Research Article
Ethnobotany and Biodiversity Conservation in the Niger Delta, Nigeria
Department of Botany and Ecological Studies, University of Uyo,P.M.B. 1017, Uyo. Nigeria
Biodiversity is a concept that involves different facets of biological variety (Peters, 1991; Khan et al., 2003; Duchelle, 2007) including inter alia, taxonomic richness, genetic differences in each taxon, communities, ecosystems, landscapes within which organisms inhabit and the indigenous knowledge of nature possessed by the natives living on the land (Kunwar et al., 2009). Biodiversity is thus a prized variety of interwoven moral, aesthetic, utilitarian and economic reasons. The role of biodiversity for agriculture and medicine is often underestimated. Plant breeding often turns to wild relatives and increased genetic materials from them (Spellerberg, 1995; Abioye et al., 2009). The biodiversity of the Niger Delta is intimately associated with the habitat diversity, each supporting diverse and distinctive plants and animals within their niches, some endemic to the region.
The Niger Delta region of Nigeria is particularly important for its oil exploitation. In addition, its vast plants and animal resources have also been immensely exploited. Niger Delta occupies 37700 km2 of the 923700 km2 land area of Nigeria (Fig. 1). It is situated in the Southern most part of Nigeria and bordered to the south by Atlantic Ocean. It comprises eight states of Nigeria: Akwa Ibom, Bayelsa, Cross-River, Delta, Edo, Imo, Ondo and Rivers. The area is essentially a lowland belt about 30 m below sea level. The area supports about 19.21 million people and various densities of live-stock. These exert pressure on the resources in addition to oil exploitation by numerous multinational companies. Plants and animal species of economic importance are threatened or endangered. Endemic species of ecological importance are also threatened and need be conserved.
Rural communities, in this region, depend on their interactions with plants for commercial values and thus exploit, albeit, sustainably their environment, including forests. Exploitation of these forests (can) jeopardize certain species existence or even lead them to extinction. Commercial values of the plants are the direct and indirect economic, aesthetic and ethical values. Emphasis on direct commercial value of forest products is placed on a small number of timber species and a short term profit derived from portions of forests for agricultural purposes. Multi-use exploitation and conservation of forest resources, as practiced by these rural communities, have not been adopted as a viable alternative to modern production schemes (Clay, 1998; Gorman et al., 2006). From ecological perspective rural communities can achieve production in harmony with natures laws that their production capacity tends to maintain the renewing capacity of the ecosystems, albeit, forests (Hamayun et al., 2006). From this standpoint, the sum of empirical knowledge that the people in the Niger Delta region possess about plants, soils, climate and ecophysiographic units serving their production strategy becomes important in unciphering and understanding traditional economic rationality.
Fig. 1: | land area of Nigeria Thirteen study sites |
Each method of production reveals a strategy of appropriation from nature, a mix of technologies, knowledge about the components of the ecosystems and its interrelations (Bussmann et al., 2008). These depend upon forest compositions, species abundance, appreciation and usage of the species by the native (Sofidiya et al., 2007; Vargas-Ponce et al., 2007; Banzouzi et al., 2008a, b). Due to exploration and exploitation of crude oil much of the area has been polluted and the needed medicinal plants and other useful non-timber species have been going extinct. Little attention has been paid to this seemingly unnoticed but important degradation and elimination of species much averred by the indigenous people of the Niger Delta. Thus, this study attempts to assess the values of forests and their species viz-a-viz the diversity of uses the plants species have been put to and marketed or traded by the natives. An attempt has also been made in eliciting and proffering conservation method(s) the natives should practice in order to protect and preserve these plants for posterity.
Study sites: The Niger Delta, one of the worlds largest wetlands in southern Nigeria, is a vast flood plain (over 2000 km2) built up by the accumulation of sedimentary materials washed down the Niger and Benue Rivers (Rangeley et al., 1994). It comprises four ecological zones; coastal barrier islands, mangrove swamp forest, freshwater swamp forest and low land rainforests. The later two forests are the most extensive ecological zones in the region. However, anthropogenic activities (timber and fuelwood removal, cultivation, capital project development, oil exploration and exploitation) are fast degrading these and their biodiversity.
The region is located between latitudes 3° 45'E and 8°10N and longitudes 3°50'E and 9°75'E. The area experiences two main seasons: wet and dry seasons. The wet season is about 7 months in duration from April to October. The dry season lasts about 5 months beginning from November and ending in March. The mean temperature for the area is 25°C; annual rainfall, 4921 mm and relative humility, 85%. The main crops are cassava, Manihot esculentus Krantz, Cocoyam, Colocasia antiquorum Schott, yam, Dioscorea sp. and oil palm, Elaeis guineensis Jacq.
Six out of eight states in the region were selected for the study: Akwa-Ibom, Bayelsa, Cross River, Delta, Imo and Rivers. Selection was based on previous knowledge, experience and cumulative work (unpublished) done in these areas by the author. Thirteen study sites (Fig. 1) were chosen for the study: two in each state except Rivers with three sites.
Field study was conducted for four years (2002, 2004, 2006, 2008) for both wet and dry seasons. The vegetation (freshwater swamp and lowland rainforests) was sampled systematically within 1x10 m quadrats along established transects and randomly throughout the sampling areas. Interviews with different informants were also conducted as to the type of species found in the areas, the use they are being put to and the methods used in conserving the species. The Shannon-Weiner species diversity was used to assess the species quantitatively (Sokal and Rholf, 1995) according to the formula:
Where:
H1 | = | Shannon-Weiner index |
S | = | Number of species |
pi | = | Proportion of individuals or abundance of the ith species expressed as a proportion of the total number of individuals of all species |
In | = | log base10 |
Endangered and endemic species were recorded; identification of species was accomplished by the assistance of Forestry Institute of Nigeria (FRIN) herbarium and texts (Hutchinson and Dalziel, 1954-72; Akobundu and Agyakwa, 1987). Classification of ethnobotanical uses of species involved interviews, complimented by literature (Sofowora, 1982; Kokwaro, 1995; Etukudo, 2000, 2003). Diversity of uses was calculated using Shannon-Weiner index (H1 = Σpi log pi) where i = uses and pi = proportion of species for the ith use (Rico-Gray et al., 1991). Sorensen index (S.I = 2a/a+b+c) was used to calculate species similarity between sites; a = number of species common to sites compared, b = number of species in site 1 and c = number of species in site 2.
Plant diversity: Three hundred and thirty nine plant species were encountered in the forests and homestead gardens in the study area (Table 1, 2). Of these, 206 species were recorded for the forests and 79 species for the homestead gardens. All the 339 species belong to 88 families (44 families for forest, 44 for gardens) and 266 genera (205 for forests, 61 for gardens). Fabaceae has the highest number of species (45), followed by Euphorbiaceae (25), Rubiaceae (12) Apocynaceae (11), Asteraceae (11) and Cecropiaceae (10). The species diversity index between the forest and the homestead gardens is 4.89. Species similarity index among the forest is low (47.78%) where 147 species are common to all forests. Similarity index between the homestead gardens is high (49.5%) as 76 species are common to the gardens.
Diversity of uses of plant species: All plant species have at least one reported use. Two hundred and fifty nine forest species and eighty homestead garden species are used for at least a single purpose (Table 1, 2). Species with more uses include Elaeis guineensis (12), Raphia hookeri (12), Cocos nucifera (11), Irvingia gabonensis (11), Hevea brasiliensis (9), Lonchocarpus cyanescens (9), Lovoa trichilioides (9), Pterocarpus santalinoides (9), Dacryodes edulis (8), Khaya grandifoliola (8), Lophira alata (8), Anthocleista vogelii (8), Pachystela brevipes (8) and Symphonia globulifera (8). Ethnobotanical use with more species include Medicine (178/52.5%), Fuel (107/31.6%), Food/condiment (100/29.4%), Timber (72/21.2%), Food/feed (70/20.6%), Commercial (58/17.1%), Furniture (55/16.2%) Fibre/cordage) 55/16.2%), Homestool (45/13.2%) and Fence (38/11.2%). These figures are inappropriate for medicinal and fuel plants as almost every species is used in healing a disease or is used as fuelwood. Diversity index for species ethnobotanical use is high, 7.9 for forest species and 5.0 for homestead garden species. This is indicative of the multiple uses the species are put to.
There is an indication that people from rural areas within the study areas use more forest and homestead garden species than people in towns as the former places are more distant and isolated villages. The surplus forest produce is traded locally. The people in better-communicated towns buy and sell their produce in well-organized markets in and around the towns. Thus, the use of forest and homestead garden produce in the Niger Delta communities is affected by communication systems such as roads and transport.
Economic importance of the forests plants: The type, quality and quantity of resources from the Niger Delta forests have diverse uses (Etukudo, 2000). More important are the timber species (Antiaris africana, Albizia zygia, Brachystegia enrycoma, Ceiba pentandra, Diospyros alboflavescens, Erythrophleum ivorense, Funtumia elastica, Hallea stipulosa, Hannoa klaineana, Hylodendron gabunense, Khaya grandifoliola, Lannea welwitschii, Lovoa trichilioides, Nauclea diderrichii, Oxystigma mannii, Staudtia stipitata, Tripochiton scleroxylon and Uapaca togoensis); the fruit species (Canarium schweinfurthii, Dialium guineense, Irvingia gabonensis, Maesobotrya bateri, Microdesmis peberula, Momordica charantia, Pentaclethra macrophylla, Synsepallum dulcifilum and Tetracarpidium conophorum); the spices, flavouring and thickeners (Aframomum melegueta, Irvingia gabonensis, Piper guineense, Tetrapleura tetraptera, Xylopia aethiopica); the beverages (Cocos nucifera, Elaeis guineensis, Ananas comosus, Annona muricata, Sacoglottis gabonensis and Synsepalum dulcificum) and the medical species (Table 3).
Table 1: | List of plant species encountered in the forests of study areas. Nomenclature follows Hutchinson and Dalziel (1954-72) and Akobundu and Agyakwa (1987) |
Ethnobotanical uses: 1: Bait, 2: Building, 3: Toothbrush, 4: Commercial, 5: Dyes, 6: Fence, 7: Fibre/Cordage, 8: Field-tool, 9: Fodder/Feed, 10: Food/Condiment, 11: Fuel, 12: Furniture, 13: Gum/Resins, 14: Handcrafts, 15: Home Tool, 16: Latex, 17: Medicine, 18: Oil, 19: Oranmental, 20: Plaiting/Weaving, 21: Religious/Cultural, 22: Soap, 23: Spice/Flavouring, 24: Stimulant, 25: Sweetners, 26, 27: Timber, 28: Toxic, 29: Work tool, 30: Wraps/Packing. *Endangered species. **Endemic species |
Table 2: | List of plant species present in the homestead gardens in the study areas. Nomenclature and ethnobotanical uses of the species follow those in Table 1 |
Ethnobotanical uses: 1: Bait, 2: Building, 3: Toothbrush, 4: Commercial, 5: Dyes, 6: Fence, 7: Fibre/Cordage, 8: Field-tool, 9: Fodder/Feed, 10: Food/Condiment, 11: Fuel, 12: Furniture, 13: Gum/Resins, 14: Handcrafts, 15: Home Tool, 16: Latex, 17: Medicine, 18: Oil, 19: Oranmental, 20: Plaiting/Weaving, 21: Religious/Cultural, 22: Soap, 23: Spice/Flavouring, 24: Stimulant, 25: Sweetners, 26, 27: Timber, 28: Toxic, 29: Work tool, 30: Wraps/Packing.*Endangered species. **Endemic species |
The homestead gardens contain a great number of these species (Table 2).
The forests and animal diets: The forests are natural habitats of various animal species, some endemic to Nigeria (Cercopithecus sclateri, Cercocebus torquatus, Cercopithecus mona and C. nictitans). Some of the animals are important bush meat source most appreciated by the people of the Niger Delta. The most important venison of these forest are Cephalophus sp. and Thryonomys swinderianus. The population sizes of these animals have been greatly reduced due to indiscriminate poaching, habitat fragmentation and loss to various forms of anthropogenic activities including oil exploration and exploitation. The plant species used by Cephalophus sp. and T. swinderianus as food sources include those cultivated in homestead gardens (e.g., Colocasia sp., Corchorus olitorius, Curcubita moschata, Dioscorea dumentorium, Manihot esculentus, Solanum macrocarpum, Telfairia occidentalis and Zea mays) as well as the fruits of Elaeis guineensis, Irvingia gabonensis, Persea americana and Psidium guajava and those found in the forests: Alchornea cordifolia, Allanblackia floribunda, Centrosoma pubescens, Dialium guineense, Lonchocarpus cyanescens, Macaranga barteri, Maesobotrya barteri, Manniophyton fulvum, Microdesmis puberula, Pterocarpus sp. and Voacanga africana. The monkeys (Cercopithecus sp. and Cercocebus torquatus) feed on the above fruits species.
The forests as sources of building materials: The traditional house in the Niger Delta is built from the materials obtained from the forests. This is obvious in the more isolated villages. Materials for the buildings come from species such as Acioa barteri, Alstonia sp., Bambusa vulgaris, Berlinia grandiflora, Cocos nucifera, Elaeis guineensis, Klainedoxa gabonensis, Myrianthus arboreus, Uapaca sp. and Raphia hookeri among others. These traditional houses are fast disappearing and are being replaced by modern ones because over-exploitation of the forests had brought about scarcity of these building materials, the regenerating forests do not contain materials old enough to be used in building; it takes more time to search for and obtain available and needed materials; and since the advent of oil exploration and exploitation some of the rural dwellers who are gainfully employed want to have same standards of living as city dwellers (Rico-Gray et al., 1991). This has resulted in dwindling economic values of these natural materials and their turn-over rates.
Table 3: | Some uncultivated plant species identified for medical use in the Niger delta region, Nigeria |
It is suggested that rather than abandoning (the use of ) these materials, modern ideas should help improve the production, quality and sustainability of these natural materials, which will enhance their cost-benefit status and high turn-over rates. These could be used for alternative or different purposes.
Homestead garden produce: A variety of produce is obtained from the homestead gardens: fruits, flavouring, oils, ornamentals, spices, vegetables and thickeners in quantities that are sold or traded locally. Their commercial values can be enhanced if production is co-ordinated and harnessed effectively from the different villages to towns where they are in high demand. These can advance the per capita income of the producers and in turn improve their living standards.
Medical plants from the forests: The Niger Delta forests habour a large number of plant species known to be of importance in the medical and pharmaceutical industries. Alchornea laxiflora, Cnestis ferruginea, Fagara zanthoxyloides, Icacina trichantha, Piper guineense and Uvaria cristata are widely known and used as species of medicinal utility. Aspilia africana contains thiarubine -A in its root, a red oil that kills parasites, viruses, fungi and bacteria. Smilax kraussiana contains saponinic glycosides, resin and essential oil that promote elimination of urea, uric acid and other organic wastes as well as decreasing blood cholesterol level. Strophanthus sarmentosus is a source of drug called cortisone for the treatment of rheumatoid arthritis. Vernonioside -B1, is a constituent of Vernonia amygdalina which has an antitumoral and antibacterial properties. It is used in treating schistosomiasis. The list of some plants occurring in the Niger Delta forest with their medicinal values is presented in Table 3. The information contained therein is based on indigenous knowledge of the local people. The usage of the plants has been, in the main, through extracts or in raw form for ages. However, there is need for scientific analyses of these plants for proven efficacies by biochemists, pharmacognosists, pharmacologists and pharmaceutical industries.
Endemic and endangered plants species: A number of plants species in the Niger Delta forest are endemic and endangered (Table 1 and 2). Endemism and a number of sub-species presence in the study area are evidenced in phylogenetic plasticity and the dynamics of ecological and environmental perturbations (Khan et al., 2003).
The loss of plant biodiversity in the Niger Delta is precipitated by anthropogenic factors of over-extraction, unsustainable agriculture and forestry practices, pollution, land use changes, urbanization and probably global climate change. These culminate in biodiversity depletion and diminished productivity. Over extraction target species are those used as fuelwood, in medicine, in building, as timer and as fodder. Observations show that due to extensive use of plant species for these purpose, a large number of plants are endangered.
Conservation methods: An important element in the relationship between ethnobotany and conservation is the detailed knowledge of the components of biodiversity possessed by the natives over the years and the dynamics of the ecosystem. Through observations, assessments and experimentations, these natives have successfully adopted their production methods towards the characteristics of these biological resources. The possession of this biodiversity-related knowledge should be preserved through capacity building in order to compliment scientific knowledge and provide information on biological system (Singh et al., 2008). This will also make it possible for the socio-cultural, economic and religious significance of many plants to be transferred from generation to generation. This requires education strategies that will raise the level of awareness of the natives in the conservation of biodiversity.
The indiscriminate over-exploitation of plants that impinges on food security and health care should be avoided and halted. No wild plant species should be endangered through international trade. There should be the promotion of in situ and ex situ cultivation of the endemic, medicinal and more obvious economic species (Rana, 2007). Conservation of the plants should also take the form of systematic protection through breeding. The protected areas in form of groves and nature reserves in the region should be preserved. All these could be achieved through collaborative cooperation of governments, Non-governmental organizations (NGOs), community-based organizations (CBOs) the natives, schools, colleges and other higher institutions.
As biodiversity involves global environmental change, species extirpation or extinction and changes in societal values (Khan et al., 2003), ethnobotany offers an effective approach to plant biodiversity conservation, since this provides a wealth of data on timber and non-timber products which can be rationally exploited. Thus, commodities can be extracted from plant communities with minimal environmental damage and hence provide incentive for conservation. Conservation for diversity and stability, aesthetic, ethical, scientific values and utilitarian purposes is rooted in ethnobotany, which is the most cost-effect method to be practiced.
The economic importance of the tropical lowland rainforests rural dwellers in Niger Delta is emphasized. Though the natural environments of these forests have been modified by activities of man (arable farming, animal and oil exploitation, capital development, forestry production), the establishment of management systems that are flexible, adaptive and experimental would allow for sustainable exploitation while conserving them (Sayer et al., 2000). These management systems should involve immediate economic benefits by integrating components (e.g., agroforestry, agrosilviculture) that will promote and complement long-term economic benefits. In addition, enforcement of forests laws, improvement of forest policy and adoption of rules and regulations should be in practice (Li et al., 1999). When these strategies are combined with other vegetation studies and effectively applied, they would provide sustainable means of utilizing the natural resources of these forests and probably bring about compatibility of conservation of nature.
The author thanks the Akwa Ibom State Environmental Protection Agency, Uyo; Universal, Scientific and Industrial Company, Uyo and the Prodec-Fugro, Port Harcourt for their financial supports.
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