Doctoral

Modelling above Ground Carbon Stock in Lamto Scientific Reserve and Lokoli Ecofarm, Ivory Coast

2025-01-01T00:00:00Z

Modelling above Ground Carbon Stock in Lamto Scientific Reserve and Lokoli Ecofarm, Ivory Coast Kouakou, Amani Abell Mike This study analysed the spatiotemporal dynamics of carbon stock and vegetation in two key areas of Côte d’Ivoire: the Lamto Scientific Reserve (LSR) and the Lokoli Ecofarm (EFL), from 1990 to 2022. The results highlight a notable increase in forest formations, especially in Lamto, where savanna landscapes have gradually become more wooded, gaining 108 hectares. In Lokoli, a similar trend is observed but remains at an earlier stage, with wooded savannas predominating. Projections for 2060 and 2100 suggest continued expansion of forests if environmental conditions are maintained. Regarding floristic diversity, Lamto hosts 302 species (193 genera, 72 families) compared to 216 species (147 genera, 56 families) in Lokoli, both sites being dominated by the Fabaceae family. Carbon stocks are significant: on average, Lamto exhibits 151.36 t/ha of biomass (75.68 tC/ha), with gallery forests reaching the highest values, while Lokoli shows 38.16 t/ha of biomass (19.08 tC/ha), with dense dry forests recording the maximum. The economic value of the sequestered carbon ranges between EUR 2,634 and EUR 13,171. Predictive models confirm that vegetation densification correlates with rising carbon stocks, particularly in Lamto. eXtrem Gradient Boost (XGBoost) and Random Forest provide the most accurate estimates, supporting advanced modeling approaches for sustainable ecosystem management. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Assessment of Climate Change Impacts on Internal Migration in Burkina Faso

2025-02-01T00:00:00Z

Assessment of Climate Change Impacts on Internal Migration in Burkina Faso Ouattara, Aboubakar This study addresses one of today's most pressing issues: the impact of climate change on migration, with a particular focus on internal migration in Burkina Faso. The research first examines the factors influencing migration and its consequences from the perspective of local actors in the provinces of Comoé, Ziro, Boulkiemdé and Oubritenga. A participatory approach was adopted, with local workshops serving as the main methodological tool to gather insights from affected communities. In addition to exploring the socio-economic and environmental determinants of climate-induced internal migration, the study examines how these migrations affect the well-being of migrants at their destinations. To account for selection bias and to capture the heterogeneity of migration outcomes, the marginal treatment effects methodology was applied. The analysis is based on cross-sectional data collected from 493 households in the province of Comoé. The study also examines the occurrence of droughts and their relationship with internal migration in the provinces of Comoé and Boulkiemdé. The Standardised Precipitation Index (SPI) and the Standardised Precipitation-Evapotranspiration Index (SPEI) were used over 3-, 6- and 12-month time scales to assess drought conditions, while the Pearson correlation matrix was used to assess the relationship between drought and migration. From the perspective of local stakeholders, several key factors contribute to migration from areas of origin. Socio-economic constraints such as poverty, lack of employment opportunities, inadequate vocational training, population growth, and land scarcity, alongside environmental stressors such as drought and soil degradation, are identified as primary drivers of migration. Each of these factors was classified as being of greatest importance, receiving a weight of 3 in stakeholder assessments. Conversely, destination areas attract migrants primarily due to the availability of water and land, as well as favourable rainfall patterns. These factors were also assigned the highest importance level by stakeholders, with a weight of 3. While push factors are both socio-economic and environmental, pull factors are predominantly environmental. This pattern reflects the occupational profile of most migrants, who are primarily farmers seeking regions with climatic and environmental conditions more conducive to agricultural activities. Stakeholders further identified the most significant future repulsive factors for migration in specific provinces. In Oubritenga, drought and the absence of incentives or political interventions were cited as the most critical factors likely to drive further out-migration. In Boulkiemdé, land scarcity and inadequate vocational training emerged as the primary deterrents to long-term 4 settlement. These findings underscore the complex interplay of environmental, economic, and policy-related factors shaping internal migration patterns in Burkina Faso. The results of the econometric analysis reveal that environmental stressors are important migration drivers, especially insufficient rainfall, ongoing droughts, and soil infertility. Higher asset values are accumulated by migrants than by non-migrants, highlighting migration as a tactic for achieving economic resilience. The consequences of migration on remittances, however, are not uniform; although it reduces remittance flows for migrants, it may have favourable implications for non-migrants. The study emphasizes how migration can be both a vulnerability and an adaptation strategy, particularly for households that depend on agriculture. While migration supports income diversification and asset accumulation, those unable to migrate remain trapped in worsening conditions Drought assessment reveals distinct regional patterns: Comoé, located in the Sudanian zone, experiences less frequent but more intense droughts, whereas Boulkiemdé, in the Sudano-Sahelian zone, endures prolonged and severe droughts. The study highlights the relationship between drought conditions and migration. In 1985, Comoé experienced slightly wet conditions, with a strong positive correlation between SPEI6 and inflows (r=0.81) and SPEI6 and net migration (r=0.80), indicating that wetter conditions were associated with increased migration inflows and a higher net migration rate. Conversely, Boulkiemdé faced drier conditions, with SPI12 showing a strong negative correlation of -0.912 with net migration, suggesting that declining SPI12 values were linked to reduced net migration. Pearson correlation analyses confirm a strong relationship between drought and migration trends. In 1996, the SPEI12 in Comoé showed a moderately negative correlation (-0.68) with inflows, indicating that prolonged droughts were expected to reduce incoming migration. However, migration data revealed an increase in inflows from 15.44% in 1985 to 17.11% in 1996, contradicting this expectation. Similarly, in Boulkiemdé in 2019, the SPI12 exhibited a very strong positive correlation (0.92) with inflows, suggesting that as SPI12 increased, inflows should also rise. Yet, migration data did not align with this trend, as inward migration declined from 22.94% in 2006 to 10.69%. This paradox underscores that while drought conditions influence migration patterns, they do not act in isolation. Instead, internal migration results from a complex interplay of environmental constraints and socio-economic factors, emphasizing the need for a multi-dimensional approach to understanding climate-induced migration dynamics. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Cattle corralling for improved maize production and climate change resilience in the Sudano-Savanna area of Benin, West Africa

2024-11-01T00:00:00Z

Cattle corralling for improved maize production and climate change resilience in the Sudano-Savanna area of Benin, West Africa Atakoun, Awouminassi Marcellin Cattle corralling is an essential traditional soil fertility management practice with potential for enhancing agricultural productivity and climate resilience in resource-constrained farming systems. This study aimed to investigate the socio-cultural and biophysical dimensions of cattle corralling in northern Benin and its implications for maize productivity under current and future climate scenarios. The research was structured around four objectives: (i) assess the socio-cultural benefits, constraints, and determinants of corralling-based strategies, (ii) evaluate the impact of traditional corralling on soil health, (iii) assess the contribution of corralling to maize production under different water management systems, and (iv) model the effects of corralling under projected climate conditions. To achieve the first objective, a socio-economic survey was conducted among 392 smallholder farmers spanning three distinct agroecological zones in Benin. Descriptive statistics, Factorial Correspondence Analysis (FCA), and binary logistic regression were employed to characterize corralling practices and identify adoption drivers. For the second objective, a field experiment assessed the impact of corralling on soil physical and chemical properties over time, using laboratory analysis of soil bulk density, hydraulic conductivity, macronutrient levels (N, P, K), and soil organic carbon (SOC). The third objective involved on-farm trials to evaluate maize growth, yield, water-use efficiency, and nutrient factor productivity under deficit and additional irrigation. Finally, for the fourth objective, the DSSAT crop simulation model was calibrated and validated to simulate long-term impacts of cattle corralling on maize productivity under future climate scenarios (RCP 8.5). The results revealed that 71% of farmers adopted cattle corralling practices, with key determinants including agroecological zone, education level, access to credit, and extension services. Corralling improved soil fertility by reducing bulk density (up to 12%) and enhancing NPK and SOC levels (up to 25%). Maize yields increased significantly, with corralling and additional irrigation resulting in yield improvements of up to 55% compared to control plots. The crop model projections showed that corralling could sustain maize productivity under future climate conditions, with increased resilience to heat and water stress, contributing to soil carbon sequestration. This study underscores the relevance of cattle corralling as a sustainable land management strategy for enhancing soil health, crop productivity, and climate resilience. It provides critical insights for policymakers, extension agents, and researchers aiming to promote sustainable agriculture in the Sudano-Savanna region. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Land-based climate change solution options for Sahelian West Africa from land-used and land-cover model

2024-12-01T00:00:00Z

Land-based climate change solution options for Sahelian West Africa from land-used and land-cover model Yahaya Seydou, Abdel Nassirou Assessing the impacts of anthropogenic land use and land cover change (LULCC) on climate extremes is crucial for understanding the complex interactions between the land surface and the atmosphere, significantly influencing regional climate dynamics. Therefore, the study is essential in Sahelian West Africa, where rapid population growth, desertification, and agricultural expansion intensify environmental changes and amplify climate variability and extremes. Despite numerous studies, there needs to be more consensus on the regional effects of LULCC on climate extremes in West Africa. This research provides the first multidisciplinary systematic review of biophysical LULCC impacts in West Africa. Additionally, high-resolution (15 km) LULCC simulations spanning 2012 to 2022 were performed to investigate these effects in Sahelian West Africa, using a fully coupled Weather Research and Forecasting (WRF-Only) system integrated with the Noah-MP land surface model with dynamic vegetation. Also, the WRF for hydrological forecasting (WRF-Hydro) system was employed, coupled with Noah-MP. These experiments aimed to elucidate the potential impacts of anthropogenic LULCC on regional climate extremes, providing critical insights into land-atmosphere interactions in this vulnerable region. Results indicate that deforestation contributes to regional warming, with significant historical temperature increases of +0.26 ± 0.12 °C and projected increases of +0.88 ±0.25 °C under future scenarios. Conversely, afforestation could significantly cool the climate, reducing temperatures by -0.24 ± 0.14 °C historically and -0.22 ± 0.14 °C in future scenarios, excluding carbon sequestration effects. Deforestation historically decreases regional precipitation by -47.45 ± 29.2 mm/year and -55 ± 102.2 mm/year under future scenarios. In contrast, large-scale afforestation could substantially mitigate droughts, increasing precipitation by +200 ± 124 mm/year historically and +635 ± 521 mm/year in future projections. Analysis of 12 climate indices (mean and extreme) reveals that LULCC negatively affects temperature extremes, with modest average warming. This effect is more pronounced in WRF-Hydro simulations (+2.6%) compared to WRF-Only simulations (+1.88%). Similarly, precipitation increases are more significant in WRF-Hydro (+4.86%) than in WRF-Only (+3.16%). Extreme climate indices demonstrate greater sensitivity to LULCC than mean conditions. The findings emphasize the critical role of hydrological processes in WRF-Hydro, which improves model performance, contributing up to +0.95% for temperature and +2.45% iii for precipitation on average. Exceptions are seen in TXn and CCD indices, where hydrological contributions decrease by -0.3%. Land surface temperature shows a maximum increase of up to +0.5 K with WRF-Only and +0.6 K with WRF-Hydro during the wet-to-dry seasonal transition (August to January), primarily driven by reduced plant transpiration (ΔEt) due to decreased canopy foliage. Over the entire year, LULCC induces a slight rise in land surface temperature (<0.3%) in both WRF-Only and WRF-Hydro simulations, with a marginally stronger response in WRF-Hydro. These findings underscore the importance of fully coupled modelling frameworks that integrate the complexities of LULCC and land-atmosphere interactions. Such approaches are essential for effectively evaluating land-based mitigation strategies, enhancing regional climate resilience, and supporting improved livelihoods in Sahelian West Africa. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use