A Rebound in Cultivated-Land Ecological Security Masks Persistent Pressures in Northeast China’s Black-Soil Region: Evidence from Heilongjiang Province

The sustained rebound in cultivated-land ecological security (CLES) indices across Northeast China’s Black-Soil Region is often interpreted as ecological improvement. However, aggregate recovery may mask unresolved or strengthening pressures and heterogeneous constraints among land systems. To diagnose these hidden constraints and support targeted governance, we evaluated 13 prefecture-level units in Heilongjiang Province from 2009 to 2023 using a 25-indicator DPSIR framework, entropy-weighted TOPSIS, cultivated-land-area aggregation, persistence-informed obstacle diagnosis, and robustness tests. Provincial CLES declined from 0.4135 in 2009 to 0.3521 in 2016 and rebounded to 0.4187 in 2023, but remained within the critical-security class. Improvements in the state, impact, and response subsystems supported the rebound, whereas the pressure subsystem remained 58.8% below its 2009 level. Nine prefectures exceeded their 2009 scores by 2023, yet only Daxing’anling reached the secure class. Cultivated-land endowment, development capacity, and governance response remained persistent constraints, while the obstacle degree of estimated agricultural carbon emissions per unit of cultivated land increased during recovery. By integrating temporal evolution, constraint persistence, and land-system heterogeneity, this study advances CLES assessment beyond static endpoint ranking toward recovery-quality diagnosis. It establishes a two-level management framework combining a shared provincial baseline with land-function-specific interventions and closes the management cycle through outcome-based reassessment.