Efficient improvement of ecosystem service quality through green space morphology optimization in cold-arid regions: evidence from the Hexi Corridor, China

Ecosystem services (ESs) in cold-arid regions are constrained by climate-driven threshold effects and may decline nonlinearly under extreme hydrothermal stress. Under water and land constraints, simply expanding green space may increase water consumption and ES trade-offs, necessitating green space morphology optimization integrating area and spatial configuration. However, its nonlinear effects on ESs and favorable ranges for coordinated improvement under cold-arid conditions remain unclear. Using the Hexi Corridor, China, as a case study, this study used 2024 multi-source data, including land-use and climate variables, and developed an integrated framework combining morphological indicator dimensionality reduction and reconstruction, Priority Optimization Areas (POA) identification, and machine-learning-based nonlinear interpretation to examine how green space morphology improves ES quality efficiently. The results showed that: (1) POAs for four ESs, namely water yield (WY), soil conservation (SC), carbon sequestration (CS), and habitat quality (HQ), were mainly concentrated in the Qilian Mountains ecological conservation area, each covering about 30%; (2) climatic factors dominated ES spatial differentiation, with precipitation (PRE) showing stable positive effects, the highest contributions (31.4%–66.0%), and clear nonlinear thresholds, whereas temperature (TEM) generally exerted negative effects; (3) green space morphology showed weaker but service-specific effects, with area size (G1) most strongly promoting CS and HQ, while patch morphology (G2) and spatial connectivity (G3) had differentiated or even contrasting effects; and (4) threshold ranges associated with the coordinated improvement of four ESs in the Hexi Corridor in 2024 were identified. These findings provide scientific support for efficient ecological spatial governance in cold-arid regions under climate change.