This study analyzed what type of adhesive is most suitable for use in the manufacture of Aspidosperma quebracho-blanco wood blockboards impregnated with polyethylene glycol (PEG). Three types of adhesives that could potentially be used to form the boards were analyzed: polyvinyl acetate (PVAc), urea-formaldehyde (UF) and phenol-formaldehyde (PF). Bond quality was determined by the glue-line strength in boards made with impregnated and non-impregnated wood. The use of PEG as a stabilizer of Aspidosperma quebracho-blanco wood did not interfere in the adhesion process when UF and PF adhesives were tested. The PVAc adhesive decreased (

This paper is a review regarding the role of agroforestry systems (AFS) as an alternative for carbon sequestration in ecosystems in the Mexican tropics. The AFS are presented as a productive and ecologically friendly strategy. It also highlights the importance of the AFS in the global carbon cycle, citing some factors related to carbon sequestration in vegetation and soil. Looking to the future, the need for further studies on the implementation and sustainable development of AFS is outlined. We conclude that AFS are a sustainable alternative to help increase productivity and play a significant role in mitigating global warming in the tropics.

Environmental indicators in the Zahuapan-Atoyac hydrological system (ZA:HS) in Tlaxcala, Mexico, a region impacted by wastewater discharges from urban, agricultural and industrial sources, were assessed. Samples were collected in the spring 2008 dry season. Sixteen sampling stations were selected, stretching from the source of the Zahuapan River, including three samples from the Atoyac River, to its exit point from the state of Tlaxcala. Arsenic, lead, pH and temperature were measured in the water samples; in the sediments, the following were measured: arsenic, lead, texture, organic matter content, total organic carbon, pH and electrical conductivity according to NMX-AA-051-SCFI-2001, Goyberg-Rein and Vázquez, 2003 and NOM-021-SEMARNAT-2000. The results showed that the arsenic concentrations ranged from 0.06 to 0.87 mg•L-1 in water and from 1.3 to 127 mg•kg-1 in sediment, whereas lead levels reached up to 1.05 mg•L-1 in water from a place called El Ojito and 89.5 mg•L-1 in sediment from the Apizaco station. These levels exceeded the national and international levels set for drinking water and protection of aquatic life. The results suggest an anthropogenic contribution at some stations that adds to natural pollution.

A greenhouse experiment was established to determine the concentration of lead (Pb) in soil, root and aerial part of broad bean and oats. The bioconcentration and translocation factors in the two species were calculated, and 50, 100 and 150 mg•Pb•kg-1of soil, including a control, were tested. Plants were collected 60 days after sowing and plant height (PH), root volume (RV) and total dry biomass (TDB) were measured, as well as Pb content in soil, root and aerial part. The quantification of Pb was performed by atomic absorption spectrophotometry. The soil cultivated with broad bean presented 28.48 % PbEDTA. The PH, RV and TDB variables were not drastically affected by the Pb concentrations tested. The broad bean and oat plants absorbed a total of 55 mg•kg-1 and 45.3 mg•kg-1, respectively, which are considered toxic concentrations for cultivated plants. The results can serve as a base to expand knowledge of Pb content absorbed and translocated in broad bean and oat plants, as the ability to tolerate and absorb Pb is specific to the species, including the variety of plant.

The present investigation characterizes the post-fire woody regeneration recovered after the fire that occurred in 1998 and affected 500 ha of temperate forests in the Chipinque Ecological Park (NE Mexico). The objectives were to estimate the richness and diversity of woody vegetation (≥ 1 cm diameter) regenerated after the fire and assess the ecological parameters of abundance (ARi), dominance (DRi), frequency (FRi) and importance value index (IVI) of the species. There were 10 orders, 11 families, 21 genera and 26 species. The genus Quercus was the most representative, presenting 148.16 % of ecological importance in the area. The most representative species were Quercus polymorpha (IVI=71.13 %) and Pinus pseudostrobus (IVI=50.67 %). Tree density was 2864 N/ha, with foliage cover of 12526 m2/ha, which indicated coverage of 100 % and overlapping crowns. The values of Margalef richness index (DMg = 3.64) and Shannon diversity (H´= 2.39) indicated high diversity.

One hundred and fifty-one castor oil plant (Ricinus communis L.) accessions, collected in the state of Chiapas, Mexico, were characterized by the oil content, shape, size and weight of the seeds, with the aim of generating information that can serve as a basis for a breeding program for this species, which could be a profitable option for the production of biodiesel and turbine biofuel. Based on the distribution of the accessions, the following four climatic zones were established: Region 1) tropical rainy climate without a dry season; Region 2) tropical savanna with dry winters; Region 3) tropical savanna with less dry winters than those of Region 2; and Region 4) tropical rainforest. There was a wide variation in seed size (from 0.05 to 2.49 cm2), color, weight (from 7 to 123.9 g per 100 seeds) and oil content (from 12.20 to 64.84 %).The relationships established between the size and weight of 100 seeds with temperature and precipitation were negative, being significant only in regions 3 and 4. There was no significance to oil content relationships with temperature and precipitation, but the trend was positive in regions 1 and 4, the most humid ones of the four regions, and negative in regions 2 and 3. It is concluded that individuals of this species have a great ability to adapt to different environments and create special phenotypes for each place where they develop.

Timber harvesting operations in four ejidos in the El Salto region of Durango, Mexico, were analyzed using a time and motion study to determine the operational productivity of manual felling, delimbing, bucking, skidding and mechanized loading. A total of 704 cycles for felling, 900 for mechanical skidding and 1,294 for mechanical loading were timed. The results indicate that the operational productivity in the manual felling cycle is 28.67 m3•h-1. Crane skidding was 19.83 m3•h-1 at an average distance of 43.13 m. Mechanized loading productivity was 35.27 m3•h-1. Productivity was shown to be sensitive to variations in the diameter and length of the trees and logs, as well as the distances found in the work cycles analyzed.

Juglans pyriformis is a threatened species endemic to a cloud forest environment. In order to determine the morphological variation within the J. pyriformis population in Coacoatzintla, Veracruz. Six morphological and two dasometric variables were evaluated, through non-probability sampling, in 1 to 5 individuals per site, located at a distance equal to or greater than 50 m or until locating the next individual. The data were analyzed using tests of independence between variables, Principal Components Analysis, cluster analysis, coefficient of variation and Levene’s test of homogeneity of variance. The results obtained allowed identifying two indicators for the CROWN and TRUNK morphological variables, and one for the HEIGHT-DIAMETER dasometric relationship. The HEIGHT-DIAMETER indicator provided more variation within the population (42 %). Significant differences were found within the population for the CROWN and HEIGHT-DIAMETER indicators.

The structure, diversity and floristic composition of two oak communities in the State of Mexico were characterized in this work. The density and basal area of the canopy trees and shrub cover were evaluated, and the herbaceous species were recorded. The vegetation attributes were used to calculate the relative importance value of the species. The number of taxa and the diversity value of the two communities were similar. In the town of Cieneguillas de González, Temascaltepec, there is a mountain cloud forest where the oak of greatest structural importance is Quercus candicans; other important species were Clethra mexicana, Ternstroemia lineata, Pinus pseudostrobus and Pinus leiophylla. In the town of Llano del Huilo, Villa del Carbón, there is an oak-pine forest where Quercus crassifolia has the highest importance value, followed by Pinus teocote, Quercus obtusata, Quercus candicans, Q. crassipes and Arbutus xalapensis. The shrub layer, although more diverse in the mountain cloud forest, had greater coverage in the oak-pine forest.

The goal of this study was to identify the histological alterations in hartweg pine (Pinus hartwegii) caused by three species of ophiostomatoid fungi by means of light microscopy. There was an accumulation of resin in the inoculated zone within 10 days, and foliage of inoculated seedlings turned yellow and reddish-brown at 60 days. With inoculation of Leptographium guttulatum and Ophiostoma olivaceapinii, it was observed that they induce the metabolization of polyphenols, which were deposited on the cell walls of the inner bark, the phloem, vascular cambium and in the pith, where they became necrotic. Compared to L. guttulatum and O. olivaceapini, O. ips caused a more severe necrosis of the inner bark, cambium, and pith. In the xylem of inoculated seedlings, the hyphae of the three different fungi penetrated into the tracheids and moved through the bordered pits and radially through the parenchyma cells in the rays.

Thirty models were evaluated to predict timber volume growth and yield in 28 Permanent Plots (SPIS), in the Ejido Pueblo Nuevo, Durango, Mexico. The predominant plant association is mixed stands of Pinus and Pinus Quercus, along with the vegetation associated with these forests. The models in logarithmic form incorporate 10 competition indices (IC) independent of distance, 3 density indices (ID), age (t) and canopy height (H) at the average level of the stand. The mathematical models indirectly relate the effect of competition and density on tree growth and yield. According to the variance analyses and the test hypothesis, the best IC incorporated in a mathematical model for the volume increment prediction was the basal area density competition index (IABN), the diameter quadratic density competition index (IDCN), the basal area total density competition index (IABTN) and the maximum total height competition index (IHMAX). The best models presented average values of R2 = 0.99 and a highly significant level of accuracy (Pr>|t| = 0.0001).

Information about the diameter distribution of a forest stand is an essential component for deriving a variety of stand attributes, understanding stand dynamics under varying ecological conditions and planning future forest prescriptions. Diameter distributions from multiple even-aged stands of Pinus occidentalis from three different ecological zones within La Sierra region in the Dominican Republic were modeled using a three-parameter Weibull probability prediction method using either maximum likelihood or modified method of moments, and two bases on parameter recovery method using either percentile-based or cumulative distribution function regression. Stand characteristics such as age, total tree height, trees per hectare, site quality and basal area were employed as predictor variables. Methods were evaluated based on goodnessof-fit of the distributions and RMSE of stand yield. In these data, the parameter recovery method based on percentile based distribution proved to be considerably more efficient in describing the diameter distribution.

A new report is presented herein of the Mexican orchid Oncidium cavendishianum (Bateman) in cloud forest areas at the Las Joyas Research Station, the Sierra de Manantlán Biosphere Reserve, Guadalajara, Jalisco, Mexico. The species has also been reported for the municipalities of Temascaltepec, Cieneguillas de González, San Lucas del Pulque, Telpintla, Carniceria and Real de Arriba. Species identification was carried out by the botany department faculty of the Centro Universitario de la Costa Sur, Autlan de Navarro. The collection was processed and preserved in the herbarium of the above-mentioned entity. This work includes a photographic image of the plant, along.

Natural resource management based on Participatory Community-based Environmental Management (PCEM) is a support tool to implement rural development projects at the community level, from a regional planning framework through the use and application of technical tools to analyze the potentials and limits of natural resources and the use of a methodology to drive participatory processes. Management elements and production processes were characterized and defined using landform, land use and vegetation through field samplings of 1000 m2 plots for forests and 1 m2 ones for pasturelands, validated by sub-supervised SPOT image classification and the edaphological conditions proposed by INEGI (1978). Through participatory planning workshops conducted in 2006, the results of the technical analysis were compared and validated and the community proposals were identified. Among the strategic guidelines are: appropriate livestock, agricultural, forestry and ecotourism uses; conservation, reconstruction of water bodies; and restoration of degraded ecosystems, which is based on taking decisions such as establishing buffer zones between use areas and conservation areas where the original ecosystem remains.

Litterfall production and quality in pure and mixed fodder banks of Leucaena leucocephala (Lam.) de Wit, Guazuma ulmifolia Lam. and Moringa oleifera Lam. were evaluated during the rainy and dry season, using a completely randomized block design with five treatments and four replications in densities of 10,000 and 20,000 plants•ha-1. In each experimental unit, a 1.6 m2 litter mesh collector was installed, and the litterfall was collected throughout one year. Dry weight was recorded by treatment and seasons to determine the fraction of N, C and P and the C:N ratio. The highest litterfall production was in the rainy season. L. leucocephala in monoculture and intercropped with G. ulmifolia showed the highest production with 1,022 and 1,542 kg DM•ha-1•1yr-1, respectively, and L. leucocephala had the highest total contributions of N, C, and P with 22.0, 443.0 and 0.96 kg DM•ha-1•yr-1. L. leucocephala with M. oleifera provided greater amounts of N and C (23.2 and 363.8 kg DM•ha-1•yr-1. The greatest input of phosphorous was by L. leucocephala and G. ulmifolia (0.74 kg DM•ha-1•yr-1). It was concluded that the association of species promotes greater litter production and nutrient intake compared with monocultures.