|
1. Root needs include:
Growing room. Before
planting a tree, assess the area available for root
growth; and before building near
existing trees,
consider how this will affect future root spread.
Air, for respiration. This means choosing planting sites
where the soil is not
water-saturated; loosening
the soil before planting; and avoiding compacting the soil
around trees.
Water -- enough, but not too much --
to dissolve nutrients and transport them
(along with sugars,
hormones, etc.), and to cool the tree.
Minerals - nitrogen, phosphorus, and
potassium; calcium, iron, boron & other
micronutrients; a medium
(clay, organic matter) from which they can be extracted
from the soil; proper pH (balance of acidity/alkalinity).
A SOIL TEST is the only way
to determine whether a need for soil amendment, to
compensate for needs that the soil can not meet.
2.
Problems for roots -- and some solutions, include:
Exposure -- usually
caused by soil erosion, or by a high water table or
hardpan. Fill with loose,
loamy soil; add mulch & exclude traffic. A few shrubs
nearby are OK, but don't "garden" regularly in the root
zone.
Compacted soil and oxygen exclusion. Exclude traffic,
and don't smother or flood. Mulch and injected air or
water may help.
Girdling roots (wrapped around other roots,
constricting them to some extent). The best solution is to
use young trees with properly-formed root systems, and
plant them properly. Cutting through a girdling root on a
mature tree may
cause more problems than it cures, and it may not
address the worse problems
that are out of sight.
Direct injury, such as:
-
Grade change (both cuts & fill)
-
Chemicals
-
Trenching soil compaction
-
Lawnmowers, string trimmers, rototillers
-
Fire flooding
-
Competition from grasses & weeds
3. Damage Control
When roots must be
cut, it is important to minimize the injury to the tree.
Cutting them off
cleanly maximizes the tree's ability to control decay and
generate new roots. The cut should be as far as possible
from the base of the tree. Wound dressings won't help the
tree.
4.
Mulch
A substitute for
the layer of natural leaf-litter on the forest floor, and
it serves many of the same functions:
-
Moisture
management: It is easy for rain or irrigation to soak
downward through a layer of mulch, but difficult for it
to evaporate away, so mulch can be extremely important
in moisture conservation. Mulch can also play an
important role in slowing down water movement where
paving and roofing has increased run-off volumes.
-
Most
plants require sunlight for early growth, so a layer of
mulch can help
suppress weed growth; and since mulch helps keep soils
moist and loose, weeds and turf runners that do grow
into mulched beds are usually easy to pull. Some types
of herbicide may be used in conjunction with mulch, but
these must be managed carefully to avoid unintended
damage to desirable plants and soil organisms.
-
Since
mulch helps keep weeds and turf are kept out of planting
beds, trees and
shrubs are less likely to be wounded by mowers and
string-trimmers.
-
Mulch
gradually breaks down and becomes part of the humus near
the surface of the soil. Humus holds moisture, holds
fertilizer elements where plants can pick them off, and
also provides a favorable environment for earthworms,
mycorrhizal fungi, and the other soil organisms that
benefit plants.
-
Less
utilitarian, but no less valuable, mulch can be a major
contributor to the appearance of a landscape, connecting
plants with each other within a bed, and connecting beds
to each other by a common surface treatment.
Still, it is important not to overdo
mulch. It should be a natural material --
NO PLASTIC! --
applied loosely to a depth of 2-4 inches. Remember that a
tree or shrub can be killed by a heap of mulch around its
base: insects and decay
organisms thrive in such a dark, moist, protected
environment.
5. Understand the
Rules of 'CODIT' (Compartmentalization of Decay In
Trees)
Let them guide your
pruning and other tree work:
When a tree is injured, all wood present at the time of
wounding may be decayed, depending on how well the tree's
defenses work. Wood formed after the original injury will
not decay, unless the tree's defenses are broken down as a
result of further injury or other stress. Don't confuse
tree wounds with animal wounds. We actually "heal",
replacing the injured tissues. Trees simply wall off
decay, controlling its spread long enough so that new wood
added to the outside of the tree can take over the
functions of the wood rotted away. All trees work
basically alike -- broadleaf and narrowleaf, and trees
that form heartwood as well as those that don't. The best
way to deal with tree problems is by avoiding them. Learn
to work with the tree's natural defenses.
|
|
