Resumo

MORALES-ARIAS, José Guadalupe et al. Environmental variation and floristic composition of tree species in a humid mountain forest in western Mexico. Rev. Mex. Biodiv. [online]. 2018, vol.89, n.3, pp.769-783. ISSN 2007-8706.  https://doi.org/10.22201/ib.20078706e.2018.3.2456.

Humid mountain forest (BHM) in Mexico circumscribes a set of very heterogeneous forest communities that differ in structure, floristic composition and environmental complexity. To contribute to the knowledge of the effect of environmental variation on the floristic composition of a BHM located in the sierra de Cacoma, in western Mexico, this research aims to answer the following research questions: i) What are the environmental factors that explain the floristic composition of the BHM of the sierra de Cacoma, in western Mexico? ii) What is the correspondence between the micro-physiography, with the floristic variation of the juvenile layer of the BHM? iii) Is there floristic similarity in the adult-juvenile relationship, adult-seedling and juvenile-seedling? The database was derived from a permanent plot of 1 ha (100 × 100 m) divided into 25 permanent sub-plots (400 m2 each). In each sub-plot, woody species were categorized into 3 stages of the life cycle (adults, juveniles and seedlings). In addition, 24 variables were registered, analyzing the vegetation-environmental variation relationship with canonical correspondence analysis. The results suggest that micro-physiography, along with soil depth, elemental chemical composition (Ca, Fe, Mg), rock cover, azimuth, slope and leaf area index (LAI), were the variables that best correlates with the floristic composition of the BHM (variance accounted was 44.1%, 41.9% and 30.6% in adults, juvenile and seedlings, respectively). The floristic similarity between the 3 stages of the life cycle, according to the Mantel test, showed a high correlation in adults-seedlings and adults-juveniles. However, no correlation was found between juvenile-seedlings, which suggests that the passage from one life cycle to another is a difficult phase to progress and where the ability to the species establish is likely defined.

Palavras-chave : Canonical correspondence analysis; Environmental heterogeneity; Sapling; Micro-physiographic variation; Seedling; Mantel test.