Adaptive Dynamic Evolution of Social-Ecological Systems in the Huaihe River Ecological and Economic Belt (HREEB) Based on Complex Adaptive System Theory

Understanding the adaptive dynamics of social-ecological systems (SESs) is critical for regional sustainability as human–environment interactions intensify. However, existing indicator-based research frequently lacks a clear theoretical framework and methodological clarity when analyzing SES adaptation. Using complex adaptive system (CAS) theory as an interpretive lens, this research creates a social-ecological system (SES) adaptability evaluation framework that incorporates the pressure–state–response (PSR) model from a CAS perspective. This study examines the Huaihe River Ecological and Economic Belt (HREEB) as a case study, combining remote sensing (RS) and geographic information system (GIS) data from 28 prefecture-level cities from 2005 to 2020. The entropy-weight approach is used to create a composite adaptability index, and obstacle-degree analysis is used to identify key limiting factors, followed by an examination of spatiotemporal evolution patterns. The study found that: (1) SES adaptability in the HREEB increased steadily (mean annual growth rate: 3.97%), with the social subsystem exhibiting a larger connection with the overall trend and the ecological subsystem displaying greater volatility; (2) there was significant spatial heterogeneity, forming a “high in the east and west, low in the center” pattern (supported by a global Moran’s I = 0.535, p < 0.05); (3) obstacle degree analysis identified per capita afforestation area (ecological response), per capita GDP (social state), and population density (ecological pressure) as persistent key constraints.