A comparison of the tropical montane pteridophyte floras of Mount Kinabalu, Borneo, and Parque Nacional Carrasco, Bolivia

Aim To compare the species richness, and taxonomic and life-form composition of tropical montane pteridophyte floras on two well-documented sites: Mount (Mt) Kinabalu, Sabah, Borneo and Parque Nacional (PN) Carrasco, central Bolivia. Methods Using published lists, we compared the elevational distribution of overall species richness, specific ptericlophyte families, and of life-forms along both study sites. Additionally, we compared point-diversity by establishing 108 plots of 400 m(2) at PN Carrasco, and 15 such plots at Mt Kinabalu and three at a lowland site at Danum Valley in south-eastern Sabah, Borneo (200 m). Results The numbers of species, genera, and families recorded on Mt Kinabalu were 14-23% higher than at PN Carrasco, most probably as a result of more intensive longterm collecting activity. Opposed to this, species richness per 400 m(2) plot was somewhat higher at PN Carrasco, especially amongst epiphytes at mid-elevations. Overall, there was a remarkable similarity in the elevational distribution of species numbers, of individual pteridophyte families, and of life-forms. Major differences included a more pronounced peak of species richness at 1500 m on Mt Kinabalu, considerably higher species numbers of Elaphoglossum at PN Carrasco and of Grammitidaceae at Mt Kinabalu, and a higher proportion of debris-trapping epiphytes and lithophytic species at Mt Kinabalu and of terrestrial herbs at PN Carrasco. Main conclusions The majority of present-day species of the studied ptericlophyte floras evolved largely independently from about 66-100 common ancestors. The striking convergence of the ptericlophyte floras of both sites indicates that the taxonomic and morphological composition of the pteridophyte floras is subject to selective pressure, and that specific ptericlophyte families are evolutionarily pre-disposed to occupy specific ecological niches.