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

The objectives of this research were to analyze the sustainable community forestry in northern Mexico, in the states of Chihuahua and Durango, regarding the current status of communitarian organization, flexibility, responsiveness and innovation, competitiveness and collaboration, and marketing forest, at the continued opening of markets. Also, to establish an integral strategy to promote sustainable community forestry in both states, as a joint forest region-forest cluster, in the context of economic globalization. In the study, surveys were applied to ejidos/communities, considering Conafor´s type of the four categories of forest producers, and to external key informants; also, documentary evidences were consulted in accordance with the objectives of the study. The results show that ejidos and communities are not competitive and that they have limited organization; for this reason, the proposed integral strategy includes the horizontal and vertical integration of the productive chain, empowerment, and community participation. The integral strategy aims to foster the competitiveness of sustainable community forestry development in the globalization.

Trees have played an important role in the development of civilizations, both for provisioning of resources and for other environmental services. However, there is a strong decrease in the quantity and diversity of tropical forests trees due to land use changes. One of the main causes of this situation is the livestock activity, which in the state of Veracruz, Mexico, occupies a surface of about 3.7 million hectares (representing 50.6% of its territory). The objective of this study was to research into cattle ranchers’ knowledge of arboreal species, their uses, their cultural importance and the changes that have taken place over time. Sixty eight species of trees were mentioned and their uses were classified in 22 types of uses. The cultural importance index was calculated for each species and the most important changes in the communities’ lifestyle were described. The results showed that ranchers have a wide knowledge about trees but it is rapidly disappearing. Trees are used not only to get benefits for the livestock activity but also to satisfy other needs of daily life. The quantity and diversity of arboreal species reflect the lifestyle, influences and changes over time within the communities. The decisions of ranchers configure the landscape, and therefore the recommendation is to increase the amount of trees, their conservation and uses to maintain the environmental services they provide.

The enormous needs of material goods and services that humanity has can only be met with the use of natural resources. This exploitation exerts a great impact on these resources, implying large impacts on the ecosystems. To preserve part of natural resource areas so that they are not altered significantly, the concept of protected natural areas (PNA) was originated. This paper is an analysis and discussion of the natural protected areas located in coastal areas and more specifically, the wetlands areas. These natural areas are protected by the Ramsar Convention. Mangroves are wetlands highly vulnerable to degradation and protected mangroves often come into conflict with local communities and other resource users. The scheme which has proven to be more appropriate to seek a balance between the parties is the creation and maintenance of protected reserves. On the subject of mangroves and wetlands of Tropical America, Ariel Lugo and collaborators have made important contributions, some of which are highlighted here. His works have served as reference for studies and research which are the scientific support for the creation and/or management of protected wetlands under the Ramsar Convention in countless countries. The conservation work undertaken by Governments and local communities which are based on information provided by the scientists are the best bet of the world to preserve their natural resources and maintain hopes of a better future for the inhabitants of the planet.

A dasometric characterization was made and the site quality was determined in eight mahogany plantations, in permanent plots established in the Tropical region of Mexico. Plantations studied were about 7 to 16 years old, starting densities of plantations from 156 to 1111 tree.ha-1; survival from 40% to 100%, dominant height from 4,39 m to 23,45 m, basal area from 2,3 m²ha-1 to 15,7 m²ha-1, volumen of wood with bark from 14 m²ha-1 to 185 m³ha-1, Reineke index from 176 to 505. With the dasometric characterization basis, it was determined that plantations with increased productivity are located in the area of Chontalpa. To determine the quality of mahogany plantations areas, several models were tested: Bertalanffy, Chagoya, Logistics, Monomolecular, Weibull, Korf and Wescom. The Korf model resulted in a best fit with a probability of (a ≤ 0,05). An equation was determined to evaluate the index site of mahogany, site index values for mahogany in the State of Tabasco were classified as: low (11,5 m), medium (14,5 m) and high (17,5 m) with a base of 10 year sold trees. With the basis of the obtained results, the potential productivity of this species may be considerer for future plantations in the areas with the greatest possibilities.

Altitudinal gradients are associated with climatic gradients that promote species diversity. This study describes the composition, diversity and structure of trees along an altitudinal gradient in subtropical mountain forests (Yungas) in Serranías de Zapla, Jujuy province, Argentina. Three 1-ha plots at 1150 m, 1600 m and 2050 m above sea level were established. Each plot was subdivided into 25 subplots, where all trees ≥10 cm of diameter at breast height (dbh) were measured and identified as for species; number of species, diversity, and density of individuals, basal area, and dominance of individuals per species among elevations were compared. The effect of distance on species turnover was analyzed, and the relations between abundance of individuals per species and frequency of species occurrence was evaluated. We sampled 1375 individuals belonging to 46 species. A significant turnover in species composition along the gradient was found: only three species were present at all elevations, and most species (29) were found at a single altitude. Species richness and diversity decreased with altitude, density of individuals showed no clear pattern, basal area peaked at 1600 m, and dominance was more pronounced at higher altitudes. Low Montane Forest (1150 m) and High Montane Forest (2050 m) were clearly different in terms of species composition. Species similarity was negatively associated with distance within each altitudinal level. Abundance of individuals per species was positively associated with frequency of species occurrence. This study confirms the community organization of tree species in altitudinal ecological levels determined by environmental variables in Yungas forests, and emphasizes the importance of local factors in determining the diversity, composition and structure of these communities.

The most common method to estimate forest variables to a large or small scale is the forest inventory based on field sampling. Currently, remote sensing techniques offer a range of possibilities in forest resources estimation; this is the case of LiDAR (Light Detection And Ranging) that allows the characterization forest structure in three-dimensions. We analyzed the relationship between LiDAR and field data to estimate forest variables such as: basal area (AB), total biomass (BT), crown cover (COB) and timber volume (VOL) through four methods: 1) multiple linear regression, 2) non-linear regression, 3) ratio estimators and 4) traditional forest inventory (stratified sampling). Total estimates derived from the ratio estimator were within the 95% confidence interval calculated by traditional inventory for AB, BT and VOL; this estimator showed the closest values and precision to those obtained by traditional forest inventory. In general, estimates through non-linear models were the most optimistic compared to the traditional forest inventory. Our results indicated a good relationship (R2 > 0.50) between LiDAR metrics and field data, particularly the percentiles of height and rates of return on a defined height. From the linear models fit we generated maps for each of the forest variables analyzed.

Structure and tree diversity was studied in coffee agroforestry systems (SAF-café): rustic (RU), polyculture complex (PC), simple polyculture (PS), and as semi-evergreen forest (SM) from the Sierra de Atoyac, Veracruz, establishing three sampling units (UM) per altitudinal band (600-900 and 900-1200) m on each system and forest above mentioned, for a total 24 UM of 600 m2 (20 m x 30 m) each one. Each system was characterized by the diameter and height distribution of individuals as well as the calculated importance value (IVI), forest value (IVF), diversity (Shannon H ‘, α Fisher) and floristic similarity (Sorensen: Si) indices. To analyze patterns of species distribution of vegetation classification (cluster analysis: β flex) and ordination (canonical correspondence analysis: CCA) techniques were applied. 79 tree species were determined, richness per system was: SM= 65; PC= 61; RU= 32; PS= 18. Cordia alliodora (Ruiz & Pav.) Cham. was the most important structurally species in the SAF-café coffee and Myriocarpa longipes Liebm., and Bursera simaruba (L.) Sarg. in the SM. The diversity was significantly higher in PC (H ‘= 3.56) and SM (H ‘= 3.58) without significant differences (p < 0.05) between them. The highest floristic similarity was between SM and PC (Si = 0.69). Also the altitude was the most influential environmental factor in the floristic composition of the systems.

Diameter growth was estimated and periodicity of the growth rings was determinated for Schizolobium parahyba and Vochysia guatemalensis in a tropical rain forest of Comaltepec, Oaxaca. Diameter growth was measured bimonthly by using dendrometer bands. Six diameter categories, three symmetries categories and three sunlight exposition levels were tested. Moist and relatively dry periods of time were selected during measurements operations, and their influence on tree growth was examined. To determine growth periodicity, the cambium of one tree per diameter category was labeled. Ring width was related with precipitation. S. parahyba grew faster than V. guatemalensis which showed a continuous growth rate. In S. parahyba, the largest diameter categories grew the most (P ≤ 0.05) and no affinity with any radiation condition was found. No differences in growth in diameter categories, symmetries and illuminations crown of V. guatemalensis were found. Both species produced annual rings, completely conspicuous in S. parahyba and slightly delineated in V. guatemalensis. Ring width was highly related with moist periods in S. parahyba (P ≤ 0.01).

A dasometric analysis of three Cordia dodecandra A. DC. plantations under different types of management at Xmatkuil, Yucatan was undertaken. The plantations were nine years old. Height, bole and DBH were measured. Coverage and quality of the trunks of all individuals of each plantation were assessed. Log quality of the trunk was evaluated comparing digital images obtained from the trunk of each tree with the quality rating scale for trunks assigning a number from 1-6 depending upon the straightness of the trunk of each tree. With the data obtained, a multivariate analysis of covariance (MANCOVA) was performed to see if there were significant differences in the variables height, bole and diameter at breast height (DBH) considering coverage as an auxiliary explanatory variable. The nonparametric Kruskall-Wallis analysis was utilized for the statistical analysis of trunk quality. The MANCOVA indicated significant differences in height, bole and DBH in the three plantations. Likewise, the Kruskal-Wallis test with p-value ≤ 0, 05 indicated significant differences. Results demonstrated how management influences the growth of C. dodecandra. These results provide information necessary for the future establishment of agroforestry plantations as well as for taking adequate decisions for the sustainable management of the species.

Predicting the growth and yield of timber tree species is a prerequisite for planning sustainable forest management. The objective was to update several functions that integrate a compatible growth and yield system for Pinus patula, developed under the explicit whole-stand model approach. System parameters were estimated using seemingly unrelated regression. For that, forest biometric information was used from four periodical inventories conducted in 42 permanent plots of 400 m2 in Hidalgo, Mexico. Almost all the functions of the system had good fit and satisfactory graphical behavior in their original structure. A polymorphic growth pattern explains stand productivity, which is interrelated with growth equations of basal area, mean diameter and total stem volume per hectare. The mortality function corresponds to an exponential model fitted under non-linear least squares method. The re-fitted system broadened the range of the growth equations to 31 years. The new system suggests a maximizing volume rotation of about 20 years for the average site. These results suggest that the commonly used 40 year rotation period used in the management plans in the region could be shortened if a proper density management strategy is applied.