Climate Change and Land Use - Batch 2

Soil carbon change and CO2 fluxes under different agricultural land use in the Vea catchment, Upper East Region of Ghana

Sun, 01 May 2016 00:00:00 GMT

Soil carbon change and CO2 fluxes under different agricultural land use in the Vea catchment, Upper East Region of Ghana Dicko, Gaoussou Soil organic carbon is an index for soil fertility and sustainable land management. Monitoring soil respiration and carbon provide quantitative information on soil carbon stocks at a given location. This study assessed soil carbon change across predominant land-uses and soil types in the Vea catchment of Upper East Region, Ghana. The goal was to assess soil carbon change and CO2 emissions from selected (rice, maize, millet and sorghum) cropping systems in the Vea catchment. To achieve this, farmers were interviewed for information on cropping history; establish the proportion between land use and soil type; determine crop yield components, yield and biomass for selected crops under different tillage (i.e. power tiller, bullock and manual) and amendment; estimate soil carbon stock; and determine the fractions and future trend of soil carbon stock and measure soil CO2 flux using respiration chamber under different land uses. The majority of the land is occupied by cropland about 41 % with 63 % of Leptosols, 52 % of Fluvisols and 46 % of Lixisols (i.e. the three main soil type) being cultivated. The highest grain yield obtained was 5675 kg/ha, 1375 kg/ha and 970 kg/ha for rice, maize and sorghum, respectively. The mean soil organic carbon stock for the major land-uses obtained in the study area were 10.24 ± 1.2 t/ha for cereals (maize and sorghum), 14.96 ± 2.4 t/ha for paddy irrigated rice 15.88 ± 2.1 t/ha for semi natural area, 16.53 ± 2.3 t/ha for grazing area, 18.5 ± 4.9 t/ha for eucalyptus forest and 23.5 ± 7.1 t/ ha for paddy rain fed rice. Eucalyptus forest had high carbon stock, but this carbon is mainly composed of the light fraction, which is a non-stable fraction. The Introductory Carbon Balance Model (ICBM) simulation revealed a future trend of soil carbon depletion of 8 - 15 % was obtained continuous cereal (i.e. maize and sorghum) production with or without fertilisation with the current management system. However, fertilised maize production in rotation with groundnut will prevent the depletion of soil carbon stock. Soil CO2 emission had similar trends under the maize - kenaf and sorghum - kenaf cropping systems. However, the cumulative soil CO2 emission for sorghum - kenaf cropping system was higher (22 %) than that of maize - kenaf cropping system. The study also showed that the trend of soil CO2 emission was different for the different management practices (power tiller, bullock and manual tillage) of rice. Furthermore, the soil CO2 emission was sensitive to soil moisture stress but not soil temperature for maize and sorghum cropping systems. For high yield but low CO2 emission, rice cropping system with bullock tillage and urea in deep placement (UDP) as amendment as well as power tillage with NPK + urea application are the best options for climate change mitigation for rainy and the dry season under irrigation, respectively. Therefore cereal-legume rotation is one of the best ways to sustain SOC in the study area. 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

Landscape Patterns and Modelling of Soil-Vegetation Relationship and Related Ecosystems Services to Support Landscape Conservation in the Mo River Basin (Togo)

Sun, 01 May 2016 00:00:00 GMT

Landscape Patterns and Modelling of Soil-Vegetation Relationship and Related Ecosystems Services to Support Landscape Conservation in the Mo River Basin (Togo) Diwediga, Badabate In order to support integrated landscapes and restoration efforts, this research focused on the assessment and monitoring of the spatio-temporal land use/cover change (LUCC) and degradation in the Mo River Basin (a subunit of the Volta basin of about 1,490 km2 in Central Togo). Field measurements, legacy and ancillary data were subjected to sequential multivariate methods, correlation analyses, geostatistics and modelling to analyse landscape conditions. First, along a gradient of land protection regime, data from extensive soil sampling and forest inventory were used to analyse soil organic carbon (SOC) and total nitrogen (TN) storage up to 30 cm depth, and the interactions between vegetation-soil conditions. Next, Landsat images of 1972, 1987, 2000 and 2014 combined with most updated global topographic and soil databases were used to analyse the landscape changes and its impacts on SOC, TN, soil loss potential and landscape patterns. Finally, the Landscape Management and Planning Tool adapted for the Mo basin (LAMPT_Mo), a spatially explicit model based on the Revised Universal Soil Loss Equation (RUSLE), was used to model the historical soil loss, and evaluate the efficiency of some land management scenarios. Different databases and field characterisation were used for model calibration and validation. The results showed that SOC and TN varied significantly according to land use/cover types, soil depths, topographical positions and land protection regime. With forests and woodlands exhibiting highest amounts of nutrients, mean TN varied from 0.06 to 0.16 % in the topsoil (0 – 10 cm) and 0.04 to 0.09 % in the subsoil (10 – 30 cm). Similarly, SOC ranged from 1.81 % in farmlands to 3.58 % in forests in the topsoil while woodlands had highest SOC in the subsoil (2.23 %). The river basin is made up of four and three vegetation types in unprotected and protected areas, respectively. The synergized effects of land protection status, soil conditions, landform, and human disturbances drive these vegetation patterns. From the historical analyses, natural lands dominated the basin, though their area constantly decreased since 1972. Contemporary LUC (in 2014) is dominated by savannahs/shrubs (53 %), woodlands (27 %) and forests (11 %). Non- cultivated and vegetation regrowth areas were the most dominant of the LUCC trajectories to whom SOC, TN and soil loss potential were responsive. Trajectories of land cover decline induced soil quality deterioration while correlation analyses showed soil loss to be more landform-driven than LUCC. Simulations using LAMPT_Mo yielded values of net soil loss (NSL) far higher than the tolerable limits for the Tropics. NSL markedly changed over time with about 26, 23, 27 and 44 Mg ha-1y-1, for 1972, 1987, 2000 and 2014, respectively. Steep slopes (≥ 15 ᴼ), poorly covered lands, and riversides (distances ≤ 100 m) are critical areas of sediment source. Some intervention measures such as controlling erosion hotspots through LUC protective measures could help reducing NSL up to 70 %, to the tolerable limits for the Tropics. The combination of methods and approaches used for the monitoring and assessment of landscape change and degradation enabled to capture the different spatial aspects of the problem of land degradation in the Mo basin. The study demonstrated that important appropriate conservation measures would be necessary for the catchment rehabilitation, protection and sustainable resource use. 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

Integrating Geoinformation and Socioeconomic Data for Assessing Urban Land-use Vulnerability to Potential Climate-change Impacts of Abuja

Sun, 01 May 2016 00:00:00 GMT

Integrating Geoinformation and Socioeconomic Data for Assessing Urban Land-use Vulnerability to Potential Climate-change Impacts of Abuja Mahmoud, Mahmoud Ibrahim This dissertation is framed as a retrospective research concept that analysed and monitored land use change to assess the impacts of urbanization on climate in cities. Multi-source datasets such as remote sensing images, vector layers, topographical maps, historical climatic variables and socioeconomic information were used for the retrospective landscape studies. Land-use Land-cover (LULC) maps were produced from historical Landsat series data using support vector machine information extraction algorithm. Subsequently, spatio-temporal settlement expansion analysis, change detection and urban growth modelling into the future was implemented to assess potential climate impacts due to urbanization. Thermodynamics of the urban landscape was investigated using relevant discrete historic climatic data and continuous thermal spatial datasets. Climate indices calculation and multiple spatial statistical approaches were used to analyse changes in air and land surface temperature and to detect urban warming and heat island impacts. Urban flood-risk assessment was investigated by integrating multisource geoinformation and morphometric analysis approach. Using object-based image analysis, the generated urban density information and urban structural types were useful in demonstrating the relevance of integrated geospatial datasets analysis for land use and climate change studies. Two silent urbanization impacts identified in this study were, increased imperviousness which result in land surface temperature modification and urban flood-risk propagation. LULC was observed to have moderated urban micro climate in different urban landscapes of Abuja. The proposed disaggregation concept used in the morphometric analysis in this study also revealed the hydrological processes such as flood-risk can be perennial and imminent due to inadequate natural drainage densities and low bifurcation ratio status of the landscape. The output of synergizing multi-source geospatial datasets facilitated fine-scale human wellbeing and security vulnerability assessment for improved disaster risk reduction in the context of climate impacts in cities. The main findings of this dissertation is a proof of concept of how integrated datasets and methodical research approach can be used for empirical climate and land use change science at local scale. Therefore, relevant institutions such the Federal Capital Development Authority and policy makers in other regions of Nigeria can adopt the concept demonstrated in this research for rapid assessment of urban landscapes to potential climate change impacts. A Thesis Submitted to the Department of Civil Engineering, College of Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Climate Change and Land Use

Charcoal production and its implication for woodland degradation and climate change in the Forest-Savannah Transition Zone of Ghana: the case of Kintampo Municipality

Sun, 01 May 2016 00:00:00 GMT

Charcoal production and its implication for woodland degradation and climate change in the Forest-Savannah Transition Zone of Ghana: the case of Kintampo Municipality Raymond, Aabeyir Charcoal production plays an important role in global socio-economic development as a source of income, energy and rural poverty alleviation. However, increasing commercial charcoal production has raised concerns about its effects on woodland and climate change mitigation. This thesis assessed the effects of commercial charcoal production in 23 charcoal production sites in Asantekwa and Kunsu communities of the Kintampo Municipality of Ghana. The effects of charcoal production on woodland were assessed in terms of the general land cover dynamics, extent of harvested sites, basal area, changes carbon dioxide equivalent (CO2e) emission based on allometric models. The influence of tenure arrangements for charcoal production on woodland was also assessed. The general land cover changes were analyzed using Landsat satellite images for 1986, 2001 and 2014. The extent of each harvested site was mapped and the median compared with 0.05 ha, the Intergovernmental Panel on Climate Change (IPCC) area threshold for degraded woodlands using Wilcoxon test. Inventory of all tree species of diameters at breast height (dbh) of 5 cm or more was carried out prior to the harvest. The basal area of the harvested trees were compared with the remnant trees using Mann Whitney test. Seven allometric models were developed based on the mass of the harvested trees and a combination of wood density, dbh and height of harvested trees, the best of which was selected based on the corrected Akaike Information Criterion. The CO2e from the harvested trees were computed from the harvested biomass while CO2e in the remnant trees was estimated using the best allometric model developed. The two were compared using the Mann Whitney test. Binary logistic regression was used to identify significant factors that influence the likelihood of woodland being degraded based on the views of 103 charcoal producers. The results of the study show that the annual rates of gain and loss in woodland for 2001 – 2014 were 0.88 % and 2.10 %, respectively signifying that woodland cover is losing faster than it is gaining for the period 2001– 2014. The median of the harvested sites (n = 23, M = 0.23 ha, P = 1.00) was significantly greater than 0.05 ha, the IPCC area threshold for degraded woodlands at 95 % confidence level while median basal area of the harvested trees (5.2 m2 ha-1) was also significantly greater than that of the remnant trees (n = 23, 2.6m2 ha-1, P < 0.001) at 95 % confidence level. The best allometric model for estimating AGB in the Forest-Savannah Transition zone is AGB = 0.0580ρ(dbh2H) 0.999. The median CO2e from the harvested trees (74.82 t ha-1) was significantly (P < 0.001) greater than that in the remnant trees (24.71 t ha-1). Procedure of access to woodland and attitude of charcoal producers were factors that significantly influence the likelihood of woodland being degraded in the study area. The results suggest that intensive large scale charcoal production could initiate woodland degradation and could be a source of CO2e emission, which could have negative implications for climate change mitigation in the study area. Stump-shoot pruning at the harvested sites should be rigorously implemented to enable the sites regain their pre-harvested state and climate change mitigation potential of woodland in the study area. A Thesis Submitted to the Department of Civil Engineering, College of Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Climate Change and Land Use