Podostemaceae family (Dicraeanthus zehnderi)

Mohamed bin Zayed Species project number 0925264

IN SITU CONSERVATION OF PODOSTEMACEAE ON THE SANAGA RIVER AT EDEA - CAMEROON.

 

Podostemaceae are aquatic flowering herbs, annual, often of bizarre shape, sometime resembling lichens, bryophytes... or even different from any known plant. They have no clearly differentiated roots, stems and leaves.

Research on Podostemaceae is difficult because their habitat is inhospitable: They live submerged, fixed on the rocks’ surface in waterfalls and rapids. Apart of the water speed, Very few is known about the physico-chemical factors determining their presence or their absence in a river.

Cameroon, with 10 Podostemaceae genera (20% of of the world's and 59% of all Afro-Malagasy's) and c. 37 species (13% of the world's Podostemaceae species) is the eldorado for this family. 

Podostemaceae are often threaten because their Area of Occupancy (AOO) is generally low (some times a few sq-m only): They might be found in a single river or more over in a single waterfall. Most threat to Podostemaceae is human-induced through water pollution. Also, waterfalls and rapids, their exclusive habitat are very appreciated for tourism, hydro-electricity production and religion. Therefore in Cameroon, 28% of Podostemaceaae are Critically Endangered (CR), 28% are Endangered (EN) and 35% are Vulnerable (VU). In Central Africa, talking about the freshwater plants, the Podostemaceae family is the most represented in terms of threatened species and for all threat categories (29%).

Project objectives.

Considering the alarming figures presented by the Podostemaceae conservation status in Cameroon, our general objective within this project is to undertake the first in situ protection and conservation of Podostemaceae in the country. Although our general objectives are broader, as experimental field, we choosed in this project the Sanaga waterfalls at Edea, hosting the hydro-electric dam. Our conservation work included field research action, education and social initiatives. Namely, our detailed objectives were: 1. To rediscover Winklerella dichotoma: Although mentionned in the Podostemaceae volume of Flore du Cameroun, this species was so far absent from the collections of the national herbarium. 2. The Sensitization: Concretely this means to entertain the Sanaga riverside communities, the dams' officials and the public's authorities on the Podostemaceae conservation topic around the dam.

 

Conservation status of the target species and the importance of the associated habitat:

The target species are as follow: 1. Dicraeanthus zehnderi H.Hess 2. Winklerella dichotoma Engl. 3. Zehnderia microgyna C.Cusset 4. Leiothylax quangensis (Engl.) Warming 5. Dicraeanthus africanus Engl. Their conservation status as defined by IUCN is Critically Endangered (CR) for 1, 2, and 3; Endangered for 4 (EN) and Near threatened (NT) for 5. All these species are found in the Sanaga waterfalls at Edea (Cameroon), coexisting with a dam built about 50 years ago, and three of them (1, 2 and 3) are endemic to this waterfalls. The threat for the above five species is permanent: Since the construction of the dam, this site remains the only place where the nearby population can fish, hunt and do agriculture. More over, the ongoing extension work of the dam's objective is to drive into the turbines any single drop of the river's water.

Result. 

The people of Eding, closer locality to the Edea dam are now forming an association. We rediscovered Winklerella dichotoma at the Edea dam site living in small population patches. Its Extent of Occurency (EOO) is now reduced by agriculture. The conservation status of this species stills CR. Another small site has been discovered for Zehnderia microgyna on the Ngwei River, # 10 Km E of Edea on the road Edea - Yaounde. This new discovery might not change the current conservation status (CR) of this rare species. A new species of Dicraeanthus (Dicraeanthus sp. Nov.), now very rare and very threaten has been discovered. Although the species stills undescribed, its conservation status will certainly be CR. Three (03) species of insects or their larvae live on Podostemaceae's roots and stems under the fast running stream. Four (04) species of birds feed on Podostemaceae when the water level drops. Our first hypothesis is that birds as well as (or) insects may play an important role in Podostemaceae long distance dispersal.

With the help of the Mohamed Bin Zayed Species Conservation Fund, we are convinced that the conservation of Podostemaceae is now on the way in Cameroon in general and at the Edea waterfalls in particular. We think more collaboration with this organisation in the future is the best way to avoid the extinction of this discrete plant familly.