Quantifying influences of anthropogenic-natural factors on ecological land evolution in mega-urban agglomeration: A case study of Guangdong-Hong Kong-Macao greater Bay area

Modeling ecological land evolution and determining the responsible driving forces is a common research topic in land use and landscape ecology. However, the interaction effect and dynamic change of anthropogenic-natural factors on the ecological land evolution of urban agglomerations is still unclear. Supported by Google Earth Engine, this study used Landsat satellite imagery and random forest algorithm to obtain the land cover datasets of Guangdong-Hong Kong-Macao Greater Bay Area from 1990 to 2019. Furthermore, a geographic detector was used to identify the driving factors’ impact on ecological land evolution by quantifying nonlinear associations, change characteristics, and mechanisms. The results show: (1) Ecological land shifted from decline and fragmentation (1990–2010) to growth and integration (2010–2019). (2) Population density (q = 0.83) and land urbanization rate (q = 0.75) mainly controlled the ecological land evolution, illustrating more explanatory power than other factors, and accounting for higher proportion of area as the determinant factor in the study region. All driving factors interactions were bivariate, and the interaction between population density and elevation had the largest influence (q = 0.92). (3) Anthropogenic factors had a generally greater influence on ecological land than natural factors, and the impact of population density and GDP per capita exhibited a continuous increase, while land urbanization rate first decreased (1990–2000) and then increased (2000–2019) in response to industrial restructuring and accelerated urbanization. Due to the intensification of anthropogenic activities, the effect of average annual temperature and precipitation declined by 69% and 77%, respectively. The conclusions indicate that the interaction and spatially heterogeneous distribution of anthropogenic-natural factors should be comprehensively considered when designing a system based on cooperative mechanisms to improve ecological protection efficiency.