Governance innovation is an important topic in public administration research. Based on the empirical evidence of governance innovation in China, this paper analyzes the pathways to the sustainability of project-driven innovation in urban grassroots governance and reveals its complex causal relationships. Using the selected cases, a multidimensional analysis framework is constructed, and the qualitative comparative analysis method of fuzzy sets is used. It is found that there are three combined paths for the sustainability of innovation, namely dependent development, social embeddedness and government–society cooperation. The first two paths are the most common for the sustainability of innovation, and they cover most of the selected cases. Case tracking also reveals that innovation driven by project operation can stimulate the behavior of grassroots governance innovation, but it does not guarantee the sustainability of the innovation. The sustainability of innovation requires more mobilization of the grassroots society to enhance social embeddedness. Moreover, this study results provide inspiration for the sustainability of innovation in the later stages of projects.

Optimizing public investment in urban green infrastructure under water scarcity is a core challenge in resource economics. Against the backdrop of global climate change—characterized by rising temperatures, increased frequency and intensity of droughts, and altered precipitation patterns—this study addresses the critical knowledge gap in quantifying the economic returns on the physiological adaptations of urban trees, which are central to their value as natural capital. We integrated dual-water isotope (δ²H, δ¹⁸O) and leaf carbon isotope (δ¹³C) analyses to mechanistically decode the water use strategy of Machilus yunnanensis (M. yunnanensis) in drought-prone Kunming, China. The results show strategic seasonal plasticity: a shift from shallow soil water (10–50 cm) in the wet season to deeper soil sources (50–90 cm) and stem reserves in the dry season, coupled with a dynamic, diurnally variable water use efficiency (WUE_13C). We then constructed a transparent economic valuation model translating these traits into three quantifiable benefit streams: (1) operational cost savings (EV₁) from reduced irrigation demand; (2) enhanced marginal productivity of water (EV₂) in ecosystem service generation; and (3) climate resilience value (EV₃) via mitigated mortality risk. Our “Water–Carbon–Economy” nexus framework provides a generalizable methodology for assessing the cost-effectiveness and risk-adjusted returns of urban forest species, demonstrating that tree selection based on such eco-efficient traits is not merely an ecological choice but a sound economic investment, offering direct implications for budget-constrained municipalities seeking to maximize green infrastructure benefits under climate uncertainty.

Optimizing public investment in urban green infrastructure under water scarcity is a core challenge in resource economics. This study addresses the critical knowledge gap in quantifying the economic returns on physiological adaptations of urban trees, which are central to their value as natural capital. We integrate dual water isotopes (δ²H, δ¹⁸O) and leaf carbon isotope (δ¹³C) analysis to mechanistically decode the water-use strategy of Machilus yunnanensis in drought-prone Kunming, China. Results show strategic seasonal plasticity: a shift from shallow soil water (10–50 cm) in the wet season to deeper soil sources (50–90 cm) and stem reserves in the dry season, coupled with a dynamic, diurnally variable water-use efficiency (WUE). We then construct a transparent economic valuation model translating these traits into three quantifiable benefit streams: (1) Operational cost savings (EV₁) from reduced irrigation demand; (2) Enhanced marginal productivity of water (EV₂) in ecosystem service generation; and (3) Climate resilience value (EV₃) via mitigated mortality risk. Our “Water-Carbon-Economy” nexus framework provides a generalizable methodology for assessing the cost-effectiveness and risk-adjusted returns of urban forest species. It demonstrates that selecting trees based on such eco-efficient traits is not merely an ecological choice but a sound economic investment, offering direct implications for budget-constrained municipalities seeking to maximize the benefits of green infrastructure under climate uncertainty.