Terrestrial monocots in an Ombrophilous Dense Forest fragment at Northern Coastal Plain of Rio Grande do Sul

Abstract

Monocots are a very important group in the structure of the Ombrophilous Dense Forest, despite scarcely studied, specially the terrestrial ones. This study was conducted in a forest fragment located at Northern Coastal Plain of Rio Grande do Sul (29°23'S e 49°50'W) comparing terrestrial monocots in two areas with contrasting drainage features (well drained and swampy). The aim was to examine whether the taxocenosis structure (concerning floristic composition, phytosociological parameters and diversity) is different between the environments. In order to do this, a floristic survey in the whole fragment and a phytosociological study in each habitat using plots were carried out. The parameters evaluated for species were relative density and frequency, and similarity and diversity were analysed for environments. The floristic survey resulted in 31 species belonging to ten families, Orchidaceae, Poaceae and Arecaceae being the richest ones. In the well drained area, the phytosociological survey sampled 572 individuals, belonging to 17 species, of which 12 were herbaceous. In the swampy area, the survey sampled 797 individuals, belonging to 14 species, of which seven were herbaceous. Nine species were common to both environments, and the Sorensen’s similarity value was 0.58. Calathea monophylla showed high density in both environments and is a new record for the State. We concluded that the taxocenosis structure is different between the environments, although the difference is stronger when just the herbaceous component is considered.