Flooding & Trees: Are Your Trees Damaged?- Advise from a Portland Tree Services Company

portland tree servicesThis winter has brought flooding to many parts of the Pacific Northwest. We are on the cusp of setting a new record for the wettest December in Oregon. When flooding happens, it affects plants in different ways. In this post as a Portland tree services company are going to take a look at the effects of flooding on your trees and shrubs. We will examine how both short-term and long-term flooding impacts plants. Next, we will review physical damage that could occur due to flooding and finally, outline how flooding affects tree and shrub growth.

Tree and Shrub Flood Damage

There are several ways in which flooding can hurt trees and shrubs. Flooding can be very harmful to trees and shrubs when their roots are saturated with water for an extended period of time. When flash floods contain fast-moving water, debris can damage the bark and vascular tissue. Finally, underlying soils may erode, leading to instability and eventually uprooting.

With all that said, flooding effects vary with the plant species. Some bushes and tress thrive in the wet conditions of seasonal, sporadic, or constant flooding. Mangrove trees have evolved aerial prop roots that act as lungs, performing gas exchange. Other trees and shrubs will suffocate when their roots are completely underwater.

Loss of Oxygen

When tree and shrub roots are submerged in water, the plants are prevented from breathing. Without oxygen, roots cannot take up nutrients. Without getting lost in the weeds of soil chemistry, suffice it to say that the conversion of an aerobic environment (soil contains about 5% oxygen normally) to a nearly-anaerobic environment (such as water) creates a lot of problems. Soil pH and levels of organic matter are also affected by flooding conditions.


Flooding can deposit large amounts of silt around the bases of the trees and shrubs. Some tree species respond to this condition more quickly than others, and can adapt by growing new roots. However, other species cannot respond in time and could suffer or die due to thick silt deposits.

Scouring and structural injuries

Floating flood debris may injure trees. In addition, younger trees can be uprooted or seriously damaged by floodwaters. In some cases, soil saturation may cause the tree to uproot and fall over. The toppling of one tree creates instability for nearby trees.

Other Dangers

Floodwaters may be contaminated with chemicals that could have an adverse effect on tree health. Flooding conditions can also introduce water- or soil-born pathogens that may infect damaged root endings.

Flooding symptoms vary with the severity of the flooding, and the individual species’ ability to adapt. In severe flooding, it’s not uncommon to see dead trees toppled by storms. In other cases, roots may sustain flood damage that leads to less productive growth in following years. Leaves may fall off, or turn yellow. Waterspouts may also form in the crown as a response to stress. A greater indepth look at varying flooding symptoms, can be found here

Call UFP. Urban Forest Pro’s certified arborists are experts in mitigating flood damage to shrubs and trees. After flooding, our Portland certified arborists can visit your home and advise you on the best options for your landscaping. We can safely remove toppled trees, if need be. All aspects of tree and shrub health are included in our Portland tree service.

Landscaping is an investment in your home and your future. It requires special care for maximum value and enjoyment. Call us today to discuss how to best care for your trees and shrubs. Urban Forest Pro is on hand to help, whether it be selecting and planting new flood-tolerant trees or assessing and dealing with existing flood-stricken trees. Portland homeowners have come to trust UFP as the Rose City’s tree care experts.

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