Estructura, composición florística y diversidad de especies leñosas de un bosque mesófilo de montaña en la Sierra de Manantlán, Jalisco

In this paper we describe the structure, floristic composition and woody (tree and shrub) species diversity of a cloud forest at Cuzalapa, Sierra de Manantlán, Jalisco. Two localities with four 2,500 m2 plots each were established at El Durazno and La Pareja. All species present in the plots were identified and recorded, and their diameters at breast height (DBH ≥ 3cm) and heights measured. Forest structure is described using the relative values of density and basal area; in addition, a diagram  of forest profile was drawn for each plot. Among-plot similarity was assessed with Sørensen 's Index. Species diversity was evaluated using Shannon-Wiener 's, Simpson's, and Fisher's α indexes. In the total sampled area (2 ha) 2,086 individuals  belonging to 101 species (including two new records for the flora de la Sierra de Manantlán, Sapranthus foetidus and AIchornea  latifolia), distributed in 75 genera and 44 farnilies, were recorded. The families with the largest numbers of species were:  Leguminosae (8), Solanaceae and Fagaceae (7 each), Moraceae and Compositae (6 each), Lauraceae (5), and Rubiaceae (3).  Tree density at El Durazno and La Pareja was 1,084 and 1,002 trees ha-', and basal area was 38.7 and 31.9 m2 ha-', respectively.  At both localities, Styrax radians had the highest relative importance value. Forest structure and species composition at both  localities correspond to tracks of transitional forest between early to intermediate stages, which results from recurrent anthro- pogenic disturbances such as logging 50 years ago. Species diversity in Cuzalapa is one of the highest ever recorded for cloud  forests of Mexico, which presumably is a consequence of anthropogenic and natural disturbances. Both kind of disturbances  are important forces in maintaining the structure, species composition, and high species diversity in this cloud forest.