Urban conditions (soil compaction, tolerance of salt, drought, low maintenance), local climate conditions (rain, wind, temperature, humidity, winter hardiness) and the soil type all need to be considered when choosing which tree to plant.
Avoid the ‘green tunnel effect’ along streets where polluted air is trapped by too dense or too large trees and no ventilation. Either plant smaller trees or be sure that the porosity is more than 40% by choosing trees with open canopies or through sufficient maintenance. Also consider the amount of space available underground where the roots need to develop and above ground for crown development.
Trees for shade should have big canopies in the warm months, trees for streets should have a high branch structure to prevent obstacles in the streetscape, use columnar trees in narrow streets, trees in small gardens should not overtake the entire space, park trees should fit with their location, function, and managment regime. A tree that overgrows its boundaries will create negative opinions of trees in urban settings
Do not plant trees with falling fruit, seeds, uplifting roots or branches that fall in the wind in areas where they can cause damage, such as along streets, in parking areas and next to houses.
Trees should be able to survive in changing weather / climate conditions or periods when the public maintenance budget is not secure
Choose the tree variety based on the desired function as well as the site conditions.
“Trees can only fully mature and function when they are carefully selected, taking into consideration their growth characteristics, site conditions (including available space) and the functions to be performed by the trees. These three aspects are equally important and always need to be considered simultaneously.”
Jelle Hiemstra (Applied Plant Research – Wageningen UR)
In new development:
Trees should be included in the design at an early stage so they can be used for aesthetics and perform other beneficial functions such as air filtering, shade and wind. Let trees determine the character of development instead of the other way around: The right place for the right tree.
In existing development:
Existing conditions should be studied to determine which tree variety, size and characteristics fit best aesthetically and functionally in the space.