Understanding the indirect impacts of urbanization on vegetation growth using the Continuum of Urbanity framework

A new method for evaluating the coordinated relationship between vegetation greenness and urbanization

Understanding and measuring the link between vegetation greenness and urbanization is crucial for public health and sustainable development. However, previous methods may oversimplify urbanization indicators and fail to adequately reflect changes in their relationships. To address this, we introduced a comprehensive urbanization vegetation coordination index (CUVCI) on the basis of comprehensive urbanization and a compound annual growth rate and applied this index to the Yellow River Basin in China. We examined the spatiotemporal evolution of the NDVI, comprehensive urbanization level (CUL), and CUVCI from 2000 to 2019 and explored potential driving factors. The results indicate that: (1) from 2000 to 2019, 87.8% of the areas in the Yellow River Basin demonstrated a trend of vegetation growth, with growth levels highest in the midstream regions, followed by the upstream and downstream areas. (2) The CULs of most cities in the basin have shown an increasing trend, with the CUL levels in the middle and downstream cities being significantly higher than those in the upstream cities. (3) CUVCI from 2000 to 2019 was characterized mainly by general coordination (57.4%) and minor conflict (18.5%), with minor-conflict cities located primarily in the middle and lower basin. The coordinating relationships in most cities show signs of improvement. (4) While natural environmental factors such as precipitation, temperature, and relief have a significant impact on CUVCI, scientific researchers can promote the coordinated development of vegetation greenness and urbanization. Our findings suggest that cities in the basin are experiencing economic prosperity and increased greenery. However, strong- and minor-conflict cities should prioritize cultivating and attracting scientific research talent and learning from coordinated provincial capital cities.

Dual effects on vegetation from urban expansion in the drylands of northern China: A multiscale investigation using the vegetation disturbance index

Drylands contribute roughly 40 % of the global net primary productivity and are essential for achieving sustainable development. Investigating the effects on vegetation from urban expansion in drylands within the context of rapid urbanization could help enhance the sustainability of dryland cities. With the use of the drylands of northern China (DNC) as an example, we applied the vegetation disturbance index to investigate the negative and positive effects on vegetation from urban expansion in drylands. The results revealed that the DNC experienced massive and rapid urban expansion from 2000 to 2020. Urban land in the entire DNC increased by 19,646 km2 from 8141 to 27,787 km2, with an annual growth rate of 6.3 %. Urban expansion in the DNC imposed both negative and positive effects on regional vegetation. The area with negative effects reached 7736 km2 and was mainly concentrated in the dry subhumid zones. The area with positive effects amounted to 5011 km2 and was comparable among the dry subhumid, semiarid, and arid zones. Land use/cover change induced by population growth significantly contributed to these negative effects, while the positive effects were largely caused by economic growth. Therefore, it is recommended to strike a balance between urban growth and vegetation conservation to mitigate the adverse effects on vegetation from urban expansion in drylands. Simultaneously, it is imperative to expand urban green spaces and build sustainable and livable ecological cities to facilitate sustainable urban development.