The socio-ecological implications of shifting patterns of cropland use in northeast China

Globally, mid-latitude Mollisol regions are vital breadbasket areas, but their ecosystems are being exhausted by overproduction. Understanding the evolution of agricultural practices and the associated consequences across different socio-ecological contexts is crucial for planning future crop production. Most studies to date have focused mainly on tropical regions, and have concentrated on fixed effects while overlooking spatiotemporal heterogeneity. We present an important case study from northeast China, using shifting patterns of cropland expansion, intensification and specialization from 2000 to 2019 to demonstrate how agricultural practices have evolved and encroached on natural resources. The locational Gini coefficient, revised universal soil loss equation, modified InVEST models, and geographically and temporally weighted regression model were applied to estimate the underlying socio-ecological implications. The results indicated that, cropland expansion (+44.22 %) and specialization were prominent, with grain cultivation increasing to almost 87 % while crop diversity was drastically reduced. Cropland intensification revealed a homogenizing transition, with an increase in machinery power (+97.25 %) and fertilizer (+28.80 %) applications. In the northern Songnen Plain and Sanjiang Plain, alongside expansion, cropland distributions have changed, with the majority of intensification and specialization indicators being pushed to higher latitudes. For example, maize production has driven soybean production to the Lesser Khingan Mountains, and rice has been transferred from the Liaohe Plain to Sanjiang Plain. During 2000–2019, some social indicators, including rural household income, grain production and inequality of agricultural development, improved, but not necessarily in relation to the changes in cropland use. Cropland expansion was beneficial to grain production, but detrimental to spatial equality. Water stress and pollution were identified as major ecological threats as a result of cropland expansion. Carbon sequestration also experienced an expansion-driven increase, but at the expense of crucial local ecosystems with higher carbon densities. Although the overall quality of natural habitats had improved, these habitats were threatened by most of the changes witnessed on the plains. Soil loss was sensitive to expansion in hilly reclaimed areas, but in Songnen Plain and Liaohe Plain, where conservation tillage has been promoted, intensification and specialization pressures were mitigated. A northwards shift of cropland distribution is currently a primary driver of the intensifying socio-ecological implications, representing the ongoing adaption of farming in marginal areas. The intensification and specialization of agricultural practices in Mollisol regions should be the focus for addressing the necessary future reconciliation of agriculture and nature.