The tree-shrub compartment from a fragment of tropical montane semideciduous forest was surveyed in Lavras, MG Brazil, to characterize the floristic composition and community structure within the frame of other seven nearby fragments. Locally known as Mata da Lagoa, the fragment measures 4,0 ha and is situated at the coordinates 21º13'11"S e 44º58'15"W, at an average altitude of 884 m. Individual trees and shrubs with diameter at breast height (dbh) > 5cm were sampled within 29 (20 <FONT FACE=Symbol>´</FONT> 20 m) plots. 1294 individuals distributed into 144 species, 94 genera and 45 families were recorded. The diameter distributions of the ten most abundant species showed two distinct patterns, which are apparently related to the effects of fragmentation and disturbance on the dispersion mechanisms. Detrended correspondence analyses (DCA) of floristic and quantitative data of eight forest fragments indicated strong dissimilarity among them, particularly with respect to floristic composition, and it is probably influenced by the high environmental heterogeneity of the region Alto Rio Grande. The floristic dissimilarity patterns suggested a stronger influence of the altitude and geographical proximity, whereas the patterns of structural dissimilarity suggested a stronger influence of the soil nutritional status and ground water regime.
Tropical semideciduous forest; community of trees and shrubs; community structure; physiognomic structure; floristic and structural comparisons
