Forest expansion, farmland transition, and grain–ecological change in Henan, China: a coupled secondary-data analysis

Objective In a major grain-producing province, forest expansion, cropland contraction and grain-output change are often discussed as a single conservation–production trade-off. This study examines whether that framing is supported when land-transition pathways, grain-production accounting and ecological outcomes are aligned explicitly across common time intervals. Methods We integrate five benchmark years (2000, 2005, 2010, 2015 and 2020) from official grain statistics and published datasets on land use, ecosystem services and cultivated-land emergy accounting. Independent land-transition matrices decompose gross cropland loss by destination, while grain output is separated into sown-area and yield components. A coupled interval diagnostic aligns transition shares, grain changes and ecosystem-service trajectories for 2000–2010 and 2010–2020. Candidate policy, socioeconomic, management and biophysical drivers are interpreted after the observed trajectories are established by triangulating the integrated results with Henan-specific and national source evidence. Results Mapped cropland declined by 7.5% from 2000 to 2020, forest area increased by 8.9% and built-up land by 55.6%, while grain production increased by 66.4%. In both decadal transition matrices, about 13.7% of gross cropland loss moved directly to forest and 71.1–73.4% to built-up land; the remaining 13.0–15.2% moved mainly to water and grassland. Grain sown area increased by 18.9% and yield by 39.9%; in the logarithmic production identity, sown-area change represented 34.0% and yield change 66.0% of total output growth. Soil- and water-related services fell to a 2010 trough and then recovered, whereas carbon storage and habitat quality declined modestly. Net ecological supply in the separate emergy framework increased by 69.8%. Conclusion Henan’s 2000–2020 trajectory is best understood as the interaction of urban expansion, agricultural intensification and service-specific environmental controls. Built-up conversion was the dominant direct destination of lost cropland, while larger annual sown area and higher yield supported continued grain-output growth. The reversal of soil- and water-related services after 2010, despite a stable cropland-to-forest share, is consistent with strong hydroclimatic, topographic, vegetation and accessibility-related controls. These findings highlight the need to coordinate cropland protection, urban land management and service-specific ecological restoration in major grain-producing regions.