Flooding in Oklahoma

All this rain is great for our trees right? Nope! Not really!

There is no doubt that the heavy rain we have had lately has filled the city's water stores and ended a drought that has lasted several years. On the surface, it would seem that this is good for our plants and trees. In reality, there are several reasons why the flooding and excess moisture, especially after a long periods of drought, are very hard, if not fatal, to trees.

Much of Oklahoma's soil is poorly drained. Especially in the Norman area where we have large areas of clay. Many residents still have standing water in their yards from the heavy rains. In these poorly drained soils, the water can fills what is called macropore space for extended periods of time. Macropore space is usually filled with air and makes oxygen and carbon dioxide available to tree roots. During flooding, however, the air replaced by water, leading to a suffocation of the tree's roots and soil compaction. Not having enough aeration in the root's soil can cause numerous problems, including fermentation in root cells, root rot, and buildup of toxic compounds.Flooding also washes away the important nutrients that are in the top soil. The lack of oxygen can also lead to changes in the chemical composition of the soil, so that the living organisms that enjoy a symbiotic relationship with trees are also often drowned out, depriving trees of this valuable resource.

The longer the excess water remains, the more tree health deteriorates. For some species, just a few hours under flooded conditions will cause damage. This is especially true if the trees have not adapted to heavy flooding.After several days, some root loss is experienced in almost all species. If conditions persist, some species will decline and die. Even if trees do survive, there are still probably going to be long-term consequences. Trees that have survived the flooding will be more predisposed to stress factors including drought and pests that cause root disease, collar rot, cankers, and borer insects. These trees will have a more difficult time defending themselves against these threats.

We have seen many trees toppled over due to the high winds and wet soil. In the upcoming months we may see more due to the degradation of the soil and/ or the root loss.In addition to all of this, grade changes and erosion can lead to long-term stress for trees.

So what can we do?

Changes in grade should be corrected if possible, and measures to improve soil aeration should be considered. Keep in mind that wet soil is much more prone to soil compaction-tread lightly, and no driving in the root zone, which often extends to the tips of the furthest branches if not further. Composting around your trees would be a good way to replace the nutrients that have been washed from the soil. Also, be sure to water your trees properly in the upcoming months, they will be VERY susceptible to drought this year!

An uprooted tree in Norman, Oklahoma took the entire deck with it when it uprooted.