广州荔湾高密度老城区行道树的特征、问题和对策

Roadside Trees in Liwan Highdensity Old Town of Guangzhou

城市行道树对改善城市生态环境有重要的作用．但行道树在城市中（尤其是在老城区）常受到许多问题的困扰．通过对荔湾区高密度老城区１４条街道１３５６棵行道树的详细调查，结果表明：高密度老城区的行道树种类多样性程度低，主要树种为大叶榕和麻楝，大部分树种属于常绿阔叶树．生长空间不足是高密度老城区树木与生境之间最主要的问题．由于生长空间狭窄和树种选择不当，目前，大部分树木已受到生长空间的限制．另外，由于管理上的问题，大部分树木受到不同程度的伤害．根据以上问题，在树种选择和管理上提出一些相应的意见和建议．

The trees in roadside are often affected by narrow space, bad soil quality and intensive human activity This is especially true for highdensity urban areas A detail survey for 1 356 roadside trees was conducted in 14 streets of Liwan highdensity old town of Guangzhou Of the 18 species encountered and 9 species was local Comparing with roadside trees in Liwan district and Urban Guangzhou, the dominant species in study area was more popular Most of species were evergreen broadleave trees and more than half of species had a potential high up to 20 m, which was too big to grow fully in the highdensity old town About 70% of roadside trees were planted in small tree pits without grille And 29% of the trees was paved to the trunk base by concrete The breast high girths of 43% trees were in range between 40 to 80 cm and the height of 40% trees were in range between 6 to 9 m Very few trees were cultivated in recent few years The big trees were mainly composed of Ficus virens Crown of 64% trees were less than 6 m width due to space limit There were a series of defects and disorders for roadside trees in highdensity old town Of which, 305% of trunks were leaning to streets and 364% of trunks were at or beyond kerbs This was a reason why many trunks were hurt by vehicles In addition, 776% of tree crowns had been restricted by building etc The others would meet the same problem in next few years The overall rating for most of trees were fair Only 136% of trees were good and 157% of trees were poor The very small amount were excellent and dying The selection of tree species and management of roadside trees are discussed and some suggestions are made