In order to explore the relationship among environmental regulation, the transformation of resource-based cities, and spatial spillover of resources, a semi-parametric threshold spatial Durbin model (STSDM) was constructed based on data from 113 resource-based prefecture-level cities from 2011 to 2021, starting from the perspective of spatial spillover. The nonlinear relationship between environmental regulation on the transformation performance of resource-based cities and the impact of asymmetric spatial spillover is explored. The results show under the linear assumption, environmental regulation is not conducive to improving the transformation performance of cities. However, under the nonlinear assumption, environmental regulation is beneficial to improving the transformation performance of resource-based cities in the early stage. It has a non-linear long-term characteristic with a "diminishing marginal effect", and the partial derivative plot shows a weak "U-shaped" feature. There is asymmetry in the spatial spillover effects on the transformation performance of resource-based cities. The higher the stage of environmental regulation in resource-based cities, they can obtain the fewer spatial spillover bonuses for the transformation of urban performance. Based on this, policy suggestions are put forward, such as adapting environmental regulation policies to local conditions and establishing a long-term environmental protection mechanism.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |