Diversity and distribution of the orchids of the Tacaná-Boquerón region, Chiapas, Mexico

The Tacaná-Boquerón region (TBR) in Chiapas is considered an area of high biodiversity in Mexico, with a rich but poorly studied orchid flora, which is an important component of the vegetation and threatened by an accelerated rate of deforestation. By means of fieldwork, and the revision of scientific collections and literature, an orchid checklist for the TBR and adjacent areas was made; using geographic information systems the distribution of this orchid flora was analyzed in the study area. From 1,235 records we report 105 genera and 325 species, two of them determined to infraspecific level and two are natural hybrids; nine species were additions to the Mexican flora; 39 species are considered at risk in Mexico; the national distribution of a further 20 species are restricted to the TBR. This orchid flora represents 24 % and 44 % of the national and state orchid species richness, respectively, is the second richest in Mexico, and only surpassed by the region El Momón-Las Margaritas-Montebello (Chiapas). The greatest orchid richness is concentrated between elevations of 500 to 2,499 m, in areas now given over to permanent agriculture (including coffee and cocoa plantations); in primary forest the richness is lower. The Tacaná Volcano Biosphere Reserve is the only protected area in the TBR and the proposal to extend it to the Boquerón peak would promote the protection of the orchid flora growing above 1,000 m in the region. Traditional coffee plantations could be alternative to conserve orchids that grow below 1,600 m.