Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Pith bagasse is a sub-exploited residue produced in large quantities in sugar mills and paper mills. It is a mixture of parenchyma cells, vessels and small-size cellulose fibers. The content of carbohydrates and lignin in pith is similar to the fiber fraction. In order to take advantage of this significant carbohydrate content, two distinct processes were applied to the pith material: Pulping-bleaching, and enzymatic hydrolysis. In the first case the pith was treated with pre-hydrolysis, soda pulping, bleaching and beating process, obtaining bleached pith-pulp with 68% ISO brightness and 0,38% of residual lignin. The largest increase in strength (77,6% increase in tensile index, IT) happened when 30% of this unbeaten pulp was added to paperboard, while with 10% of refined bleached pulp, IT increased in 43,8%. In the second, the pith was enzymatically hydrolyzed. In 6 h of hydrolysis a yield of 86,6% of fermentable sugars was obtained in both, cooked pith-pulp and bleached pith-pulp, close to 100% hydrolysis of carbohydrates present in the substrate, which is significant because the yield of fermentable sugars from untreated pith was only 26,1%.

This research describes the social process of extraction and commercialization of the perlilla sticks (Symphoricarpos microphyllus H.B.K.) in three communities of the Protected Wildlife Area of the Nevado of Toluca. This research was done through the participant observation, semi-structured interviews, transects and sampling of areas of extraction. The results show that the social agent who generates the demand of this resource is the Government of the Federal District to make rustic brooms used for public cleaning. The social organization around resource extraction is dominated by outside brokers and therefore they obtain most of the economic benefits the perlilla´s extraction. They take advantage of their family and friend relationships with the leaders of cutters. The field work that identifies that the extraction of perlilla has been intensified that some areas already show problems of regeneration of this species that are linked to inadequate cutting technics. This situation could be causing severe ecological, economic and social problems in this natural protected area.

In this study, the main wood chemical composition of Ceiba pentandra, Hevea brasiliensis and Ochroma pyramidale was determined with the aim of providing knowledge on wood chemistry of tropical species and information to explore possible chemical applications. For this, the contents of ash, ethanol-benzene extracts, ethanol extracts, lignin, holocellulose, cellulose and hemicelluloses were quantified in the stem at three height levels (bottom, middle, and top). Results of the chemical analysis showed that concentrations of the determined constituents varied within the stem of the individual wood species and also among species. The average amount of chemical compounds among the species was 0,44% - 1,64% for ash; 1,42% - 3,42% for ethanol-benzene extracts; 1,88% - 5,07% for ethanol extracts; 3,83% - 8,46% for total extracts; 19,71% - 26,83% for lignin, 77,73% - 83,52% for holocellulose; 39,67% - 47,63% for α-cellulose and 33,79% - 42,85% for hemicelluloses. According to the obtained contents of lignin, α-cellulose and hemicelluloses, the wood of these species could be used in pulping and bioconversion processes.

Effects of Skidder on Soil Compaction, Forest Floor Removal and Rut FormationAn extensive field trial was set up to examine the influence of traffic intensity (5, 10, and 15 skidding cycles) (i.e. pass back and forth on the skid trail) and skid trail slope (0-10, 10-20, and > 20)% on soil compaction, forest floor removal, and rut depth after logging. The results showed that dry bulk density and rut depth increased with the increase of traffic frequency and slope, but floor coverage decreased. Within each traffic treatment soil compaction raised with the increase of skid trail slope, so that significant differences in dry bulk density were observed between slopes lower than 20% and those greater than 20%. Bulk density has become quite close to the critical value after 15 cycles. We observed soil rutting on the treatments started with 10 cycles. Soil disturbance increased significantly on slopes with less than 20% inclination with a dry bulk density of 1.157 g cm-3 after 5 cycles compared to 0.923 g cm-3 on slopes lower than 10%. In addition the litter mass on the treatments with 10 cycles and slopes greater than 20% (386.586 kg ha-1) was significantly lower (p < 0.05) than treatments with 15 cycles and slopes lower than 10% (545.382 kg ha-1). Data suggest that disturbance increased earlier in the steep treatments than in less sloping conditions. The dramatic increase of soil disturbance on treatments with slopes greater than 20% may be associated with increasing load on the rear axle combined with slipping on steep slope trail.

This research evaluated the performance of fourteen stem taper models for their use in Eucalyptus tereticornis forest plantations. Three types of models were evaluated: polynomials, segmented and variable-exponent models. A sample of 130 trees collected in forest plantations with stand ages between five and twelve years-old located at the Atlantic Colombian coast was used. During the parameter estimation process a continuous time autoregressive model (CAR) was used in order to expand the error structure, reducing the effect of the autocorrelation generated by the longitudinal measurements taken along the stem. The model evaluation considered a comparison of the predictive ability respect to the prediction of upper-stem diameter, upper-stem heights, merchantable volume until a given stem-height and merchantable volume until a given stem-diameter. Measures of bias, precision and error were used for evaluating the models. A third-order continuous-time autoregressive model CAR(3) allowed to adequately model the residual autocorrelation for all stem profile models. The variable-exponent models showed the best performance in terms of goodness of fit and predictive capability.

Bactericidal effect was assessed in crude extracts of different tissues of Magnolia schiedeana about the phytopathogenic bacteria Pectobacterium carotovorum and Pseudomonas cichorii. The tissues studied were polifolicule, seed, bark (obtained from adult specimens and young specimens), flower and leave (from both adult and young specimens as well), using as solvents ethyl acetate and ethanol. The extracts that showed bacterial inhibition were obtained one with ethyl acetate from floral tissue, which did not equaled the inhibiting properties of a commercial antibiotic (tetracycline, 5 µg/µl) on P. cichorii (p < 0.001); and the other was floral ethanol extract that inhibited P. carotovorum in the same proportion as the antibiotic (p = 0.079).

The greatest threat to the cloud forest around Xalapa, Veracruz, is the conversion to human settlements and urbanization, therefore ecological restoration of this forest in peri-urban areas represents a decisive action for recovery and reconnection of green areas and forest remnants. This article describes the initial ecological conditions or baseline of an ecological restoration project from an abandoned pasture in a peri-urban landscape. The baseline was established with information about 1) history of land use, 2) temporal and spatial variability of abiotic (climate) and biotic (vegetation structure and floristic composition) characteristics of the site, and 3) the ecosystem resilience as regeneration potential from soil seed banks and seed rain. The baseline results guided the active restoration (i.e., multi-species plantations), and passive restoration (i.e., suppression of disturbance) actions. Active and passive restoration areas will be part of public displays of the Francisco Javier Clavijero Botanical Garden to inform about the long and complex process to recover a peri-urban cloud forest.

Today there is a huge interest and wide discussions in the academic world to find effective methods of evaluation of the impact of the work of the scientists. It is argued here that the impact of the information generated by researchers has relevance beyond a mere accounting of citations to academic products. However, there remains the need to assess in a more immediate way the effect or influence of scientific work. The central argument of this contribution is that the number of citations generated by the engine Google Scholar (GS) represents a far more accurate and complete the work of individual researchers that FI impact Factor. Associated with GS, there is the concept of index h5. To see if there are any regularity in the proportion of citations between the two databases, a search for citations was made to articles for authors considered representative: Williams-Linera et al. and Yáñez-Arancibia et al. for being the most cited. The value of the coefficient of determination shows the extraordinary regularity of this relationship. In the case of the valuation of the journals, it is argued that the index h is the most appropriate to the JCR. We reiterate that the real impact of the research work is beyond the scope of academic work and is reflected in the use of information in remote areas of academia, but that have broad impact on society as for example, the information required to define the protected natural areas.

A study was conducted during 2007, 2008 and 2009 to evaluate the distribution and abundance of oak species (Quercus spp), the environmental factors which affect their distribution, and the identification of pathogens and insects associated with oak decline and mortality in the Sierra Fria, Aguascalientes. To evaluate oak distribution and abundance, 60 plant inventories were made in 60 sampling sites randomly distributed within the landscape, using 600 m2 plots.  To identify plant pathogens 28 transects were established, inspecting 100 oak trees per transect. To identify insects associated with oak decline, emergence traps were  installed on the bole of trees that show wood boring symptoms; bole sections were taken to the lab for beetle capture. Ten oak species were identified and the variables that have influence on their distribution and abundance, were elevation, relief, aspect and physiography. As plant pathogens we identified Phellinus robustus, P. gilvus, P. everhartii, Ganoderma lucidum andHypoxylon thouarsianum, the last one being the more widely distributed.  The oak borer Crioprosopus magnificus was identified, infesting live oak trees. The presence of this insect is a new report for the area of study. The information gathered in this study contributes to the management of the Sierra Fría and further studies are suggested.

Water in Mexico is considered scarce resource. In this essay La Antigua watershed was chosen as a study case. In this site, watershed condition and land management policies were linked to water resource attributes suitable for different consumption uses. La Antigua watershed catches plenty of water; still people perceive problems. Evidence and analysis in this study uncovered a collective belief shared by the public, government, analysts and scientists in La Antigua. The belief sustains that water is vital, valuable and scarce. However, public behaviour contradicts such collective understanding. People choices are more consistent with a plentiful low cost resource, with no significant externalities. La Antigua scenario is not irrational, it represents the practical response towards only a fraction of all water stocks, a fraction which involves cultural processes redefining availability and good use of water moving through social systems. Understanding this scenario is essential to offering reliable insights in water policies to the decision makers in La Antigua, other parts of Mexico, and the world. Emphasizes that it is better to move away from technological solutions to deal with an imaginary scarcity, which is in fact unreal given a resource with so many and so different functions and valuations.