Investigation and Analysis on Resources and Structure of Street Trees in Shannan City

Sampling survey was carried out during June and September of 2016 on resources, structure and allocation of street trees in Shannan city, Tibet Autonomous Region.The results showed that there were 24 species of 17 genera and 10 families, with mean DBH, crown width and height of 13.29 cm, 7.31 m and 3.72 m respectively.The most common in the city was ordered by Salicaceae (6 species), Rosaceae (5 species) and Pinaceae (3 species), occupied 25.00%, 20.83% and 12.50% of the total investigated street trees.Importance value of street trees was followed by Salix alba (70.525), Populus × beijingensis (35.690) and Cedrus deodara (33.171), with low diversity index.Seasonal phenomena of street trees was dependent on spring-autumn and autumn aspection.Trees had white and yellow color.Vertical structure of street trees was mainly two layer (39.06%).