Abstract

GARCIA-GARCIA, Samuel Alberto et al. Composition, structure and status of tree regeneration in an altitudinal gradient in a temperate forest of Guadalupe y Calvo, Chihuahua. Polibotánica [online]. 2023, n.56, pp.81-100.  Epub Sep 18, 2023. ISSN 1405-2768.  https://doi.org/10.18387/polibotanica.56.5.

The study of vegetation along altitudinal gradients allows understanding the effects of environmental changes and guiding conservation and adaptation actions for species. The objective was to characterize the horizontal and vertical structure, assess composition, richness, diversity, tree regeneration status, and its relationship with abiotic factors in an altitudinal gradient (floor 1: 2200-2600 m, floor 2: 2600-2800 m, and floor 3: 2800-3200 m) of temperate forest in Guadalupe y Calvo, Chihuahua, Mexico. Thirty-seven circular sampling sites of 1000 m2 were established within six stands, with two rectangular plots of 25 m2 for regeneration assessment. Richness was estimated using the Margalef index (D Mg ), diversity with the Shannon-Weiner index (H') and true diversity (D’), and similarity with the Bray-Curtis ordination model. Horizontal structure was evaluated with the Importance Value Index (IVI), vertical structure with the Pretzsch Index (A), and regeneration with density (N ha-1). A total of 1,466 trees from 16 species, nine genera, and six families were recorded, with Pinaceae and Fagaceae being the most prevalent. Floor 3 showed the highest diversity (D), and greater compositional similarity was found between floors 2 and 3. IVI revealed that in floor 1, Quercus sideroxyla (19.45%) and Pinus engelmannii (13.18%) were the most typical species, while in floors 2 and 3, Pseudotsuga menziesii (28.95% and 22.06%) and Abies durangensis (27.20% and 45.56%) dominated, respectively. Floors 1 and 2 were dominated in height by Pseudotsuga menziesii, while floor 3 by Abies durangensis. The A index showed a decline in vertical structural diversity with increasing altitude. Good regeneration was observed for most species in floor 1 (92.86%), floor 2 (63.64%), and floor 3 (66.67%). In conclusion, the altitudinal gradient showed similarity in species composition, density, and basal area due to the dominance of families such as Pinaceae and Fagaceae. The vertical structural diversity of the evaluated floors decreased with increasing altitude, and among the considered abiotic factors, canopy openness had the greatest influence on regeneration establishment.

Keywords : Abies; Diversity; Mohinora; Pretzsch; Pseudotsuga; Richness.

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