Colombia Forestal

9

Authors: Iván Andrés Delgado Vargas, Jhonnie Mauricio Daza Castillo, Gloria Cristina Luna Cabrera, Hugo Ferney Leonel, Luz Amalia Forero Peña

The carbon stored in radical biomass of Morella pubescens (Humb. & Bonpl. ex Willd.) Wilbur, was quantified, in San Pablo, Nariño, Colombia, with height of 2010 m, average annual rainfall of 1300 mm and average temperature of 17ºC. Three experimental unites: silvopastoral system pasture alley cropping (Ac) in two planting distances 4x3m and 4x4m, and natural regeneration system (Rn), 7 individual ware taken by experimental unite with (diameters 5 – 7 cm), by experimental unit, the sample was taken to 70 cm and 140 cm from the tree and three depths (0-15, 15-30, and 30-45 cm). In total 24 simples/trees were taken in 21 selected individuals. The mayor quantity of radical biomass and C stock was presented in the Ac arrangement 4x3 m of 27.6 t.ha-1 (14.1 t.C.ha-1); 24 4 t.ha-1 (12.1 t.C.ha-1) distance 4x4 m and 7.5 t.ha-1 and 2.9 t.ha-1In natural regeneration. In system Ac distance 4x4 m there were not differences in C stored by tree Rn, there was a decrease by 4x3 m, thus, the differences of accumulation between the systems, can obey to the density of the sowing.

13

Authors: Isabel Cristina Restrepo Carvajal, Ana María Aldana, Pablo Stevenson

Selective logging is a growing forestry activity with less impact on biodiversity than complete deforestation. Despite this, both the magnitude and the direction of ecological change after logging, strongly depend on the intensity, and subsequent temporal forest dynamics. For this reason, it is important to conduct studies to understand the dynamics of different ecosystems after selective logging. We analyzed forest dynamics at El Paujil Reserve (middle Magdalena River, Colombia), in terms of demography, gap dynamics, changes in floristic composition, and ability to gather biomass, comparing two 1 ha plots in a fragment of undisturbed “primary” forest, and two 1 ha plots in a fragment of forest that was subject to selective logging in the past. As expected, forest structure and biomass accumulation were altered as a result of selective logging; however, it did not generate a significant impact on the other aspects evaluated. We suggest that perhaps local steep slopes generate high mortality and gap formation in both forest types.

17

Authors: Fernando Fernández-Méndez, Verónica María Velasco-Salcedo, Juanita Guerrero-Contecha, Manuel Galvis-Rueda, Andreza Viana Neri

The tintales watershed, located in the Santuario de Flora y Fauna (SFF) of Iguaque, Boyaca, was affected by a wildfire. In that area, the natural regeneration was evaluated in 29 permanent plots. Two phyto-physiognomies, a rocky outcrop and oak were evaluated to compare their richness, diversity and dominance, with rocky outcrop yielding a greater richness and diversity. The Asteraceae family was the one that obtained greater representation, with a dominance of species such as Hypoxis decumbens, Pterídium aquilinum and Andropogon bicornis. The diversity in the whole sampling was low and uniform due to the repeated incidence of forest fires that have caused changes in the structure and composition of vegetation. The vegetation found did not differ substantially from other studies reported for this life zone and the region, where the dynamics of land use are similar, with high deforestation and fires. The vegetation established after the fire is dominated by colonizing and pioneering species. In the two phyto physiognomies studied after a year of the fire, two plant communities with statistically significant differences in wealth and homogeneity could be stablished. To start the restoration process, it is recommended to use as one of the inputs, the taxonomic differences found between oak and rocky outcrop.

21

Authors: Oswaldo Angel Jadán Maza, Bolier Torres, Daniela Selesi, Denisse Peña, Cornelio Rosales, Sven Gunter

The diversity, horizontal and vertical structure of tree and shrub vegetation in traditional cocoa plantations and primary forest were characterized. The alpha and beta diversity were evaluated and the relationships between richness with the structure of the arboreal vegetation were identified. The forest recorded the highest values in species richness, abundance and structure, followed by the traditional agroforestry system with cacao seed. The most important ecologically species in the forest were Iriartea deltoidea and Otoba glycycarpa. In all traditional agroforestry systems were Cordia alliodora and Cedrela odorata. In agroforestry systems with cocoa crops, the richness of species is positively correlated with the density and the basal area, marking a direct dependence between these variables. This result cannot be generalized because in the primary forest and the agroforestry system of subsistence, these dependencies are not recorded. This is possibly explained by the ages of trees, the size of the vegetation and the random distribution of individuals over the richness of the species. It was concluded that the primary forest and the agro-forestry system with cacao seeds are the most important systems for the conservation of tree and shrub species, according to the richness, diversity, similarity indices and vegetation structure.

11

Authors: Carlos Fiori Fernández, Maura Isabel Díaz Lezcano, Luis Roberto González Segnana

Acrocomia aculeata es una especie potencial para la industria energética; sin embargo, la latencia de sus semillas retrasa la germinación, afectando al rendimiento. El experimento se realizó en el Laboratorio de Biología de la Facultad de Ciencias Agrarias de la Universidad Nacional de Asunción, el objetivo fue establecer un protocolo de embriogénesis cigótica y enraizamiento de esta especie. Se utilizó un diseño completamente al azar, aplicándose el test Kruskal-Wallis y Mann-Whitney con 5% de probabilidad de error, previa comprobación de supuestos de distribución. Los tratamientos fueron medios MS (Murashige y Skoog) con bencilaminopurina (BAP) en 1, 2 y 4 ppm, medios MS con 2 g/L de carbón activado (CA) y MS simples. Se utilizaron 45 embriones cigóticos cultivados inicialmente en medios MS con 2g/L de CA, expuestos a oscuridad inicial por 20 días; posteriormente subcultivados en los tratamientos. La variable medida fue la longitud radicular, evaluada en dos periodos de 20 días. No existió efectos significativos en los tratamientos con BAP, el CA suprimió la oxidación en explantes; mientras que, los mejores resultados presentaron los tratamientos 1 (MS+1 ppm de BAP) y 4 (MS+CA 2g/L) con 6 y 5 cm de longitud radicular respectivamente, luego de 40 días de incubación.

14

Authors: Carlos Alfonso Devia Castillo, Fredy Reyes, Ivónn Morales, Michel Morris, Juan Pareja

El presente artículo propone sustituir losas en concreto utilizadas para el sistema de transporte masivo Transmilenio por prefabricados de madera, como son las vigas laminadas, como estructura de pavimento con capa de rodadura. Se evaluó el comportamiento mecánico de la madera de dos especies (Pinus caribaea y Eucalyptus tereticornis) a partir de simulaciones por el método de elementos finitos, posteriormente se determinó la configuración óptima para el diseño en madera y finalmente se verificó en laboratorio la configuración óptima determinada con la simulación para un diseño de 440 000 ejes. Con el uso de la máquina Universal de Ensayos y una carga de 6.50 toneladas equivalente a la de un semieje simple con dos ruedas, se encontró que el espesor de la losa de madera varía entre 0.125 y 0.24 metros para resistir esta carga. Se encontró que técnicamente los sistemas constructivos prefabricados con madera son una alternativa válida dentro del mercado de la construcción de pavimentos en la parte estructural. Adicionalmente corresponden a una innovación al ser una modificación en el sistema estructural de las losas, además de reducir el impacto ambiental.

18

Authors: Maria Claudia Torres Romero, Gloria Amparo Galeano Garces, Rodrigo Bernal

En este estudio se caracterizaron los sistemas de manejo de Copernicia tectorum en dos localidades de la Región Caribe de Colombia: Plato (Magdalena), y Magangué (Bolívar). También se analizó el impacto de la cosecha de cogollos en la estructura de la población, el número de hojas y la longitud de los cogollos. En Plato sólo se cosechan cogollos de palmas subadultas y adultas, lo que parece no afectar las palmas a nivel individual, ni poblacional. En Magangué se cosechan palmas de las clases juveniles, lo que limita su crecimiento; esto da como resultado palmares con muy pocos adultos, comprometiendo su sostenibilidad, incluso en el corto plazo. El modelo de uso comunitario y de libre acceso a los palmares ha permitido su conservación en Plato; en Magangué, por el contrario, se hizo apropiación individual de la tierra, tanto legal como ilegal, lo que trajo fraccionamiento de la población, tala y restricción de acceso para la cosecha. En Plato el manejo debe enfocarse en detener la tala y la afectación a los complejos cenagosos donde crece la palma. En Magangué se debe controlar la sobre explotación y favorecer el reclutamiento de las clases juveniles.