• Above is a true picture of a tree's root system & how it extends out.
  
• Up to 40% of a tree's biomass is underground.
• Roots grow closer to the soil surface than you think. Sometimes within the top 6 inches.
• When space is available, roots will extend out 2 to 3 times the reach of the branches.
• Roots absorb nutrients & water, store carbohydrates, & stabilize a tree's trunk & canopy.
• Growth regulators, produced in the roots, affect growth in the upper part of a tree.
• Studies show that 75% of a plant's potential for survival depends upon the root system.

The roots of the above eucalyptus start to grow up the bank, then grow out & down the slope. This is the way roots grow on steep slopes. This is why large trees on steep slopes fail.

Roots grow sideways and then down banks. They do not grow straight into the bank because of nutritional requirements (oxygen, water, etc.). They also do not grow very far up a bank. This is due to geotropism, which is the gravitional effect on growth regulators within the roots. That is why roots grow down.
The roots that "hold" a tree up grow in the opposite direction. Therefore, they actually "pull" a tree up. With no roots going into the bank, but rather down, you see most tree failures, on steep banks, fall in the lower 180 degrees of the slope. So do not allow trees on slopes to get too big or better yet, plant trees that don't grow as large. Check it out next storm!

An unhealthy root system increases tree stress
making the tree more susceptible to disease & insects.

• Grass & trees do not thrive together in nature.
• Turf can reduce the amount of tree roots in topsoil by 90%.
• A tree with an underdeveloped root system will;

  • be slower growing,
  • predisposed to certain insect and disease problems as seen in the picture (left),
  • have a shorter life span

This live oak had been here for over 150 years until a lawn was put around it. The increased irrigation necessary for the grass was not compatible with this species. It led to Armallaria mellea, oak root fungus, which decayed the roots and led to complete tree failure. The decayed root stubs can be seen
on the stump. Fortunately, no one was injured.

MULCH

Organic mulch is possibly the best and least
expensive soil enhancer around. This is the way
nature does it, as a tree mulches its own root
system, returning nutrients to the soil.

A mulch covering should be 2 to 4 inches deep
and extend outside the dripline.

Decomposing mulch may be all the only
nutrients your tree will ever need.

Deadman's foot,
Pisolithus tinctorius

This is a common mycorrihzae
fungus found in hard, compacted or rocky soils in southern California.
Very beneficial in reforestation, I commonly find it on hard rocky
slopes around eucalyptus.

WATERING

Extremely dry soil causes hair root & mycorrihzal death, reducing the
tree roots ability to absorb water long after the soil is re-moistened.

619-443-1770 fax 619-443-3324