| Summary: | 碩士 === 東海大學 === 景觀學系 === 91 === This project provides research on the root damage of street trees to sidewalk hardscape, and its costly maintenance. A total of 2,113 street trees including 10 species were surveyed in Kaohsiung. The goal of this project is to investigate the difference of the root damage by different street-tree species in hardscape─frame, pavement and curbs of sidewalk. Hardscape damage was found to increase with tree height. The level of root damage to hardscape is related to tree size(dbh). Alstonia scholaris and Cinnamomum camphora started to cause damage when their dbh > 10cm. Trees planted into pavement caused more significant damage than trees planted in planting strips. There are significant differences in the proportions of trees of different species causing hardscape damage. Ficus elastica, Ficus microcarpa, and Ficus religiosa may cause more significant damage than other species, and should not be grown in confined spaces. The proportion of tree roots causing the sorts of hardscape damage varied significantly in different pavement.
According to the analyses and results, the suggestions are as follows:
1. It is noticeable to choose the tree species of deep roots, slow growing roots and local protogenic as the ideal species. We can avoid the tree species of large surface roots, horizontal roots and board roots.
2. For the planter size, it should be enlarged separately. For the tree pits, it should be combined (something) one into a planter-belt. For those street trees with shallow roots which cause the hardscape damage, the planters should be installed root-barrier as preservation of surrounding structure.
3. Root pruning selectively can save a mature tree and prevent future damage to hardscapes. It is necessary to have a regular investigation of the air capacity and drainage situation of the soil in the planter.
4. The sidewalks can be paved with the pervious pavement.
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