Can Regional Integration Reduce Urban Carbon Emission? An Empirical Study Based on the Yangtze River Delta, China.

Regional integration can significantly affect carbon emissions, but scholars have paid more attention to the impact of integration level, ignoring the importance of regional integration expansion. This study attempts to demonstrate whether, in the process of promoting carbon peak and carbon neutrality in China, the transformation of the administrative region's economy into an integrated economy based on urban agglomeration regional integration expansion affects urban carbon emissions. This study considers the regional integration expansion of the Yangtze River Delta Urban Economic Coordination Committee as a quasi-natural experiment, exploring the carbon emission reduction effect of regional integration with the difference-in-differences model. With the mediating and moderating effect models, this study examines the mechanism of regional integration affecting urban carbon emissions. The results show that regional integration, considering regional integration expansion, can significantly reduce urban carbon emissions. The carbon emission reduction effects of regional integration show significant heterogeneity. For example, there is a significant carbon emission reduction effect of high-hierarchy cities and an insignificant carbon emission reduction effect of general-hierarchy cities. Further research into the driving mechanism finds that deepening collaborative governance, industrial structure optimization, and green technology promotion brought about by regional integration are important mechanisms influencing urban carbon emissions. In addition, the carbon emission reduction effect of regional integration is influenced by the level of urban marketization and development efficiency. Different from the existing studies focusing on the effects of regional integration level, this study assesses the feasibility of promoting urban green development through urban agglomeration regional integration expansion. Based on the relevant empirical research, we propose to better promote high-quality development by strengthening urban agglomeration cooperation, optimizing urban development paths, strengthening innovative development, and improving macro political systems. It also indicates that the relevant policies should be formulated after considering local conditions.

Differential characteristics of carbon emission efficiency and coordinated emission reduction pathways under different stages of economic development: Evidence from the Yangtze River Delta, China.

Regional carbon emission efficiency (CEE) has differentiated characteristics under different economic development stages and patterns, and identifying such characteristics is important for formulating corresponding policies for high-quality regional development. Using input‒output data related to economic development and energy consumption, a comprehensive evaluation model of the Super-SBM and Malmquist‒Luenberger (ML) index is constructed to evaluate the spatial and temporal changes and driving forces of CEE. Based on this index, a proposal is designed for collaborative carbon emission reduction zoning. The results indicate that the CEE of the Yangtze River Delta shows a fluctuating upward trend with obvious spatial agglomeration characteristics, and CEE changes are closely related to economic development stages. The annual average CEE values in each stage show positive changes, indicating that economic development gradually evolves to low carbonization levels. Moreover, CEE improvement gradually shifts from being driven by efficiency changes to being driven by technological changes. Finally, according to the characteristics of total carbon emissions and the efficiency of different cities, a synergistic emission reduction path is proposed with four aspects: land use optimization, ecological co-preservation, innovation cooperation and low carbon development.

Clonal integration affects growth, photosynthetic efficiency and biomass allocation, but not the competitive ability, of the alien invasive Alternanthera philoxeroides under severe stress.

BACKGROUND AND AIMS: Many notorious alien invasive plants are clonal, but little is known about some roles and aspects of clonal integration. Here, the hypothesis is tested that clonal integration affects growth, photosynthetic efficiency, biomass allocation and competitive ability of the exotic invasive weed Alternanthera philoxeroides (Amaranthaceae). METHODS: The apical parts of Alternanthera were grown either with or without the lawn grass Schedonorus phoenix (tall fescue) and their stolon connections to the basal parts grown without competitors were either severed or left intact. KEY RESULTS: Competition greatly reduced the maximum quantum yield of photosystem II (F(v)/F(m)) and growth (biomass, number of ramets and leaves, total stolon length and total leaf area) of the apical Alternanthera, but not the biomass of S. phoenix. Stolon connections significantly increased F(v)/F(m) and growth of Alternanthera. However, such effects on growth were smaller with than without competition and stolon connections did not alter the relative neighbour effect of Alternanthera. Stolon connections increased Alternanthera's biomass allocation to roots without competition, but decreased it with competition. CONCLUSIONS: Clonal integration contributed little to Alternanthera's competitive ability, but was very important for Alternanthera to explore open space. The results suggest that the invasiveness of Alternanthera may be closely related to clonal integration.