**2. Study Area**

Zhengzhou (34◦16 –34◦58 N, 112◦42 –114◦14 E) is the capital city of Henan Province in Central China. It is south of the North China Plain and the Yellow River (Figure 1). It is one of the largest transportation hubs in China. The population of the city was approximately 9.56 million, according to the 2017 census [43]. The population density is the second highest in China. Zhengzhou lies in the north warm-temperate zone, characterized by a warm climate, because of this it has four distinct seasons, characterized by a dry spring (March–May), and a hot and rainy summer (June–September).

Urbanization was taken place at a rapid rate in the past few decades in Zhengzhou city. This makes it an ideal sample city to understand the problems which are seen across urbanized cities across the world. Population growth and government level development policy is the main driver for the dramatic urban expansion. For example, the population of Zhengzhou increased from 4.2 Million in 1978 to 9.9 million in 2017, which means more than 100% growth in 40 years [44]. At the same time, Zhengzhou was designated as the core city of "Central Plain Economic Zone" and "Central Plains Urban Agglomeration." In 2016, Zhengzhou was officially named as the eighth "National Central City" in 2017 by the central government in China. This state-level policy provides a significant number of opportunities for the development of Zhengzhou.

**Figure 1.** Location of the study area Zhengzhou, Henan province in China and 123 park samples in Zhengzhou.
