Pteridophyte species richness in Andean forests in Bolivia

I assessed the magnitude and distribution of pteridophyte species richness on the eastern Andean slope in Bolivia based on 676 study plots of 400 m(2) each in forest habitats at 65 study sites. In total 755 species were recor ded, including 426 (56%) epiphytes and 598 (79%) terrestrials, with 266 spe cies (35%) recorded under both groups. Mean number of species per plot at a given site varied from 0 to 31.1 for epiphytes, 0 to 20.9 for terrestrials , and 0 to 47.9 for all species combined. The highest numbers of species re corded at a given study site were 110 epiphytes, 101 terrestrials, and 167 species in total. While overall there were more terrestrial than epiphytic species, at individual sites and plots the reverse was true, indicating tha t terrestrial species tended to be more patchily distributed than epiphytes . Despite high survey intensity, many species went unrecorded; the minimum estimate of total species richness obtained through extrapolation was 975 s pecies overall, including 559 epiphytes and 880 terrestrials. A correlation analysis of species richness to 14 environmental parameters revealed a hig hly positive correlation to mean annual precipitation and bryophyte cover o n tree branches (a proxy for air humidity). Significant correlations to oth er parameters (e.g. human impact, canopy height, etc.) reflected the covari ance of these factors with precipitation and bryophyte cover. Despite a lac k of data on the pteridophyte communities from much of the Bolivian Andes, it appears that in most of the countries, pteridophyte diversity can be pro tected by focussing the most humid parts of the Andean forests.