Resumo

LOPEZ-TOLEDO, José Francisco; VALDEZ-HERNANDEZ, Juan Ignacio; PEREZ-FARRERA, Miguel Ángel  e  CETINA-ALCALA, Víctor Manuel. Tree composition and structure of a seasonally dry tropical forest at la sepultura biosphere reserve, Chiapas. Rev. mex. de cienc. forestales [online]. 2012, vol.3, n.12, pp.43-56. ISSN 2007-1132.

The structure and composition of tree vegetation were studied in three environmental conditions (CA): Stream, Ravine, and Hill. Three sampling units (UM) of 20 x 30 m each were established per EC, in which diameter at breast height (DBH), total height and canopy diameters were measured in poles (DBH ≥ 2.5 cm). In thickets (DBH < 2.5 cm, height ≥ 1.3 m) and saplings (height < 1.3 m), height was measured. Several indices were calculated: importance value (IVI), forestry value (FVI), species diversity (Shannon: H'), and floristic similarity (Sorensen: So). A total of 83 tree species were found. For poles, the most important species were Lonchocarpus minimiflorus (FVI = 25.9; IVI = 16.8) in Stream, Adenaria floribunda (FVI = 17.3; IVI = 14.7) in Ravine, and Guazuma ulmifolia (FVI = 27.6; IVI = 18.5) in Hill. For thickets, Piper sp. (IVI = 29.1) in Stream, Eugenia capulli (IVI = 14.9) in Ravine, y Cassia sp. (IVI = 20.6) in Hill. For saplings, L. minimiflorus (IVI = 27.1) in Stream, and Cassia sp. (IVI = 15.3) in Ravine, and Lantana achyranthifolia (IVI = 26.8) in Hill. Species diversity was significantly higher (p<0.05) in the SU of Stream (H' = 2.21-2.92) and Ravine (H' = 2.37-2.98) than in those of Hill (H' = 0.92-2.44). Floristic similarity was higher among the SU of Ravine (So = 0.46-0.71) and lower among those of Stream (So = 0.33-0.39). The structural attributes and floristic composition suggest that Stream and Ravine have mature forests, while Hill shows an early secondary forest.

Palavras-chave : Seasonal dry tropical forest; species diversity; importance value index; forestry value index; floristic similarity; Sierra Madre de Chiapas.

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