Threshold effects of multi-scale landscape pattern on cultivated land ecosystem service in the Northeast Black Soil Region of China

• Trade-offs/synergies of Cultivated Land Ecosystem Services (CLESs) analyzed at county-level and grid scales. • Landscape-level metrics drive synergies at county-level scales, while patch-level metrics dominate at grid scales. • ENN_MN ≥ 0.464 and PAFRAC ≥ 0.941 boost FP and regulating service synergy. • Grassland > 18.1 % in cultivated land-dominated areas (>56.7 %) enhances multifunctionality. • Emphasizes scale-specific planning to balance agricultural productivity and ecology. Cultivated land systems play a dual role in food security and ecological sustainability, yet the mechanisms underlying trade-offs/synergies among ecosystem services remain unclear, particularly in intensively farmed regions. Focusing on the Northeast Black Soil Region (NBSR) of China, this study evaluated the trade-off/synergy relationships among Cultivated Land Ecosystem Services (CLESs) across multiple spatial scales, and identified threshold effects of landscape composition and configuration. We quantified five key services and applied Self-Organizing Maps (SOM) to classify service bundles. In addition, Random Forest (RF) and Multivariate Regression Tree (MRT) models were used to detect threshold effects of landscape patterns metrics on CLESs. The results reveal three findings: (1) interactions among CLESs are scale-dependent, with food production (FP) showing trade-offs with habitat quality (HQ) and carbon storage (CS) at the county scale, but shifting to synergies at the grid scale; (2) at the county scale, service synergies are primarily driven by landscape-level metrics, such as connectivity and diversity, whereas grid scale synergies depend on patch-level metrics like habitat composition (e.g., grassland, woodland and cultivated land) and their shape complexity; (3) distinct threshold effects were identified, e.g., high landscape connectivity (ENN_MN ≥ 0.464) and boundary complexity (PAFRAC ≥ 0.941) jointly enhance functional complementarity between FP and regulating services such as water yield (WY) and carbon storage (CS). Conversely, increasing grassland proportion (PLAND_GL > 18.1 %) in cultivated land-dominated areas (PLAND_CUL > 56.7 %) significantly strengthens ecosystem service coordination. These findings highlight the necessity of scale-specific, spatially explicit strategies to enhance both agricultural productivity and ecological resilience, offering actionable guidance for sustainable black soil management.