AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH © 2011, Science Huβ, http://www.scihub.org/AJSIR ISSN: 2153-649X doi:10.5251/ajsir.2011.2.5.774.785 Distribution, regeneration and conservation status of Nuxia congesta R. Br. ex Fresen. (Buddlejaceae) in Côte d’Ivoire Adou Yao C. Y.1,2,3 , N’Da D. H.1, Bakayoko A.2,4 , Kouassi K. E.1, N’Guessan K. E.1, Aké- Assi L.3 1Laboratoire de Botanique, UFR Biosciences, Université de Cocody-Abidjan, 22 BP 582 Abidjan 22, Côte d’Ivoire (e-mail: [email protected]) 2Centre Suisse de Recherches Scientifiques (C.S.R.S). 3Centre National de Floristique (C.N.F.) 4Laboratoire de Biologie végétale et Amélioration des Productions Agricoles, UFR Sciences de la Nature, Université d’Abobo-Adjamé, Côte d’Ivoire ABSTRACT In Côte d’Ivoire, Nuxia congesta (Buddlejaceae) was known only on some highest peaks of the country (Mounts Tonkpi and Boho) until 2006. Recent studies conducted from January to June 2007 and in 2008 identified two new locations in the region of Marahoué (department of Bouaflé), relatively far from the previously known ones and confirmed the disappearance of the species in Mounts Tonkpi and Boho. The distribution of this species was mapped and some ecological characteristics observed in those different locations were specified. The conservation status of the species was also assessed and discussed on the basis of the threats that its habitats were liable to, using the criteria of the IUCN Red List. The species can be characterized as rare in Côte d’Ivoire. Key words: Rare species, Conservation status, Nuxia congesta, Côte d’Ivoire INTRODUCTION The evaluation of the state, of the trends of the biodiversity and the identification of the habitats The loss of the biodiversity is presently a crucial subjected to particular threats constitute the two main problem for conservationists and for ecologists. The objectives of the Convention on Biological Diversity biodiversity of Tropical African countries represents a (CDB, 2001). In this respect, three attributes of the very important part of the global biological diversity biodiversity particularly draw the attention of the (Myers et al., 2000; Brooks et al., 2001). The international community: the species’ richness, the knowledge of the biological diversity in tropical Africa richness of rare and endangered species, and the began with the works of the first colonial endemism (Caldecott et al., 1996). These rare and administrators. It continued with the first botanists threatened species are indicator species for the until present time. In Côte d’Ivoire, the botanical functioning of the ecosystems, and can inform about investigations began in 1882 with Chaper (Aké-Assi, an imminent degradation of the biodiversity elements 2001) in the regions of lagoons and continued on all (Golding, 2002). They are likely to replace those that the Ivorian territory. The collections allowed listing a are presently abundant in case of important change big quantity of plant species constituting the Ivorian in the ecological conditions. flora that is estimated at 3,853 species (Aké-Assi, 2001, 2002). If a significant number of the species of A red list of plant species is a fundamental tool for this flora is not threatened, a more reduced part biodiversity conservation. Indeed, in front of the high undergoes pressures due to the human activities on cost of the preservation of the habitats which contain the ecosystems that shelter them or directly on them. a biological diversity, these species have to benefit Other species are naturally rare or even threatened first and foremost from the efforts of conservation because living in fragile biotopes with fewer (Myers et al., 2000). For Côte d’Ivoire, there is a list populations. In this last group of habitats, the edges of rare and threatened species drawn up by Aké-Assi of rivers, mangrove, the swamp forests and (1998) and updated in 2001-2002. For western mountains appear as appropriate sites for choice Africa, there is also a list of Hawthorne (1996) and (Adou Yao et al., 2010). Poorter et al. (2004) who listed the rare, threatened Am. J. Sci. Ind. Res., 2011, 2(5): 774-785 and endemic species of western African forests. The conservation status of this species, its distribution, Red List of the IUCN lists on a precise criteria, the and its structural parameters, as well as its threats to the species. It thus allows to take companion species were analyzed in this study. measures and to establish conservation priorities MATERIEL AND METHODS (IUCN, 2001, 2003). The lists of fauna and flora are established for every State of the World. The IUCN Study area: The study took place in two densely list concerning the Ivorian flora published in 2009 populated administrative regions of Côte d’Ivoire: the contains 129 species among which the threat status regions of the ‘18 Montagnes’ and of the ‘Marahoué’ of 120 at least have to be updated because of the (Figure 1). The first region, as its name suggests, is lack of recent works. the highest peak in Côte d'Ivoire. The elevations range from 500 to 1,000 m a.s.l. Among plants which live in threatened covers such as the vegetation of mountain, there is Nuxia Several mountains can be met in the ‘18 Montagnes’ congesta (Buddlejaceae), an orophyte species, met such as Mount Tonkpi (1,189 m a.s.l) and Mount for the first time in Mounts Tonkpi and Boho in the Boho (760 m a.s.l.) near the village of Zoanlé (Zonlé) West of Côte d’Ivoire, in the region of Man. The about 24 km from the city of Man (Figure 2). Fig 1: Map of population density and location of the administrative regions of the study sites. 775 Am. J. Sci. Ind. Res., 2011, 2(5): 774-785 Fig 2: View of the landscape around Man from Mount Tonkpi (Photo Assi, 2009). It can be noticed the mountainous landscape and the dominate. Until 2006, Nuxia congesta was known city of Man (in background). only on Mounts Tonkpi and Boho. Thanks to an The mean annual temperatures are about 27°C. The environmental impact study in the region of the region belongs to the mountainous sector of the ‘Marahoué’ in January 2007, the species was Guinean domain (Guillaumet and Adjanohoun, 1971), encountered randomly on the hills at 250 m and 600 which is covered by mountain vegetation as defined m a.s.l. by Yangambi (1956) (Guillaumet and Adjanohoun, Data collection: 1971). The summit of Mount Tonkpi includes, in Herbarium data: Materials of N. congesta from the addition to communications facilities, an interesting two following Herbaria specimens were studied agricultural station that hosts introduced species such (Table 1): National Herbarium of Côte d’Ivoire as quinquina (Cinchona officinalis and C. succirubra), (Herbarium Ivorensis, UCJ) located in the ‘Centre tea (Cameliea sinensis), pines (Pinus sylvestris, P. National de Floristique’ of the University of Cocody- patula).. The vegetation of Mount Tonkpi is a Abidjan and the National Herbarium of France transition to the semi-deciduous forest. Uapaca (Herbarium Musei Parisiensis, P) hosted by the esculenta, Uapaca guineensis, Chidlowia sanguinea, National Museum of Natural History in Paris. This Tarrietia utilis, and Chrysoplyllum perpulcrhum are review helped to notice the sites where the species the dominant species of this vegetation. samples were recorded. To identify the occurrence The second study site is located in the administrative zones in Africa and in World, on the basis of different Department of Bouaflé, precisely at Kossou, in the works (Palmer and Pitman, 1972, Bouquet and Centre West of Côte d’Ivoire. This zone belongs to Debray, 1974, Govaerts, 2006). Taxonomically, the mesophilic sector of the Guinean domain. Its Nuxia congesta belongs to plant families of vegetation corresponds to that of a mountain dry Buddlejaceae and Stilbaceae according to the forest occupying hilltops (N’Da et al., 2008) where classification adopted (Table 2). Zanthoxylum spp and Anthonotha crassifolia Table 1: Summary of specimenas visa with information on places of deposit. Locality of harvest Collectors, n° de record, place of deposit Mount Tonkpi February 16th 1964 L. Aké-Assi 7361 UCJ Mount Tonkpi January 10th 1970 L. Aké-Assi 11006 UCJ Mount Tonkpi s.d. Leeuwenberg & Bouquet 3867 P Haut Sassandra, Mount Boho (760 m) near Zoanlé May 6th 1909 A. Chevalier 21494 P Mount Tonkpi December 1952 Miège & L. Aké-Assi 1986 P - 1932 Service Forestier Côte d’Ivoire1011 P Herbarium Musei Parisiensis (P), Herbarium Ivoriensis (UCJ). 776 Am. J. Sci. Ind. Res., 2011, 2(5): 774-785 Table 2: Taxonomic position of Nuxia congesta R.Br. ex Fresen according to the classification of Cronquist (1981) or APG 3 (2009). Taxonomic position of Nuxia congesta according to of Taxonomic position of Nuxia congesta according to the CRONQUIST (1981) classification APG3 (2009) Règne : Plantae Règne : Plantae Sous-règne : Tracheobionta Sous-règne : Tracheobionta Division : Magnoliophyta Division : Magnoliophyta Classe : Magnoliopsida Classe : Magnoliopsida Sous-classe : Asteridae Sous-classe : Asteridae Ordre : Scrophulariales Ordre : Lamiales Famille : Buddlejaceae Famille : Stilbaceae Genre : Nuxia Genre : Nuxia Espèce : Nuxia congesta Espèce : Nuxia congesta Field data: The identified localities of occurrence of and on the sites of the region of the ‘Marahoué’. The Nuxia congesta and some other localities presenting mapping was performed using the software Excel similar elevations and vegetation were visited twice in and Arcview 3.2. the region of the ‘18 montagnes’ and its surroundings The works of Keay and Hepper (1954, 1972), White during 2006 and 2009. The visited sites of the ‘18 (1983), and Aké-Assi (2001, 2002) were used to montagnes’ were named S1 on mount Tonkpi and S2 supplement the localities of occurrence in Côte on mount Boho. d’Ivoire. Plant species richness and diversity in the 10 In the region of the ‘Marahoué’, eight (8) field visits circular plots were estimated using the software were conducted during 2007 and 2009, one visit Estimate S 8.10.