Coupling human and natural systems for sustainability: experience from China's Loess Plateau

Addressing the sustainability challenges that humanity is facing in the Anthropocene requires the coupling of human and natural systems, rather than their separate treatment. To help understand the dynamics of a coupled human and natural system (CHANS) and support the design of policies and measures that promote sustainability, we propose a conceptual cascade framework of "pattern-process-service-sustainability", which is characterized by coupling landscape patterns and ecological processes, linking ecological processes to ecosystem services, and promoting social-ecological sustainability. The use of this framework is illustrated by a review of CHANS research experience in China's Loess Plateau (LP), a well-known region for its historically severe soil erosion and successful ecological restoration achieved in recent decades. Ecological restoration in the LP has greatly increased its vegetation coverage and controlled its soil erosion. However, some accompanied issues, like soil drying in some areas due to the introduction of exotic plant species and the mismanagement of planted vegetation and water use conflicts between vegetation and humans caused by the trade-off between carbon sequestration and water supply, have started to threaten the long-term sustainability of the LP. Based on a comprehensive understanding of CHANS dynamics, the social-ecological sustainability of the LP can be improved through enhancing water and food security, implementing basin-wide governance, maintaining ecological restoration achievements, and promoting rural livelihood transition. The research experience accumulated on the LP offers examples of the application of the pattern-process-service-sustainability framework. Future research using this framework should especially focus on the integrated research of multiple processes; the cascades of ecosystem structure, function, services, and human well-being; the feedback mechanisms of human and natural systems; and the data and models for sustainability.