Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Mexique → Efecto del manejo forestal en la adversidad, composición y estructura de un bosque de Pinus arizonica ENGELM. En el ejido El Largo, Chihuahua, México

Universidad Autónoma de Nuevo León (UANL) 2012

Efecto del manejo forestal en la adversidad, composición y estructura de un bosque de Pinus arizonica ENGELM. En el ejido El Largo, Chihuahua, México

Hernández Salas, Javier

Titre : Efecto del manejo forestal en la adversidad, composición y estructura de un bosque de Pinus arizonica ENGELM. En el ejido El Largo, Chihuahua, México

Auteur : Hernández Salas, Javier.

Université de soutenance : Universidad Autónoma de Nuevo León (UANL)

Grade : Doctorado en Ciencias con Especialidad en Manejo de Recursos Naturales 2012

Résumé
Pine forests in ejido El Largo have been harvested for more than 70 years, have had at least five silvicultural interventions, produce benefits for more than 1600 landowners and currently are the largest timber producer in Mexico. The purpose was to determine the effect of forest management on diversity, composition and forest structure, to help strengthen or redefine forestry practices to ensure forest sustainability. The Moctezuma cutting area was monitored for 20 years, through three periodic assessments prior to silvicultural interventions, using 58 permanent plots of 0.1 ha each one, spread over 3650 ha. In these plots timber harvesting is done every 10 years. The plots are located in the site quality 2 (CE2) and 3 (CE3). The species composition, structure and diversity of individuals from arboreal stratum with diameter at breast height greater than 7.5 cm, with different ecological indices, were quantified. The growth dynamics of the main parameters that define dasometric horizontal and vertical structure of a forest was evaluated. Probability density function (pdf) models for the best fit to Weibull diametric distributions were also determined. Comparing the ecological indicators and dasometric parameters between evaluations by ANOVA, Kruskal-Wallis test, t test, and Nemenyi, allowed to detect changes or stability in diversity and structural composition of arboreal stratum after one or two cutting cycles. The arboreal stratum of CE2 recorded seven species, decreased alpha diversity (Shannon-Weiner index -P ≤ 0.1-) and changed its composition 16% (beta diversity). The genus Pinus increased in its ecological indicators while Quercus decreased. Pinus arizonica was the most important ecological species (IVI = 57.05%). The arboreal stratum of CE3 was integrated by six species, showed no differences in alpha diversity, and beta diversity had a similar pattern to the CE2. The most important ecological species was P. arizonica (IVI = 74.93%). The genus Pinus and Quercus maintained their ecological indicators. Dasometric parameters (basal area, quadratic diameter, average height and total volume of tree) for the forest and Pinus, showed significant growth in the first period. In the second period only quadratic diameter of the forest grew significantly. Although tree density decreased and spacing significantly increased in the forest, the HartBecking index did not change. The pdf Weibull models describing the best-fitting diameter distributions in their assessments have three parameters ; they were determined by the least squares method and showed a unimodal distribution close to normal, which is typical for evenage forests. It was concluded that the forest is regular, is in growing phase, maintains the composition and diversity of trees, and sustains production through intermediate cuttings that are needed for its development.

Présentation

Version intégrale

Page publiée le 19 janvier 2015, mise à jour le 29 décembre 2019