Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Influência do tempo de incubação e do tamanho de partículas sobre os teores de compostos indigestíveis em alimentos e fezes bovinas obtidos por procedimentos in situ

Abstract: The aim of this work was to evaluate the effects of in situ incubation time and particles size on the estimates of indigestible fractions of dry matter (iDM), neutral detergent fiber (iNDF), and acid detergent fiber (iADF) in cattle feeds and feces. Samples of corn grain, wheat bran, corn silage, elephant grass, sugarcane, signal grass hay, corn straw, and feces obtained from cattle fed high and low concentrate diets were used. The samples were ground through 1 mm, 2 mm, and 3 mm screen sieve and put in 4 × 5 cm non-woven textile bags (20 mg DM/cm² of surface). The samples were divided in three groups, being each group incubated in the rumen of a crossbred heifer. The incubation procedure was conducted three times with the change of groups among animals. The following incubation times were used: 0, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. The contents of iDM, iNDF, and iADF were evaluated sequentially in each bag. The degradation profiles were interpreted by a non-linear logistic model. The particles size did not influence the estimates of iNDF and iADF. However, the particles size altered the rumen degradation dynamic rates of DM for corn silage and corn grain; of NDF for sugarcane, corn silage, and corn straw; and ADF for sugarcane. For those samples, the particle size has been positively associated with the incubation time necessary to estimate the indigestible fraction. Incubation times of 240 hours for DM and NDF, and 264 hours for ADF were suggested for obtaining more accurate estimates of indigestible fractions. The use of 2 mm particle size can increase the precision of estimates.

Pervasive transition of the Brazilian land-use system

Abstract: This Review considers the evolving relationship between land-use change and greenhouse gas emissions in Brazil. Despite the intensification of agriculture over the past decade or so, deforestation has decreased, resulting in reduced greenhouse gas emissions. However, inequality in land ownership and city growth fuelled by rural–urban migration remain pressing issues for policymakers. Agriculture, deforestation, greenhouse gas emissions and local/regional climate change have been closely intertwined in Brazil. Recent studies show that this relationship has been changing since the mid 2000s, with the burgeoning intensification and commoditization of Brazilian agriculture. On one hand, this accrues considerable environmental dividends including a pronounced reduction in deforestation (which is becoming decoupled from agricultural production), resulting in a decrease of ∼40% in nationwide greenhouse gas emissions since 2005, and a potential cooling of the climate at the local scale. On the other hand, these changes in the land-use system further reinforce the long-established inequality in land ownership, contributing to rural–urban migration that ultimately fuels haphazard expansion of urban areas. We argue that strong enforcement of sector-oriented policies and solving long-standing land tenure problems, rather than simply waiting for market self-regulation, are key steps to buffer the detrimental effects of agricultural intensification at the forefront of a sustainable pathway for land use in Brazil.

Ecology and evolution of plant diversity in the endangered campo rupestre: a neglected conservation priority

Abstract: Botanists, ecologists and evolutionary biologists are familiar with the astonishing species richness and endemism of the fynbos of the Cape Floristic Region and the ancient and unique flora of the kwongkan of south-western Australia. These regions represent old climatically-buffered infertile landscapes (OCBILs) that are the basis of a general hypothesis to explain their richness and endemism. However, few ecologists are familiar with the campo rupestre of central and eastern Brazil, an extremely old mountaintop ecosystem that is both a museum of ancient lineages and a cradle of continuing diversification of endemic lineages. Diversification of some lineages of campo rupestre pre-dates diversification of lowland cerrado, suggesting it may be the most ancient open vegetation in eastern South America. This vegetation comprises more than 5000 plant species, nearly 15 % of Brazil’s plant diversity, in an area corresponding to 0.78 % of its surface. Reviewing empirical data, we scrutinise five predictions of the OCBIL theory, and show that campo rupestre is fully comparable to and remarkably convergent with both fynbos and kwongkan, and fulfills the criteria for a classic OCBIL. The increasing threats to campo rupestre are compromising ecosystem services and we argue for the implementation of more effective conservation and restoration strategies.

Seasonality in CO2 and H2O flux at an eastern Amazonian rain forest

Abstract: [1] Previous studies of CO2 fluxes in Amazonia have suggested seasonal variation in net ecosystem exchange. We find little evidence of this seasonality at a new site in eastern Amazonia, despite the expectation that this site would be particularly sensitive to seasonal fluctuation of rainfall. The average rate of peak net ecosystem exchange was −19 ± 0.9 (1 S.E.) μmol CO2 m−2 s−1. Canopy conductance, evaporation, and vapour pressure deficit were all increased during the dry season, consistent with an increase in bulk temperature and solar radiation. The lack of a dry season decrease in photosynthesis was thought to be due to the observed increase in leaf area following dry season flushing. This was accompanied by an increase in solar radiation, and we suggest that the effect of “dryness” was merely to preclude optimality of photosynthetic response to this increase in radiation. The gross primary productivity of this site was estimated to be 36 t C ha−1 yr−1. This is similar to that reported for other Amazon forest stands. The year may have been a particularly productive one due to the lack of an El Nino event.