Two strata of cerrado stricto sensu vegetation were surveyed, in a fragment covering an area of 300 ha, at Brotas, SP, Brazil. The sampling area had 5000 m² (250 x 20 m). The upper stratum (diameter 50 cm above ground <FONT FACE=Symbol>³</FONT> 5cm) was surveyed in 50 plots, 100 m² each, and the lower stratum (diameter < 5 cm and height < 50 cm) was surveyed in 50 sub-plots, 10 m² each, for phytosociological analysis. Crown cover was estimated by the line interception method and the aggregation index of Payandeh was also calculated, for each species and for the community as a whole. Trees, shrubs, palms and herbs were identified, comprising 78 species (36 families). The upper stratum had 1150 ind/ha, basal area of 7.2 m²/ha and crown cover of 19.6 %. In this stratum, 44 species (27 families) were surveyed (H'=3.02) and the community was aggregated (P=4.26). The most important species (decreasing importance value) were: Acosmium subelegans, Aspidosperma tomentosum, Eriotheca gracilipes, Styrax ferrugineus and Tabebuia ochracea. The density of the lower stratum was 10,220 ind/ha, the community was also aggregated (P=3.89) and the diversity index (H'=3.32) was higher than in the upper stratum. From the 61 species surveyed (32 families), the most important in decreasing order of relative density were: Campomanesia adamantium, Bromelia balansae, Attalea geraensis, Xylopia aromatica e Ocotea pulchella. Some of the most abundant species of the upper layer, such as Styrax ferrugineus, Eriotheca gracilipes, Piptocarpha rotundifolia and Annona crassiflora, were not found in the lower stratum. It is suggested that the regeneration process was interrupted and such populations may be locally threatened.
Cerrado stricto sensu; phytosociology; stratification; diversity
