Colombia Forestal

8

Authors: Iris Rocío Payares-Díaz , Oscar Armando Mario-Contreras, Manuel Antonio Medrano-Vélez, Euriel Millán-Romero

Myroxylon balsamum is in great demand in Central America as its botanical and wood properties are useful in the pharmaceutical, timber and cosmetics industries. In Colombia, it is classified as near threatened (NT) due to over-exploitation for resin or wood, or habitat destruction in the department of Sucre. A guide was necessary to establish propagation practices for population restoration in natural areas. Here we quantify and analyze the germination behavior ofM. balsamum. During the germination process, testa rupture occurred 15 days after sowing; obtaining a germination percentage of 77, 2% and germination rate of 23.3 days. The coefficient of variation for variable seedling height (AP), root length (LR), number of leaves (NH) and number of nodes per seedling (NN) generally showed a wide dispersion, but it was greater in the variables LR y NN. This high behavioural diversity maybe due to the provenance of the seed by different mother plants, their maturity or differences in genetic and physiological characteristics.

12

Authors: Alonso Barrios, Ana M. López, Víctor Nieto

Eight total volume and four volume-ratio models were evaluated for use in a system for predicting marketable volumes in Eucalyptusgrandis plantations. Data were collected from 101 trees in stands at harvest age, located in Salento, Quindio. Weighted regression was used to avoid problems of heteroscedasticity in the fit of total volume models. An autoregressive error structure was used to reduce autocorrelation of longitudinal data used in the fit of the volume-ratio models. After evaluation of goodness of fit and prediction, the models of Schumacher & Hall (1993) as total volume model and Cao etal. (1980) as volume-ratio model were selected. The bias and average error in the prediction of marketable volumes to variable-top diameter limits of 0, 5 and 10 cm were always below 4.4% and 11.5%, respectively. The functionality of the system to quantify marketable volumes during the construction of stand and stocks tables was demonstrated.

14

Authors: Natalia Norden

Plant regeneration plays a critical role in the maintenance of species diversity in tropical rainforests. This is a multistage process, including seed production, dispersal, germination and subsequent seedling establishment. All these stages represent major bottlenecks in plant demography, as early stages in the plant cycle (seeds and seedlings) are the most vulnerable to environmental hazards, and are therefore subject to high mortality risks. The outcome of these ecological filters will determine not only seedling spatial distribution, but also the potential area of tree distribution. Seed dispersal and subsequent seedling establishment therefore play a critical role in the structuring of tree communities. Here, I review the main four ecological processes driving seedling recruitment in tropical forests. First, dispersal limitation is the failure of seeds to reach suitable microsites for seedling establishment. Once this filter is overcome, environmental factors can considerably affect seedling spatial distribution. Temporal fluctuations in these processes result in an important variation in recruitment success over time, and add a stochastic component to seedling regeneration. Finally, negative-density dependence regulates species relative abundance in the seedling layer by limiting conspecific recruitment through the attack of pathogen, fungi and herbivores.

26

Authors: Miguel Andrés Cárdenas-Torres

A structure and composition study of poles in two wooded areas of Colombian Orinoquia totalling 10 465 hectares is presented. A 1: 10 000 scale map was made for mapping gallery forest and high dense forest from tierra firma, in order to implement a field stratified sampling, in which each sample unit is selected randomly. Data from 16 sampling units of 0.1 ha each from both ecosystems (for each of them) were collected, and included information about individuals with diameter at breast height(DBH) more than 10 cm and taking data of species, circumference at breast height (CBH), total height and height to crown base . Higher species richness was found in gallery forest with 81 species whereas tierra firma had 76. The latter however, had greater heterogeneity and a better vertical structure. Both ecosystems included the presence of 12 endangered species in different categories according to the Colombia red data book, Resolution 0192 of 2014 of Colombia, IUCN and CITES.