Background With the accelerated urbanization of the Pearl River Delta(PRD), urban and rural construction land has been expanding, resulting in a series of problems such as serious soil erosion, damage to the ecological environment, and unbalanced development of urban and rural areas. The contradiction in the utilization of "production-living-ecology" space in the PRD is prominent, but the development relationship between internal coupling and coordination is not clear. We propose to quantitatively identify the evolutionary characteristics of the spatial coupling and coordination relationship among the three living things in the PRD.

Methods We used the coefficient of variation method and entropy weight method to construct the evaluation index system of three spatial functions. Using the coupled coordination model, we calculated the degree of coupling and the degree of coupled coordination of the three living spaces in the PRD for the year 1999, 2004, 2009, 2014 and 2019. Then, we analyzed the spatio-temporal variation characteristics based on ArcGIS software.

Results 1) The interaction of the three spatial functions of the cities in the PRD urban agglomeration was getting closer and closer, and the number of high-coupling cities has nearly doubled, showing the characteristics of moving from the running-in stage to the high coupling stage. 2) The evolution of the relationship between three space functions showed the characteristics of overall coordinated development, and the number of imbalanced cities decreased by nearly double. These manifested the overall coupling coordination degree changing from imbalanced to coordinated. Besides, the north-south cities' coupling coordination degree increased significantly. 3) The difference between the two coupling coordination degrees was obvious, and the coupling coordination of "production-living" functions was poor, which was the key direction for the optimization of the three spatial functions for the PRD urban agglomerations.

Conclusions By exploring the characteristics of the functional coordination evolution of the PRD in the past 20 years, this study revealed that a systematic analysis of the interaction between the multi-functional relationships of the PRD may help identify the unbalanced and uncoordinated development of ecology, production and life, so as to provide a scientific basis for the overall improvement of soil and water conservation functions and the restoration of ecology in the PRD.