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

The relationship between fruit size of Juniperus deppeana and damage caused by seed predator insects, in a forest fragment of Juniperus deppeana ( sabino), typical of the state of Tlaxcala, Mexico was analyzed. Female trees were selected to quantify fruit maturation. Their availability were classified into three categories: small (5 to 9 mm), medium (10-12 mm), and large (13 to 15 mm). At the same time, the amount and density of intact fruits and those presenting insect damage were quantified on five different samplings. Between 21-46 of the individuals presented fruits in 50 to 70% of the tree (by visual estimation). Also, categories of 5 to 30% of galbule abundance in the crowns were presented in 19 to 31 of the female individuals during the five different dates when the per cent quantifications were made. Female individuals produced fruits continuously from august 2004 to august 2005 . Although there was always a wide availability of large, medium, and small fruits, the first ones were the most damaged, since up to 30% of the fruits in that category presented exit holes caused by seedpredator insects.

The Inventory and Monitoring of Natural Resources of Jalisco, Mexico (IMRENAT), is an innovative process suggesting a practical application for geospatial statistical modeling to credibly report the condition of land resources. Taking advantage of interconnections among terrain attributes, vegetation, human activities and multispectral remote sensing information, it is possible to develop statistically valid models depicting land resources spatial attributes and dynamic trends. These types of models enable us to create geoinformation products of greater practical utility than regular cartographic products, or geographic information derived from imagery interpretation. Geospatial products have the capability to describe different scales and resolution levels.

Mexico is considered a secondary center of diversity of the genus Pinus. Published literature indicates that this genus migrated from the north hemisphere through down natural corridors to the actual Mexican territory, forced by past climatic changes. The diversification of the genus happened on main mountain chains and those acted like biogeographical islands or biological corridors, modeling the actual distribution patterns of the Pinus in five mayor regions. Recently, forty six species, three subspecies and twenty two varieties from pines are recognized to Mexico. At least 55% from those species are endemic). Because of that, is the biggest diverse country of pine species from the world, with 42% of them. Mexican pines are one of the most valuable natural resources because of their traditional and commercial relevance and the environmental services that they provide. In spite of the national and regional significance, the continuous decreasing of covering areas from pine and pineoak forests because of the human activities and fire forest is alarming. At least 20 Mexican taxa are in some risk status and two of them: Pinus maximartinezii and P. muricata are classified like endangered species. National and international programs for sustainable use and conservation from Pinus are not efficient and sufficient yet.

Gmelina arborea is planted in large areas of forest with the objective of producing solid wood using well known silvicultural techniques and taking advantage of the properties of the wood quality of fast-growing tree species managed in short rotation systems. The aim of this study was to analyze the morphology and dimension of fibers from the pith to the bark in trees from fast growth plantations in northern Costa Rica.The results indicate that fiber morphology is irregular in both diameter and shape; with 1 to 4 septa, abundant crystals deposited in fiber lumina and minutely bordered pits with oblique and nonvestured apertures. Fiber length, width and cell wall thickness increased with tree age in the early stages. Lumen diameter was not correlated with tree age.

Germination and growth of four plant species were evaluated from 90 to 1960 m above sea level, with the aim to determine whether global warming could influence growth at higher elevations in northeastern Mexico. Three native species (Cordia boissieri, Ebenopsis ebano and Caesalpinia mexicana) and a naturalized species (Melia azederach) were tested. Seeds were set to germinate in containers four times (Spring 2003, 2004, Autumn 2003 and 2004) at five elevations (90, 350, 520, 1600 and 1960  m above sea level). The lowest three elevations encompass the current distribution range of the species, and it was in these elevations that in general germination percentage was higher across species. The highest germination for C. boissieri occurred at 350, 520 and 1600 m above sea level. Highest germination for E. ebano and C. mexicana occurred at 90, 350, 520 and 1600 m above sea level. The highest germination for M. azederach occurred at 90, 350 and 520 m above sea level. In addition, seedling growth and number of leaves produced by seedlings were, in general higher at elevations with highest germination percentages. Results presented here suggest that plant species studied have the capacity to germinate and grow at higher elevations from their current distribution.

The objective was to evaluate seedling performance of Pinus cooperi Blanco planted at two contrasting field conditions: El Carmen, Durango, and Santa Lucía, Pueblo Nuevo, Dgo. The seedlings were produced under the following routines at the nursery: two sizes of container (80 cm3 and 170 cm3), and three irrigation frequencies (every 48, 96 and 168 hours). A split-split plot experimental random block design was established at the two sites. Seedlings survival, height, diameter growth, and phytomass production were evaluated during 18 months. The container of 170 cm3 had a significantly superior effect (p<0,05) on diameter growth and phytomass production, with averages of 9,26 mm and 19 ,0 g, respectively. The 96 hours irrigation frequency had a significantly superior effect (p<0,05) on diameter growth and phytomass production, with 9,17 mm and 17,9 g, respectively. It was not found a statistical significance (p>0,05) of container sizes and irrigation frequencies on seedling survival and height growth. The plantation site factor had a significance statistical (p<0,05) on seedling survival and height growth. The highest survival rate, 85,6 %, was found at El Carmen, Durango, Dgo, and the largest height growth, 18,5 cm, was recorded at Santa Lucía, Pueblo Nuevo, Dgo. 

Willingness to pay (WTP) for environmental services from a cattle ranching region encompasing Veracruz, La Antigua, and Boca del Río, Veracruz State, Mexico, is reported. A survey questionnaire, randomly applied to a stratified sample of 199 individuals, about regional demographic attributes, natural resources, wildlands condition, environmental quality and animal husbandry was administered. Contingent valuation techniques were applied, and supplemented with interviews and anthropologic field work. Results revealed that 83,42% of the sampled individuals have a positive WTP for an improved environment, and 84,42% of respondents will accept increases in taxation as the venue to that end; 85,93% of the public in the sample will rather see that cattle ranchers should be compensated by government for the extra cost of an environmentally conscious management. WTP through increased taxation has statistically significant influences (p<0,05) from household income, severity of regulations, and restrictions to ranching practices. Direct payment resulted acceptable, as well as additional government regulations mandating best ranching practices. Hence, these results led to support that public opinion favors a variety of payment mechanisms. Approval of additional environmental legislation, as well as strict enforcement of existing cattle raising regulations was also noticed.

In the community of “Mariano de Matamoros”, Tlaxco, Tlaxcala, 25 trees of Pinus patula Schl. et Cham., were selected and aboveground biomass and carbon contents were determined to fit the model Y=b*Xk, using diameter at breast height as an independent variable (X). A sample of each component (bole, branches and leaves) was obtained from each tree and both sample and total component fresh weight were determined in the field. The samples were taken to the laboratory to be dried and weighted so that, each tree’s biomass could be estimated, using the dry weight to fresh weight ratios of the samples. To determinate carbon contents for the different components, samples were taken from 25 trees and analyzed in the laboratory to obtain carbon content for leaves of 52,21%, branches 49,47%, bole 49,26% and an average concentration 50,31%. To estimate aboveground biomass the equation B = 0,0357 * DN2.6916 was fitted and to estimate carbon content the equation fitted was CC = 0,021 * DN 2.6451, with a coefficient of determination for both equations of 0,98.

The Great American Chaco, a vast region having an apparent ecological unit, is immersed in a severe degradation process of its natural resources and biodiversity that includes and land use change, deforestation and desertification. It is the objective of this paper to estimate diversity indexes and analyze the ecological situation of seven demonstration units operated under PIARFON, Semiarid Chaco, Argentina Project. It is a continuation of the project PICTO Biodiversity in natural environments of the Argentinian Chaco. A research was done in the following locations: Quebracho Park, Santos Lugares, Buen Lugar, Maravilla, Ahí Veremos in the Alberdi Department; Tala Atun and Quimilioj in Garza, all in the Province of Santiago del Estero and Miramar-Bermejito, General Güemes Department in the Province of Chaco. The closure zone with plots devoted to the study of woody vegetation was established in a selected 5-hectare forest area. Diversity study was performed on 4m x 25m lots included among those of the Forest Inventory (1.000 m2). Species, number of individuals, and stratum they belong to were determined on each plot. In addition a species list was generated including the values of relative abundance, species frequency and richness (Margalef index), Simpson´s dominance indexes and Shannon-Wiener equity indexes were elaborated. Ecological considerations on the basis of the obtained results are made.

The objective of the present research was to estimate the biomass and the carbon content in Pinus cooperi Blanco forests, in Pueblo Nuevo, Durango at La Victoria ejido. Using data originating from 8 sampling plots of 5 000 m2 and 633 sample trees the mathematical process was carried out, finding that the model that presents a better adjustment for the biomass variable was B=22,3476 +(-4,9470) * D + 0,4911 * D2+ 0,0039 * (D2H), with a determination coefficient (R2) of 0,99 and a percentage standard error Sx% 11,69. The model for the carbon content variable was Cc=11,5090 + (-3,1229)* D + 0,3100 * D2 + 0,0004 * (D2H), which produced a R2 = 0,99 and a Sx =  2,46 respectively. Once the best model was determined the estimation tables for biomass and carbon content were ellaborated for the different diametric and height categories.