CHANGING ASPECTS OF ENDEMISM AND ENDANGERMENT IN PTERIDOPHYTA

In conserving biodiversity, increasing attention is being given to pat terns and centres of endemism, rarity and endangerment at various leve ls including biome, species and gene. Primary and secondary centres of pteridophyte diversity are discussed in relation to mesic and xeric t axa. There is need for more ecological data, especially relating to th e gametophyte and the effects on it of stress and competition. Humans are a significant factor in contemporary pteridophyte biogeography, es pecially through inducing habitat fragmentation. The response of pteri dophytes to fragmentation is probably mixed: although most are capable of long distance dispersal which facilitates recolonization of fragme nts, many have a high level of habitat fidelity which demands retentio n of core areas. Priorities for action are suggested.