Resumo

GONZALEZ-RODRIGUEZ, Humberto et al. Composition and structure of vegetation in three sites in the state of Nuevo Leon, Mexico. Polibotánica [online]. 2010, n.29, pp.91-106. ISSN 1405-2768.

During the summer of 2004, a study of the status of woody vegetation was performed at three sites in the Tamaulipan thornscrub. The sites were located in the municipalities of Los Ramones (S1), China (S2) and Linares (S3) in the state of Nuevo Leon, Mexico. At each site three random transects (50 m X 7 m) were laid out, and relative abundance, relative dominance and relative frequency were estimated along each transect. In addition, dasometric parameters, such as height and crown diameter, were determined. Plant diversity was estimated by the Shannon-Wiener index, and similarity between sites was calculated using the Jackard index. A total of 1 741 individual plants belonging to 20 families were registered. Fabaceae had the highest number of species (10) followed by Euphorbiaceae (4) and Rhamnaceae (4), Rutaceae (3) and Cactaceae (2). The other 15 families were represented by only one species. The Shannon index showed that there were no statistical differences in biodiversity between sites; however, the Jackard index showed similarity among species only between S1 and S2. The most frequent species in the three sampling sites were Acacia rigidula (255) followed by Viguera stenoloba (171), Havardia pallens (167), Karwinskia humboldtiana (132), Forestiera angustifolia and Castela texana (125). This group represented about 56% of the total. Less frequent species were: Condalia spathulata (7), Ebenopsis ebano (7), Condalia hookeri (6), Wedelia acapulcensis (5), Cordia boissieri (4), Acacia farnesiana and Yucca treculeana with (3), Helietta parvifolia (2), Croton torreyanus (1) and Prosopis sp. (1), and they represented only about 2%. S3 registered the highest species richness with a little more than 100% of that of S1 or S2. That Linares was the site with the greatest species diversity might have been due to the higher precipitation recorded historically.

Palavras-chave : Tamaulipan thornscrub; Linares; China; Los Ramones; Nuevo León; composition and structure of vegetation.