ISSN e:2007-4018 / ISSN print: 2007-3828

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# Vol. XVII, issue 2 May - August 2011

### EFFECT OF SEED SIZE AND TEMPERATURE ON GERMINATION IN Quercus rugosa Née

Rubén Huerta-Paniagua; Dante Arturo Rodríguez-Trejo
Keywords: Seed analysis, oaks, germinative energy.
Accepted: 0000-00-00
Pages: 179-187

The effect of temperature and seed size on germination in Quercus rugosa Née was analyzed. Germination capacity and germinative energy were studied in three seed sizes: large (3.09 cm long by 1.55 cm wide, on average), medium (2.45 cm long by 1.29 cm wide) and small (2.15 cm long by 1.18 cm wide). Two day/ night temperature regimes in a controlled environment chamber were used: 24/19 °C and 19/14 °C, both with a 12 h photoperiod. A randomized complete block experimental design was used with six replications. The blocks were nested within the temperature factor. Germination capacity and germinative energy were analyzed with an analysis of variance using a mixed model. Seed size significantly influenced (P=0.0009) germination, with the large seeds having the highest germination. For germinative energy, the interaction between the two factors under study was significant (P=0.0045). The highest germinative energy was found in the medium-sized seeds at high temperature.

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### SPATIAL STRUCTURE OF Pachycereus weberi (Coult.) Backeb. IN CAÑADA DEL ZOPILOTE, GUERRERO

Blanca Estela Linzaga-Román; Gregorio Ángeles-Pérez; Cesario Catalán-Everástico; Patricia Hernández-de la Rosa
Keywords: Pachycereus weberi, Ripley’s index, Index of Relative Importance Value, spatial distribution pattern, spatial correlation pattern
Accepted: 0000-00-00
Pages: 189-198

The aim of this study was to determine the population structure of Pachycereus weberi in Cañada del Zopilote (Buzzard Canyon), Guerrero, Mexico. An observation plot of 50 x 50 m (2,500 m²) was established and divided into quadrats of 10 x 10 m to facilitate the field survey. All P. weberi individuals with height ≥ 0.10 m were tagged, and their total height, diameter at breast height (dbh), and location by X and Y coordinates were recorded. In addition, all individuals of associated woody species with dbh ≥ 5 cm were tagged, identified and their diameter and coordinates within the plot recorded. We calculated the spatial distribution and correlation patterns of the P. weberi population divided into two developmental stages, juveniles and adults, using Ripley’s index. A total of 18 species associated with P. weberi were recorded. P. weberi attained the highest Index of Relative Importance Value with 41.1 %, followed by Acacia tenciifolia with 22.6 %. P. weberi individuals with total height greater than 8.5 m and diameters from 5 to 43.8 cm were recorded. The spatial distribution pattern was clumped for individuals in both juvenile and adult development stages. The spatial correlation showed a repulsion pattern at distances of 2 to 13 m between juvenile and adult P. weberi. The diameter distribution suggests an episodic recruitment behavior, with low recruitment rates in intermediate diameter classes between juveniles and adults.

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### LUMBER YIELD AND PRODUCTION TIME IN THE EL SALTO REGION OF DURANGO, MÉXICO

Juan A. Nájera-Luna; Oscar A. Aguirre-Calderón; Eduardo J. Treviño-Garza; Javier Jiménez-Pérez; Enrique Jurado-Ybarra; José Javier Corral-Rivas; Benedicto Vargas-Larreta
Keywords: Ergonomics, lumber, logs, sawmills.
Accepted: 0000-00-00
Pages: 199-213

To determine log characteristics that affect lumber yield and production time, a study was conducted of productivity indicators at five sawmills in the El Salto region of Durango, Mexico. Logs of five diameter classes, three lengths and six taper classes were analyzed. To estimate log-sawing times, the “back to zero” methodology was used; for determining lumber yield, volume in cubic meters inside and outside of bark of 412 pine logs was calculated and compared with the resulting volume in lumber products. Total inside- and outside-bark volumes were 293.73 and 323.93 m3 of roundwood, respectively, which yielded 7,085 board feet and 169.01 m3 of sawed wood, which represents a 57.5 % and 52.17 % conversion of inside-bark and outside-bark volumes, respectively, to sawn boards. The average time for sawing 1,000 board feet was estimated at 25.09 minutes for a production of 7.57 m3∙h-1, with an average carriage feed rate of 46.47 m∙min-1. Our findings indicate that lumber recovery is affected by log diameter, length and taper.

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### ARBOREAL ARCHITECTURE AND DEVELOPMENT OF Guaiacum sanctum L. IN BALAM-KIN, CAMPECHE, MEXICO

Gustavo Enrique Mendoza-Arroyo; Angélica Navarro-Martínez; Susana Ochoa-Gaona; Hans van der Wal
Keywords: Eco-units, guayacan, logging, regeneration, tropical dry forest.
Accepted: 0000-00-00
Pages: 215-224,

Guaiacum sanctum (guayacan) is a characteristic species of dry tropical forests. Owing to the properties of its wood, it has been harvested from its natural habitat for more than 100 years. At present, it is considered to be at risk of extinction and is protected by its listing in Appendix II of CITES. In spite of its economic importance, existing information about this species is limited. In Balam-kin, within the Calakmul region of Campeche, G. sanctum is protected where it occurs at high abundances in patches known as guayacan forests. In order to broaden our knowledge of the ecology and dynamics of the forests where this species occurs, an architectural analysis of the vegetation was conducted in low height semi-deciduous tropical forests of Balam-kin. We established 40 systematically located plots, and where G. sanctum occurred vegetation was sampled along transects within these plots, one per plot. The majority of the area was occupied by eco-units in phases of aggradation and biostasis. Typical species found in the biostasis eco-units included G. sanctum and Thouinia paucidentata, while the aggradation phase was dominated by Gymnopodium floribundum. G. sanctum was found in all architectural phases. Our understanding of forest development allowed us to elaborate a hypothetical model of post-harvesting forest dynamics. Information about the mosaic of eco-units within a forest offers a useful tool that should be incorporated in decision-making related to harvesting and forest management.

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### EXTREME TEMPERATURES IN THE CITY OF MONTERREY N. L. MÉXICO

José G. Ríos-Alejandro
Keywords: Extreme values, Gumbel distribution, return level.
Accepted: 0000-00-00
Pages: 225-230

Considered as a random variable, the lowest temperature of the year in the city of Monterrey, N.L, Mexico is modeled with the Gumbel distribution. Its parameters and some return levels are estimated. Let x be the minimum temperature of the year. In extreme value theory, risk is assessed with p xwhere the prob¬ability that (in a period) x is less than p xis equal to p , so that p / 1is the average number of periods (years) that elapse until the annual minimum temperature is less than p x. In addition, p xis estimated for some values of p , information which is considered important for decision makers. Linear regression, maximum likelihood and Bayesian methodologies are applied.

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### ECONOMIC VALUATION OF THE BENEFITS OF A RECOVERY AND CONSERVATION PROGRAM IN MOLINO DE FLORES NATIONAL PARK, MÉXICO

Juan Walter Tudela-Mamani; Miguel Ángel Martínez-Damián; Ramón Valdivia-Alcalá; José Luis Romo-Lozano; Marcos Portillo-Vázquez; Rafael Ventura Rangel-González
Keywords: Contingent valuation, binomial logit, willingness to pay.
Accepted: 0000-00-00
Pages: 231-244

An economic estimation was made of the social benefits generated by the implementation of a recovery and conservation program which has impact on the attributes of the Molino de Flores National Park (MFNP). Using the contingent valuation method, it is concluded that the MFNP has a conservation value of US$384,000 per year, and a value in perpetuity of US$ 4’ 266, 667. Also estimated was the potential entrance fee to the park at Mex\$24; value a person attaches to the benefit. The rate was estimated using a binomial logit model and the variables hypothetical price to pay, income level, educational level and environmental perception.

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### ANAMORPHIC SITE INDEX CURVES FOR Pinus caribaea Morelet var. caribaea Barret and Golfari plantations belonging to the MACURIJE INTEGRAL FOREST COMPANY IN THE PROVINCE OF PINAR DEL RIO, CUBA

Héctor Barrero-Medel; Frédéric Mothe; Gérard Nepveu; Daniel A. Álvarez-Lazo; Ilya García-Corona; Mariel Guera
Keywords: Site quality, increment, age, functions
Accepted: 0000-00-00
Pages: 245-252

In this work we selected the best model for obtaining anamorphic site index curves for Pinus caribaea Morelet var. caribaea Barret and Golfari stands belonging to the Macurije Integral Forest Company, located in the municipalities of Guane and Mantua in the province of Pinar del Rio, Cuba. We used data recorded from 14 permanent plots established in the year 2006 with four consecutive measurements taken throughout the different Basic Forest Production Units, 256 temporary lots randomly distributed throughout the enterprise area and the forest inventory carried out by the company in 2002-2003. The anamorphic-based site index curve system was constructed using the nested regression method applied by Bailey and Clutter (1976) and described by Alder (1980) as a method of hierarchical regression with a common slope estimator. The model fitted dominant height (Ho)-age data, and six site indices were derived for 13, 16, 19, 22, 25 and 28 m at 35 years old. In addition, the equation for determining the site index was obtained.

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### CHLOROPHYLL PRODUCTION IN Pinus pseudostrobus JUVENILES UNDER DIFFERENT DEVELOPMENT ENVIRONMENTS

Víctor Hugo Cambrón-Sandoval; María Luisa España-Boquera; Nahum M. Sánchez-Vargas; Cuauhtémoc Sáenz-Romero; J. Jesús Vargas-Hernández; Yvonne Herrerías-Diego
Keywords: Half-sib families; total chlorophyll, a chlorophyll, b chlorophyll, a/b chlorophyll, competition environment.
Accepted: 2011-01-24
Pages: 253-260

Limiting the amount of sun radiation reduces photosynthetic activity, causing stress and morphological and/or physiological changes in plant development. This study analyzed the stress effect caused by two levels of competition in Pinus pseudostrobus Lindl half-sib families: high inter-family (environment II) and high intra-family (environment III) competition, compared with a low level of competition (environment I). Total chlorophyll, chlorophyll-a, and chlorophyll-b content, plus the chlorophyll a/b ratio, were quantified as an indicator of stress level in 10-month-old plants using the Barnes method. Plants were established in a common garden test under a split-plot design with four replications and three individuals per plot. Total chlorophyll was significantly higher (P0.05) were observed be¬tween the other competition environments. A separate analysis of chlorophylls showed lower chlorophyll-a content in plants surrounded by genetically-similar plants (environment III) as opposed to genetically-different ones (environment II); conversely, chlorophyll-b content was higher in genetically-similar plants (environment III). In conclusion, intra-genotypic competition was generally stronger than inter-genotypic competition, under high levels of stress.

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### ALLOMETRIC EQUATIONS FOR ESTIMATING THE ABOVE-GROUND BIOMASS AND CARBON IN Quercus magnoliaefolia Née

Jesús David Gómez-Díaz; Jorge D. Etchevers-Barra; Alejandro Ismael Monterroso-Rivas; Julio Campo-Alvez; Juan A. Tinoco-Rueda
Keywords: Allometric equations, Quercus magnoliaefolia, above-ground biomass, wood specific density.
Accepted: 2011-04-07
Pages: 261-272

At the El Zapote ejido in the “Sierra de Huautla” Biosphere Reserve in the state of Morelos, Mexico, twelve Quercus magnoliaefolia Née trees were selected and their above-ground biomass determined. The proposed allometric model was expressed as: B = 0.0345 * DBH2.9334, where B is biomass (kg) and DBH is diameter at breast height (cm), with a coefficient of determination (R2= 0.98; P

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### IN VITRO MORPHOGENESIS IN Pseudotsuga menziesii VAR. glauca

Keywords: Embryo, callus, plantlets, growth regulators.
Accepted: 2011-04-11
Pages: 273-282

This study assessed the morphogenic response of in vitro cultured zygotic embryos obtained from Pseu¬dotsuga menziesii var. glauca seed collected in Tlaxcala, Mexico and stored for one year. Seeds were disinfected with detergent and H2O2 (3 % v/v) for 48 h under stirring at 50 rpm and cultured on Murashige and Skoog (1962) medium without regulators. Germination occurred after seven days and then the explants were subcultured on MS medium with 2,4-D (3 mg.L-1) and BA (1 mg.L-1). With the calluses obtained on HS medium, three ABA concentrations intended to promote formation of embryonic structures were evaluated. The best treatment was with a concentration of 10.0 mg.L-1 (P

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### CARBON CONCENTRATION IN THE ABOVE-GROUND BIOMASS IN THE TAMAULIPAN THORNSCRUB

Keywords: Global warming, carbon storage, Cordia boissieri, Acacia farnesiana, Forestiera angustifolia
Accepted: 2011-04-09
Pages: 283-291

The carbon concentration per unit of biomass (dry weight basis) was determined for 10 species in the Tamaulipan thornscrub and for each of their components (bole, branches, twigs, leaves and bark). Carbon concentration expressed as a percentage of biomass was obtained using a Solids TOC Analyzer, which determines the carbon concentration in solid samples by complete combustion. By ANOVA, no differences were found among the species in average carbon concentration (P>0.05). This concentration ranged from 44.25 to 47.08 % with an overall average of 45.4±1.32 %. Cordia boissieri (44.25±1.52 %) and Acacia farnesiana (44.52±1.37 %) are the species that had the lowest carbon concentration values, while Forestiera angustifolia (47.08±1.27 %) had the highest. The bark component of Cordia boissieri obtained the lowest carbon concentration percentage (39.62±0.70 %), while the leaves of Acacia schaffneri had the highest (50.14±1.21 %). The interaction of both factors was significant (P

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### A DYNAMIC PENETROMETER FOR MEASURING MECHANICAL RESISTANCE IN FOREST SOILS

Irma Vásquez-García; Armando Gómez-Guerrero; Alejandro Velázquez-Martínez; Arnulfo Aldrete; Aurelio M. Fierros-González
Keywords: Mechanical resistance, dynamic penetrometer, soil physics, bulk density, forest soils.