[1] We investigated the seasonal patterns of water vapor and sensible heat flux along a tropical biome gradient from forest to savanna. We analyzed data from a network of flux towers in Brazil that were operated within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA). These tower sites included tropical humid and semideciduous forest, transitional forest, floodplain (with physiognomies of cerrado), and cerrado sensu stricto. The mean annual sensible heat flux at all sites ranged from 20 to 38 Wm À2, and was generally reduced in the wet season and increased in the late dry season, coincident with seasonal variations of net radiation and soil moisture. The sites were easily divisible into two functional groups based on the seasonality of evaporation: tropical forest and savanna. At sites with an annual precipitation above 1900 mm and a dry season length less than 4 months (Manaus, Santarem and Rondonia), evaporation rates increased in the dry season, coincident with increased radiation. Evaporation rates were as high as 4.0 mm d À1 in these evergreen or semidecidous forests. In contrast, ecosystems with precipitation less than 1700 mm and a longer dry season (Mato Grosso, Tocantins and São Paulo) showed clear evidence of reduced evaporation in the dry season. Evaporation rates were as low as 2.5 mm d À1 in the transitional forests and 1 mm d À1 in the cerrado. The controls on evapotranspiration seasonality changed along the biome gradient, with evaporative demand (especially net radiation) playing a more important role in the wetter forests, and soil moisture playing a more important role in the drier savannah sites.

The savanna of Central Brazil (locally known as cerrado) has a long history of land cover change due to human activity. These changes have led to the degradation of cerrado forests and woodlands, leading to the expansion of grass-dominated cerrados and pastures. Thus, the aim of this study was to evaluate the temporal variation in energy flux in areas of degraded, grass-dominated cerrado (locally known as campo sujo) in Central Brazil. The amount of partitioned into H declined as monthly rainfall increased and reached a level of approximately 30% during the wet season, while the amount of partitioned into increased as monthly rainfall increased and reached a level of approximately 60% during the wet season. As a result, H was significantly higher than during the dry season, resulting in a Bowen ratio ( = H/ ) of 3-5, while Le was higher than H during the wet season, resulting in a ≈ 1. These data indicate that the energy partitioning of grass-dominated cerrado is relatively more sensitive to water availability than cerrado woodlands and forests, and have important implications for local and regional energy balance.

RESUMOO objetivo deste trabalho foi (a) estimar o efluxo de CO 2 do solo em uma Floresta de Transição Amazônica Cerrado e em uma área de Pastagem localizadas no norte do Mato Grosso, e (b) verificar a influência da umidade e temperatura do solo, e serrapilheira acumulada no efluxo de CO 2 . As medições foram realizadas com aparelho , respectivamente. Uma resposta satisfatória do efluxo de CO 2 do solo e a serrapilheira acumulada, ocorreu somente na estação seca. Na estação seca o comportamento do efluxo de CO 2 do solo foi semelhante na Floresta de Transição Amazônica Cerrado e na área de Pastagem, e na estação úmida os ecossistemas apresentaram comportamentos distintos, e o efluxo de CO 2 do solo na área de Pastagem foi superior ao na Floresta de Transição. É essencial que se avalie a influência de outros fatores no efluxo de CO 2 em ecossistemas localizados em um mesmo ecótono para a obtenção de novas respostas que contribuíam para esclarecer as dúvidas da emissão de CO 2 em nível mundial. , respectively. In the dry season the behavior of the CO 2 efflux of the ground was similar in the Mature Transitional Tropical Forest Amazonian and in the area of Pasture, and in the wet season the ecosystems had presented distinct behaviors, and the CO 2 efflux of the ground in the area of Pasture was superior to the one in the Transitional Forest. It is essential that if it evaluates the influence of other factors in the CO 2 efflux in ecosystems located in one same ecótono for the attainment of new answers that contribution to clarify doubt atmospheric CO 2 emission to them the worldwide level.

Natural starches obtained by fruit seeds have been a subject of studies because of their applications, as a consequence of their chemical properties. As it is known, the fruits depend on the geographic region. Because of this, several factors affect the seed starches nature, such as granules size, morphology, components, and composition. Thus, to better understand starch properties, it is necessary to investigate the chemical behavior of these factors. This work focused on the chemical components and molecular dynamic behavior of the Dipterxy Alata Vogel (cumbaru) starch, because this fruit is very popular and is used in abundance for people because they think that it is good for some kinds of diseases. The main chemical components and the molecular dynamics of starch from the Dipterxy Alata Vogel were studied by applying solid-state 13 C nuclear magnetic resonance spectroscopy (NMR).

Land evaporation, or evapotranspiration ( E ET ), is the phenomenon by which water is converted from a liquid into its vapor phase over land. It plays a significant role in the modulation of global climate feedbacks