The inselberg flora of Atlantic Central Africa. I. Determinants of species assemblages

摘要: Aims  To identify the relative contributions of environmental determinism, dispersal limitation and historical factors in spatial structure floristic data inselbergs at local regional scales, to test if extent species aggregation is related abilities. Location  Rain forest Equatorial Guinea, northern Gabon southern Cameroon (western central Africa). Methods  We use phytosociological releves herbarium collections obtained from 27 using a stratified sampling scheme considering six plant formations. Data analysis focused on Rubiaceae, Orchidaceae, Melastomataceae, Poaceae, Commelinaceae, Acanthaceae, Begoniaceae Pteridophytes. were investigated ordination methods (detrended correspondence analysis, DCA; canonical CCA), Sorensen's coefficient similarity autocorrelation statistics. Comparisons made scales ordinations life-form spectra data. Results  At scale, forest-inselberg ecotone main gradient structuring data. this still spectra, but other become predominant analyses assemblages. CCA identified three variables explaining significant part variation Spatial showed that both flora are spatially autocorrelated: compositions within formations decreasing approximately linearly with logarithm distance. The distribution was correlated their priori abilities as assessed by diaspore types. Main conclusions  composition best explained continuous cline edaphic conditions along ecotone, generating wide array ecological niches. these niches occupied different depending available pool. These subregional pools probably result varying conditions, history past vegetation changes due climatic fluctuations.