Information on the dynamics of savannah is important to a country's plan to overcome the problems of uncontrolled development and environmental hazards. Taking the reserve partielle de Dosso, Niger as the case study area, this paper analyzed the long-term land use land cover change from 2002 to 2022. Satellite images were processed by using Google Earth Engine (GEE). Therefore, four major land cover classes were identified based on spectral characteristics of Land sat, namely, built-up, vegetation, cropland, bare land and water. The result revealed that barren and built-up areas increased at the expense of vegetation and water. From the four major land use land cover the large area is covered by vegetation which comprises about 192963.5 hectares followed by cropland and water consisting of 32506.43 and 1596.4 hectares respectively. The built-up area gained substantial area (most) during the study period. The reduction in some of the land cover/uses underlines the dangerous trend of the pressure poised by population growth and the changing functionality. Land cover change is influenced by a variety of societal factors operating on several spatial and temporal levels. The area estimates and spatial distributions of the LULC classes produced from the current study will assist local authorities, managers, and other stakeholders in decision-making and planning regarding forest land cover and uses.
Niger is a sensitive region where identifying land cover change is critical to understanding global environmental change. Deforestation and habitat loss in Niger are the two major environmental changes because of their impact on the increase of biodiversity loss [
Like most reserves, the reserve partielle de Dosso is encroached on by local populations through the use of the land for agriculture and unsustainable wood extraction [
Evaluating vegetation cover loss in reserves can provide valuable information for the analysis of the environmental impacts of population pressure, agriculture, urban expansion, resettlement programs, climate change, and others. This analysis provides accurate information related to LU/LC changes and a baseline for sustainable reserve management and conservation.LU/LC study is vital for the development and planning of appropriate environmental management policies and strategies [
The reserve partielle de Dossois adjacent to the W Park and located on the left of the Niger River, is the only protected area in Dosso. With an area of 306,000 ha, it is marked by the influence of human activities. It is located between 11˚53'9.59'' N 3°26'28.79'' E. The climate is Sudano Sahelian type characterized by two seasons: one rainy season from mid-May to mid-October and one dry season from mid-November to mid-March. The average rainfall is 904.9 mm/year, and the average annual temperature is 27.8˚C [
Landsat satellite images captured in 2000, and 2022 were used to analyze the dynamics of land-use change over the last 22 years in the reserve partielle de Dosso. These years were selected to detect the possible change occurring at short and long spans, beginning from the most recent year. Consideration was also given to the availability of cloud-free images for the reserve. The images were downloaded from the United States Geological Survey (USGS, https://earthexplorer.usgs.gov/) earth explorer.
We used the Google Earth Engine (GEE) cloud computing platform to create cloud-free data. LULC images were generated using a pixel-based Maximum Likelihood (MLC) unsupervised classification method. Unsupervised classification was performed on two satellite images for the years 2000, and 2022 to identify differences in land cover. The feature classes were categorized by unsupervised classification according to the spectral reflectance of the electromagnetic spectrum, which has specific spectrum characteristics with the integration of a real ground survey [
The image was classified into five classes namely: Waterbody, Built up areas, Barren/bare land, Vegetation and Cropland (
| Land cover | Description |
|---|---|
| Water body | Lakes, reservoirs, stream, rivers, swamps |
| Built up areas | Land covered by buildings and other man-made structures. Residential; mixed urban or built up lands |
| Barren/bare land | Lands with exposed soil, sand or rocks, and never has more than 10% vegetated cover during any time of the year. Bare ground, bare exposed rocks, quarries and gravel pits |
| Cropland | Lands covered with temporary crops followed by harvest period, Crop fields and pastures |
| Vegetation | Lands with woody vegetation |
On trends in land cover change, analysis of vegetation change across the reserve between the years 2000 and 2022 reveals an overall change of 28% of the total annual integrated vegetation index of the reserve (
If we refer to the scale [
| Landsat imagery | Overall errors (%) | Overall accuracies (%) | Kappa index |
|---|---|---|---|
| 7ETM + of 2000 | 13 | 87 | 0.82 |
| 8OLI of 2022 | 10 | 90 | 0.85 |
Urbanization is one of the most pressing environmental problems facing the reserve partielle de Dosso. It increased loss of biodiversity through the fragmentation of the reserve into isolated patches surrounded by anthropogenic habitats. The urbanization rate increased from 7.6% in 2000 to 32.6% in 2022.The reserve has over three quarters of their vegetation cover depleted, and it is estimated that if current trends continue, the reserve, will experience a severe shortage of ecosystem services and goods. After urbanization, the expansion of cultivation has primarily targeted fertile lands where agricultural production can be sustained. Land is scarce within the reserve due to high population and conservation measures are not enforced.
For this reserve, population increase is the major driving force for land-use change. The increase in population apparently translates into expansion of cultivation and settlement areas. Increased focus on commercial agricultural production is another driver of agricultural expansion. As people change from subsistence farming to the production of commodities for local and external markets, the need for larger farms increases in order to produce enough to sell for higher income. People cultivate more land in order to produce enough. In many parts of the reserve, land degradation has reduced productivity of the land leading to poor yields. Similarly, the declining quality of pastures because of land degradation makes livestock and wildlife graze on wider orbits thus demanding more land for grazing.
Urbanization around the reserve is another cause for land-use change. Close to the reserve, municipal centers have created markets for food commodities coming from the reserve and thus the increase in demand in town results in an in-crease in demand for supplies of food produced in the rural areas.
Changes in land use have resulted in land fragmentation, over-cultivation, and reduced fallow periods leading to a decline in land productivity and ultimately in intensification of agriculture requiring more farm inputs. The extent and quality of grazing lands have also been reduced, thus intensifying conflict between the cultivators and the herders and even overgrazing by herders and agro-pastoral- ists due to continuous grazing without rest from grazing or rotation grazing plans.
Estimations indicate that 50 percent of the reserve partielle de Dosso land surface has been affected or modified in some way by human activity [
Land-use changes driven by human activities are a consequence of any development. As stated by [
The conversion from vegetation to standing built-up area, crop land, and barren was mainly driven by urban household dynamics, population growth, distance to cities and major roads, and precipitation dynamics. It is estimated that this process of agricultural extensification, coupled with deforestation and other land use changes, translates to a conversion of 4% of the land from tree cover to bare soil over this period. Cropland expansion is a major factor in vegetation loss and wildland fragmentation. This finding is in agreement with results from previous studies ( [
Over the next century, the global population is projected to increase by 50-100% and, likely, there will also be an increase in land use and land cover change at all scales. However, more time series and higher-quality samples need to be shared for high-accuracy cropland or other LULC mapping applications. Explicit and precise information on the reserve extent and location is essential for achieving sustainable development goals and is also fundamental for management.
It is undoubtedly that the rapid population growth in rural areas has a great impact on the land use/cover in protected areas. Information on land use and land cover (LULC) including forest cover is important for the development of strategies for land planning and management. The research found a decrease of high and dense vegetation areas into lower and non-vegetated areas within 22 years. It means there is a decrease in vegetation cover due to changes to non-vegetation cover or land cover areas with less vegetation.
The outcome of the study shows that the policy maker and stakeholder of this region need to be conscious about the rapid development and changes in the land use pattern in the reserve partielle de Dosso. Thus, a major LULC change is identified, and the rapid urbanization and cropland extension are the driving factors to trigger the transformation in the study area during the last two decades. These results contribute to orienting policies for sustainable land management in protected areas.
This research was supported by FARSIT 2022 from the Nigerien government.
The authors declare no conflicts of interest regarding the publication of this paper.
Abdourhimou, A.I., Boubacar, M., Rabiou, H., Idrissa, S. and Ali, M. (2024) Trends of Land Use and Land Cover Change in the Savannah Ecological of the Protected Area Reserve Partielle de Dosso, Niger. Natural Resources, 15, 61-68. https://doi.org/10.4236/nr.2024.153005