Identification of factors influencing net primary productivity of terrestrial ecosystems based on interpretable machine learning --evidence from the county-level administrative districts in China.

Global climate change is rooted in the imbalance between carbon sources and sinks, and net-zero greenhouse gas emissions should focus not only on the source-side drivers but also on the sink-side influencing factors. Taking the county-level administrative districts in China as the sample, this study uses machine learning models to fit the relationship between socioeconomic development (SED) and net primary productivity (NPP) of terrestrial ecosystems. Moreover, it identifies key influencing factors and their effects based on the SHapley Additive exPlanations (SHAP) algorithm. The results show that the districts with low terrestrial NPP show the characteristics of agglomeration distribution. The eight key factors, in order, are as follows: agricultural development level, latitude, population size, longitude, animal husbandry development level, economic scale, time trend and industrialization level. In this study, via SHAP interaction plots, we found that the effects of population, economic growth, and industrialization on terrestrial NPP are regionally heterogeneous; via cluster analysis, we found the stage characteristics of the mode of SED affecting terrestrial NPP. Therefore, the conservation of terrestrial NPP needs to be combined with the stage changes of SED, as well as inter-regional differences, to develop a regionally coordinated and time-coherent ecological carbon sink conservation plan.

Improvement of regional environmental quality: Government environmental governance and public participation.

The improvement of regional environmental quality (REQ) not only requires local governments to adopt environmental investment, legislation and law enforcement, but also requires the coordination of government environmental governance and public participation. This study analyses the impact mechanism of government environmental governance, public participation and their coordinated effect on the improvement of REQ, which is a comprehensive indicator measured by the emission of waste gas, waste water and waste solids. After empirical analyses using sample data from 30 provinces in China, the results show that, REQ has been increasingly deteriorating; the effects of government's environmental investment, legislation and law enforcement on REQ improvement are significantly positive, and public participation also helps to stimulate REQ. There also exists a coordinated effect between government environmental governance and public participation. Compared with citizen participation, environmental non-government organisations' participation has a more significant positive effect on REQ improvement. Finally, the influence of government environmental governance and public participation on REQ has significant spatial heterogeneity. The conclusions above can provide inspiration for Chinese government to improve the environmental governance system, which is good for the improvement of REQ.