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

The candelilla (Euphorbia antisyphilitica) grows in arid regions of Mexico, having social and economic importance, although its availability is not clearly defined. The objective of the study was to estimate their potential distribution and abundance in the north of Zacatecas state. A potential distribution modeling was performed through MaxEnt® using 18 data of presence, 8 historical and 10 current, and 27 predictive variables. The presence was corroborated in the field by means of 29 random points within the area of potential distribution, and 19 others outside it. The population density was estimated with plots, measuring the size of the individuals, and considering the following variables: vegetation and soil type, altitude, and slope. A Kruskal-Wallis test was used. The model generated an accurate prediction (AUC = 0.920), in which 11 variables contributed with 82.1% to the potential distribution, the most important being: vegetation type, exposure, slope, altitude, and vegetation cover. The potential distribution area was 19.2% of the total study area, with a population density of 295 767.3 individuals per square kilometer. This was significantly influenced by the vegetation type and altitude, while the slope affected the plant height. There were positive presence results in 37.9% of the validation sites with potential distribution in the study area, plus 10.5% outside of the potential distribution area. It is concluded that by using the MaxEnt® algorithm the potential distribution of wild plants, such as candelilla, can be modeled; the potential distribution was discontinuous and less than 20%.

The arboreal communities of a silvopastoral agroecosystem play an important role in the arid and semiarid ecosystems of the country, by conserving the biodiversity and the development of the livestock activities that are of vital importance in the North of Mexico. With the objective of characterizing an arboreal community of a silvopastoral agroforestry system in a transition zone of tamaulipan thornscrub and mezquital in Nuevo Leon, five sampling sites of 2500 m2 were established; we made an inventory of all tree species with diameter at the height of 1.30 m (DBH) > 7.5 cm. The vertical and horizontal structure and composition were evaluated through vegetation analysis (relative abundance, relative frequency, relative dominance), importance value index, forest value index and models for the variables normal diameter – canopy cover. The main species from an ecological standpoint were Prosopis laevigata (Hump. & Bonlp., Ex.Will.) M. C. Johnst. and Ebenopsis ebano (Berland.) Barneby & J. W. Grimes, the community presented high density of individuals, high canopy cover and a vertical structure with a high proportion of individuals ≥6 m in height. The linear model showed the best adjustments by presenting an R2 = 0.621. Silvopastoral management has conserved and promoted the structural attributes of the native plant community.

Biomass measurements allows knowledge about processes like matter and energy movement, carbon sequestration and storage, among others. Therefore, the objective was to analyze the distribution of structural components of Pinus patula biomass in the green twig stage, as well as the compartments in clearcutting stripe sites at Ixtlán de Juárez, Oaxaca. In 2014, nine sites of 400 m2 each were located using selective sampling and tree inventory was applied. Destructive sampling of 90 trees in the green twig stage was used in order to obtain samples of each structural component, which were subsequently analyzed by regression, to estimate the biomass content per tree and unit of area. The biomass of other compartments (necromass, mulch, bushes and litter fall) of the site was quantified. Variance analysis and mean tests (Tukey, 0.05) were applied for the biomass compartments according to the tree density. The regression models showed adjustments between 0.79% and 97% by structural component and total tree, using inventory variables (diameter at breast height and total height). The high recommended density (> 1500 trees ha-1) presented the largest biomass stores in stem (8048.3 kg ha-1), branches (141.3 kg ha-1), leaves (146.2 kg ha-1) and roots (1350.0 kg ha-1). The clearcutting silvicultural treatment at seven years of its application favors the natural regeneration of the forest with 11.91 t ha-1 of biomass distributed in different compartments.

In order to obtain strains of the edible mushroom Pleurotus ostreatus that can be cultivated in pine wood shavings, 36 monosporic cultures were isolated and propagated in vitro, selecting 6 cultures of rapid mycelial growth in order to obtain interspecimen crosses and dikaryon-monokaryon mating. Eleven of the crosses obtained and their 6 parental strains were cultured in vitro in order to determine their growth in pine shavings and barley straw (control), selecting 6 strains (3 crosses, 3 parental strains) for sporome production in the two growth substrates. At in vitro level, significant differences were found between the mycelial areas of monokaryons and dikaryons in the treatments (time, substrate) evaluated. In terms of sporome productivity, the cultures in barley straw presented higher biological efficiency (22.6%-46.4%) and production rate (0.31%-0.77%) values than those in the pine shavings (3.3%-12% and 0.03%-0.11%, respectively). Sporome pileus diameters of 5 cm to 9.9 cm were the most frequent in both substrates. In general, the crosses surpassed their parents in both mycelial growth and sporome production, although further study is required in order to facilitate increased productivity of the strains in this potentially useful agroforestry residue.

A productive and economic analysis was conducted on a sample of 184 logs of lenga (Nothofagus pumilio) from Monte Alto Land, XII Region, Chile. Logs were allocated to produce select (S), regular (C1, C2 and C3), and short lumber qualities. The productive efficiency analysis was done by production stochastic frontiers Cobb-Douglas and Translog. This approach is based on production functions and generates technical efficiency measures (EFt) to assess production systems. Logs attributes used as inputs were small end diameter, length and process productivity. The average EFt values of logs were 0,85 and 0,78 calculated by Cobb-Douglas and Translog frontiers, respectively. These measures imply that, on average, the logs could use reduced attributes by 15% or 22% and still achieve the same output. The most efficient logs (EFt ≥ 0,9) were characterized by obtaining an average small end diameter of 33 cm, and an average recovery value of USD 33 m-3 and 29 m-3, for Cobb-Douglas and Translog frontiers, respectively. There were significant positive correlations between efficiency and the logs recovery values (r = 0,53; p ≤ 0,05).

The Totonac culture is characterized by having a richness of knowledge about the use and management of natural resources; nevertheless, due to several factors, there has been a decrease in the conservation and transmission of such knowledge. Hence, the main objective of this work was to describe the different ecosystem services of the flora of a Totonac population, in order to contribute to the preservation of traditional knowledge. The municipality of Filomeno Mata, Veracruz, Mexico was chosen as the case study. This municipality is characteristic of the mountain region of totonacapan. To meet the objective, semi-structured interviews were applied to the target population in 2016. There were talks with key informants and a field trip through a directed transect that served for the observation and collection of the species. It was found that the ecosystem services most recognized by the population are grouped into four categories; in order of importance, the most named were placed in the category of supply, information, habitat and regulation, respectively. It was concluded that there is a need to conduct multidisciplinary studies in indigenous communities for the rescue and preservation of valuable knowledge about the use of natural capital, as well as the understanding of the indissoluble association between culture and ecosystems. Local actions to protect and restore ecosystems, benefit both direct and indirect users at the national or international scale.

Trees are the largest and heaviest living beings that have ever lived on Earth. In order to achieve this, trees have wood, an exceptional structural material, and they offer several design strategies. This work is a review of the state of the art related to the strategies of growth, anatomy and morphology that use trees, highlighting general concepts related to structural aspects related to plant biomechanics. Moreover, this paper emphasizes the features of natural plant materials, which have a hierarchical organization, and in most cases are fiber-reinforced composite materials, materials with cellular structure, or both, such as wood.

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