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

Brushwood species have been spurned traditionally, their use being limited to the production of fences, firewood and charcoal. This paper presents research results on the microscopical anatomy and physical-mechanical properties of four brushwood species typically found in Northeastern Mexico, with the purpose of expanding the possibility of their commercial use. The species are barreta (Helietta parvifolia (Gray ex Hemsl.) Benth), canelon (Melia azedarach L.), ebony (Ebenopsis ebano ( Berl. ) Barneby & Grimes), and tenaza (Havardia pallens ( Benth.) Britt. & Rose). The physical-mechanical properties determined are density, percentage of shrinkage and swelling, modulus of elasticity, and flexural strength. Test results for baretta prove that its wood is heavy, hard, easy to dry, and flexible with little shrinkage during the drying process. Canelon (also known as chinaberry or umbrella tree) is characterized by having a higher density compared to other species. This wood has wide annual growth rings, being easy to dry and work with, and resistant to insect attack. Ebony exhibits a heavy wood that it is only possible to work while green or through special machinery when dry. Ebony's heartwood has a low susceptibility to insect infestations. Shrinkage is similar to that of pine wood (sometimes slightly lower), it is easy to dry, very flexible when wet, however not very resistant to insect infestations.

Mangroves constitutes an irreplaceable ecosystem, from which human communities extract diverse resources to survive. It is fundamental to inform the public about the importance of this ecosystem as a refuge of many species of the flora and fauna as well as its rational use. The environmental education is necessary to help in the awareness on the problematic that mangrove forests face at the present time. The activities of environmental education constitute part of the project Restauracion de areas de manglar impactadas por obras de dragado en el sistema lagunar de Chantuto initiated in April of 2003 by El Colegio de la Frontera Sur with funding from the Comision Nacional de Acuacultura y Pesca (CONAPESCA), at the Juan Escutia and Francisco Villa Elementary Schools in the Community of Santa Isabel, within the Reserva de la Biosfera La Encrucijada. The objective is that by using conferences, exhibition of videos, games and other activities, to create conscience in the children of elementary school level about the ecological and economic importance of the care and preservation of the resources of mangroves in benefit of the communities. The main subjects are: Mangrove and its resources, main impacts of the activities on the coastal zone, importance of the conservation, handling and restoration of the forests of mangrove, the coastal lagoons and estuaries, problematic of works of dredging on these systems, handling of the water, the soil, garbage and human well being, etc. Additionally by means of shops for the protection of mangrove it has been possible to involve senior citizens in this project, through activities that show the problematic and actions for a rational usage of mangrove and its resources.

The importance of estimating biomass volumes for the management of wood and non wood forest products has been recently recognized by the government of Mexico. This is partially recognized by the implementation of government programs for the payment of environmental services, by the Mexican Forestry Commission. This research was carried out at the Municipalities of Tezonapa and Uxpanapa, Veracruz, Mexico with the objective of estimating statistical coefficients with the least variance by comparing different additive techniques of biomass component estimation (stem, branch, and total) for the latex clon IAN-710 coming from commercial forest plantations for latex production. Field data collected were fresh and dry weight values. Coefficients of two biomass equations were evaluated: 1) the combined variable of Spurr (1952) and 2) the best regression model. Four ways of estimating parameters were tested: 1) conventional linear regression, 2) weighted linear regression, 3) seemingly unrelated linear regression, and 4) weighted seemingly unrelated linear regression. When comparing the t values of the coefficients, it was found that the least variance coefficients were estimated in weighted seemingly unrelated linear regression and the coefficients did not show significant change. Therefore, this equation is recommended for estimating coefficients of equations for biomass components and total for the latex clon IAN-710.

Statistical analysis between three weighted additive biomass equations are presented for planted pine species typical of the coniferous forests of the Western Sierra Madre mountain range of Durango, Mexico. Statistical and graphical analyses were used to select the best single and multiple individual biomass component equation. Linear equations better fitted the biomass components. Therefore, three linear additive procedures were tested: (i) the conventional, (ii) a harmonization, and ( iii) the seemingly-unrelated regression in two types of equations of component biomass estimation using both simple regression and multiple regression techniques. These tests were performed at two scales: (a) each of three pine species and (b) all three species. For both the simple linear and best multiple regression equation, the seemingly-unrelated equations provided more precise biomass component estimates, with tendencies consistent with the conventional non-additive non-linear regression procedures, and provided average biomass component estimates when equations were applied to a data set of 23 sample quadrants.

Extractive reserves represent a recently developed strategy to protect forest areas continuosly subject  to extraction of non-wood forest products. This kind of protected area was originally developed in Brazil because of  the rubber tappers needs to diminish the continuous and fast loss of large forest areas of the Amazonas, while extracting Para rubber (Hevea brasiliensis [ Willd. Ex Adr. Juss.] M. Arg. ) Brazil nuts (Bertholletia excelsa Humb. & Bonpl.) and other forest products. Extractive reserves strategy was incorporated in the Brazilian law in 1990, and currently they are avoiding the reduction of the deforestation rates. In Mexico this concept was applied in 1910 at the Maya area of Quintana Roo state. Because chicle market decreased, this kind of reserve area moderated the communitary extraction activities of other forest products and avoided drastic land use change of important tropical forest areas. In this paper we discuss the relevance of extractive reserves strategy in terms of its functionality to reduce the effects of deforestation in tropical rain forest areas.  We conclude that this kind of protected area has limitations and should be considered as an alternative only to extract non-wood forest products in low quantities while containing the tropical rain forest areas deforestation.

The management of water resources is one of the most important environmental challenges facing mankind this century. In Mexico, the crises caused by mismanagement of water resources is severe and has been accentuated by high rates of deforestation and the subsequent loss of the hydrological services provided by forests. This essay presents a brief overview of the important hydrological services provided by forests in Mexico including water capture, regulation of flood and drought cycles, as well as soil conservation and the regulation of sedimentation rates and regional climate. The creation of markets for these ecosystem services is proposed as a promising mechanism for increasing forest cover and promoting the sustainable use of natural resources in Mexico. In particular, markets aimed at conserving drinking water and water flow for hydroelectric power, as well as the prevention of natural disasters are discussed and, recommendations provided for decision makers interested in this topic. While Mexico’s hydrological problems are serious and cause for concern, they have also sparked renewed interest in the conservation of forests and their ecosystem services as a way of assuring the well being of future generations of Mexicans.

Forests are complex open systems with multiple functions. To maintain high standards and credibility among the public, forest managers need to draw on the expertise of a variety of scientific disciplines, including the humanities, the physical, the engineering and biological sciences, not necessarily in that order. It is often postulated that forest management should be sustainable, based on validated research results, conform to acceptable environmental standards and be transparent to the public. These objectives can be met a) if various silvicultural options are compared using validated research results, b)  if management practices are understandably demonstrated in the field, and c) if management activities are effectively monitored, considering a variety of ecological conditions. Based on these premises, a practical framework for the management of a forested landscape includes three elements: Forest Options Design, Research and Demonstration and Harvest Event Analysis. The objective of the paper is to present a framework for science-based management of a forested landscape, which includes these three elements.

Records of four vegetation types represented by 10 vegetation communities are presented for the Municipio of Guanaceví, Durango. For mixed-conifer forests five asso- ciations were determined, ten for pine-oak forest (Pinus-Quercus), nine for oak-pine forest (Quercus-Pinus), five for oak woodlands (Quercus) and four for manzanita-oak schrub (Arctostaphylos-Quercus). Brief descriptions for those vegetation communities not sampled such as grasslands, riparian vegetation, aquatic and semi-aquatic vegetation, and vegetation characteristic of disturbance and crop lands are also presented.

A review of biophysical information about Brosimum alicastrum Sw. in the Pacific coast of Mexico was carried out with the purpose of identifing and characterizing zones according to ecological attributes, as well as to relate some environmental variables with density and basal area of this tree species. Twenty two ecological zones were identified in five vegetation types and it was in the semi-evergreen tropical forest where Brosimum alicastrum showed its larger abundance and development. Rainfall, altitude, and water holding capacity of the soil, were the variables that explained better the ecological variation of the species in the area of distribution.

Forest certification is an economic instrument based on the market which has as objective to promote the sustainable forest management by means of the access to the market as well as an increase in the price of the wood what will allow to cover the costs of the good forest management. In this work it is analyzed the impact and the effectiveness that forest certification has had on the social, economic and environmental dimensions on which is based and its contribution to the sustainable forest management, analyzing  its costs and behavior of the market of certified wood. It was concluded that the certification costs are high for small producers and companies in developing countries. The market of certified wood is marginal, demand and offer are limited, the increase in the price is uncertain and far from clear, it does not contribute to the socioeconomic development of communities located in forests degraded with tree species of low commercial value with poverty, degradation and deforestation being still present in those areas. Forest certification considers the wood as the only product obtained from the forest with market value, non-wood forest products along with environmental goods and services are not considered as commercially valuables due to the lack of standards applicable to these, underestimating the actual value of the forests. These limitations carry the risk discouraging the forest management and inducing the illegal logging, and changing the use of forest land. Forest certification contributes partially to the sustainable forest management and it is, only considered as an alternative tool, which is still being developed.