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Land Degradation and Its Impacts on Ecosystem Services in the Nigerian Guinea Savannah: Implications for Sustainable Land Management

Adenle, Ademola Andrew (2022). Land Degradation and Its Impacts on Ecosystem Services in the Nigerian Guinea Savannah: Implications for Sustainable Land Management. (Thesis). Universität Bern, Bern

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Land degradation is a major environmental concern. Globally, land degradation directly impacts about 1.5 to 3.2 billion people by affecting water and nutrient cycles, reducing food and biomass production, and adversely affecting livelihoods that are dependent on land and natural resources. Land degradation, its drivers, and its impacts manifest differently depending on the social and ecological contexts. Thus, attention to the context in analysing land degradation and its proximate and underlying causes will yield insights to foster sustainable land management (SLM). Although land degradation has been implicated in various environmental and development challenges in Africa, knowledge about land degradation in some regions remains inadequate to support the identification of SLM practices. The Guinea savannah zone in Nigeria is one such region, facing widespread and severe land degradation. The region has lost much of its native vegetation due to the combined effects of land degradation, deforestation, and land use changes. Land degradation has been associated with farmer–herder conflicts, communal clashes, out-migration, and food insecurity. These impacts are likely to worsen as climate change progresses and in the absence of SLM. Thus, the overarching aim of this study is to improve understanding of the spatial distribution of land degradation in the Nigerian Guinea Savannah (NGS) and its drivers and thus derive insights into the sustainable management of its land resources. The insights will also help inform pathways to achieving land degradation neutrality (LDN), a global environmental goal. Its objectives are to (1) assess human-induced biomass loss as a proxy for land degradation in the NGS; (2) identify characteristic patterns of social and ecological factors associated with land degradation in the region and analyse their implications for land governance and SLM; (3) examine land users’ perceptions of land degradation and its implications for SLM, using Niger state as a case study; and (4) examine the potentials for operationalizing LDN in Nigeria. These four objectives were addressed in four studies. The research questions were investigated with a mixed-methods approach combining satellite remote sensing data and analysis and geographic information systems (GIS) with field surveys, focus group discussions, key informant interviews, and a review of environmental policies in Nigeria. Results from assessing human-induced biomass loss, as a proxy for land degradation (Study 1) showed a declining trend in annual mean normalized difference vegetation index (NDVI) and annual NDVI anomalies observed in the NGS between 2003 and 2018. The indices were from the Moderate Resolution Imaging Spectroradiometer (MODIS). Overall, the study revealed that 38% (251K km2) of the NGS experienced degradation, 14% (91K km2) experienced improvement, and the remaining 48% (320K km2) was stable. Land degradation is mostly evident in states bordering the northwest to the central and northeast of the NGS, such as Niger state. These results show that land degradation affects a substantial part of the study area. Thus, identifying characteristic patterns of social and ecological factors associated with land degradation in the region and analysing their implications for land governance and SLM (Study 2) provided further insights. The archetype analysis identified nine archetypes dominated by (1) protected areas; (2) very high-density population; (3) moderately high information and knowledge access; (4) low literacy levels and moderately high poverty levels; (5) rural remoteness; (6) remoteness from a major road; (7) very high livestock density; (8) moderate poverty level and nearly level terrain; and (9) very rugged terrain remote from a major road. Among these archetypes, four archetypes characterized by very high-density population, moderately high information and knowledge access, and moderately high poverty level, as well as remoteness from a major town, were associated with 61.3% large-area degradation. The other five archetypes, covering 38.7% of the area, were associated with small-area degradation. Although the MODIS satellite analysis (Study 1) and the archetype analysis of spatial data on land degradation drivers, hint at the different types of land use and management including the ecological aspects of land degradation (Study 2), Study 3 examines the perspectives of land users on land degradation. A questionnaire survey was used to capture local land users’ perceptions of land degradation. The assessment of local land users’ perceptions of land degradation in predominantly rural remote farming communities was necessary to provide insights to further guide land governance and management. Thus, focused on the rural remote archetypes and its analysed communities far from major towns but with a moderately low prevalence of land degradation drivers such as population density, protected areas, and flat terrain. Using a case study on Niger state, an administrative unit in the NGS and a Principal Component Analysis, Study 3 identified key components in land users’ perceptions of land degradation characteristics and drivers and SLM. They include (1) four perception dimensions of land degradation characteristics: (2) two perception dimensions of land degradation drivers, and (3) six perception dimensions of sustainable land management. The four major dimensions of perceptions of land degradation in the study context include vegetation-condition-dominated characteristics, soil-condition-dominated characteristics, and vegetation with Sudano-Sahelian characteristics as well as land use land cover (LULC) with the prevalence of drier conditions. The two categories of land degradation drivers are human-activity-dominated drivers at a smaller scale and nature-dominated drivers at a larger scale. The two categories of land degradation drivers are human activities dominated drivers at a smaller scale and larger-scale drivers (nature-driven). The dimensions of SLM identified include institutional actors’ effect; natural resources management and environmentally friendly agricultural practices as well as tree-based initiatives; conservation initiatives and policy initiatives. The study showed that land degradation in Niger State is due to land use pressure from within the state and from migrant resource users with limited cultural attachments to local land management approaches. A spatial differentiation in dependence on natural resources showed that of the three geopolitical zones in Niger State, the zone with more diversified livelihood alternatives from agriculture, B, has less degradation than the other two zones, A and C. The archetypes approach (Study 2) identified policies and practices addressing increasing population in combination with other socio-economic factors such as poverty reduction as important. Other strategies include creating awareness about land degradation, the promotion of sustainable practices, and various forms of land restoration, such as tree planting, as ways of progressing towards LDN. In addition, Study 3 on key dimensions based on land users’ perceptions identified environmentally friendly agriculture initiatives such as farmer-managed natural regeneration and a bottom-up approach involving traditional village heads to tackle land degradation. Ranking of SLM using the relative importance index (RII) (Study 3) showed that land users perceive institutional actors (70.0%), technological practices (67.6%), conservation practices (66.8%), and policy initiatives (66.5%) as effective SLM. Connecting the insights from the three previous studies on land degradation in the NGS, Study 4 examined ways to operationalize LDN in Nigeria. Study 4 reviewed literature, assessed spatial datasets, and analysed national policies to examine the need to contextualize LDN according to the main agro-ecological zones in Nigeria, which include the NGS. The study also identified two promising entry points for operationalizing LDN; these are incentivizing and promoting SLM practices among local resource users and mainstreaming SLM initiatives in sectors such as agriculture and the environment. To support SLM measures, reform of national land use policy is needed to address the current limitations of land tenure in Nigeria. In conclusion, this study has identified large areas of the NGS affected by land degradation and identified the typologies of degradation extent, thus making it easier to target SLM measures. Because land degradation depends on land users’ perceptions and contexts, knowledge gained can inform approaches to motivate the land users themselves to address land degradation. Insights gained from the focus on the NGS have informed contributions to examine how changes in land use affect biodiversity and ecosystem services in the Río de la Plata grasslands (RPG), one of the most modified savannah biomes in the world, managed by Argentina, Brazil, and Uruguay. Results showed that a strict regulation of LULC change in the RGP is required to address land degradation. Studies in both contexts thus show the importance of appropriate policies to support SLM. These studies also highlight further research questions, such as what the key socio and economic determinants shaping land users’ perceptions of land degradation are and how land users prioritize ecosystem services, as additional pathways to align SLM practices to the social and ecological context.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 8 June 2022
Subjects: 900 History > 910 Geography & travel
Institute / Center: 08 Faculty of Science > Institute of Geography
Depositing User: Hammer Igor
Date Deposited: 02 Feb 2023 07:46
Last Modified: 08 Jun 2023 22:25

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