The Earth’s terrestrial ecosystems rely heavily on vegetation for water, energy exchange, and the biogeochemical cycles of the planet’s land surfaces [1] [2] [3]. A wide range of ecological processes, from the local to the regional to the global scales, are profoundly influenced by vegetation [4] [5] [6] [7] [8]. The NDVI (normalized difference vegetation index) is sensitive to phenology [9] and is often used as the best indicator of vegetation growth and coverage change [10]. The NDVI has also been widely used in the study of vegetation changes at different scales [11] [12].

Nigeria is blessed with several biodiversity hotspots with Akwa Ibom State as one of the states in the Niger Delta with such potential [13] [14] [15] [16]. More simply, a biodiversity hotspot can be defined as a region with very large concentrations of plant species that are natives in the area but with increasing rates of habitat loss [17]. Coastal areas are indispensable biodiversity areas that are very useful internationally [9]. These regions are known to have delicate environments with profitable fauna and flora species used for sustenance, medicine, fuel, development and other different uses [2].

Protected forests or areas are geographical regions where human activities are severely limited by legislation in order to improve biodiversity conservation [18]. [19] defined it in terms of her functional roles and provision of services, which include support (ecosystem life-cycle maintenance, forest stability through seed disposal mechanisms), regulatory (climate regulation by promoting carbon sink and storage of other greenhouse gases, erosion and soil fertility regulation), cultural (agricultural heritage, archaeological and religious heritage), and provisioning services in terms of food supply, agro-forestry, and fuel. The protection of biodiversity, long-term protection of our natural resources for the sake of food security, health, tourism, academic research, and the provision of ecological services and cultural values are some of the goals outlined in [20].

It is suspected that the establishment of institutions like the Oil Minerals Areas Producing Commission (OMPADEC) of 1992 by the Federal Government of Nigeria, Niger Delta Development Commission (NDDC) which was created in 2000 by the act of Parliament and the Ministry of Niger Delta Affairs of 2008 leading to massive constructions of roads, housing schemes, canalization, dredging, land reclamation and shoreline protection, has caused great and severe damage to the natural environment and protected forest areas of the state than imagined. Also worthy of note is the fact that several activities like hunting and wood gathering as well as that of oil multinationals have impacted the protected forest areas in one way or the other.

Thus, monitoring and assessment of these protected forest areas are important for better forest management and conservation. The vegetation index is one of the most useful and used indexes to quickly identify vegetated areas with the use of multispectral remote sensing data [21]. NDVI has higher sensitivity corresponding with crown density change than other vegetation indexes [10]. Therefore, with the aid of Geographic Information System (GIS) and Remote Sensing technologies using the NDVI function of relevant software for vegetation assessment has proven useful in recent times. The studies by [9] and [22] on land use and land cover change in Akwa Ibom State have also provided guidance on the methods of data collection, data processing and analyses that will lead to vegetation assessment in relation to land use. Forest cover can be estimated using the Normalised Difference Vegetation Index (NDVI) from satellite data. Therefore, the study focused on the assessment of protected forest areas in Akwa Ibom State using the vegetation index of three-time series MODIS imageries between the year 2000 and the year 2021. Thus, are there changes in the vegetation index of protected forest cover areas between the year 2000 and the year 2021? What are the change estimates in vegetation index and associated impacts?

The original mean NDVI values generated from the processed maps in Figures 2-4 labelled maximum (High) values and minimum (low) values and depicted with green and red colors respectively were multiplied by 0.0001 as a factor to scale the NDVI value to range from −1 to +1 [14] as shown in Tables 2-4.

The study employed the descriptive statistics in the of form minimum value, maximum value, mean value, and standard deviations on Tables 2-5 were used to explain the results of the vegetation health in relation to the different sizes of protected forest areas in Akwa Ibom State. Inferential statistics of ANOVA analysis was employed to determine the variation in vegetation health of protected forests between 2000 and 2021. Findings showed that there was a reduction in the vegetation health and the size of protected forests areas in Akwa Ibom State between 2000 and 2021. This may be attributed to the rate of increase in deforestation in recent times because of human activities in line with the view of [33] who reported that the sizable area of Stubbs Creek Forest reserve has been degraded because of the anthropogenic activities as well as increased in shoreline erosion in the area as reported by [34]. This reduction in the size of the protected forests as displayed on Table 5 is an indication that some human activities such as farming, construction, oil production and tank farm expansion have impacted on forests areas in Akwa Ibom State overtime [13] [15]. Similarly, according to the Convention on Biological Diversity (2001), people living around forests are in the habit of practicing uncontrolled forest hunting and gathering. Majority of rural communities have used forests resources as sources of income only considering immediate gains and benefits without future sustainable benefits.

Similarly, the observed reduction in the vegetation health as displayed on Figures 2-4 is an indication and reflection in size reduction of the identified protected forests which means that they are currently facing depletion. This undoubtedly will pose severe consequences on environmental sustainability which has been the thrust for the establishment of such forest reserve by the Government/community. The reductions in sizes also mean reduction in ecosystem services provided by these forests covers overtime. Forest reserves provides both tangible and intangible benefits to sustain the environmental balance. The tangible products include wood, leaves, barks, fruits, and seeds while the intangible benefits include soil protection, platform for carbon sink to reduce ozone layer depletion, prediction of global warming & climate change, wildlife management, and water catchment protection [35]. The consequent actions of the oil and gas industries are equally considerable in the loss of vegetation health of protected forest areas in Akwa Ibom State. The activities of the oil and gas industries which can generate and releases hazardous effluents into the environment with related consequences have grave consequences on the vegetation health and status of protected forests in Akwa Ibom State.

The thrilling fact revealed by the application of the Normalized Difference Vegetation Index (NDVI) mapping model for the study is that it has provided insight into the status of protected forests in Akwa Ibom State. It has revealed the drastic level of reduction in the size of the forest reserve with the corresponding level of deterioration of their vegetation health, curbing down carbon sink and possibly heightened climate change occurrence. It is also an indication that the goals of establishing such forest reserves by the Government of Akwa Ibom State include: the provision of a platform for carbon sink as contained in vision 2030 Sustainable Development Goal’s objectives of the United Nations, biodiversity enhancer and growth, tourism for economic empowerment and pollution-free environment, which has been defeated. Based on the findings, the study recommended that uncoordinated and expansive hunting and gathering within the protected forests should be checkmated; the activities of the oil and gas industries should be controlled and monitored; stricter laws and guidelines should be put forward to ensure the overall protection of the protected forest areas in Akwa Ibom State; controlled urbanization and land-use model for the 31 LGAs in Akwa Ibom State should be enacted in order to ensure effective land use planning; creation of enlightenment programs directed at educating rural people on the sustainable use of forests resources is paramount to ensuring the management and conservation of the protected forests in Akwa Ibom State.

The authors declare no conflicts of interest.

Udoma-Michaels, D. and Akinola, O. (2022) Analysis of Vegetation Index of Protected Forests in Akwa Ibom State, Nigeria between 2000 and 2021. Open Access Library Journal, 9: e8698. https://doi.org/10.4236/oalib.1108698