What are the characteristics of urban greening layout in Chinese history?

City greening was based on the tradition since the Han Dynasty of planting acacias on both sides of major thoroughfares, while in Luoyang, cherry and pomegranate were used as street trees from the Sui Dynasty onwards, and willows were planted on the riverbanks, which were used in Chang'an in the Tang Dynasty and in Tokyo in the Northern Song Dynasty. More importantly, from the Northern Song Dynasty, the closed workshop system has existed in name only, and the abolition of the centralized market, instead of a mixture of residential and commercial street form, but the layout of the capital city in the feudal system and traditional rituals under the influence of the city still strive to square and symmetry, and the volume and color of the buildings to emphasize the role of the main body of the palace as the city's central axis.