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

The quality tree occupancy concept is presented as a basis for evaluation of plantations. This concept joins the null plot idea with a vitality rating that goes from a dead tree to an excellent tree. Quality frequencies are then fitted to explanatory variables that represent environment, and tree development patterns. A sample of tropical plantations from Los Tuxtlas, Veracruz, Mexico, serves as an example illustrating the concept’s capability to depict quantitatively a plantation condition. The model fitted to the Tuxtlas example demonstrated that it is possible to infer a biological interpretation of current conditions, estimate a prognosis of further development, and suggest prescriptions to correct trends, should the need arose.

The mangroves constitute an important forest resource in all of the intertropical band of the planet. Mankind actions increase the threat and risks over the ecosystems and this has been more catastrophic than the global climate change itself. This induces new uncertainties in the environmental stability and augments the vulnerability of the critical habitats. Considering the challenge that the economic, social and ecological systems face -in order to know and mitigate the global climate change-, evidences of the functional structure of this ecological system are presented, posing the hypothesis the “the mangroves as a critical forest habitat of the coastal zone present accomodation responses to the environmental variability that induces global change playing an structural and functional role in the stability of the coastline, the persistance of habitats and biodiversity, the metabolism of the ecosystem, reducing risks and uncertainty for the sustainable development of the use of its resources”. 

As a complement to a classificaction system created previously for green wood a system was created to classify Mexican woods in clear (defect free) air-dry condition (MC = 12%) taking as input the same data base. The classification criterion is, likewise, specific gravity. The mechanical properties considered were: static bending, compression parallel to grain, compression perpendicular to grain, Janka hardness and shear parallel to grain. This system allows to classify woods in five groups: very high, high, medium, low and very low, through a power law regression.

Histochemical and some quantitative features of sapwood and heartwood cells of Quercus glabrescens, Q. potosina y Q. eduardii are described. The trees were collected in different sites of Huayacocotla, in Veracruz State. The results show that sapwood of the species are very similar in histochemical and quantitative trends but heartwood differ on chemical deposits of gelatinous fibers, and violet deposits of polisacharids present on rays and also the petrification processes in Q. potosina rays. Cell wall quality and the relationship between dimensions and types of chemical compounds are discussed as well.

The creation of a hydrological environmental services market implies to have information about the hydric supply and demand in a watershed. With the purpose to contribute on the last aspect, this study estimated the hydric demand in Tapalpa watershed in Jalisco, Mexico. Additionally, the water use value that was estimated by using the willingness to pay (WTP) technique and also by the opportunity cost analysis on the forest land use for water “production” is presented. The watershed has an area of 21  000 ha and half of it is forested. The demand analysis indicated that the hydric resource (HR) used is about 23 171 885 m3/year. 93 % of this total is used in the agricultural sector, mainly for vegetable production (50%) and basic crops (23%). When compared to other sectors, the calculated willingness to pay (WTP) value for the HR is higher in the service sector (76,7% of the interviewers said to be welldisposed). However, the biggest contribution to the total WTP was given by the domestic sector (46,5 %) with $3 064 301 Mexican pesos/year. Additionally, a direct relationship between study level and WTP for HR was determined. Age showed an inverse relationship with WTP. The estimated total WTP value resulted to be smaller than the estimated opportunity cost to conserve forest in the watershed, giving an annual deficit of $27 201 313 Mexican pesos. The total WTP represents only 10% of the opportunity cost. In addition, if the associate costs for recovering forest areas currently in other use (areas in conflict) were added, the annual deficit would increase to $45 130 988 Mexican pesos and the WTP would be reduced to 6 % of the total opportunity cost.

Satisfying the needs of the population in a rational, permanent and ecologically sensible way is the greatest challenge facing modern societies. Forest resources have played a significant role in the development of civilization and have contributed significantly to national income. This is not the case in Mexico. The central hypothesis of this paper is that the use of wood is not harmful to the environment. Wood is one of the most benign construction materials available. It is a natural, renewable resource that is economically attractive for structural and architectural uses. Non-renewable materials use up a great deal more energy per production unit than wood. Wood as a construction material has many advantages. As an insulating material, it is more energetically efficient. Its structural efficiency, in terms of the energy required to produce it, is greater. Growing forests are huge carbon sinks and no other material performs the ecological service of reducing the greenhouse effect. Another notable benefit is the role of the forest as an element of the biosphere that regulates hydrology and earth biogeochemistry. The secret to reaping all of these benefits is to cultivate forests, to use them for the production of commodities with low energy expenditure and to let them grow so that they produce more oxygen, capture carbon dioxide and maintain forest soils intact. 

The moisture content of wood, and its variation with atmospheric changes, is one of the factors with the greatest influence on wood properties. Therefore, it is necessary to know the degree to which mechanical properties vary as moisture content changes.  Using the results from research conducted by Madsen, and selecting the species most similar to Mexican pines in strength and density, expressions were derived to adjust the results obtained in the national study of the strength of coniferous wood. In this paper, we present the procedure used to obtain the adjustment expressions for bending, tension, compression parallel to grain and shear parallel to grain. Moisture content was adjusted to a uniform value in order to obtain comparable strength values for design.

This work is the result of a multivariate analysis of 87 A mazon wood species, as function of their basic density and their mechanical properties. Five different groups of species were identified. Within each group, the species showed similar properties. These species present new alternatives to replace the tradicional A mazon wood species.

The lack of knowledge about wood machining properties may be one of the reasons that potentially commercial wood is not utilized. For this reason it is necessary to perform wood machining tests. This paper presents the results of planing and sanding tests carried out on thirty-three wood species from different regions of Mexico. In a previous study, three types of tests were carried out: boring, mortising and shaping. The ASTM D-1666-64 (American Society for Testing and Materials) Standard methodology was followed. For planing, three different knife angles were used: 20º, 25º and 30º. For sanding tests, three kinds of sandpapers were used: 60, 80 and 100 grade. Results were grouped according to the surface quality obtained. This information could be useful for those involved in manufacturing wood products since it indicates the surface quality for each of the species tested when subjected to the above mentioned machining processes.

One hundred and thirty two woody, broadleaved Mexican species were studied. The quality index of pulp for paper was determined. Pulp quality was classified according to the Runkel ratio. S ixty-nine percent of all species studied provide excellent (2.3% ), very good (7.6% ), good (34.8% ) and regular (24.2% ) pulp quality. Thirty-one percent produce poor quality pulp. According to these results woody, broadleaved species are a potential source of material for the cellulose and paper industry. The results showed an inverse relationship between basic wood density and pulp quality: the lower the wood density, the better the pulp quality. The use of a mixture of different hardwoods in combination with long-fiber wood species which have desirable characteristics for producing particular types of paper, is recommended.