Latitudinal and elevational gradients of fern diversity and community composition in Africa and the Indian Ocean Islands
Final Report Abstract
Within the framework of the BRYOLAT project, we studied the elevational distribution of pteridophytes (ferns and fern allies) at five locations within one biogeographic region (Africa and Indian Ocean Islands) as a further natural experiment of assessing the relationship between patterns of species richness and potential diversity drivers. The simultaneous approach of studying bryophytes and pteridopyhtes enables direct comparisons of richness patterns and their underlying environmental drivers. Since both groups share the distinct dependence on ambient humidity, but to a different degree, a direct comparison especially interesting with respect to distribution patterns and their relation to the environment. In total we studied 156 plots in La Reunion, Madagascar, Comores, Kenya, and South Africa, with an additional 80 plots in New Guinea, which has been visited as further research site. We found at all localities together >750 species with a strong bias between sites: 18 species at Mt. Kenya and >450 in New Guniea, confirming the notion that the African flora has suffered from disproportionately high extinction rates during Pleistocene dry periods. In contrast, elevational species richness follow similar trends across all study localities with highest richness at about mid elevations, where the cloud condesation layers accommodate the highly humidity demanding nature of pteridophytes. Future work and analyses will center upon the following questions: – elevational species distribution of ferns with respect to climate and source-sink dynamics – relating these data to respective patterns of bryophytes, which will be determined by end of 2013 – including localities from the follow-up project MOVECLIM (2011-2014), which implements the same sampling methodology for bryophytes and pteridophytes on further oceanic islands (Guadeloupe, La Palma, Acores, Thaiti). All localities will be analysed in context to enhance or knowledge on the biogeography of spore-borne plant groups.
Publications
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2009. Elevational gradients of species richness derived from local field surveys versus ‘mining’ of archive data. Pp. 57-63 in Spehn, E.M. & C. Körner (eds) Data mining for global trends in mountain biodiversity. CRC Press/Taylor & Francis, Boca Raton
Kessler, M., Krömer, T., Kluge, J., Karger, D.N., Acebey, A., Hemp, A., Herzog, S.K. & Lehnert, M.
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2010. Mycorrhizal colonizations of ferns and lycophytes on the island of La Réunion in relation to nutrient availability. Basic and Applied Ecology 11: 329-336
Kessler, M., Jonas, R., Strasberg, D. & Lehnert, M.
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2011. The effect of area on local and regional elevational patterns of species richness. Journal of Biogeography 38: 1177-1185
Karger, D.N., Kluge, J., Krömer, T., Hemp, A., Lehnert, M. & Kessler, M.
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2011. The impact of sterile populations on the perception of elevational richness patterns in ferns. Ecography 34: 123-131
Kessler, M., Hofmann, S., Krömer, T., Cicuzza, D. & Kluge, J.
