The expansion efficiency of urban land in China's urban agglomerations and its impact on ecosystem services

Analyzing the impact of urban land expansion efficiency (ULEE) on ecosystem services (ESs) is crucial to constructing high-quality territorial spatial patterns within urban agglomerations (UAs). While numerous studies have investigated the coercion and disturbance of urban sprawl on the ecological environment, research examining the impact of urban sprawl from an efficiency perspective remains relatively rare. In this study, ten UAs of different levels of development in China are selected as the research objects, and prefecture-level cities are used as the primary research units. CO2 emissions are included as undesired outputs in the measurement and research framework of expansion efficiency to reflect the vision and requirements of emission reduction and carbon neutrality. At the same time, the Spatial Durbin Model (SDM) is used to reveal the impact of ULEE on ESs in years 2005-2021. The main results are as follows: (1) The ULEE within the entire UAs areas exhibited a fluctuating trend across different periods. Efficiency variations were evident among UAs with different development levels. Spatially, the UAs in the central region showed relatively low ULEE, while the northwest and southeast UAs displayed relatively high ULEE. Besides, the expansion efficiency of core cities in each UA exceeded that of surrounding cities. (2) The ecosystem service value (ESV) within the ten UAs demonstrated a consistent downward trend. In terms of the rate of ESV decline among UAs with varying developmental levels, breeding UAs exhibited the most rapid decline, followed by growing UAs, while mature UAs experienced the slowest decline. (3) Over the study period, the ULEE in UA areas positively contributed to enhancing ESs, with varying effects observed across different time frames. Natural factors directly influenced ES changes, thereby affecting both ULEE and Es dynamics. In contrast, changes in social factors indirectly caused changes in ESs. This study underscores the importance of a comprehensive assessment of ULEE and ESs to provide a scientific reference for formulating high-quality social and economic development and territorial spatial planning.