Seasonal variation in the diversity of flowering orchids at Santa Catarina Lachatao, Oaxaca, Mexico

Background: Orchidaceae represents around 7.1-8.52 % of the angiosperms known in the planet. In Mexico, orchids are the third family more diverse, and Oaxaca is the state with the highest richness in the country. Orchids are widely distributed in tropical environments, but they are also distributed in temperate forests, where they have been scarcely studied. Questions: What is the diversity of orchid species at the locality of Santa Catarina Lachatao? Which subfamilies and growth forms are distributed at that locality? Do the community of orchids flowers differentially between seasons? Studied species: Species of the Orchidaceae family. Study site and dates: Santa Catarina Lachatao, Oaxaca, 2017-2018. Methods: Orchids were collected monthly throughout a year. Collected specimens were identified. Richness, abundance and diversity index were estimated for the whole flowering community, and per subfamily and growth form. These parameters were compared between seasons. Results: The community of orchids was composed by 4,933 flowering individuals from 74 species from the subfamilies Epidendroideae and Orchidoideae. Orchids with terrestrial, epiphyte, and rupicolous growth forms were collected. Total diversity index and species composition varied between seasons. Seasonal variation in abundance, diversity and species composition per subfamily and per growth form was also detected. Conclusions: Orchid diversity at the locality is high (9.68 % of the richness recorded for Oaxaca), and varies between seasons. The high species richness, the endemisms and endangered species found, call to take prompt actions to protect and manage the forest to assure its conservation and the diversity within it.