Redevelopment of underutilized land to optimize ecosystem service value in a post-urbanization city: a multi-scenario study of Lianyungang, China

Cities in the post-urbanization stage face simultaneous pressures of land scarcity and ecological restoration, yet underutilized land remains insufficiently integrated into planning. This study develops a two-stage baseline-projection and redevelopment-optimization framework to evaluate parcel-level underutilized land redevelopment pathways for improving ecosystem service value (ESV) while considering fiscal feasibility. In Step I, a validated GeoSOS-FLUS model projected the 2032 baseline LUCC pattern without redevelopment intervention. In Step II, the remaining underutilized parcels were combined with policy-designated idle, abandoned, or functionally withdrawn land to construct a policy-adjusted inventory, after which redevelopment timing and sequencing were optimized under three scenarios—Fixed Annual Redevelopment Area (FARA), Fixed Annual Investment Amount (FAIA), and Minimizing Fiscal Investment Pressure (MFIP). Applied to Lianyungang, China, the framework assigned underutilized parcels to ecological, agricultural, or construction-oriented pathways. Compared with the BS1 no-redevelopment baseline of 0.55 billion Yuan, cumulative ESV during 2023–2032 reached 3.23 billion Yuan under FARA, 3.09 billion Yuan under FAIA, and 3.04 billion Yuan under MFIP. The results show that coordinated redevelopment can substantially enhance ecological benefits, although outcomes vary with implementation and fiscal constraints. The framework provides a potentially transferable approach for underutilized-land planning in land-scarce coastal cities.