1. What is the function of street trees? Road system is the infrastructure for building a modern civilized society. Solving the problems in Difficult Travel has become a problem that governments at all levels must consider in developing the economy, and has become the primary measure to get rid of poverty and get rich and stimulate domestic demand. The criss-crossing streets and roads build the internal operation mechanism of the city, and the suburban roads extending in all directions strengthen the external contact function of the city. The selection and application of street trees have positive environmental and ecological effects on improving road service system and quality.

2. The main cultivation places of street trees are sidewalk green belt, dividing line green island, citizen square trail, riverside avenue and both sides of urban and rural roads. Due to poor site conditions, it is seriously polluted by smoke and harmful gases, damaged by pedestrian collision, blocked by underground pipelines or overhead lines, blocked by buildings and radiated by cement pavement. The ideal selection criteria of street tree species should be barren resistance, pollution resistance, injury resistance, less insects and light diseases, strong and long life, easy modeling and neglect of management; From the requirements of landscape effect, it should be shaded in spring and autumn, winter and summer, dry and beautiful, beautiful flowers, excellent crown shaping and lasting landscape.

3. Road greening, as the network and skeleton of urban green space system, has become the main part of the system continuation, and it is also the deepest bright spot for local citizens and outsiders to feel after traveling. It plays an outstanding role in directly reflecting the urban landscape, so it has attracted more and more attention from people at all levels. In the selection and application of street trees, urban roads are dominated by deciduous broad-leaved trees, with broad crowns, lush greenery and beautiful shapes. Suburbs and general grade highways pay more attention to maintenance cost factors such as rapid growth, pollution resistance, barren resistance and easy management. The selection and application of street trees in memorial places such as tunnels and tombs are mainly evergreen conifers, such as juniper, cypress, cedar and masson pine. Deciduous trees include willow, locust and elm. In addition, palm trees are often selected. In recent years, with the improvement of urban environmental construction standards and the implementation of greening, purification, beautification and fragrance indicators, the selection and application of evergreen broad-leaved trees and colorful fragrant flower trees have made great progress, showing an upward trend, especially in urban trunk roads, expressway trunk roads, airport roads, Tonggang roads, railway station roads and pedestrian streets in commercial downtown areas, which have made a qualitative leap in the specifications, varieties and taste requirements of street trees.