The effects of wetland use/cover changes on soil organic carbon in masese wetland, Jinja city

Abstract

Human activities, particularly in rapidly urbanizing areas, are increasingly placing significant pressure on wetland ecosystems, compromising their ecological integrity and their role as carbon sinks. This study focused on the Masese wetland in Jinja City, Uganda, to evaluate land use/cover changes and soil organic carbon (SOC) across different wetland sections. The key objectives were to: (1) analyze spatial and temporal changes in wetland use/cover between 2014 and 2023; (2) examine the primary drivers of wetland use/cover changes; and (3) assess Soil Organic Carbon under various wetland use/cover types in Masese. The researcher adopted a mixed research design; cross cross-sectional research design; the quantitative and qualitative approach of data collection. The researcher used Landsat 8 (2014) and Sentinel-2A (2017, 2020, and 2023) satellite imagery for spatial-temporal analysis through the Google Earth Engine platform, collected social and economic data on wetland use/cover drivers from 276 households across five wards, administered questionnaires and conducted interviews with local stakeholders, analyzed soil samples from 15 sites using Walkley and Black’s rapid titration method and processed satellite imagery using maximum likelihood supervised classification, discriminant analysis, and change detection in ArcGIS 10.8.2. The researcher found a 3% reduction in permanent wetland areas between 2014 and 2023, driven by industrial development, economic growth, inadequate policy enforcement, and significant differences in soil properties like pH, phosphorus content, and sand/clay composition. The ANOVA results showed that there were no big differences (p > 0.05) in the SOC between the different types of wetland use. Therefore the study concludes that industrial and weak government policy and regulations have led to substantial wetland degradation in Masese wetland. However, the current land use practices have not yet caused significant depletion of SOC. The study recommends prioritization of vertical development instead of horizontal expansion practices to avoid encroaching on fragile ecosystems, particularly wetlands and strong policy enforcements related to land use planning and wetland protection, accompanied by community engagement to promote sustainable practices. Further research should examine the long-term impacts of land use changes on SOC and ecosystems, ensuring urban development considers ecological factors to preserve the wetland's role as a carbon sink.