Biodiversity loss and environmental change in Nigeria encompass the cumulative effects of interacting land-use, economic, climatic and institutional pressures. This section critically examines the principal drivers, including habitat transformation, agricultural expansion, resource exploitation, pollution, climate variability and governance deficiencies.

Synthesizing these dimensions provides an evidence-based foundation for assessing ecological vulnerability and strengthening integrated biodiversity conservation and environmental management in Nigeria.

2.1.1. Land-Use Change, Deforestation and Habitat Fragmentation

Land-use change is a fundamental pathway through which biodiversity is lost because conversion or degradation of natural habitat reduces ecosystem area, quality and connectivity. Studies demonstrate that this pressure remains substantial in Nigeria. Okoduwa et al. [6] reported substantial forest loss in Okomu Forest Reserve between 2000 and 2024, with forest loss exceeding forest gain and regrowth occurring in fragmented locations.

At a broader regional scale, Wingate et al. [7] estimated an almost 17% decline in structurally intact forest between 2000 and 2024 across Togo, Benin, Nigeria and Cameroon, alongside a roughly one-third reduction in protected areas connected by intact forest corridors. This is a four-country West African result, not a Nigeria-only estimate. It nevertheless illustrates the regional importance of maintaining corridors that connect protected areas. For Nigeria, the policy implication is to map and safeguard corridors, buffer zones and stepping-stone habitats while monitoring local changes with national and state-level data.

Comparative evidence from southwestern Nigeria also indicates that relatively less disturbed forest can retain stronger species diversity and structural characteristics than more disturbed protected forest [8].

2.1.2. Agriculture and Land Degradation

Agricultural expansion supports livelihoods and food security, but poorly planned expansion can replace natural habitats, reduce vegetation diversity, intensify soil disturbance and affect water systems. Evidence from Western Africa indicates that agriculture, logging and fire are among the pressures associated with perceived and measured forest degradation, while local perceptions do not always correspond closely with measurable ecological change [9].

FAO similarly emphasizes innovation in technology, institutions, policy and finance as important to sustainable forest management [5]. In Nigeria, agricultural land-use decisions should therefore be integrated with forest conservation, watershed protection and restoration planning, with greater emphasis on productivity within existing agricultural landscapes and biodiversity-compatible practices such as agroforestry.

2.1.3. Unsustainable Exploitation, Mining and Petroleum Activities

Illegal logging, hunting, mining and petroleum activities can remove biological resources directly while also altering habitats and local livelihood systems. Evidence from Cross River State demonstrates that conservation education, alternative livelihood support and anti-poaching patrols can contribute to biodiversity conservation in protected areas [10].

Human-wildlife coexistence research in Okomu and Cross River also shows the importance of community benefits and compensation mechanisms in reducing tensions around protected areas [11]. Evidence on threatened raptors in Nigeria further indicates that socio-cultural factors and human-wildlife conflict should be considered in species conservation planning [12]. Governance arrangements matter as well: research in Enugu and Cross River States found that forest policies and enforcement conditions shape local access and conservation outcomes [13].

These findings indicate that effective control of resource exploitation requires both credible enforcement and locally legitimate livelihood strategies.

2.1.4. Pollution and Gas Flaring

Pollution affects biodiversity through contamination of air, soil and water and through changes in ecological conditions. Industrial noise is an additional but often overlooked pressure; research in Okomu found that industrial activities can alter wildlife behaviour and contribute to wildlife displacement [14].

Gas flaring is especially important in petroleum-producing areas because it combines greenhouse-gas emissions with local environmental and socioeconomic risks. Okwilagwe and Olubusoye [15] estimated that 11.06 trillion cubic feet of associated gas were flared in Nigeria between 2002 and 2024, generating approximately 714.62 million tonnes of CO₂-equivalent emissions and direct revenue losses of about US$56.75 billion. These estimates quantify emissions and economic costs; they do not directly measure changes in species abundance, population viability or biodiversity. The biodiversity pathway is plausible where flaring co-occurs with habitat disturbance, air pollution, noise and associated oil-and-gas infrastructure, but it requires direct ecological monitoring to establish the magnitude of effects, generating approximately 714.62 million tonnes of CO₂-equivalent emissions and direct revenue losses of about US$56.75 billion.

These findings strengthen the case for credible monitoring, transparent reporting, effective penalties and improved gas utilization.

2.1.5. Freshwater, Coastal and Marine Biodiversity

Nigeria’s aquatic biodiversity is exposed to pressures that differ by ecosystem but often originate from connected catchment and coastal processes. In freshwater systems, untreated municipal and industrial effluent, agricultural runoff, sedimentation, dams, wetland conversion, overfishing and destructive fishing practices can degrade spawning and nursery habitats and alter water quality. In estuaries and coastal waters, oil spills, produced water, plastics, shoreline development and mangrove removal affect fish, invertebrates, birds and the habitats on which fisheries depend. A recent assessment combining remote sensing and field evidence estimated that Nigeria lost 4.5% of its mangrove area between 1990 and 2023; oil-spill pollution was identified as the direct cause of at least 37% of mangrove ecosystem loss, while the invasive Nypa fruticans palm dominated nearly 10% of mapped mangroves by 2023 [16]. Research on Niger Delta contamination has also reported elevated petroleum hydrocarbons in sediments and water, with exceedances of relevant quality criteria indicating likely risks to aquatic and sediment-dwelling organisms [17]. These findings are Nigeria-specific, although they do not represent every freshwater or marine ecosystem in the country. They support routine water-quality and biological monitoring alongside spill prevention, wetland protection, sustainable fisheries management and restoration of native mangrove communities.

2.1.6. Invasive Alien Species

Invasive alien species can compete with native species, alter habitat structure and disrupt ecosystem processes; IPBES identifies them among the major direct drivers of global biodiversity loss [1]. They warrant inclusion in a Nigeria-focused review because their effects can extend from changes in vegetation composition to altered habitat availability and ecosystem functioning.

A particularly well-documented Nigerian example is the introduced mangrove palm Nypa fruticans in the Niger Delta. Using field surveys and multiple remote-sensing datasets, Fatoyinbo et al. estimated that Nigeria lost 4.5% of its mangrove area between 1990 and 2023; by 2023, Nypa dominated approximately 93,178 ha, close to 10% of the mapped mangrove area, after expanding by about 70,000 ha over 15 years [16]. The same study attributed at least 37% of mangrove ecosystem loss to oil-spill pollution [16]. These results show that invasive-species spread and petroleum pollution can act together, although the reported area estimates should not be interpreted as direct measurements of all associated species-level effects. Priority actions include mapping invasion fronts, monitoring native mangrove recovery, testing site-appropriate control methods and preventing further spread. Comparable, consistent national data for other invasive species and freshwater systems remain a monitoring need.

2.1.7. Climate Change and Environmental Variability

Climate change interacts with existing ecological pressures by altering temperature, rainfall patterns, drought risk, fire regimes and species’ suitable habitats. IPBES identifies land- and sea-use change, direct exploitation, climate change, pollution and invasive alien species among the major direct drivers of biodiversity loss [1].

Yahaya et al. [18] explained the value of combining remote sensing and species-distribution modelling to identify vegetation condition and habitat suitability under environmental variability.

This evidence supports an integrated approach in which climate adaptation is considered alongside habitat protection, restoration and resource governance rather than treated as a separate environmental agenda.

2.1.8. Governance and Environmental Monitoring Constraints

Governance determines whether environmental policies are translated into consistent action. Nigeria’s revised NBSAP provides a stronger national policy platform, but implementation requires coordination among federal and state institutions, local governments, communities, researchers, civil society and the private sector [4].

Evidently, monitoring technologies can improve the spatial identification of forest disturbance and recovery. UAV LiDAR and multispectral data, for example, have been successfully integrated to map disturbance severity in a West African forest patch [19], while newer remote-sensing research emphasizes multi-sensor approaches for evaluating forest recovery [20].

The governance requirement is therefore not simply more data, but institutional arrangements that connect data to planning, enforcement, budgeting and conservation decisions.

Table 1 shows the synthesis of evidence for this study.

Table 1. Evidence synthesis.

Source: Authors’ synthesis of the reviewed evidence.

Nigeria needs to shift from the current emphasis on protecting discrete areas towards ensuring ecological connectivity between diverse habitats. Federal and state environmental authorities should identify critical corridors, buffers, biodiversity hotspots and other priority areas using GIS and remote sensing, and incorporate them into spatial plans and development-containment decisions.

Protected area management should be supported by patrolling and community supervision and clear accountability structures. This directly addresses KMGBF Targets 1 and 3 on biodiversity-inclusive spatial planning and effectively conserved, well-connected areas [3].

Priority actors: Federal and State Ministries responsible for environment and forestry, protected-area agencies, planning agencies, research institutes and host communities.

Indicator: Area of priority habitats and ecological corridors mapped, acknowledged and under active management.

Restoration efforts need to focus on ecological function and not merely on tree planting. Restoration should set out species lists, degraded riparian zones, forest reserves, mangroves and other priority ecosystems and include maintenance and survival monitoring in project budgets.

Nigeria can use forest-inventory information and geospatial monitoring to set baselines and assess restoration. This reflects KMGBF Target 2, which calls for effective restoration of degraded terrestrial, inland-water, coastal and marine ecosystems [3]. Recent remote-sensing research supports the use of multiple sensors to separate out structural recovery from simple increases in canopy greenness [20].

Priority actors: Forestry agencies, states, communities, NGOs and development partners.

Indicator: Hectares under verified ecological restoration and percentage of restoration sites meeting survival or ecosystem-function targets.

Agricultural policy needs to discourage the conversion of high-biodiversity ecosystems while seeking to intensify production from already-cultivated land. Agroforestry, soil conservation, integrated watershed management and climate-smart practices can reduce pressure on natural habitats.

Biodiversity considerations should be part of agricultural extension, land-use planning and infrastructure appraisal. This is consistent with the NBSAP’s mainstreaming approach and supported by evidence that agricultural pressure is closely linked to forest degradation in Western Africa [4][9].

Priority actors: Federal and State Ministries responsible for agriculture and the environment, extension services, local government and farmer organisations.

Indicator: Proportion of priority agricultural landscapes under biodiversity-friendly land-management practices.

Environmental enforcement should target those activities with the highest ecological and social costs. This requires improved field supervision and clearer licensing and traceability for timber and minerals, improved prosecution for major wildlife offences, pollution monitoring and credible deterrents for non-compliance.

In petroleum-producing areas, independent verification of gas-flaring volumes should be made and reported and investments in gas gathering and utilization should be undertaken with an eye to environmental protection. Studies highlight the scale of Nigeria’s cumulative flaring emissions and economic losses and identify weaknesses in infrastructure and regulation that constrain progress [15].

Priority actors: Environmental regulators, petroleum regulators, security agencies, state governments and operators.

Indicator: Verified reduction in illegal extraction incidents, pollution exceedances and routine gas-flaring volumes.

Nigeria needs to strengthen biodiversity and environmental monitoring systems that are interoperable, making use of satellite, field, community and administrative data and accessible to researchers and to planning agencies.

These indicators should routinely be used for budgeting, enforcement and policy appraisal. Community participation should go beyond consultation and include conservation education, livelihood incentives and meaningful roles in monitoring.

Experience in Cross River demonstrates positive contributions from conservation education, alternative livelihoods and anti-poaching patrols, while research on sacred groves demonstrates that working with customary institutions and formal governance systems can be key to long-term biodiversity protection [10][21].

Priority actors: Federal and State Governments, research institutes, universities, communities, NGOs and development partners.

Indicator: Frequency of biodiversity-monitoring updates, proportion of priority ecosystems with current spatial data and number of communities participating in conservation monitoring. Table 2 shows the proposed monitoring framework for this study.

Table 2. Proposed biodiversity monitoring framework for Nigeria.

Source: Authors’ proposed framework. Agencies listed are proposed lead or data-holding institutions; responsibilities should be confirmed against current statutory mandates and state-level arrangements. Where no consistent national ecological baseline is available, the first verified survey should be documented as the baseline rather than presenting an unverified value.

The evidence indicates that Nigeria’s biodiversity problem is a landscape-governance issue. Forest loss, wildlife exploitation, agricultural expansion, pollution and petroleum activities do not act independently or additively but can interact to produce cumulative impacts when biodiversity is fragmented in a context of weak environmental governance and limited community livelihood options. The Okomu evidence indicates the value of landscape-scale monitoring, and the West African connectivity study indicates that conservation gains can be compromised if protected areas are increasingly isolated [6][7].

A second implication is that conservation measures should be designed as complementary packages. Protected areas without connectivity may leave species isolated; restoration without protection may be followed by renewed degradation; enforcement without livelihood alternatives may generate resistance; and monitoring without institutional response may create information without conservation impact. The five measures proposed in this review are therefore interlocking rather than individual recommendations.

The policy environment is more conducive than that reflected in the original manuscript. Nigeria’s NBSAP 2025-2030 sets out 23 national biodiversity targets aligned to the KMGBF and adopts a whole-of-government and whole-of-society approach [4]. The implementation challenge is to translate those national commitments into state and local spatial plans, sectoral programmes, annual budgets, development-control decisions and measurable indicators.

Further implication concerns evidence and monitoring. Nigeria has some elements of a National Forest Monitoring System, including satellite land monitoring and forest-inventory components, although the FAO country resource indicates that national forest monitoring is an evolving institutional process [22]. FAO also reported in 2026 on Nigeria’s efforts to enhance transparency in forest monitoring and climate reporting [23]. Evidently, the value of satellite and multi-sensor approaches for measuring forest loss, disturbance and recovery [18][19]. Future conservation policy should therefore establish common baselines and repeat monitoring rather than rely solely on periodic narrative assessments.

Therefore, biodiversity conservation should be framed as a development issue rather than only an environmental-sector responsibility. Forests, wetlands, mangroves and other ecosystems provide services that underpin food systems, water security, climate regulation and livelihoods. The central policy question is therefore how Nigeria can meet development needs while maintaining high-value ecosystems functional. This requires cross-sectoral planning, credible enforcement, ecological restoration, community participation and sustained financing.