Assessing the effects of spatial temporal land use on vegetation health in Karamoja rangeland, northeastern Uganda

Abstract

Rangelands globally are naturally managed ecological units grazed in their natural or semi-natural form. In Uganda, Pastoralism is the main livelihood activity in the Karamoja rangeland, albeit with unknown spatial quantities of cover changes and declined productivity due to environmental and anthropogenic factors. This study, therefore, aimed at (i) examining the spatiotemporal extent, trend and transitions of changes in rangeland use between 2002 and 2022, (ii) assessing the spatiotemporal variations in rangelands productivity of standing biomass between 2002 and 2022, and (iii) examining the dominant factors underlying rangeland degradation in Karamoja region. A cross-sectional and longitudinal design and mixed methods approach was adopted in this study to assess the spatiotemporal rangeland use changes and productivity in the Karamoja region, Northeastern Uganda. To examine the rangeland, use change, the study used satellite data from the USGS Earth Explorer for 2002, 2012, and 2022 series. Variation in rangeland productivity was computed using image analysis in ArcGis 10.8 and SAVI tools. In addition, 264 household interviews were conducted and analysis was conducted using a chi-square test to derive the drivers of rangeland productivity. Also, content analysis was employed to extract meaningful narratives from the 20 key informants. Results revealed that woodland, bushland, and bare ground declined in spatial extent by 38%, 9%, and 2%, respectively, by 2022. Meanwhile, grassland, cropland, and built-up increased by 20%, 12% and 2%, respectively by 2022. Maximum SAVI results of 0.660954, 0.567067, and and0.501258 in 2002, 2012 and 2022, respectively and minimum values of -0.299879 and 0.064051, and and0.0607339 in 2002, 2012, and 2022, respectively, revealed that vegetation health had been degenerating over the study years. Annual mean SAVI values of 0.15, 0.26, and 0.22 in 2002, 2012 and 2022, respectively, revealed that 2012 stood out with higher productivity compared to 2022 and 2002. The crop zone had robust vegetation compared to depleted zones of pastoral and agro-pastoralist over the study time. The perceived drivers of rangeland productivity also varied significantly across the zones with x2 (264) =8, P=0.05. From this study, it is clear, therefore, that Karamoja rangelands have undergone a lot of cover and use changes between 2002 and 2022, mainly as a result of human activities. The government should develop and enforce rangeland conservation policies and invest in community-based education to raise awareness of the dangers of rangeland use/cover changes on the productivity of vegetation. The community should implement rangeland sustainable practices to enhance conservation and restoration of the ecosystems, especially in the agro-pastoral ecological zones that grapple with severe vegetation depletion.