Pteridophyte Diversity in the Tropical Lowland Rainforest of Khao Nan National Park, Nakhon Si Thammarat Province, Thailand

Abstract

An enumeration of the pteridophytes in the lowland (60-600 m) part of a tropical rain forest of Khao Nan National Park, Nakhon Si Thammarat Province, southern Thailand, is presented and is the first report for the area. A total of 418 specimens of pteridophytes were collected and classified into 205 species from 27 families, the highest pteridophyte biodiversity in lowland Thailand and likely highest overall biodiversity region for pteridophytes in Thailand. Although ferns dominated at all taxonomic levels, fern allies were significant accounting for ~7% of all species found. According to habitat types, the specimens can be classified into 4 groups: terrestrials (116 species), epiphytes (27 species), lithophytes (81 species), and aquatic plants (1 species), although 19 species were found in more than one habitat. Two species are new records for Thailand, i.e. Huperzia carinata (Desv. ex Poir.) Trevis. var. laxum (C. Presl) Christ and Selaginella commutata Alderw., but were found only once and in rather small numbers suggesting they are vulnerable. Five additional species (from five genera) could not be determined to species level due to the lack of fertile structures and nine other species (from six genera) require further observations and investigation to determine their correct status, either as new species to science or new records for Thailand.