On streetscaping (vi) Trees

The urban tree problem …

Trees in the built-up city face difficult conditions. Among these are tiny porous surfaces around the bases (the city minimum porous surface was 4’x4’ and this became the maximum space, even when room was available); packed earth or paving base as “growing media”; pollution; car damage; snow removal damage from city crews or contractors; hostile property owners who remove street trees; cultural hostility from groups that feel trees are invasive or unlucky; sidewalk repairs that reduce tree wells; overhead wiring and over-zealous “pruning” and trimming by utilities, etc.

City standards are sometimes unhelpful. The city may require large canopy areas before planting trees, and prefer to centre trees in the front space of a building rather than along the curb or sidewalk.

The tree solution …

More aggressive selection of tree and shrub planting opportunities. Selection of fastigate (columnar shaped trees) or smaller trees to fit into smaller spaces.

Use of structural earth permits trees to thrive close to curbs, sidewalks, on bulbouts. Read more at http://westsideaction.blogspot.com/2009/11/structural-earth.html ; http://westsideaction.blogspot.com/2009/11/tree-will-thrive.html.
Structural earth is a mix of gravel and clay and water-retaining modules. The gravel packs down into a honeycomb-like mass, so the tree roots have room to spread and grow while the gravel is stable enough to support sidewalks, bus stops, or parked cars above. The result: trees can once again thrive in the city.