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Forest community studies traditionally investigate arboreal structure and composition. Herb-shrub
layers have little or no importance in these works. Initial information on herb-shrub layers of Brazilian forests
was provided as a complement to arboreal studies. However, herb-shrub layers have recently gained a central
importance in some works. The main objective of this study was to describe the phytosociological structure of the
Silvicultura forest’s herb-shrub layer to understand the synecological relations and study the populational dynamic
processes involved. The phytosociological parameters used were obtained from 1 m2 split plots of 100 m2 samples.
All individuals with less than 10cm PBH (perimeter at breast height) or over 20 cm were sampled. Dynamic
processes were evaluated by using the size frequency distribution of sampled populations. The herb-shrub
phytosociological structure consisted of 1193 individuals of 109 species of 41 families in samples of 100 m2. The
Shannon diversity index (H´) was equal to 3.38 nats/individual and the equability (J´) was equal to 0.72, both

showing high heterogeneity under herb-shrub conditions. The most important species (VI) were Piper lucaeanum,
Psychotria conjugens, Olyra micrantha, Psychotria sessilis, Siparuna guianensis, Bambusa tuldoides, Ottonia
leptostachya, Aparisthmium cordatum and Psychotria hastisepala. The most important (VI) families were
Rubiaceae, Piperaceae, Poaceae, Monimiaceae, Leguminosae (Mimosoideae), Myrtaceae, Euphorbiaceae,
Meliaceae, Lauraceae and Flacourtiaceae. The size frequency distribution analysis raised the hypothesis that
there were two species groups, with different strategies. One group would consist of species allocating
photosynthates preferentially to their photosynthetic system, and the other group of species allocating
photosynthates preferentially to their trunks.