Abstract

PEREZ-SUAREZ, Marlín; ALFARO-RAMIREZ, Farid Uriel; RAMIREZ-ALBORES, Jorge Enrique  and  PLASCENCIA-ESCALANTE, Francisca Ofelia. Vegetation life forms at treeline a high mountain forest in Mexico. Rev. mex. de cienc. forestales [online]. 2024, vol.15, n.81, pp.4-32.  Epub May 13, 2024. ISSN 2007-1132.  https://doi.org/10.29298/rmcf.v15i81.1421.

The objective of the present study was to characterize the diversity of life forms and plant community structure along an altitudinal gradient of the Pinus hartwegii treeline ecotone on Nevado de Toluca, Mexico. Plant species in the tree boundary ecotone were sampled, identified and quantified based on plant morphology under adverse conditions (life forms). The diversity of life forms in the ecotone was calculated using Shannon's diversity index and the structure was evaluated in terms of density and abundance of plant species. A total of 43 plant species belonging to 30 genera and 18 families were identified. Chamaefites were the most abundant life form (>50 %); as altitude increased, life form diversity increased, while abundance decreased. Species diversity was proportionally and significantly (p<0.05) related to increasing altitude along the treeline ecotone. The tree height and density of the Pinus hartwegii treeline ecotone diminished gradually along the treeline ecotone (diffuse form), which was characterized by more pronounced abiotic stress conditions at higher altitudes due to the altitudinal range sampled and because this ecotone represents the distribution limit of forest species and the beginning of grassland distribution. The diversity and distribution of life forms present in the P. hartwegii treeline ecotone may modify microenvironmental conditions or processes and, therefore, they regulate the response of other species associated with climate change.

Keywords : Alpine ecosystems; altitudinal gradient; altitudinal migration; Climate change; facilitation; Nevado de Toluca.