Nigeria has extensive mangrove forests in the coastal region of the Niger Delta. Considered one of the most ecologically sensitive regions in the world, the Niger Delta mangrove forest is situated within a deltaic depositional environment. These mangrove forests serve a critical role in regional ecological and landscape composition, and support subsistence gathering practices, and market-based income opportunities.
Overview
Mangrove forests are found in 118 countries and territories worldwide,Giri, C. et al. Status and distribution of mangrove forests of the world using earth observation satellite data. Glob. Ecol. Biogeogr. 20, 154–159 (2011). 75% of mangrove vegetation zones are located in intertidal tropic and sub-tropic habitats situated between 25° N and 25° S . Typically surrounding salient river deltas, mangrove regions support a variety of halophytes. These robust shrubs and trees, which have adapted to changing coastal conditions (such as inundation, sun exposure, anaerobic soil, and salinity concentration), play a substantive role in cultivating the biodiversity and wellbeing of the surrounding landscape.
The Niger Delta mangrove is the third largest in the world and the largest in Africa. Since the 1960s oil and gas exploration has become an important economic activity, resulting in significant alteration of the landscape via pollution, urbanization and invasion.
African mangroves have faced significant challenges in recent times, experiencing substantial losses. The decline, devastation, and deterioration of mangrove forests can be linked to several factors such as urbanization, quarrying, salt and sand extraction, pollution from industries and agro-industrial chemicals, as well as petroleum and gas exploitation. Additionally, the absence of adequate legislation and deforestation for fish smoking contribute to this issue. The mangrove forest zone in Nigeria not only enhances the socio-economic prosperity of rural coastal communities but also holds promise in shielding them from severe weather occurrences intensified by climate change. The anticipated rise in sea levels is expected to heighten flooding in coastal areas at lower altitudes, subsequently amplifying the physical and socio-economic susceptibilities of coastal urban centers. Nigeria has been acknowledged as one of the most susceptible African nations to climate change, and its impacts are currently manifesting in various regions of the country.
In Nigeria, there are more than 2,000 industrial facilities, with approximately 80% of them concentrated in the coastal areas, particularly in urban hubs like Lagos, Port Harcourt, and nearby regions. The industries in Nigeria's coastal zone encompass a range of sectors including oil and gas, petrochemicals, iron and steel, fertilizer plants, aluminum smelting plants, as well as diverse manufacturing industries such as textiles, food processing, plastics, pharmaceuticals, cement production, soap and detergent manufacturing, paint production, brewing, and wood pulp and paper production.
Biological composition Biologically, six mangrove species make up these forests, including three species in the family Rhizophoraceae (Rhizophora racemosa (red mangrove; tall), Rhizophora harrisonii (red mangrove; dwarf), Rhizophora mangle (red mangrove; dwarf)), and species in the family Avicenniaceae (white mangrove) and Combretaceae.Abere, S.A. and B.A. Ekeke. The Nigerian Mangrove and Wildlife Development.1st International Technology, Education and Environment Conference, September 2011, Omoku-Rivers State, Nigeria Date of Conference. Unpublished Conference Paper. Rivers State University of Science and Technology, Port Harcourt, 2016. Print. Of these species, Rhizophora racemosa occupies the greatest density of the forest, accounting for approximately 90% of all mangrove biota. Despite expansive geographic coverage, the Niger Delta mangrove forest has approximately 80% of its vegetation distributed in three states (Bayelsa, Delta, and River states).
Although the forest is composed of six mangrove species, mangrove growth is primarily situated in brackish muddy creek banks. Studies have indicated that Rhizophora racemosa (which is the tallest mangrove species) reaches its optimized growth potential when exposed to brackish water and soft mud, whereas R. racemosa'''s relatives, R. mangle and R. harrisonii, favor higher salinity and hard mud. In its natural state, mangrove soil or "chikoko" (a mixture of acid sulphate, silty clay, clay loam and peat), has a pH of 4 and 6 for mangroves inhabiting low-tide and high-tide locations, respectively.Adedeji, O.H., Ibeh, L., and F.F. Oyebanji. Sustainable Management of Mangrove Coastal Environments in the Niger Delta Region of Nigeria: Role of Remote Sensing and GIS. Proceedings of the Environmental Management Conference, 2011, Abeokuta, Nigeria. Unpublished conference paper. Federal University of Agriculture, Abeokuta, 2016. Print. If salinity levels shift too much from these levels, mudflats become unsuitable for mangrove production, and the process of mangrove reforestation (from infertile mangrove land to productive mangrove mudflat) can take upwards of one century.
Distribution of mangroves in Nigeria In the coastal areas of Nigeria, the mangrove forest is distributed as follows:
Lagos, a coastal area in Nigeria, has a total expanse of 42.20 square kilometers. Within this area, specifically 3.13 square kilometers, are designated as forest reserves. This portion within the forest reserves represents 7.42% of the overall area of Lagos. Essentially, this signifies that a small but significant part of Lagos is designated as a forest reserve, contributing to the preservation and conservation of the region's natural habitats and ecosystems. In Ogun, a region in Nigeria, the total area covered by mangroves is 12.18 square kilometers. Interestingly, unlike some other areas, there are no mangrove areas specifically designated within forest reserves in this region. This implies that all the mangroves in Ogun are in non-reserve areas, lacking the protective designation of a forest reserve. This situation could have implications for conservation efforts and suggests that mangrove preservation and management in Ogun may need to rely on other forms of protection and sustainability initiatives beyond designated reserves. In the region of Ondo, Nigeria, mangroves cover an area of 40.62 square kilometers. However, unlike some other regions where mangroves may be allocated within forest reserves for protection and management, Ondo does not have any mangrove areas designated within forest reserves. This means that all the mangroves in Ondo are situated outside of the officially designated forest reserve areas. This lack of mangroves within forest reserves can influence the conservation and management approach for these important ecosystems in Ondo. Preserving mangroves in this region would likely necessitate alternative strategies and efforts aimed at safeguarding them outside of formal reserve designations. It underscores the importance of comprehensive conservation measures and sustainable practices to ensure the continued health and vitality of the mangroves in Ondo. In the Edo/Delta region of Nigeria, the mangrove forest area covers a substantial 3,470.32 square kilometers. Within this extensive area, 143.75 square kilometers of mangroves are located within designated forest reserves. This signifies that approximately 4.14% of the total mangrove area is officially protected within these forest reserves. Having a portion of the mangrove area within forest reserves is vital for their preservation and sustainable management. The forest reserves serve as protected zones where activities detrimental to the mangroves, such as indiscriminate logging or habitat destruction, are regulated or prohibited. This helps maintain the ecological balance and the diverse array of flora and fauna that depend on mangrove ecosystems. In the Rivers/Bayelsa region of Nigeria, the mangrove forest area spans a vast 5,435.96 square kilometers. Within this extensive expanse, 90.62 square kilometers of mangroves are designated within forest reserves. This indicates that approximately 1.67% of the total mangrove area is safeguarded within these specific forest reserves. In the Cross River/Akwa Ibom region, the mangrove forest spans an expansive area of 721.86 square kilometers, and within this expanse, 67.19 square kilometers fall under the protection of forest reserves, accounting for a notable 9.31%. Altogether, considering all regions, the total mangrove forest area amounts to an impressive 9,723.14 square kilometers, with 304.69 square kilometers nestled within designated forest reserves.
Socio-ecological vitality
The Niger Delta mangrove forests play critical roles for 60% of local peoples who rely on the land and sea for survival. The forests contribute local therapeutic, amenity, heritage, spiritual, and existence values. Responses from a survey conducted in 2007 and 2008 evaluating mangrove social value in three Niger Delta communities indicated approximately 85% of participant households had previously utilized mangrove vegetation as a medicinal remedy and between 65% and 71% of villagers recognized the mangrove forests as a place of repose. The Niger Delta mangrove forests directly (through raw materials) and indirectly (through forest-based products) offer economically beneficial resources for Nigerian rural and urban communities alike, with eight out of the ten most lucrative vocations dependent on thriving mangrove populations. These occupations include canoe carving, logging, timber harvesting, building, fishing, sawmilling, traditional medicine, and trading.
Threats to mangrove survival There are many environmental threats to the mangrove forests in the Niger Delta.