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CommonIssues

Issue 1: Not enough soil

When there isn't enough soil, the tree will reach the carrying capacity of the available soil.

  • Stunted growth
  • Reduced foliage
  • Trees take on the characteristics of old trees (rough bark, etc.)
  • Death

Solutions:

  • Special underground planting spaces
    • Vaulted sidewalks;
      • Sidewalk is suspended about 10 cm's above open soils
    • smaller, modular versions of vaulted sidewalks
      • i.e., Silva cells
  • Special "compactable" soils (structural soils, skeletal soils)
    • Modern construction techniques compact soils pretty hard to prevent pavings from sinking or shifting
  • Access tunnels to larger soil areas
    • Tunnels to access nearby parks?
  • Design solutions
    • Maximize space with design, both above ground and below ground
  • High quality soils provide more resources

Issue 2: Soil doesn't drain

Presence of "Gleying": Blueish-gray color that indicates low oxygen conditions in the soil (reduced iron). Also visible by water not draining from the soils or indicator plant species.

  • Many trees intolerant of poor drainage.

Indicator plant species

Unlike in "natural" environments, such as forests, species are mostly managed under a city context. Indicator plant species are not used by whether or not they're present in an area, rather, they're used by the conditions in which they are present.

 

Yews are a good indicator for poor drainage

  • Leaves turn brown in poor drainage situations

Solutions

  • Remove cause of poor drainage if possible
  • Install sub-surface drainage to an outlet
  • Use plants tolerant of poor drainage