Response of ecosystem service supply-demand dynamics to urban expansion patterns on the loess plateau, China.

Urban expansion alters ecosystem service (ES) supply-demand relationships, yet pattern-specific responses remain unclear in ecologically fragile regions. Using land-use data for 2000, 2010, and 2020, we identified edge expansion (EE), leapfrog expansion (LE), and infill expansion (IE) on the Loess Plateau (LP), quantified supply and demand for four ES, and compared patch-level changes in the ES supply-demand ratio (ΔESDR) among patterns using nonparametric tests. From 2000 to 2020, construction land expanded substantially, with EE remaining the predominant expansion pattern (49.10%), followed by LE (42.33%) and IE (8.57%). After 2010, expansion accelerated and the share of LE increased markedly, becoming dominant in several ecological subregions. Food production (FP) showed negative median ΔESDR under all three patterns. Carbon sequestration (CS) showed a near-zero median ΔESDR under LE but negative median ΔESDR under EE and IE, whereas water yield (WY) and soil conservation (SC) showed positive median ΔESDR under all three patterns. For FP, CS, and WY, median ΔESDR followed LE > EE > IE, with all pairwise differences significant. For SC, median ΔESDR was significantly higher under LE than under EE and IE, whereas EE and IE did not differ significantly. Overall, LE was more often associated with weaker deterioration or more positive changes in ES supply-demand balance than IE, with EE mostly intermediate, although these relationships varied across services and subregions. These findings advance understanding of how ES supply-demand responses vary among urban expansion patterns and ecological subregions, and provide regional evidence for sustainable land-use planning in ecologically fragile regions.