Abstract
The variation in the species richness of herbaceous plants along an altitudinal gradient was analyzed in the Serra do Ouro Branco and Serra do Ribeiro, in the townships of Ouro Branco and Ouro Preto, respectively. Plant similarity between both serras was also assessed. Twenty spots were sampled along a 440 m (1105 m to 1545 m) altitudinal range; at each site, herbs were collected within ten 1 m2 plots, totaling 200 m2. We found 101 species distributed in 59 genera and 25 families. The richest plant families in Serra do Ouro Branco were Poaceae (22 spp.), Asteraceae (14 spp.) and Cyperaceae (10 spp.), while in Serra do Ribeiro, they were Poaceae (17 spp.), Cyperaceae (12 spp.) and Asteraceae (8 spp.). Variation between the number of species and altitude was not significant. The higher number of species in Serra do Ouro Branco may be due to different local environmental factors and to the occurrence of grazing and fires. The serras presented a high similarity value (J = 0.44), but cluster and ordination analysis indicated the formation of two distinct groups, reflecting the importance of local factors to determine the floristic composition of neighboring areas of campos rupestres.
Key words:
biogeography; gradient; diversity; mountains; similarity