Process over outcome: Land-use transition intensity thresholds drive structural degradation of ecological security in...

Rapid land-system reorganization in climate-sensitive ecotones poses systemic risks that are often masked by superficial vegetative recovery. Current assessments, which prioritize static land-cover outcomes, typically overlook the destabilizing role of land-use transition (LUT) intensity. To address this gap, we developed a process-state coupled framework and applied it across China's semi-humid/semi-arid ecotone at a hexagonal scale aligned with regional governance. We reveal a profound structure-function mismatch along the 400-mm isohyet: stochastic, climate-driven functional gains systematically conceal deterministic structural degradation, creating cumulative structural deficits. Using explainable machine learning (XGBoost-SHAP), we establish a decisive "process-first" hierarchy, wherein transition intensity outweighs transition direction in governing security dynamics. Specifically, we identify a critical resilience threshold at a 10%-15% cumulative transition intensity; beyond this tipping range, the system shifts from buffered adjustment to accelerated degradation. Paradoxically, even restoration-oriented transitions can exacerbate instability when exceeding this rate. Spatially, high-intensity and high-security configurations demonstrate rigid incompatibility, co-occurring in a mere 0.05% of the region. These findings challenge the efficacy of conventional outcome-based quotas and advocate for a paradigm shift toward dual-control governance, integrating strict rate-based constraints on transition intensity with spatially differentiated zoning. This approach offers a transferable pathway for mitigating latent collapse risks in climate-sensitive ecotones globally.