Characterization and Potential Evaluation of Residues from the Sugarcane Industry of Rio Grande do Sul in Biorefinery Processes

Brazil is the world largest producer of sugarcane (Saccharum officinarum) leading to a great generation of residues such as bagasse and straw, which represent two thirds of sugarcane energetic potential. Regarding these residues energetic potential, it is interesting to study their application in biorefinery processes. Thus, this work aimed at performing a chemical characterization of sugarcane straw and bagasse from RB867515 cultivar grown in Rio Grande do Sul-Brazil aiming at their use as feedstock in biorefinery processes. The obtained results were compared to data from other states and it was possible to conclude that edaphoclimatic conditions of Rio Grande do Sul have little influence in sugarcane residues chemical composition. Sugarcane bagasse presents larger potential for energetic use because of its volatiles content (74.82%) slightly higher than straw (68.90%), besides its high lignin content (21.85%) and higher calorific value (18.70 MJ/kg). Both sugarcane residues produced in Rio Grande do Sul have potential use as substrate in the obtainment of high value-added products from their cellulosic fractions (41.30% and 37.25%, respectively). The evaluation of energetic and chemical potential of sugarcane bagasse and straw produced in Rio Grande do Sul leads to the conclusion that these materials have high potential for use as feedstock in biorefineries.

Mean and Interannual Variability of Maize and Soybean in Brazil under Global Warming Conditions

Brazil is responsible for 27% of the world production of soybeans and 7% of maize. Mato Grosso and Para states in Brazil are among the largest producer. The viability to the cultivation of maize (Zea mays) and soybeans (Glycine max), for future climate scenarios (2070-2100, GHG) is evaluated based on crop modeling (DSSAT) forced by observational data and regional climate simulations (HadRM3). The results demonstrated that a substantial reduction in the yield in particular for maize may be expected for the end of the 21st century. Distinct results are found for soybeans. By applying the A2 climate changes scenario, soybean yield rises by up top 60% assuming optimum soil treatment and no water stress. However, by analyzing the inter-annual variability of crop yields for both maize and soybean, could be demonstrated larger year-to-year fluctuations under greenhouse warming conditions as compared to current conditions, leading to very low productivity by the end of the 21st century. Therefore, these Brazilian states do not appear to be economically suitable for a future cultivation of maize and soybeans. Improved adaptation measures and soil management may however partially alleviate the negative climate change effect.

Species richness and density evaluation for plants with aggregated distributions:fixed vs.variable area methods

Aims Knowledge of species richness is of prime importance to both basic and applied aspects of ecological studies.However,quantifying plant species richness in the tropics is potentially time-consuming because of high species diversity.Plant species richness estimates are also frequently biased,because many rare species are not detected.to address these problems,the use of a variable area method has been proposed as an alternative to fixed area methods,but its appli-cability to plants with aggregated distributions has been questioned based on simulation studies.We use empirical data to compare the efficiency and accuracy of a variable area method and a fixed area method for estimating species richness,density and basal area for plants with aggregated distributions,using palms as a model taxon.Methods Adult palms were sampled in twenty 10×30 m transects in an Atlantic Forest in Rio de Janeiro state,Brazil.All individuals were considered in the fixed area method,while in the variable area method only the first six adults in each transect were sampled;in this case,transect length was defined according to the distance of the sixth adult from the beginning of the transect.When fewer than six individuals were observed in a given transect,transect length was extended up to 50 m to search for additional individuals.the efficiency of both methods was compared based on species rarefaction curves,using the chao 1 statistic(for abundance data).For each species we calculated mean density per transect and basal area,according to each sampling method.Sampling effort in terms of the number of individual plants and the area necessary to characterize maximum species richness in each sampling method,as well as mean time taken to sample a single transect,were compared as measures of efficiency.Important findings An accurate estimate of species richness was achieved using both methods,but in the variable area method,a quarter of the number of individuals and half the area was sufficient to characterize maximum species richness.Density and basal area did not differ between meth-ods for any of the species studied.In the fixed area method sampling effort was 90 min per transect,whereas in the variable area method it was 30 min per transect.the variable area method,with its faster assessment of palm species richness,should facilitate greater spatial representativeness by making it easier to sample a larger number of plots at different spatial scales.We thus find sufficient evidence to recommend the variable area method for rapid and robust evaluations of species richness for palms with aggregate distributions,as well as for other plants with similar spatial patterns,in tropical forests.