European Journal of Ecology, 7.1, 2021, pp. 1-11 ECOLOGY AND STRUCTURE OF DETARIUM MICROCARPUM GUILL. & PERL. POPULATION IN THE MBE PLAIN OF THE ADAMAWA, CAMEROON Georges Maxime Lamy Lamy1,4*, Adoum Dona2, Rosette Ndjib1, Martin Thierry Ottou Abe1, Talba Dalatou3, Constantin Amougou Alega4, Guidawa Fawa4, Obadia Tchingsabé5, Lei- la Zambou Zebaze1, Phalone Kenne Meli1, Germo Justine Nzweundji1, Néhémie Tchinda Donfagsiteli1, Jason Carver Aaron1, Bernard Dongmo1, Hubert Jean Claude Mbita Messi1, Adamou Ibrahima4 & Pierre Marie Mapongmetsem4 1Center for Research on Medicinal Plant and Traditional Medicine, Institute of Medical Research and Medicinal Plants Studies, P.O Box: 13033 Yaounde-Cameroon 2Department of Life and Earth Sciences, Faculty of Life Sciences, Earth and Territorial Planning, ATI University of Science and Technology, Chad, P.O Box: 9957, Ati, Chad 3Department of Industrial Chemistry and Environment, ENSAI, P.O. Box: 454, Ngaoundéré 4Department of Biological Sciences, Faculty of Science, University of Ngaoundere, P.O. Box: 454 Ngaoundere, Cameroon 5The Institute of Agricultural Research for Development (IRAD), Nkolbison, P.O. Box: 2067 Yaounde, Cameroon *Corresponding author, [email protected] Abstract. Background: In Africa, Detarium microcarpum Guill. & Perr. is a species of high cultural, ecological, and socio-economical importance. This led to its over-exploitation, increasing in situ rarity of this species. As a consequence, a conservation alert is increasingly reported across the continent due to the risk of extinction of this multipurpose plant. Unfortunately, indicators of regeneration and conservation guidelines for this species have not been developed yet. The objective of the study was to evaluate the habitat, population structure, and dendrometric characteristics of the plant which are indicators of sustainable conservation. Methodology: A floristic inventory, as well as the vegetation transect method, was used in the villages Def, Karna Manga, and Karna Petel located in Adamawa, Cameroon. The analysis of variance was used to compare dendrometric characteristics across villages. Results: A total of 109 individuals of the plant were counted with a density of 4 individuals per hectare. No plant individuals regenerated in human-controlled habitats (bush fields and home gardens). Three species Bombax( costatum, Piliostigma thonningii, and Terminalia macroptera) were the most frequent accompanying species, as well as the Cae- salpiniaceae family. Dendrometric characteristics showed a statistically significant difference (p ˂ 0.05) among sites. Regardless of the variable studied, the structure of the D. microcarpum population was unstable and its in situ conser- vation was more successful in Karna Manga. Conclusion: Conservation indicators (habitat, population structure and dendrometric characteristics: crown diam- eter, diameter at breast height, the height of first large living branch, and tree height) revealed that in situ conservation of D. microcarpum population was not sufficient to maintain this species in the study area. For sustainable conservation, less expensive and plant-specific ex situ domestication techniques are recommended to maintain species persistence in the studied region. Key words: Extinction risk, conservation biology, biodiversity loss, in situ conservation, preventive ecology, vege- tation transect. 1 Georges Maxime Lamy Lamy et al. – Ecology and Structure of Detarium microcarpum INTRODUCTION lows us to anticipate them. Indeed, in the short term, For any conservation science, in principle, the it makes it possible to prevent these actions from be- overall goal of conservation ecology is to preserve coming subjects of major concern. Especially since all life on Earth. This goal can be achieved by pre- there is a serious gap in the capacity for ex situ plant venting species extinction, which is of global con- conservation, especially in Africa, parts of Asia, the cern, characterized by causes, manifestations, and Caribbean, Latin America, and the Middle East (Sec- consequences. Globally, the causes of extinction of retariat of the Convention on Biological Diversity biodiversity, especially plant biodiversity, are geo- 2009). The International Union for the Conservation graphically and temporally related (Sax & Gaines of Nature has developed a guide: the Red List of Spe- 2008; Le Roux et al. 2019). For instance, in Ocea- cies at ‘Risk of Extinction’ (IUCN 1989), due to the nia, introduced plants, at a rate of 89%, are the main scientific problem posed by the risk of extinction. cause of the extinction of local plants (UNEP-WC- In Africa, Detarium microcarpum Guill. & Perr. MC 2016) because of competition for resources. In (Caesalpiniaceae) is a multipurpose agroforestry a study conducted in parts of Europe, 467 vascular plant still living in situ and highly valued by local plants were classified as threatened while 436 were populations (Kouyaté 2005; Bastide & Ouédraogo in decline due to urbanization, tourism, etc. (Bilz et 2008; Kini et al. 2010; Agbo et al. 2017). It reach- al. 2011; UNEP-WCMC 2016). In Africa, the uncon- es the height of 5 to 10 m (Kouyaté 2002; Kouyaté trolled harvesting of medicinal and aromatic plants 2007) and its fruits weigh from 0.67 to 1.17 g (Aja- is the main threat to the survival of many, mainly en- ni et al. 2019). As reported by Ky-Dembele (2011), demic species (UNEP 2010). According to multiple D. microcarpum is distributed throughout Africa in studies, anthropogenic factors directly or indirectly semi-arid and sub-Saharan areas from Senegal in caused most of the plant extinction, compared to nat- Cameroon to eastern Sudan. In Benin it colonizes lat- ural causes, e.g. droughts, winds, etc. (Sax & Gaines eritic soils (Amahowé et al. 2012; Agbo et al. 2019), 2008; Sodhi et al. 2009). The manifestation of ex- while in Mali it is an indicator of fertile soils. In tinction occurs when the last existing member of a Cameroon, precisely in the Sudano-Guinean savan- species disappears (Ehrlich 1981; Jablonski 2004; nas of the Adamawa, D. microcarpum compromise a Normile 2008). However, this disappearance does prominent element of the local population socio-eco- not occur suddenly but is followed by warming signs nomic life (Gautier et al. 2002; Mapongmetsem et (e.g. habitat destruction, a decrease of dominance, al. 2010; Mapongmetsem et al. 2012). Unfortunately, etc.; Tilman et al. 1994). The total disappearance of its persistence is threatened because of over-exploita- a plant in situ would lead to a chain of consequences, tion by illegal cutting of firewood (Mapongmetsem cultural, economic, ecological, political, and social. et al. 2008; Fawa et al. 2015; Mapongmetsem et al. For example, on the ecological level, this disappear- 2015; Lamy et al. 2020). The risk of D. microcar- ance could also lead to the disappearance of com- pum extinction is increasingly reported across Africa panion species with which there were interactions (Rapport du Tchad 2016; Agbo et al. 2017). Recent- essential to the balance of an ecosystem. ly, this plant has been mentioned among the priority At the socio-economic level, the World Health wild species for domestication in the Sahel (Atanga- Organization reports that in Africa, medicinal plants na et al. 2014; Agbo et al. 2019). Despite multiple play an extremely important role in public health extinction risk alerts on D. microcarpum across the policies (WHO 2003). Since the African populations continent, the plant’s status is not yet clearly defined mostly use local plants for their health, the leaders of by the IUCN (N’guessan 2019; Kone et al. 2020). the countries of Africa, especially sub-Saharan Afri- According to many authors assessment of the hab- ca, are investing more and more financial resources itat, the population structure and the dendrometric in research on medicinal plants. The disappearance characteristics (diameter of the crown, diameter at of such plants would therefore have very serious con- breast height, height of the first large living branch, sequences on the primary health of the 80% of local and height of the tree), the conservation status of a populations who, for the tradition and lack of mod- plant in its natural environment or ex situ are miss- ern medicinal facilities depend on medicinal plants. ing (Annapurna et al. 2013; Heywood 2014; Hey- Instead of waiting to react to the consequences of wood 2015). Studies carried out on this species did human actions, preventive conservation ecology al- not provide the indicators of conservation (habitat, 2 Georges Maxime Lamy Lamy et al. – Ecology and Structure of Detarium microcarpum population distribution, structure, and dendromet- Daniellia oliveri (Caesalpiniaceae) and Lophira lan- ric characteristics). Therefore, this study aimed to ceolata (Ochnaceae) (Letouzey 1968). The density contribute to the conservation of D. microcarpum of these species is decreasing due to anthropogenic through the improvement of knowledge in situ. action (Mapongmetsem et al. 2006). Comparison of the habitat, population structure, and dendrometric characteristics of Detarium microcar- Floristic inventory pum in three localities could help to determine where The floristic inventory and the vegetation transect the plant conservation is locally the most efficient, method were used in three sites (Def, Karna Manga, to indicate sustainable in situ conservation, and then and Karna Petel) according to the methods of Fiers to conclude local (study area) and global (areas of