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

Hurricanes are considered among the most important determinants of the structure and composition of many tropical forests. In Quintana Roo, these natural phenomena are part of the natural dynamics of the forest. Hurricane Dean, on of the most recent of these weather events occurred on August 21, 2007, affecting around 900,000 ha of medium semi-evergreen forest. The damage occurred on the vegetation was quantified and changes in species composition and structure of the forest affected by Hurricane Dean were discussed. It was found that the composition of the forest was not affected. The greatest effect of the hurricane was on the forest structure. Understory trees was more damaged that canopy trees. The main types of damage were the small and medium branch damage, uprooted and snapped trees. Forest management could have increase the susceptibility of this forest to wind damage. The effects of forest management in the susceptibility of the forest are discussed based on bibliographic information and some observations during field sampling. It is proposed to reduce the number of “wood concentration” during logging activity, as well as to incorporate to management plans, the extraction of damaged trees. It is also proposed to monitor the long-term dynamics both of damaged and undamaged forest by hurricanes.

Wood anatomy of five species of Zanthoxylum is described and compared. Qualitative and quantitative characters were analyzed through multivariate analyses to identify wood characters that permit to distinguish among species or to group them in the recognized sections within the genus. The species shared the diagnostic wood character for Zanthoxylum as of vessel wall thickness < 4 µm, intervessel pits < 6 µm, except for Z. hidalgense, libriform fibers, and parenchyma in marginal bands. The semiring-porosity distinguished the studied species of other Zanthoxylum species. The occurrence of druses in vessels and septate fibers are reported for the first time for the genus. The results of principal component analysis and the phenogram support the recognition of the five species studied based con a unique combination of wood characters; however, wood characteristics do not always support inclusion in the current sections. Zanthoxylum purpusii is recognized by the vertical traumatic canals and septate fibers; Z. arborescens, Z. purpusii and Z. liebmannianum are grouped by parenchyma in marginal bands and biseriate rays. Zanthoxylum hidalgense is the species with the wider vessels, wider and longer fibers as well as taller and wider rays while Z. arborescens and Z. liebmannianum show the narrower vessels and shorter and narrower fibers. Vessel diameter and length and diameter of fibers appear to be related to the vegetation type where the species studied are distributed.

Mathematical techniques that predict the risk of forest fires use a hydro-climatic sub-model, which is generally fed with simple climatic variables such as rainfall, potential evapotranspiration, or the air relative humidity. In this research we report the effect of rainfall, pan evaporation (Et), and potential evapotranspiration (Etp), and the soil moisture content (θ), were related with the number of annual forest fires and the area annually burned by forest fires in the state of Durango, Mexico. A hydrologic, mass balance, physically-based model that feeds on climate, soil and plant cover variables as well as weighting factors was employed to calculate Etp and θ. In addition, the El Niño index was statistically related to the forest fire variables described above. The θ variable resulted to be better related than the simple climatic variables to the number of forest fires and the area burned by forest fires. El Niño index expressed during the November-December phase of the year t-1 explains above 30% of the total burned area variation during the dry season of January-May of temperate forests. It is recommended to use the soil moisture content estimated by the water balance as predictor variable in the fire risk assessment of temperate forests.

The objective of this research was to estimate basic wood specific gravity and its level of variation among biomass components of trees of several species of the genera Pinus and Quercus of northern Durango, Mexico. A total of 843 wood core sepecimens were taken at different heights and at different diameter sections from 113 trees. Fresh wood blocks of 2,5 cm x 2,5 cm x 2,5 cm were measured and once they were oven dried they were weighted to estimate the wood specific gravity. Results showed that the basic wood specific gravity was statistically different between biomass components along the diameter and height gradients (P > F = 0,0001) for trees of the genus Pinus unlike for trees of the genus Quercus. Mathematical evaluations show that wood cores for measuring the bole wood specific gravity must be taken at a height of 0,22H instead of the traditional height of 1,3 m at which it is conventionally evaluated.

Nowadays, forests have a key role to mitigating the effects global warming has on our planet. Scientific knowledge on ecosystem processes and services to human wellbeing confirm this. As an important component on REDD+ national and regional strategies, which will guide the actions needed to reduce and mitigate the greenhouse gases emissions, forest management and forest conservation are the most effective and less costly measures. This kind of strategies will contribute directly to improve the life conditions of forest owners, and socioeconomic development conditions of forest regions. Even though Veracruz state has developed a Law and an Action Plan towards Climate Change, a REDD+ perspective is still a novelty. It constitutes an opportunity for academic collaboration with government institutions on the three levels, with forest owners, and with those involved in forestry activity along the state. In this context, we present a general analysis on Veracruz´ forests situation, pointing out the deforestation and degradation trends and active processes, to outline certain aspects as opportunity areas to develop collective efforts between academia and forest owners, to improve the management of our forest ecosystems for the benefit of society.

Aboveground biomass accumulation and allocation to the structural components of trees is crucial in managed forests, both in terms of timber productivity and the reactivation of different ecosystem processes. In this study, we analyzed the pattern of accumulation of aboveground total biomass and its allocation among stems, branches, bark and foliage in a chronosequence of managed Pinus patula forests in Zacualtipán, Hidalgo. Total aboveground biomass (TAB) and its allocation to structural components were estimated by using allometric equations in stands with different numbers of years since harvest, in different years of measurement (2005, 2008 and 2012). We found that the TAB increased with time since harvest, with highly significant differences (p<0.0001) among stand ages. The stand with 30 years since harvest showed an aboveground biomass (AB) of 178.1 Mg ha-1 which was only 20% lower than that estimated for the stand without harvest (AN), indicating that a managed forest could reach levels of aboveground biomass similar to those of the AN, but in less time. Aboveground biomass allocation was made in the following order: stem> branches> bark> foliage. Allocation favored the stem as a commercial timber product, which is the main objective of these managed forests. The pattern of aboveground biomass allocation among the structural components of the trees reflects the fact that forest management in temperate forests operates as an important alternative for the recovery of degraded forests. Because of climate change, it can also represent an appropriate strategy for carbon sequestration and mitigation of carbon dioxide emissions.

Cedrela odorata L., known as red cedar, is one of the most economically valuable species in Mexican forestry production. Although timber is the main product obtained from this species, branches and leaves are generated from thinning and pruning activities, as well as sawdust from sawmilling. These materials are currently considered as waste. This study evaluated the chemical composition of the leaves, branch wood and sawdust of red cedar from samples collected in two experimental forest plantations in El Palmar, Veracruz and San Felipe Bacalar, Quintana Roo. Concentrations of total phenols, flavonoids and their capacity for scavenging free radicals were evaluated, focusing on their potential use as a lignocellulosic source for obtaining biofuels and in applications in biomedical areas. The leaves have high concentrations of extractables with maximum values of 34,78%, polysaccharides 67,11%, lignin 31,10%, reducing sugars 6,52%, phenols 211,91 mgGAE/g, flavonoids 81,05 mgCE/g, but did not show free radical scavenging activity. In contrast, the branch wood and sawdust had low extractable levels with 6,10%, polysaccharides 78,46%, lignin 32,24%, reductor sugars 8,87%, phenols 355,57 mgGAE/g, flavonoids 178,56 mgCE/g and a high capacity for free radical scavenging. Differences were found in lignocellulosic concentrations among the samples collected at the two plantations, with the highest values in those collected at Bacalar, QR. The results obtained indicate that the leaves, branch wood and sawdust are viable for obtaining carbohydrates; while the wood can be a source of phenols and flavonoids with possible therapeutic applications.

In 2015 the teak (Tectona grandis Linn f.) plantations of Guatemala covered approximately 33 000 hectares, of which 80% are located in the septentrional northern region and, in order to characterize the evolution in terms of growth and development, data from a total of 248 permanent monitoring plots (in plantations established between 1998 and 2001 with measurements each year between 2004 and 2009) have been analyzed. The results show that, on average, 13,01% of the sites present high growth, 70,66% medium growth and 16,33% low growth. For the sites of medium to high growth, i.e., 83,67 %, the Site Index at a base age of 10 years that will be achieved will be between 19,13 m and 25,32 m, a mean annual increase in total height (MAIHTOT) of between 1,98 m yr-1 and 2,62 m yr-1, a mean annual increase in DBH (MAIDBH) of between 2,23 cm yr-1 and 2,82 cm yr-1 and productivity (MAIVOL) of 9,89 m3 yr-1 to 17,22 m3 yr-1. The sites that present low growth rates will reach a site index of 12,94 m, a MAIHTOT of 1,34 m yr-1, a MAIDBH of 1,65 cm yr-1 and a maximum productivity of 2,55 m3 yr-1. The analysis of variance showed significant differences with a p-value ≤ 0,001 in site index, MAIHTOT, MAIDBH, MAIBA and MAIVOL. The site index curves based on a modified growth model allowed the identification and definition of a land classification based on its productive capacity on site, and thus evidences the growth and development of teak in Guatemala.

In order to demonstrate the influence of geographic location of a sampling site, land cover and calendar month on the expression of thirteen indirect indicators of surface meteorology and solar radiation, the technique of information re-scaling was applied based on latitude in order to calculate the zenith angle in coordinated pairs, in coniferous forests in Mexico. This historical series of information covers a period of 22 years of daily records. Ten sampling sites were defined in five geographical localities with two absolute land covers (natural forest and deforested) with a common spatial border; this neighboring condition was mandatory for the study. Statistical analysis revealed significant differences (p < 0.05), for land cover, sampling site and calendar month. In the expression of the indices, an apparent latitudinal effect was observed of proximity to the coastline, which seems to suggest its influence on the evaluated indexes. The results suggest the extension of the database to include direct information pertaining to meteorology (wind speed and direction) and solar radiation. These data are necessary in order to characterize the response of the land cover for spectral invariance according to variations in the radiant flow, for the ratio of reflectance, absorbance and transmittance.

Degradation of natural resources has generated the need for ecological restoration. It is therefore necessary to identify in a simple manner the areas to be restored and prioritize the activities. The main aim of this study was to use Multi-Criteria Evaluation to identify priority areas for ecological restoration in the Chignahuapan-Zacaltan region of Puebla, Mexico, and to use remote sensing to determine reference sites for restoration. An Analytic Hierarchy Process through a GIS environment was used to identify priorities for attention. Mapping Information of 12 environmental criteria was used, together with the knowledge of 21 experts in restoration, which was incorporated through pairwise comparison matrices. The reference sites were determined by the supervised classification of satellite images and the exclusion of areas that presented some form of disturbance. The results indicate that about 80% of the area was classified with a level of priority for restoration. However, only 0.8% was classified as maximum priority. On the other hand, the area with potential to serve as a reference within the study area is approximately 4753 hectares. With recognition of these areas to be restored and reference sites in the maps, the efficiency and planning for restoration will be improved.