Abstract: The avenue trees Platanus spp. with DBH ≥1 m in Rehe Road, Beijing West Road and the compound of Nanjing municipal government were taken as the experimental object, and the root system with diameter ≥3 cm under different paving conditions was detected by using the tree radar detection system at the circle of 0.5 m,1.0 m and 1.5 m away from the trunk. The results showed that with the increase of distance from the trunk and soil depth, the number of roots with diameter ≥3 cm gradually increased. The root number and root distribution range （12.35~120.00 cm） of Platanus spp. with diameter ≥3 cm under lawn mulching were less than those under pavement. When all the outside of the tree pool is hard paved, 65.83% of the roots with diameter ≥3 cm distributed in the depth of 40~150 cm soil layer at the circle of 1.5 m away from the trunk, and the deepest degree of root distribution is 148.07 cm. It can be seen that the greater the barrier degree of pavement to the water and nutrients from the above ground part, the deeper the root system is promoted. The shallowest depth of root system distribution is related to the thickness of paved face brick or hardened pavement.

Key words: Platanus spp., pavement, spatial distribution of root system