China's natural carrying capacity: its change and progress of decision-oriented study.

International research on planetary boundaries and social-ecological systems, which focuses on revealing the mechanisms of interaction among system elements, together with China's decision-oriented research on natural carrying capacity (NCC), jointly constitute two important paradigms of sustainability research. This paper provides a systematic review of the progress of decision-oriented NCC research in China. The research began with single-factor carrying capacity assessments of land and water resources, focusing on how many people these resources could support and informing early population and resource management policies. Later, in response to the complex spatial planning demands posed by post-Wenchuan earthquake reconstruction, NCC research evolved into a comprehensive assessment system integrating resources, environmental conditions, ecological factors, and disaster risks, addressing challenges such as functional zoning, cross-scale application, and dynamic assessment, and ultimately becoming a foundational task of territorial spatial planning. On this basis, methods for territorial function suitability assessment and regional sustainability early warning were further developed, substantially strengthening NCC's role in evidence-based decision-making. Although the interactions among elements within the Earth's surface system remain incompletely understood, China's NCC research has established a distinctive and viable pathway for decision-oriented NCC assessment. It also outlines future directions for deepening understanding of the system's dynamic mechanisms and bridging regional and global sustainability boundaries.