EXTENSION CONNECTION: Excessive water can doom trees

Published: Monday, October 7, 2013 at 10:52 AM.

Most trees are not well adapted to saturated soil conditions.

With nearly daily rainfall this spring and summer — sometimes in record amounts — the ground became inundated with water. When excess moisture dramatically changes root environment, especially during the growing season, a tree’s entire physiology is altered, which may result in the tree’s death.

Water-saturated soil reduces the supply of oxygen to tree roots, raises the soil’s pH, and changes the decomposition rate of organic material — all of which weaken the tree, making it more susceptible to indirect damage from insects and diseases.

Additionally, with heavy rainfall there is erosion and sediment movement. Exposed roots or roots covered by excess soil add stress to plants. When rain finally stops, the tree’s system often has been so compromised that it can’t perform functions necessary to survival — so it just dies.

Altered processes

When the ground becomes completely saturated, a tree’s metabolic processes change quickly.

Photosynthesis shuts down within five hours; the tree is in starvation mode and lives on stored starches. Water moves into and occupies all available pores that once held oxygen. Any remaining oxygen is used within three hours. Lack of oxygen prevents the normal decomposition of organic matter, which leads to production and accumulation of toxic gases such as carbon dioxide, methane, hydrogen sulfide and nitrogen oxide.

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