This document discusses tree biology and types of damage trees can experience. It begins with an overview of tree roots, explaining that most roots are in the top 12-18 inches of soil and can extend 2-3 times the width of the tree's canopy. It also describes the different tissue layers of the trunk: bark, phloem, vascular cambium, and xylem. The document then outlines six ways tree roots and shoots can be harmed, such as broken branches, gouged trunks, root cutting, grade changes, soil compaction, and chemical damage. It explains how each type of damage disrupts the tree's ability to transport water and nutrients.

1. Tree Preservation
Designing, constructing, and maintaining to protect
established trees

2. Tree Biology
An overview of tree roots, tissue layers, and reactions
to damage

3. Roots
Most of a tree’s roots are in
the top 12-18” of soil, with the
greatest concentration in the
top 6”.
Tree roots can extend 2-3
times the width of the canopy.

4. Trunk Layers
Bark protects trees from
damage from the outside.
Phloem moves sugars the
leaves make throughout the
tree.
Vascular cambium generates
the cells that become the
phloem and xylem.
Xylem carries water and
nutrients from the roots to the
rest of the tree.
Xylem
Active xylem

5. CODIT:
Compartmentalization
ofDecayinTrees
Trees don’t heal, they seal.
When a tree is wounded, it
must seal off the wound so
that the inevitable decay
doesn’t reach the whole tree.
On a clean wound at the right
location, a layer of callus tissue
covers the location to help seal
it from the outside.

6. Tree Damage
6 ways a tree’s roots and shoots can be harmed

7. Shoot Injury:
broken branches
Jagged break leaves more
disease entry points
Can split or tear down other
limbs or the trunk
Leftover stub is vulnerable to
decay

8. Shoot Injury:
gouged trunk
Damage to phloem disrupts
sugar transport
Damage to vascular cambium
restricts tree’s ability to grow
outward
Cannot be fully fixed, especially
if it spans more than 1/3 of the
tree’s circumference

9. Root Injury:
cutting
Creates entry points for pests
and diseases
Cuts tree off from water and
nutrients
Huge amounts of short-term
stress because the tree needs
extra water to close off the
wounds, but it has lost much of
its access to water

10. Root Injury:
changing grade
Raising the grade suffocates
the roots and reduces access to
water
Lowering the grade removes
critical surface feeder roots
Changing the grade by as little
as 2” can kill a tree

11. Root Injury:
compaction
A good soil is 50% pore space
Compacted soil makes it harder
for roots to grow, limits air, and
limits water
Can be caused by driving over
soil (especially when wet) or
stockpiling heavy materials

12. Root Injury:
chemical damage
Many chemicals common on
jobs sites can get into the soil
and damage roots
Diluting spills immediately is
often enough to mitigate
damage
Beware of leaky fuel cans and
equipment
Concrete can easily raise pH to
dangerously high levels

13. Questions?