Climate change and human activities have considerably changed the spatial patterns and functional elements of regional habitats. Understanding spatiotemporal changes in habitat quality (HQ) and their potential driving factors is essential for maintaining ecosystem health and protecting biodiversity. To explore the effect of physical and human factors on HQ changes in Southwest China, we firstly analyzed the land-use change intensity (LCI). We then evaluated spatiotemporal changes in HQ based on the InVEST model and explored the spatial heterogeneity of the main driving factors of HQ changes based on a geographical detector and a geographical weighted regression model. The results showed that LCI had obvious spatiotemporal differences, and LCI from low-quality habitat to high-quality habitat (LCI₁) was significantly higher than that from high-quality habitat to low-quality habitat (LCI₂). The HQ improved steadily in Southwest China in 1990–2015, showing a trend of low–high–low from southeast to northwest. Moreover, there were twelve factors, including aboveground biomass, ecological land area ratio, population density, slope, etc., which had a significant impact on the spatial differences in HQ, and the effects of different factors on HQ had observable spatial heterogeneity. The effect of LCI₂ on the spatial difference of HQ was greater than that of LCI₁. These results suggested that the current ecosystem protection and management policy had a positive effect on improving HQ. Our study provides an important decision-making reference for sustainable land development and utilization and regional ecological protection and restoration.

The issue of urban carbon emission efficiency (CEE) has become a critical problem for global sustainable development, particularly in China, where the phenomenon of shrinking cities has emerged after rapid urbanization. Using panel data from 283 Chinese prefecture-level cities (2000–2016), we examine how urban shrinkage affects CEE through both direct and spatial spillover effects. Our findings show that urban shrinkage significantly improves CEE both directly and indirectly; when a city shrinks, it increases the local CEE by 0.0132%, while the contraction of adjacent cities enhances the local CEE by 0.0312%, leading to a total improvement of 0.0445%. However, the overall CEE in shrinking cities remains lower than the nationwide average, with values consistently below 0.5. The main determinants of CEE are GDP per capita and population size, which show significant direct positive effects but opposing regional spillover effects. These findings offer important insights for urban development policies and sustainable city management in the context of population decline.

Economic development and environmental conservation are two important challenges for China. A series of initiatives including Eco-province (EP) policies have been taken to achieve sustainable development by the Chinese government. Increasing concerns regarding policy implications on sustainable development have increased attention to the topic. However, the research on the relationship between economic development and pollutant (COD, SO₂) emission intensities after the implementation of EP policy remains inadequate. We applied a Time-Varying Difference-in-Differences Model by employing Chinese provincial panel data to quantitatively study the policy effect, and further utilized the Mediating Effect Model to analyze the mechanism. The article generates several findings: (1) The EP policy had overall inhibitory effects on both COD and SO₂ emission intensities, and it would reduce the emission intensity by 4.99% and 6.77% on average, respectively. However, there was a five year lag in the policy effect. (2) The policy effect was significant in the western and central provinces with high pollutant emission intensities, but not in the eastern provinces. (3) The primary inhibiting mediating effects of Eco-province policy to lower pollutant emission intensity were increased GDP per capita and inventions.