How Flooding Affects Trees and Their Health

It’s been a wet rainy summer here in Connecticut, bringing flooding and increased water loads to some residents. Flooding may cause direct damage to trees by changing soil conditions, interrupting normal oxygen and carbon dioxide exchange between trees and their environment, sedimentation, and physical damage.

This article covers how flooding affects trees and how to handle any potential damage or related issues.

Identifying Flood Stress in Trees

Trees that are flood-stressed exhibit a range of symptoms that may include:

• Leaf chlorosis (yellowing), followed by leaf loss.
• Reduced leaf size.
• Early fall coloration and leaf drop.
• Water sprouts or small shoots emerge from the main stem.
• Crown dieback.
• Large seed crops or no seed crops in years following a flood.

Timing of Flooding

Trees are more likely to be damaged by flooding during the growing season than during the dormant season. Trees are most susceptible to flood damage in late spring, just after the first flush of growth. Tree species begin their spring flush at different times, so the timing of a flood influences the species that are likely to be damaged.

Types of Flood Damage:

Soil Changes

Water covering the soil reduces the supply of oxygen to tree roots. Roots must have oxygen to survive and grow. Well-drained soils are ideal for trees, allowing water to drain at one inch per hour. Poorly-drained soils, on the other hand, retain water for prolonged periods, depriving roots of oxygen.

Sediment

Sediments carried by the water and deposited over the roots reduce the oxygen supply to tree roots. Even as little as three inches of sediment can be harmful. Tree species vary in their tolerance to sedimentation, but all seedlings are susceptible to root injury from deposition.

pH

Flooding increases the pH of acidic soils and decreases the pH of alkaline soils. Tree species vary in their pH tolerance.

Decomposition

The decomposition rate of organic matter in flooded soil tends to be only half that in unflooded soil. The primary end products of the decomposition of organic matter in saturated ground are carbon dioxide, methane, and humic materials. High ethanol and hydrogen sulfide concentrations produced in waterlogged soil can damage tree roots.

Chemical Damage

Floodwaters may contain chemicals from urban areas or agricultural fields that may harm trees when absorbed by their roots.

Physical Damage

Strong currents, waves, or suspended particles may cause soil around the base of trees to be washed away, exposing their roots. Exposed roots can stress trees and make them more vulnerable to being uprooted or broken by wind (windthrow or blowdown). Ice flows and debris from rushing waters can remove bark and damage tissues, leading to wood stains and decaying organisms. Flood waters that cover foliage on lower branches will interfere with photosynthesis and gas exchange, leading to the death of those branches.

When to Call a Tree Company After Flooding

After experiencing flooding, it is crucial to assess your trees’ condition promptly. While some minor tree care tasks can be managed independently, calling a professional tree company is necessary in specific situations. Here are the instances when it’s best to seek the expertise of a tree services company:

Major Tree Damage

If you notice significant tree damage, such as uprooting, broken branches, or significant leaning, seeking assistance from a tree company is essential. Professional arborists have the expertise and equipment to safely handle damaged trees and determine the best action, whether it involves tree removal or restorative measures.

Pest Infestations or Diseases

Contacting a tree services company is crucial if you suspect pest infestations or diseases in your trees following flooding. Tree experts can accurately diagnose the issues and implement appropriate treatments to safeguard the health of your trees.

Replanting and Restoration

If replanting or restoring trees in the affected area is necessary, professional arborists can guide selecting flood-resistant tree species and ensure proper planting techniques for successful tree establishment. By calling a tree company after flooding, you can confirm the appropriate care and recovery of your trees, safeguarding your landscape’s health and longevity.