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

Site quality estimation for forest production is normally accomplished by estimating height growth potential of forest stands, by developing equations that relate height and age of sample trees. However, there are places devoid of trees where investment in productive forests is feasible; better yet if quality potential of regenerating certain forest species can be estimated a priori. We have developed regressive mathematical models to estimate site index in natural stands of Pinus occidentalis, in major productive regions in the Dominican Republic, and established the relationship between index site and edaphic and physiographical variables. Developed models allow the assessment of the productive potential in places without trees. There were no significant differences (α = 0.05) between the site indexes averaged per plot in each locality, but a significant correlation was obtained among site index, height above sea level and aspect (0.273, P = 0.000 and 0.207, P = 0.003) respectively. There were also significant correlations between site index and soil organic matter content within the soil, sodium and potassium . The variables “height above sea level” and azimuth were statistically significant, and can be used to predict the productive potential of places where there are no trees within this region. The estimate of the productive potential by edaphic and physiographical variables for natural stands of P. occidentalis in productive areas constitutes an essential tool in the sustainable management of these forested areas.

The first case of obtaining Morchella in Mexico by inoculation in situ is presented. This mushroom is economically important for its high demand in the domestic and international market, but despite the fact that some patents for commercial production have been generated; their production still depends essentially on field harvesting. An experiment was conducted in the laboratory to evaluate the mycelial growth of two species of Morchella in four types of grains (corn, oats, wheat and rye), to determine which is the most appropriate inoculant agent. The strains used were: M. esculenta (IE-750) and M. conica (IE-815, 817-IE, IE-816 and IE-814), of which the best treatment was IE-817 in rye, which was subsequently injected into the soil of a piece of land located in a cloud forest mountain disturbed (with predominance of species of the genus Inga, Liquidambar, and Sambucus). As a result three fruiting periods were obtained between in 2009 and 2011. This indicates the possibility of obtaining this mushroom through production strategies in situ, which would trigger a new approach to production under a mycosilviculture scheme.

In the Guadalupe Cuautepec community, deforestation, overgrazing and unsustainable agricultural practices, have caused soil erosion and hence the siltation of the lagoon located in the town. In order to generate basic information to create protective strategies to this water body, an ecological zoning was developed from the diagnosis of this community resources’: water, soil and vegetation. From the technical point of view a socioeconomic and biophysical characterization was performed; the latter included geomorphological, hydrologic, geological, soil, vegetation, erosion, potential land use, land use conflicts and ground instability. On the other hand, a participatory rural appraisal was conducted, in which the most relevant problems related to natural resources and the community actions needed for the sustainable management of such resources were identified. Top priority targets were set to achieve sustainable management of natural resources, among which are: soil conservation works, controlled logging activities and reforestation of non-vegetated areas. It was estimated that 77.8% of the Cuautepec territory presents high and very high risk of erosion, with indices above than 50 t/ha/ year. It was determined that the most eroded lands in need of restoration cover 609.34 ha, and that the priority area to reforest is 439.52 ha.

The Presidio San Pedro basin yields the water of one the main streams draining to Marismas Nacionales in the states of Sinaloa and Nayarit. A dominant conifer species on this watershed is Pinus durangensis a heavily logged species such that old-growth forest has disappeared. Increment cores from 63 trees of P. durangensis in a low disturbed site were extracted to analyze its dendrochronological potential. The samples were processed by standard dendrochronological techniques. Series intercorrelation (0.463), mean sensitivity (0.309), first order autocorrelation (0.41), and signal to- noise ratio (5.24) among other parameters indicated excellent potential of the species for dendrochronological purposes. Time series of earlywood, latewood and total ring width were developed with a length of 232 years (1780-2012). The earlywood chronology responded to the accumulated January-August precipitation from four weather stations in the watershed and a linear regression model was used to reconstruct seasonal winter to early summer precipitation. Similar to other previous climatic reconstructions for the Presidio San Pedro basin, ENSO was the most influential phenomena on explaining the interannual and multiannual variability. It was not found a significant relationship between latewood indices and summer precipitation indicating low inter-annual variability of the North American Monsoon System, even though this phenomenon causes over 70% of the annual precipitation on this region.

Oaxaca state is considered one of the most important Mexican hot spots because of the huge richness and diversity it contains, and the increasing conversion of forests and tropical forest that threatens the integrity and stability of these tropical ecosystems. The objectives of this study were to analyze changes in land cover and land use in two municipalities of the coastal region of Oaxaca State for 2000-2011, to understand their causes and to model future scenarios of such transformations to 2025. The study was based in the spatial-temporal mapping of vegetation and land use, derived from satellite images Spot and Landsat ETM+. Once trends of changes in land cover (2000-2011) were established, scenarios to 2025 established by a spatially explicit model. The results indicate that 18 403 ha were deforested in the rain forests in eleven years, 369 ha of temperate forests and 421 ha of mangroves. If this trend continues in 2025, 37 937 ha of rain forests 650 ha and 885 ha of mangrove forests will be lost. Given this scenario it is essential to define strategies for the conservation of ecosystems and to simultaneously improve the living conditions of the inhabitants of this region.

Mexico is a distribution center for the genus Quercus, with 161 species recorded; some 60 of these have favorable characteristics for lumber usage. Herein, we describe the anatomical characteristics of Quercus crassifolia and Q. laurina wood, and these characteristics are correlated with wood basic density, volumetric shrinkage, and hardness. Quercus laurina wood displayed high brightness and medium grain, while in Q. crassifolia these were medium and coarse, respectively. Wood from both species was ring-porous, with solitary oval pores; parenchyma was apotracheal diffuse-in-aggregates, and there were uniseriate, multiseriate and aggregate rays, as well as libriform fibers and fibrotracheids. In Q. laurina, strong correlations were found between the fiber wall thickness and basic density (r = 0,97), and between the lumen diameter and volumetric shrinkage (r > 0,99); while in Q. crassifolia the strongest correlations occurred between the volumetric shrinkage and both the fiber wall thickness (r = 0,97), and the fiber diameter (r = 0,93). In both oaks, a high volumetric shrinkage and the presence of very broad rays, indicate a high propensity of wood to develop cracks and splits upon drying.

The devastation of ecosystems in recent years is increasing the inequality and social conflict, and in particular, the marginalization of indigenous people, who in many cases are the rightful owners of the forestland. In this research we analyse the case of the Purepecha town of Cheran, Michoacan, community that in 2011, staged an armed uprising as protest for the illegal logging of their forests, in the face of the indifference of the authorities. The annual loss of forest cover between 2006 and 2012 was estimated by analyzing high resolution satellite images Spot (10 m), using a criterion based on the NDVI and the spectral signature. Soil / vegetation maps were obtained and validated for each year of the period studied; the comparison of annual maps allowed to generate the map of annual deforestation. In total, 9000 ha were deforested, equivalent to 71% of the vegetation area existing in 2006. Most deforestation occurred between 2010 and 2011 (2815 ha) and corresponds to the forest nearest the urban core area; many clearcuts were also burned. These results measure the problem of deforestation in Cheran and help understand the community’s reaction to the destruction of their forest.

The morphological diversity of the genus Mimosa and its complex taxonomy have led to the search of other sources of characters, such as those provided by the wood anatomy. The aim of this work was to carry out a comparative study of the wood anatomy of three Mimosa species: M. arenosa, M. lacerata y M. polyantha (Section Batocaulon); the first one is widely distributed along the Pacific slopes in Mexico, Nicaragua, Colombia, Venezuela and Brazil; while the other two are endemic to Mexico. One stem fragment of 80 cm was collected at 80 cm over the soil, from three plants per species. Twenty-five measurements of 15 wood anatomical characters per individual were made. The results suggest that the distinguishing characters among the studied species are: type of porosity, type and prevalence of axial parenchyma, and the presence or absence of vasicentric tracheids and prismatic crystals.

Vertical variation of density, flexural strength and stiffness of Persian silk woodThe aim of this research was to investigate the effects of longitudinal position (stem height) and heart-sapwood on density, modulus of elasticity (MOE) and modulus of rupture (MOR) in bending for Persian silk wood (Albizzia julibrissin). Five normal trees were selected from the Guilan region, Iran. Samples for testing were prepared at four stem height levels (5%, 25%, 50% and 75% of total stem height) in both positions along radial direction (heartwood and sapwood). Analysis of variance results (Anova) indicated that the effects of longitudinal position (stem height) and heartwood-sapwood on the wood density, MOE and MOR were significant. The mean of wood density, MOE and MOR along longitudinal position from base to top decreased with height. The mean of wood density, MOR and MOE in sapwood are lower compared to the corresponding values for heartwood. The relationship between wood density and mechanical strength properties were analyzed by regression models. A positive correlation was found between wood density with MOE and MOR in both heartwood and sapwood.

Culture and environment in the Sierra de Misantla, Veracruz, Mexico: the case of Oecopetalum mexicanumWe analyze the cultural and environmental dimensions of foraging the wild edible fruit cachichín (Oecopetalum mexicanum) in the Sierra de Misantla in central Veracruz, Mexico, including gathering practices, social organization, subsistence, commerce, and consumption. Gathering cachichínbrings together generations and genders in practices that provide amusement, as well as resources for economic income and personal consumption. Socialization during the gathering of cachichín renews and strengthens family bonds, friendships, and a sense of belonging. This study provides valuable insights for management, use and conservation of non-timber forest resources with biocultural roots.