Effectiveness of a protected areas network in the conservation of Tamarindus indica (Leguminosea-Caesalpinioideae) in Benin

In the absence of effective conservation of its wild relatives, exploitation of a species could lead to genetic depletion. Research on how well do protected areas contribute to the conservation of plant species subject to human exploitation is still limited. The potential niche of Tamarindus indica (tamarind) was evaluated and the contribution of the protected areas network (PAN) of Benin to its conservation was assessed. The maximum entropy approach was used to model the ecological niche of the species, and forest inventories were used to address its population structure. To test its effectiveness, the PAN map was overlapped with the habitat suitability map of the species, and its population structures in protected versus unprotected areas were compared. Tamarindus natural populations were confined to the Sudanian and Sudano-Guinean regions. The species populations in the Sudanian region appeared well represented in protected areas in contrast to those in the Sudano-Guinean region. Results showed a positive effect of protected areas on juvenile density but a weak effect on adult density and current size-class distribution. Protection seemed to be unlikely to ensure the long-term persistence of the species. Cryopreservation, assisted recruitment and artificial enrichment of tamarind stands are recommended to ensure the long-term persistence of the species.Resume En l'absence de conservation effective de ses cousins sauvages, l'exploitation d'une espece peut entrainer son epuisement genetique. Les recherches sur la mesure dans laquelle les aires protegees contribuent a la conservation d'especes vegetales sont encore rares. On a evalue la niche potentielle de Tamarindus indica (tamarin) et la contribution du reseau d'aires protegees beninois a sa conservation. Le principe d'entropie maximale fut utilise pour modeliser la niche ecologique de l'espece et l'on a eu recours a des inventaires forestiers pour aborder la structure de sa population. Afin de tester son efficacite, la carte de l'habitat appropriea l'espece fut superposee a celle du reseau d'aires protegees, et ses structures de population furent comparees entre aires protegees et non protegees. Les populations naturelles de tamarin sont confinees aux regions soudanienne et soudano-guineenne. Les populations de cette espece dans la region soudanienne semblent bien representees dans les aires protegees contrairement a celles de la region soudano-guineenne. Les resultats montrent un effet positif des aires protegees sur la densite des juveniles, mais un faible effet sur la densite des adultes et sur l'actuelle distribution des tailles. Il semble que la protection ne soit pas a meme d'assurer la persistance de l'espece a long terme. L'on recommande la cryogenisation, le recrutement assiste et l'enrichissement artificiel des peuplements de tamarins pour garantir la persistance de l'espece a long terme.