Climate Change and Land Use - Batch 3

Evaluating the Effect of Stone Bunds Erosion Control on Vegetation Trend in South-West Burkina Faso - A Fine Scale Remote Sensing Perspective in the Ioba Province

2026-05-21T14:24:15Z

Evaluating the Effect of Stone Bunds Erosion Control on Vegetation Trend in South-West Burkina Faso - A Fine Scale Remote Sensing Perspective in the Ioba Province Asare, Yaw Mensah Soil erosion by water has become a worldwide issue due to its environmental and socioeconomic impact in the light of rising concerns over climate change. To minimize the impact of soil erosion by water in West Africa, several erosion control measures have been adopted and are being practiced. The type of erosion control measure practiced depends on the climatic zone in which the area falls. In South-West Burkina Faso where this study was undertaken, rainfall is relatively high compared to the other areas within the country. As a result, the use of stone bunds/lines is the most commonly practiced erosion control measure. But after the implementation of these erosion controls, very little has been done on evaluating the impact of these erosion controls on vegetation (crops and natural vegetation) improvement using remote sensing data. This is because until recently, organized erosion control measures more especially using stone bunds over thousands of hectares of both agriculture and non-agriculture lands was rare. This study, therefore, investigated the effect of stone bunds erosion control measure on vegetation trend using remote sensing data. A time series analysis of NDVI data from 2004 to 2017 was conducted to find: (i) the trend of vegetation in the whole study area and (ii) the trend of vegetation in areas with stone bunds erosion control and areas without. Subsequently, a comparison using the ANOVA test was done between the trends of NDVI in these two areas. Also, a seasonal analysis of the crop heights of cotton and millet was conducted using photographs from UAV. Lastly, a pixel-wise trend was conducted for climate variables (rainfall and temperature) and a correlation analysis was also performed between NDVI and climate variable time series. The results showed that, the NDVI trend of the whole study area is significantly increasing at a rate of 3.7 x 10-4 ΔNDVI/month at 95% confidence interval (CI). Similarly, areas with stone bunds erosion control and areas without stone bunds erosion control had significant increasing trends ranging from 3.14 x 10-4 to 3.95 x 10-4 ΔNDVI/month and 3.83 x 10-4 to 3.91 x 10-4 ΔNDVI/month respectively. In comparing the NDVI trends of the two areas, the result from the ANOVA test showed that there is no significant difference between the NDVI trends of areas with stone bunds erosion control and areas without stone bunds erosion control (p-value = 0.319). Although, the mean NDVI trends for the whole area gave a positive trend, the results of the pixel-wise analysis showed that, positive, stable and negative NDVI trends were widespread in the study area with a range of -0.001 to a maximum of 0.002 ΔNDVI/month. Only 10.6% of the NDVI trends was statistically significant at 95% CI. In comparing the crop heights in areas with stone bunds erosion control and areas without, at 95% CI, the t-test revealed that there is no significant difference between the means of the crop heights of cotton (p-value = 0.389) and millet (p-value = 0.884) in these two areas. For trends of climate variables, rainfall and temperature had a positive increase in the monthly trend of 0.12mm/month and 0.01°C/month respectively. In terms of the correlation between NDVI and climate variables, there was a positive correlation between NDVI and rainfall (Kendall τ of 0.513), whiles a negative correlation (τ = -0.322) was observed between NDVI and temperature. The results from this study will help future studies of evaluation of erosion control measures in West Africa. By combining data from other satellites such as the Sentinel, this will go a long way to help to bridge the problem of data availability for vegetation time series analysis. 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 Use and its Management, Indigenous and Climate Smart Adaptation Strategies in Kloto District, (Togo, West Africa)

2026-05-21T13:19:54Z

Land Use and its Management, Indigenous and Climate Smart Adaptation Strategies in Kloto District, (Togo, West Africa) Koglo, Yawovi Sena This study established firstly, forest reference level in terms of land area extent as well as area losses and gains through the transitions across forest, cocoa agroforestry, cassava, maize, settlement and other land uses in the Kloto district (Togo). The pixel-based classification was adopted and combined with the extended change matrix quantity and intensity analysis using three years within a 32-years period (1985–2017), and field datasets. Results indicated an active forest loss (19.5%) with dormant gain (0.8%). Forest is involved in most transitions as the most targeted category with the largest transition being from forest to cocoa agroforestry while, the lowest transitional change occurred from forest, cocoa agroforestry, maize, cassava and settlement to unclassified classes (e.g. road, water body) and vice versa. Other important transition categories were from forest to settlement, cassava and maize. Secondly, it investigated smallholder’s climate change perception, proximate drivers of cropland and forest degradation for implementing climate smart agricultural systems. Net change analysis of land use was associated with quantitative analysis from participatory survey data with farmers and landowners. Results revealed, poor agricultural systems and cassava farming as major factors contributing to the alarming forest losses between 1985 and 2017. A significant net loss in forest cover of 23.6% and area losses under maize and cocoa agroforestry farming of 12.99% and 10.1% between 1985 and 2017were observed, respectively. These significant losses are due to intensive cassava cropping (38.78%) and settlement expansion (7.87%). Based on participatory surveys, the majority of agricultural lands are threatened by erosion or physical deterioration (67.5%), land degradation and loss of micro/macro fauna and flora (56.7%), declines in soil fertility (32.5%) and soil water holding capacity (11.7%), and changes in soil texture (3.3%). Most farmers adhere to the proposed climate smart practices, with an emphasis on cost-effective drip irrigation systems (45.83%), soil mulching (35%), and the adoption of drought-resilient varieties (29.17%). Lastly, time series of land use transitions allowed for an assessment of soil organic carbon density (SOCD) gains, losses and emissions using matrix of land use change and point-based emission and removal estimators. Data were collected using land use transition experiment plots, slope gradient composite soil sampling methods across forest and agricultural lands within, the same soil unit and climatic zones. The analysis of variance (p=5%, Fpr<0.001) revealed low SOCD (MgCha-1) under maize (54.33) and cassava (52.98) compared to cocoa agroforestry (169.52) and forest (189.34) plots. Based on land use change observed between 1985 and 2017, the transition of forest and cocoa agroforestry to cassava and maize depicted high carbon dioxide release of up to 100,059 and 74,192 for cassava and 5,342 and 5,227 MgCO2ey-1for maize, respectively. Whereas the transition from maize to forest sequestered more carbon (1,423MgCO2ey-1) compared to the transition from cocoa agroforestry and cassava to forest which, accounted for 626 and 404 MgCO2ey-1, respectively. In terms of carbon release and sequestration over 32-year, results showed slightly higher carbon sequestration through the transition of cassava and maize to agroforestry than to forest. Significant losses were estimated for the transition from forest and cocoa agroforestry to maize and cassava mono-cropping. Results revealed mono-cropping of annual crops without residue return after forest or cocoa agroforestry transitions as main driver of soil carbon loss and CO2e release. Consequently, site-specific integrated landscape management and dissemination of climate-smart agricultural practices like agroforestry are promising options to considerably reduce GHG emissions in Kloto District. 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

Carbon Stock Potential of Agroforestry Systems in Savannah West Africa: A Case Study of Agroforestry Parkland in Burkina Faso.

2025-08-29T11:11:29Z

Carbon Stock Potential of Agroforestry Systems in Savannah West Africa: A Case Study of Agroforestry Parkland in Burkina Faso. Neya, Tiga Agroforestry plays an important role in food security and farmer‘s resilience to climate change and variability in West Africa. However, the link between agroforestry parkland profiles and the capability of these parklands to sequester carbon are not well known. Therefore, agroforestry parkland profiles in three climatic zones of Burkina Faso were studied. Thirty (30) farmlands in each of the climatic zones representing about 35 ha were randomly selected and systematic woody species inventory and dendrometry data were collected. Diameter classes‘ distribution and agroforestry parkland typologies using Importance Value Index analysis were done for agroforestry parkland profiling purpose. The mean tree canopy cover and tree cover in the farms were calculated and three principal crops (millet, red sorghum and white sorghum) yield were used to estimate the trade-off using the mean tree canopy cover as the potential for no cropping area. Non-destructive method of fitted allometrics equations were used to compute carbon stock and to estimate equivalent dioxide carbon. Sustainability analysis of carbon sequestration potential was done using ]0-10], ] 10-40] and ]40-110 cm] diameter classes as long , medium and short term capability of agroforestry parklands to sequester the carbon respectively. The balance between marketable carbon value and the trade-off resulting from tree conservation and the major crops (millet, red sorghum and white sorghum) value were also analysed. The results showed 42 woody species in Sudanian, 31 Sudan-Sahel and 34 Sahel strict zones with corresponding density of 37, 30 and 35 trees/ha respectively. Agroforestry parklands in Sudan-Sahel zone appeared to be unstable compared to the two others climatic zones. Mono-woody species parkland of Vitellaria paradoxa was observed in the Sudanian zone while multi-woody species parklands were observed in the Sudan-Sahel and Sahel strict zones. Moreover, mean tree canopy cover observed was 66.25 m2 in Bouroum-Bourom, 59.92 m2 in Sapouy and 42.1 m2 in Ouahigouya . The average tree cover was 23.99% in Bouroum-Bouroum, 18.23% in Sapouy and 14.88% ix in Ouahigouya. This represents a loss in grain production of 109.5 kg/ha in Bouroum-Bouroum, 247.6 kg/ha in Sapouy and 252.8kg/ha in Ouahigouya. Carbon stock analysis revealed 24.71± 5.84 tCO2ha-1, 28.35± 5.84 tCO2ha-1 and 33.86±5.84 tCO2ha-1 in Ouahigouya, Sapouy and Bouroum-Bouroum respectively. Ouahigouya earned the first place for long term carbon sequestration potential with 1.82% of total amount of carbon. The medium term analysis gave the first place to Sapouy with 71.71% of total amount of carbon and the short-term analysis gave the first place to Ouahigouya with 68.03%. The marketable carbon value was less than the trade-off value resulting from tree keeping and crop production value. The balance analysis revealed that carbon payment system promoted by REDD+ initiative will be profitable and compensable to smallholder farmers effort to keep tree when the tCO2 ha-1 price will be around US$ 4. Both the density of tree (trees/ha) and the number of species constituting the agroforestry parklands have a direct impact of carbon stock potential. A higher tree cover implies a higher trade-off in the agroforestry parkland and suggests reduction in tree density. When considering farmers‘, interest, profitability on carbon market will be the most relevant incentive method to enhance carbon sequestration in agroforestry parkland in order to meet Paris agreement (2015) goals. 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

Vulnerability of Rice and Maize Yields to Climate Variability in the Sudano-Sahelian Zone of The Gambia: Drivers and Adaptation Options

2025-08-29T11:13:15Z

Vulnerability of Rice and Maize Yields to Climate Variability in the Sudano-Sahelian Zone of The Gambia: Drivers and Adaptation Options Sonko, Ebrima Staple food crops are considered as the driving force for household food security and source of livelihood activities for many developing nations. Farming practices face many challenges due to the adverse impacts of climate change and variability in the 21st century. This study assessed the extent to which maize (Zea mays L.) and rice (Oryza sativa L.) yields are vulnerable to climate variability in the Lower River Region of The Gambia. The influence of climate variability was assessed using the ordinary least square regression and heteroscedasticity methods. The potential soil physical and chemical properties were estimated using diagnostic soil survey of simple random sampling approach. Data were collected from 30 upland maize fields and 30 swamp rice fields. Crop yields were projected using two Global Circulation Model (GCM) models that performed best in the study area: CSIRO-RCP4.5 and NOAA-RCP4.5. Climate change adaptation options were assessed through semi-structured questionnaires with 180 selected households in eighteen communities using multistage sampling techniques. The results of climate influence on crop yields showed that CO2 and rainfall unfavourably affect rice yield and were statistically significant. Maximum and minimum temperature negatively affect yield but not statistically significant at (P < 0.05). The results further revealed that CO2, maximum temperature and sunshine duration adversely affect maize yield and statistically significant whilst rainfall and minimum temperature negatively affect maize yield but not significant at (P < 0.05). Soil survey results indicated that swamp rice ecologies had high percentage of NPK (N 0.07 %, P 0.0184 % and K 0.04 %) than percentage NPK contents in the maize fields (N 0.06 %, P 0.018 % and K 0.01 %). Soil pH is generally low and ranges from (4.6 to 4.7). The electrical conductivity of the soils for rice and maize fields are generally high (4.8 dS/m) indicating salt-affected soils. It is projected that, crop yields showed the percentage mean yield gain for maize iv under NOAA-RCP4.5 by 12 % and 41 % but most importantly CSIRO-RCP4.5 by 17 %, 31 %, and 48 % respectively, as the period gets close to mid-century compared to mean rice yield losses of -19 % and -23 % under NOAA-RCP4.5 scenario. The results showed that the majority (72 %) of farmers’ use drought-tolerant crop varieties with 67 % adapting to changing planting date. Majority (64 %) of farmers were forced to fallow their lands with 40 % of farmers practising petty trading and 47 % depending on temporal migration as a coping mechanism. It is concluded that rice and maize yield were vulnerable to climate variability coupled with fragile soil conditions. The future projection of yields will be inadequate to feed the growing population in the Lower River Region of The Gambia. There is a need for more adaptation strategies that are compatible with the local condition that can strengthen the resilience of households to cope with climate variability. Therefore, climate change adaptation policy should include local knowledge as a bottom-up approach to enhance their sustainability at the local level. 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