Assessing the Impact of the 'Ten Articles on Soil' Policy on Urban Green Space Construction: Evidence from a Double Difference Model

The prerequisite for effectively estimating the double difference model is that the parallel trends assumption holds. This requires comparing whether the time trends of the experimental and control groups before policy shocks are consistent. In the double difference model set in this paper, the main focus is on whether the estimated parallel time trends of resource-based cities and non-resource-based cities before the implementation of the 'Ten Articles on Soil' policy remain consistent. Table 2 presents the results of the parallel trend test. Before the implementation of the 'Ten Articles on Soil' policy, the estimated coefficients of explanatory variables are not significant and close to zero, indicating that the time trends of the experimental and control groups are consistent, satisfying the parallel trend assumption of the difference model. After the implementation of the 'Ten Articles on Soil' policy, the change trend of the estimated coefficients increases significantly, but the effect is not persistent, indicating that the policy has a significant promotion effect on the construction of urban green spaces (UGS) in resource-based cities. However, the lack of timely adjustment of supporting policies based on the implementation of the policy has led to unclear economic governance responsibilities and inadequate governance funds. In the future, local governments should timely follow up on the implementation of policies, and make real-time adjustments and revisions to their plans according to specific circumstances.