It is amazing how much wind certain trees can withstand while others topple over in a mere breeze. There are several factors that account for the difference.

Trees slammed to the ground during a hurricane or tornado is easy to understand. These natural weather phenomena generally occur when the leaves are on the deciduous trees which presents more resistance to the power of the wind. So, often otherwise healthy trees may go down under these circumstances.

In lighter or no wind conditions, it is often hard to understand why a certain tree came down. The key is usually one or more of the following factors:

1. Bad Root System - Under ideal soil and growth conditions, a tree should be able to withstand pretty violent wind gusts. They will have a root system that is spread out far and wide. In addition to absorbing water and nutrients, one of the key roles of a root system is to anchor the tree.

Most people mistakenly think that a tree's roots spread only to the outside of the canopy of leaves. This is wrong. The distance that roots extend out from the trunk of a tree varies by species. Some species send roots out in all direction up to 1.5 times the height of the tree. This means that a 100 foot tall tree could be sending roots out 150 feet in all directions (under ideal conditions, of course). Other trees such as spruces extend out only 2/3 the height so a 30 foot tall tree sends roots out about 20 feet around.

As mentioned above, these extensive root systems are present under "ideal" conditions. Less than ideal factors which will limit the root system of the tree would include:

A. Compacted Soils - Roots of plants need oxygen to expand and grow. Compacted, usually high clay, soils squeeze out all the air. Therefore, the roots grow nearer the soil surface and struggle to expand and grow properly.

B. Poor Drainage - If the spaces in the soil are all filled with water too much of the time, the roots are denied the oxygen they need to expand and thrive. Also, the presence of so much water will often lead to root rot diseases.

C. Physical Restrictions - We build houses, sidewalks, driveways and other obstacles which physically prevent the expansion of tree roots into their normal range and size.

D. Damage to the Roots - Construction of structures, sewers, irrigation systems, etc. will cut and damage root systems.

2. Tree Rot - Internal rot in the trunk or major branches cause more susceptibility to wind damage. Often, this type of damage can not be easily detected from the outside. More on tree rot.

About the only thing you can do is to keep your trees as healthy as possible and cross your fingers. When planting new trees, check a reference to see what their mature size will be and allow enough room. This is often difficult because you might have to look forward several decades but it is important for the long-term health of the tree.

In many cases, there is little that you can do except clean up after a tree has experienced wind damage. One exception may be when a relatively small tree is tipped over. If the roots are exposed for very long to the wind or sun, there could be severe loss of roots.

So, if it is possible to tilt the plant back so that the roots are in contact with the soil soon after the storm is over, the tree MIGHT be saved. Keep it  well-watered (but not drowned) for the next season or two to encourage re-growth of the lost roots. Who knows, it could work.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

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