TITLE:
Analysis of Fragmentation Processes in High-Mountain Forests of the Centre of Mexico
AUTHORS:
Angel Rolando Endara-Agramont, Rafael Calderón-Contreras, Gabino Nava-Bernal, Sergio Franco-Maass
KEYWORDS:
High-Mountain Forests; Fragmentation; Forest Structure; Forest Health
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.3A,
March
29,
2013
ABSTRACT: High-mountain forests (>3500 masl) are the main supplier of
environmental services to Mexico
City and its metropolitan area. Taking as a study
case the Nevado de Toluca National Park, this article focuses on the considerable
reduction on the density of its forest cover, characterised by disturbances in
the structure and dynamics of Pinus
hartwegii. This specie is located towards the upper limits of the
altitudinal gradient (3500 - 4100 masl) constituting the only
pine species in the world capable to be established in those extreme
environmental conditions. The information was collected through the
implementation of 30 Sampling Plots (SP) of 20 × 50 mts (1000 m2) in three forest density
categories: dense, semi-dense and fragmented. For each forest category, all
trees ≥2.5 cm DBH were measured in 10
SPs. The measurement variables were DBH, total and commercial height, forest
health and forest extraction. The results show the abundance of dense,
semi-dense and fragmented forest (336, 202 and 150 trees/Ha-1), with
extraction percentages of 11%, 20% and 33% respectively. The horizontal
structure distribution shows the shape of an inverted J for the three
conditions. However, the phytosanitary conditions of the semi-dense forests
(83% infested trees) and fragmented (63% infested trees), do not guaranties the
survival of the adult trees, implying an intensification of the fragmentation
process for the next decade; given the reduction of the regeneration patterns
due to the lack of healthy tree breeding.