Orchidaceae in an Atlantic Forest area: floristics and similarity to other Dense Ombrophilous Forest fragments

The Brazilian Atlantic Forest is considered a global hotspot for biodiversity although it is currently threatened and highly fragmented. Orchidaceae in this phytogeographical domain is represented by 148 genera, of which 142 are endemic; Rio de Janeiro State contains approximately one third of all Brazilian orchid species. The Wildlife Protection Zone of the Palmares Environmental Protection Area (ZVS da APA Palmares) is located in the municipality of Paty do Alferes in Rio de Janeiro State and forms a mosaic of Dense Ombrophilous Forest fragments together with other conservation areas in the state. We surveyed Orchidaceae at 12 collection sites between July 2010 and February 2012 and analyzed floristic similarities between the collection sites and between 12 fragments of dense ombrophilous forest in Brazil utilizing PAST software and the Sørensen coefficient. The survey identified 27 genera and 43 species. Low indices of similarity among the areas were observed as well as weak support for grouping the ZVS da APA Palmares with the Serra da Tiririca Mountains. Greater conservation efforts are recommended for remnant fragments of Dense Ombrophilous Forest.