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

The seasonal variation and the soil texture effect were evaluated in the phenolic contents (FolinCiocalteu) of Quercus sideroxyla ( red oak) leaves as a parameter of the genus deterioration. Leaves of six trees from eight sites were sampled and their edaphic characteristics determined as soil texture: clayed (12,5%), lime-clayed (75%) and clay-sandy (12,5%). Soils and sites were unaltered during the four season collections. It was found in spring a notorious decrease in phenolic content of Quercus leaves followed by a substantial increase during summer. A high positive correlation was found between phenolic content of leaves and electric conductivity of clay-sandy soils, and also between soil moisture retention and phenolic content, independently of the soil texture.

This paper describes a user-friendly computer application developed for forest management planning in El Salto, Durango (Mexico). The computer program BWINPro7 version El Salto allows for forest growth and predicts future stand development. It represents an easy tool that can be used by forest managers and owners of forest lands in the decision-making process. The program incorporates individual tree growth models developed for most pine and oak species during recent years in mixed and uneven-aged forests in the north-eastern region of Mexico. Specifically, the models that were incorporated into the program BWINPro7 are: (1) models to estimate crown width and the height to the live crown base, (2) individual tree basal area and height growth models, and (3) a model to predict individual tree mortality. In addition, the simulator can be used in permanent sample plots to describe stand spatial structure, and to prescribe thinning and timber harvest at industrial scale.

Knowledge of species richness of Quercus in Mexico is incomplete due mainly to its wide distribution, high intra-species morphological variability and its capacity for forming hybrids, making taxonomy of the genus difficult. The objective of the present study was to examine the floristic composition of species of genus Quercus in Los Mármoles National Park (PNM) and their distribution in the study area. This park is the second-largest natural protected area in the state of Hidalgo, Mexico. Specimens of oak were collected at 36 sites along elevation gradients. Identification of the material enabled recognition of 18 species of oak growing in the park, including Quercus furfuracea Liebm., recorded for the first time in the state of Hidalgo. The species with the greatest distribution in the park were Quercus affinis Scheidw., Q. crassifolia Humb. and Bonpl., Q. laeta Liebm. and Q. mexicana Bonpl. Knowledge of oak species richness and distribution can serve as a reference for the establishment of forest management and conservation programs in the PNM.

Wood anatomy of eight species of the series Arborescentes of Ipomoea is described. This group has arboreal or viny habit and white or yellow flowers. The species have a type of cambial variant which consists of concentric rings of xylem, phloem and conjunctive tissue. Taxa have solitary pores or sometimes they are grouped, rounded to elliptical and with medium tangential diameter; vessel elements are short with simple perforated plates, pits are alternate, polygonal. Tyloses are present. Fibre-tracheids have a medium length and diameter, and thin walls. Axial parenchyma is vasicentric although occasionally narrow bands are present. Radial parenchyma is formed by uniseriate to multiseriate rays, heterogeneous. Abundant starch grains and druses are present. Results are consistent with those found in the literature for the group, but there are statistical differences in length and diameter of fibres, height and cell number of uniseriate rays and height and series number of multiseriate rays.

The Mexican buckeye Ungnadia speciosa, is one of the plants used in forestation programs in Mexico due its adaptive features and its shrub or small tree form; however production in the greenhouse is affected by pathogens that cause leaf blight, dwarf and fork stalks, making it impossible to use in plantations. The objective of this work was to determine the causal agent and evaluation of in vitro and in situ of benzalkonium chloride to control it. Plant tissue was collected in field and greenhouse and put in nutrient agar and potato dextrose agar. LOPAT and relevant biochemical test were conducted for identification. For the incidence and severity, the model proposed by French (1982), was used. The poisoned plate flock was used for the in vitro evaluation with 13 treatments and five repetitions, assessing the colony forming units (CFU); seven in situ treatments with three replications were used evaluating damaged leaf area. It was found that for Pseudomonas syringae, according to the Koch’s postulates involved in the symptoms of blight and deformities in the Mexican buckeye, field incidence was 12,9% and 36% in greenhouse; severity was 6,5% and 32%, respectively. Benzalkonium chloride satisfactorily controlled in vitro in dosages, and the best treatment in situ was 3 000 ppm (7 g/L), which showed a leaf damaged area of 17,33% and target treatment 73,09%. 

The climate sensitivity of ten populations of Pinus pinceana Gordon was determined to analyze their potential for climate reconstruction purposes. The P. pinceana populations are distributed along a latitudinal gradient of the Sierra Madre Oriental and for this study are considered as northeast region ( Zacatecas, Coahuila), north-central region (San Luis Potosi), and central region (Hidalgo, Queretaro ).All populations were dated to the year of the annual growth formation except a population called “El Arenalito” in the central region. The youngest trees were found at populations in the central region (MAG, TEP, and CRI); therefore short tree-ring chronologies were developed for these sites. In contrast, for the northeastern region the populations PAL and NOR had the oldest trees and longer chronologies were developed for these sites. Intercorrelation values (0,61 to 0,77), mean sensitivity (0,49 to 0,69), and sign-to noise ratio values (11,72 to 33,64) are considered high for dendrochronological purposes. The statistic parameters derived from the ARSTAN software indicated that P. pinceana is climate sensitive and shows a similar behavior to other conifer species currently used for dendroclimatic studies in northern Mexico. Response function analysis indicated that the populations located in the northeast and north-central regions significantly responded to the seasonal January-June precipitation (winter-spring seasons), but the central populations did not show a clear response. Defining patterns of reduced annual growth are basic to date this species.

This research explored willingness to pay (WTP) and willingness to accept (WTA) payment for conserving water supplies in El Salto, Pueblo Nuevo, Durango. Personal interviews were applied to both El Salto water users to estimate WTP and land resource owners to estimate WTA. Production costs were estimated at the watershed “La Rosilla” near El Salto. The production costs included storage, protection, restoration and water supply to El Salto residents. In addition, production of water was estimated using a mass balance approach. The results showed that the watershed produces on the average 2,10 Mm3/year. About 90% of the water users surveyed in the study were willing to pay for the environmental hydrological service an average of $17,18 for month. Likewise, resource owners were willing to accept about $320,00 for month ($5,26/ha/year) as a compensation to forgo forest harvest and stimulate water production. Differences between WTP and WTA coincide with many other studies that indicate WTA is larger than WTP. Average production cost was estimated at $2,49/m3 of water for the first year and $2,09/m3 for the remaining years over a 10-year planning period. The cumulative WTP, based on the number of households of El Salto, would not be enough to pay for all production costs. Other external programs such as carbon sequestration and government subsidies, etc., are necessary to reduce the gap between estimated WTP and production costs.

In this research paper, information is presented on the dasometric features of standing volume, diameter, top height, tree density, diameter distributions, tree and stand productivity, aboveground biomass, carbon in aboveground biomass and the tree biological diversity of temperate forests of the state of Nuevo Leon, Mexico. This information was derived from 63 inventoried sites within the framework of the forest inventory of 2004-2006. It is concluded that temperate forests are in juvenile state with diameter distributions skewed to the right, with low tree density, low densities of standing volume, biomass and carbon stocks. Tree productivity is also small since it does not surpass on the average 0,36 cm y-1. Tree diversity at the site scale is also small since less than four species are found on the average on these sites. There was statistical evidence that productivity is related to tree diversity and structural diversity in a positive and linear manner. Therefore, there is a great potential to sustainably manage these forests for a wide range of goods and services. It is recommended a light management for goods for 15 years and to carry on the appropriate silvicultural practices to enhance tree diversity as well as structural diversity to increase productivity.

The consumption patterns of domestic firewood was analyzed in 1153  homes of six localities of Yucatan, Mexico, through questionnaires structured applied key informants and field samplings in the extraction sites.  In the studied area a high heterogeneity was found, depending on the floristic composition of the site, as well as the relative distance from the place to the metropolis; both factors modify the consumption habits. The average consumption of firewood in the six studied places is of 2,06 kg/day/person, coming from the neighbor vegetation, as well as from the cultivation field  and the particular orchards. The recollection is made at a mean distance of 3,8 km from the towns. The basic transportation is by tricycles, the direct load in the collector’s back and by truck.  The firewood is collected basically as fallen or standing dry material, due to its low relative weight, transporting easiness and rapid ignition. The extracted firewood is used basically for the domestic consumption in the cooking of foods and water boiling. The interviewed users have preference for 41 woody species as fuel, but the main ones are: Acacia gaumeri, Havardia albicans, Lysiloma latisiliquum, Gymnopodium floribundum, Bursera simaruba, Caesalpinia gaumeri, Conocarpus erectus and Piscidia piscipula, due to their higher abundance, flammability, duration in the fire and low smoke emissions.

Tree-ring chronologies for Pseudotsuga menziesii were constructed for three sites of the Sierra Madre Oriental mountain range of the state of Nuevo Leon, Mexico: El Potosí, La Encantada and La Marta. The correlation coefficients between chronologies, the normality tests on the ring width, and an index of ring width indicate both, the climate regionalization and the decadence on diameter growth of Pseudotsuga menziesii (Mirb.) Franco populations. Potential subtle climatic changes may be contributing to the decline of radial growth of the three plant communities studied.