drown, can they?
Common thinking is
that tree roots can live without air since they are already
However, 25-percent of a soil's volume is actually air,
25-percent water, and 50-percent solid. Roots need
this air space for "breathing." Burying existing root systems
with extra soil can suffocate them. Some species of trees are very
sensitive to having any soil fill placed of their root system. Don't
risk damaging your trees with soil fill -- haul away extra soil
instead of spreading it beneath existing trees!
Surface-rooted Maple tree
Roots on most trees are in the top 18 to 24 inches of the soil, not
nearly as deep as everyone thinks. Severing roots with trenching
activities and other excavations can fatally injure a tree. Often
times the worst thing that can happen to a mature tree is for a deep
trench (gas line or other utility line) to be dug inside the drip
line (between the branch tips and the trunk). Removing a large part
of the root system can make a tree unstable, and reduce its ability
to get nutrients and water from the soil. Open wounds on roots also
creates an avenue for destructive pathogens, which may already be
present in the soil, to enter the tree. While it is not
recommended for branch cuts to be painted any more, it is
recommended for large roots to be painted with a tree wound
The trees fit the plan, but the plan doesn't fit the trees!
Soil fill over these Spruce tree roots
to their slow decline and eventual death.
Before you start construction on your building lot, select the trees
you would like to keep. Some trees will have to be removed to allow
for construction of the house and driveway. A professional
nurseryman or arborist can help you identify the best trees to keep
from the remaining group. Generally speaking, the Maples and Oaks
will hold more value than weed trees like Black Locust and Wild
Cherry. However, any tree in good condition in the right spot may be
To preserve the trees you elect to keep, follow these 3 steps:
1. Cut trenches for utility lines
well away from important trees.
2. No excavating equipment or heavy trucks should be driven over the roots
(most tree roots are located from the trunk to just beyond the
branch tips). Fence this area off with temporary fencing. Following
this advice will also protect tree trunks from 'nicks' caused by
3. Don't change the grade around trees, or dump soil against tree
Ouch! Tree bark damaged by a skid steer loader.
Gag! Roots buried with excess soil fill.
Sidewalks damaged by tree roots
Trees are often planted in narrow
lawn strips between streets and a sidewalks. The first sign of
trouble is when concrete sidewalk slabs start to heave and crack,
creating hazardous tripping spots for pedestrians.
Proper species selection will help curb this problem (pun intended)
as well as the use of commercial root barriers, which act to deflect roots deeper into
the ground, away from pavement. Root barriers need to be installed when a tree is first
Tree roots heaved this concrete sidewalk and
created a hazardous situation