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

 In this study a sample size of 87 logs was determined to achieve a 95% confidence, based on the variation of the lumber recovery of a presample of 37 logs. From the logs sampled, 43% were classified as high quality, 26% as medium and 31% as poor quality. Regarding the diameter, 89.65% were within a range of 30 to 55 cm. A lumber recovery factor of 51% was determined and a proportion of slabs and end trims of 27% and 22% of sawdust. The quality and diameter of the logs did not seem to have any influence on lumber recovery, but a relationship was found between log quality and lumber quality, logs of 1st and 2nd class produced 31.70% and 19.44% of quality lumber, logs of 3rd class generated 33.60% of 3rd grade lumber, logs of 4th and 5th grade produced 34.79% and 29.18% of 4th and 5th lumber grade respectively. A log price of $432.00 per m3 and a processing cost of $510.95 per mbf were determined. Comparing the costs of these two concepts with the price of the lumber, a revenue of $968.18 per mbf was determined.

The comparative establishment costs of a semi-mechanized vs manual plantation were calculated for one hectare of rangelands with Tabebuia rosea and Cordia dodecandra. The semi-mechanized plantation method was 17% less costly and much faster when compared with the manual method of plantation establishment. In general, better survival or seedling growth attest to the biological superiority of the semimechanized plantation method. However, due to the high variability, although the semi-mechanized plantation method offered improved height growth, these differences were not always statistically significant.

The most common yarding machine in Mexico is the jammer.  This paper describes its parts, functioning and operation. Using time and movement data from 334 work cycles in a third entry coniferous forest in Michoacan, Mexico, regression equations were fitted to express the duration of each phase in a work cycle as a function of payload, residual stocking, yarding distance and topography. This set of equations allows the jammer’s performance to be estimated in terms of efficiency, both industrial and for the application of silvicultural treatments. Results provide evidence of this yarding system’s high productivity, and confirm its known drawbacks: high residual stand damage and high road construction requirements to keep average yarding distance under 70 m, despite its potential maximum distance of 400 m.

A research work on machining and treatability was carried out with a sample of rubber wood from a plantation in the state of Veracruz, in order to increase the level of technological information on those subjects. The results of the study define the machining characteristics according to ASTM Standards. Taking these results as a basis (regular for most processes), required modifications to the machining process can be acomplished in order to improve the finishing in those cases in which it is required. The rubber wood is considered to be permeable.

Wood has long been one of the materials most used by humankind. Currently, the technology related to its use is undergoing a rapid transformation owing to the tremendous increase in the use of computers. This is affecting all branches of the forest industry, from taxonomic identification to the determination of wood properties and drying methods. Research has produced a plethora of new data and has resulted in the creation of international exchange entities such as IUFRO. Current trends in research are directed towards the improvement of manufacturing processes and their impact on the environment. Wood is being recognized as the renewable material most appropriate for the protection of the environment. Wood reduces our dependence on fossil fuels and reduces the greenhouse effect through the fixation of huge amounts of gaseous carbon in the woody tissue of new plantations. The low energy requirements for the transformation of wood into products and its possibilities as a bio-material foretell benefits for the future.

Sieved heartwood meal of Quercus candicans was extracted with petroleum ether, acetone and methanol, then with cold water and, finally, with hot water. The carbohydrates content was determined in extracted woodmeal, as well as in methanolic and aqueous extracts. The content of Runkel lignin was determined. The content of carbon, hydrogen, oxygen and ashes was also determined for nonextracted wood. The ashes were analyzed by means of dispersive X Ray energy. The pH value was determined. The heartwood of Q. candicans contains 10.2 % extractives, 66.9 % polysaccharides, 21.4 % Runkel lignin, 47.2 % carbon, 6.2 % hydrogen, 45.7 % oxygen and 0.9 % ashes. The ashes contain the following inorganic elements: K, Mg, Ca, P and S. The pH value is 5.6.

The utilization of wood with an appropriate moisture content is one of the main problems that faces wood industry. This problem begins since the fabrication phase and remains during its service life. In order to contribute to the solution of this trouble, this paper presents the design of a solar kiln  for drying wood, of 1200 board feet capacity, built in the facilities of the Department of Forest Products and Forest Management. It explains the methodology of the design, its operation, the wood piling and the steps for controlling temperature and humidity while drying. To this day, results can be given for four drying loads, particulary about drying time, initial and final moisture content, temperature and relative humidity records, inside and outside the oven, as well as the relation between temperature and the daily insolation hours. This kiln is an interesting option for wood manufacturers, because its construction requires inexpensive materials easy to obtain; also, the construction can be made by medium qualified woodworkers.

Traditional forest management is giving way to forest ecosystem management. This transition leads towards achievement and sustainability of the desired ecological and forest conditions, obtaining a sustained yield of products for the satisfaction of human needs.The development of forest ecosystem management models is a complex task, which involves the participation of several society sectors, as well as interdisciplinary professional teams for decision making. The objective is to achieve the greatest interaction between social requirements, ecological needs and ecological capabilities.In this article some principles of forest ecosystem management are presented, as well as the issues that running such a system implies, pointing out different aspects from traditional forest management. Several strategies for management forest landscape and forest stands, in order to contribute to a holistic forest resource management, are discussed.

Total phenolics, flavonoids and proanthocyanidins from aqueous acetone 70% (crude extract) and semi purified extracts by liquid-liquid partition with ethyl acetate (organic fraction) of Pinus cooperi, Pinus engelmannii, Pinus leiophylla and Pinus teocote bark were evaluated. The antioxidant activity using acid 2,2´-azinobis-3-etilbenzotiazolin-6sulfonic radical (ABTS•+), deoxyribose assay (scavenging of hydroxyl radical) and human Low Density Lipoprotein (LDL) inhibition were also determined. Chromatographic analysis of High Pressure Liquid Chromatography (HPLC) of extracts was performed. Total phenolics concentration was 491 mg g-1 to 604 mg g-1, organic extracts showed higher flavonoids concentration (292 mg g-1 to 385 mg g-1) than crude ones (259 mg g-1 to 314 mg g-1), while proanthocyanidins concentration was higher in crude extracts (186 mg g-1 to 286 mg g-1) than organic extracts (70 mg g-1 to 151 mg g1). The radical scavenging activity ABTS was (49,48% to 57,44%), similar to catechin standard (57,92%). The scavenging capacity of OH radical (25,85% to 48,46%), was higher in organic extracts for all species. The LDL oxidation inhibition for organic extracts (64,41% to 89,39%), was higher than crude extracts. Catechin was identified in all species at low concentration. HPLC chromatograms showed a flavanone as the major compound in P. cooperi, P. engelmannii, and P. teocote bark extracts.

Pinus cembroides subsp. orizabensis is the pinyon pine with the more southern distribution in America; most of its populations develop into the limits of the “Cuenca Oriental”, the only cold semiarid area in Mexico, and they are distributed in at least five isolated localities. The objectives of present study were to carry out a floristic inventory and a structural analysis of pinyon pine forests, whose canopy is dominated by the taxon referred, in the “Cuenca Oriental”. The fieldwork was divided into the search and collection of specimens of vascular plants by standard techniques to further identify the specimens in the laboratory; and from sampling of forests to determine the density, coverage and importance value of species. Cluster analysis was used to estimate the similarity in species composition between forests; the relationship between environmental and environment and soil factors with respect to composition and distribution of species between localities was estimated by canonical correspondence analysis. Structural values of species were used for characterization of forests physiognomic. The results indicate that the pinyon pine forests develop on volcanic substrate, with a neutral or slightly basic pH (from 7 to 8), and they are found from 2300 m to 2700 m a.s.l. The main plant associations identified are: Pinyon-Nolina, Pinyon-Juniperus, and Pinyon-Pinus pseudostrobus; the taxa Pinus cembroides ssp. orizabensis and Nolina parviflora were constant in all the studied localities. The floristic composition of these forests is mainly related to the edaphic factors Ca, and N.