How does urbanization affect the reproductive characteristics and ecological affinities of street plant communities?

The nonlinear effect of new urbanization on water pollutant emissions: Empirical analysis based on the panel threshold model

Rapid urbanization has led to a significant increase in water consumption and wastewater discharge. Balancing the relationship between urbanization development and water pollutants emissions is crucial for the sustainable development of the country. Given the uneven regional economic development and resource distribution in China, exploring the relationship between new urbanization and water pollution emissions cannot be limited to a single perspective such as population urbanization. This study developed a comprehensive evaluation index system for new urbanization level. Based on data from 30 provincial-level regions in China from 2006 to 2020, a Panel Threshold Regression Model (PTRM) was used to explore the nonlinear relationship between the new urbanization level and water pollution discharge. The research results show that China's new urbanization level (NUBL) and its subsystems, including population urbanization (P-NUBL), economic urbanization (E-NUBL), and spatial urbanization (SP-NUBL), all have a double threshold effect on chemical oxygen demand (COD) emissions. The promoting effect of NUBL and E-NUBL on COD emissions gradually increased in the later stage of the study. P-NUBL and SP-NUBL show a trend of inhibiting COD emissions after crossing the dual threshold values. Social urbanization (S-NUBL) and ecological urbanization (EL-NUBL) had no threshold effect, but they also had a promoting effect on COD emissions. In addition, the speed of new urbanization in eastern China was significantly faster than that in central and western China, with provinces such as Beijing, Shanghai, and Jiangsu being the first to enter the high threshold stage. The central region began to gradually enter the middle threshold stage, but provinces such as Hebei, Henan, and Anhui are still in the high pollution and high emission stage. The level of new urbanization in western China is relatively low, and future development should prioritize economic construction. Provinces with high thresholds and low water pollution emissions still need to be developed. The results of this study have important implications for promoting the harmonious development of water-saving and sustainable urban development in China.

Plant-pollinator interactions in urban ecosystems worldwide: A comprehensive review including research funding and policy actions

Urbanization has rapidly increased in recent decades and the negative effects on biodiversity have been widely reported. Urban green areas can contribute to improving human well-being, maintaining biodiversity, and ecosystem services (e.g. pollination). Here we examine the evolution of studies on plant-pollinator interactions in urban ecosystems worldwide, reviewing also research funding and policy actions. We documented a significant increase in the scientific production on the theme in recent years, especially in the temperate region; tropical urban ecosystems are still neglected. Plant-pollinator interactions are threatened by urbanization in complex ways, depending on the studied group (plant or pollinator [generalist or specialist]) and landscape characteristics. Several research opportunities emerge from our review. Research funding and policy actions to pollination/pollinator in urban ecosystems are still scarce and concentrated in developed countries/temperate regions. To make urban green spaces contribute to the maintenance of biodiversity and the provision of ecosystem services, transdisciplinary approaches (ecological-social-economic-cultural) are needed.

Coupling and Coordination Level of the Population, Land, Economy, Ecology and Society in the Process of Urbanization: Measurement and Spatial Differentiation

Coupled and coordinated development is key to improving the level of regional urbanization and sustainable urban development and has important practical significance for solving a series of problems that arise in the process of rapid urbanization. First, from the perspective of system coupling, the development mechanism of the urbanization internal subsystems was deconstructed into five dimensions: population, land, economy, ecology and society. Second, based on data from 2017, the coupling coordination degree of urbanization in 13 cities in the Beijing–Tianjin–Hebei region was measured using the entropy method and a coupling coordination model. Finally, the spatial differences in the levels of subsystem development, comprehensive development and coupling and coordination development of urbanization were analyzed using spatial analysis tools. The results indicate that there are significant differences in the development indices of urbanization subsystems in the Beijing–Tianjin–Hebei region, among which the economic and social development indices have the greatest differences, and the ecological development index has the smallest. The comprehensive urbanization index shows a core–periphery distribution pattern, in which Beijing and Tianjin have the highest values, the cities in middle-southern Hebei Province generally have lower values, and the cities in northern Hebei Province have the lowest values. The coupling coordination level of urbanization in the Beijing–Tianjin–Tangshan region and Shijiazhuang, the capital of Hebei Province, is high, and the difference is small. In contrast, in middle-southern and northern Hebei Province, the coupling coordination degree of urbanization is generally low, and the difference is large. Based on the current situation of urbanization in the Beijing–Tianjin–Hebei region, policy suggestions are proposed from the perspectives of strengthening the market mechanism of urbanization, adjusting the regional industrial structure and attaching importance to the coupled and coordinated development of urbanization.