Divergent peri-urban land transitions and their carbon stock implications: A multi-method diagnostic framework applied to Hawassa, Ethiopia

Rapid urbanisation in sub-Saharan Africa transforms peri-urban land, yet the relative vulnerability of farmland and natural vegetation remains poorly understood. This study develops an integrated diagnostic framework to disentangle divergent land-transition pathways in Hawassa, Ethiopia (1984–2054), a secondary city representative of the East African Rift Valley. The framework combines class-specific driver analysis, spatial heterogeneity mapping, landscape fragmentation metrics, intensity analysis, and carbon stock-change modelling. Over four decades, urban area expanded more than seven-fold, primarily displacing peri-urban smallholder agriculture (4957 ha lost; –65.7%), while natural vegetative cover expanded moderately (+3073 ha; +37.6%). Agricultural conversion is driven by economic centrality and population pressure, whereas vegetation dynamics respond to proximity-based regulatory and biophysical controls. These effects are spatially heterogeneous, creating measurable leakage where lakeshore protection displaces development onto outlying farmland. Agricultural conversion produces fragmented landscapes; vegetation change involves larger, more cohesive patches. Urban expansion systematically targets agriculture and avoids vegetation, but once agricultural reserves are depleted, vegetation becomes vulnerable. Carbon stock modelling shows historical vegetation gains partially offset emissions from agricultural conversion; however, a business-as-usual scenario yields net emissions costing 21.0 million USD, while ecological protection yields net sequestration benefits of 10.7 million USD, and urban development results in 124.6 million USD in climate damages. These findings demonstrate that sustainable peri-urban land governance must differentiate between productive farmland and protective vegetation, employing agricultural zoning, ecosystem connectivity corridors, and densification incentives to manage trade-offs between food security, carbon sequestration, and urban growth.