tree species that is native to the Amazon Basin but has been invading the seasonally flooded wetlands of the Brazilian Pantanal, forming monospecific communities. The physiological aspects associated with cambara invasion, including the effects of flooding and shading on growth and leaf gas exchange, are unknown but may shed light on why cambara is able to invade this novel habitat so rapidly. Thus, we conducted a manipulative experiment to quantify the effects of shading and flooding on the growth, gas exchange and leaf nutrient content of V. divergens saplings. Based on previous research we hypothesized that (1) experimental flooding would have no effect on the growth and gas exchange of V. divergens,and (2) experimental shading would reduce the growth and gas exchange of V. divergens regardless of the water treatment plants are subjected. Our data indicate that shading significantly increased the height, stomatal conductance (g s), and transpiration (T) of V. divergens saplings, especially for plants exposed to normal irrigation. Experimental flooding significantly reduced rates of leaf production, plant height, and gas exchange; however, shaded plants exposed to flooding had a higher water use efficiency than plants exposed to full sun and flooding, because Twas more depressed than net photosynthesis (A) in flooded plants exposed to full sun. Despite the inhibitory effects of flooding and shading, V. divergenssaplings exhibited positive growth and C gain, regardless of the growth light environment or water level, indicating that the growth and leaf gas exchange of species is tolerant to both flooding and shading. Such tolerance to a wide variety of hydrological and growth light conditions presumably explains the ability of cambara to invade, and ultimately form dense, monospecific stands in the Brazilian Pantanal.