by Vincent Droissant
Although our knowledge of Central African orchid flora has greatly improved in recent years, very little is known about their flowering time and their interaction with pollinators, limiting our understanding and therefore our ability to develop effective in situ conservation measures. In this perspective, we develop and conduct a joint research project between the University of Yaoundé 1, the Institut de Recherche pour le Development (IRD), and the Congo Basin Institute (CBI) to tackle some remaining gaps in our understanding of African orchid ecology.
A recent paper in the International Journal of Biometerology presents the first study of the environmental and evolutionary forces driving flowering phenology of epiphytic orchids from Central Africa. We used an original dataset derived from ex situ shadehouse observations spanning over a period of 11-years in Yaoundé (Cameroon), combined with in situ herbarium records, to characterize the flowering patterns of 45 orchid species.
Our study is one of a handful of long-term research on plant phenology in tropical Africa. In order to investigate the role played by spatially contrasted seasonal fluctuations of climate on phenology, we produced an original map of climatic regions of Cameroon based on a set of biologically meaningful descriptors of the climate. Climatic delineations allowed us to discover the existence of phenological ecotypes within orchids which may be the cause of the important intraspecific genetic diversity recently shown for orchids and for trees in Central Africa.
To continue to gather deeper knowledge on African orchids reproductive biology, a new shadehouse was established in August-September 2018 in the earth of the Dja Biosphere Reserve (East Cameroon). The living orchid collection will be of importance for the long-term study of the orchid flora of the Dja Reserve as it will assist scientist and Cameroonian students (see for example Laura Azandi’s Ph.D project) to better characterize the phenology of several species in their natural habitat and to study interactions between orchids and their pollinators (mainly insects, but birds may also be involved). In addition, it will serve the role of a living museum where the orchid diversity of the Dja Faunal Reserve can be shown to the local community, international scientists and all visitors.
Texier N., Deblauwe V., Stévart T., Sonké B., Simo-Droissart M., Azandi L., Bose R., Djuikouo M. N., Kamdem G., Kamdem N., Mayogo S., Zemagho L., Droissart V. Spatio-temporal patterns of orchids flowering in Cameroonian rainforests. International Journal of Biometeorology, 2018, 1-14. DOI: https://doi.org/10.1007/s00484-018-1594-3