Colombia Forestal

9

Authors: Leonides Castellanos González, Tarsicio Santana Díaz

The present article aims to evaluate the biostimulating effect of Trichoderma harzianum Rifai in the seedling production of Leucaena leucocephala (Lam.) (leucaena), Cedrela odorata L., and Pithecellobium saman (Jacq.) Merr. An experiment for each specie was carried out under nursery conditions. A totally randomized design was used with four parcels by treatment. The treatments were: Trichoderma harzianum to reason of 20 g.L-1 and to 40 g.L-1, and a control. The germination percentage was evaluated, and the morphometric variables diameter of the shaft, height and dry matter of the root and the air part of the plant. The treatments with Trichoderma didn't increase the germination percentage in cedar, saman and leucaena. T. harzianum increased the height, the number of leaves and the dry biomass of the foliar area in the cedar seedlings, while in leucaena and saman only it incremented the basal diameter of the seedlings.

10

Authors: Georgina Vargas Simon, Reinaldo Pire, Martha Olivia Lazaro Dzul

Dialium guianense is used for its wood and fruit production, and is a tropical tree species native to evergreen forests. Given the threat these forests face, the purpose of this work was to evaluate the initial growth of the plant under greenhouse conditions, for aiming in the development of propagation programs. Seedlings of the species were transplanted to nursery bags under a completely randomized design and grown for 10 months with an initial population of 200 plants. At the end of the experiment, the shoot and root reached lengths of 32.8 and 28.9 cm, respectively. The average number of composite leaves was 12.3 each with seven leaflets. The average biomass was 2.5 g for the shoot, 1.6 g for roots, and 3.7 g for leaves, with a shoot/root around four. The average relative growth rate (RGR) was 15 mg g-1 day-. These characteristics indicate that D. guianense is a late successional species.

11

Authors: Mateo Gutierrez Gonzalez, Jessika Isabel Bonilla Santos, Maria Fernanda Cruz Amado, Juan Guillermo Quintero Aranzalez

Guadua angustifolia Kunth is a bamboo species, which has been widely used in construction. G. angustifolia is considered a hygroscopic material due to its capacity of absorb water, leading to changes in dimensions, strength, and stiffness due to variation of moisture content. The fibre saturation point (FSP) is reached when at certain moisture content, the material does not present dimensional changes and does not undergo variations in the mechanical strength. Specimens from the upper, middle and upper part of the bamboo were analysed in order to determine the FSP. Two methods were used to determine the FSP; the first method used the dimensional variation of the material at different moisture contents. The results showed that FSP is around 34.05%. The second method allowed verifying the FSP of Guadua angustifolia Kunth from the analysis of the parallel compression strength at different moisture contents. This method found that FSP was around 34%. Finally, a modification factor due to moisture content for compression strength was presented, as well as the equation for linear expansion of the material.

12

Authors: Jonathan Hernández Ramos, Adrián Hernández-Ramos, Xavier García-Cuevas, Juan Carlos Tamarit-Urias, Luis Martínez-Ángel, Jesús García-Magaña

Reliable estimates of volume are indispensable for sustainable forest management. In tropical Mexico, a tree species of major commercial interest is mahogany (Swietenia macrophylla King). Therefore, the use of up to date quantitative tools is fundamental in forest harvesting. The objective was to adjust a total volume model and to generate a commercial volume system for S. macrophylla from volume ratio models. Dasometric information from 116 trees was used to adjust two models of total volume and five of volume ratio. Considering statistics fitness and significance of their parameters, the Spurr total volume model and the volume ratio models of Van Deusen and Zepeda were selected as the best. Bias and aggregate difference show that estimates are accurate, so systems can be used reliably.

16

Authors: Diego Fernando Alzate Velásquez, Gustavo Alfonso Araujo Carrillo, Edwin Oswaldo Rojas barbosa, Douglas Andres Gomez Latorre, Fabio Ernesto Martínez Maldonado

A regionalized rain interpolation model: Regionalisierte Niederschlage (REGNIE) was implemented to interpolate rain and average air temperature for the Andean, Caribbean and Pacific Regions in Colombia. This model integrated terrain slope and aspect obtained from the digital elevation model and the climatological average of 1440 precipitation time series and 259 temperature time series registered in the same number of weather stations for each variable. Multiple linear regression models of annual rainfall and annual average air temperature were obtained according to the model and geoprocessing tools were used for the generation of interpolated surfaces. Statistical results of REGNIE surfaces were similar to those obtained with SPLINE and IDW methods for precipitation (determination coefficient of 0.81 and 55.6 mm mean error) and better for average mean temperature (coefficient of determination 0.99 and average error of 0.02 °C).