Earthworks WNC

Why Do Trees Fall After a Heavy Rain?

Have you ever noticed that some trees withstand numerous harsh storms while others fall during intense rainstorms? It might be puzzling to see a tree succumb to heavy rainfall when it has withstood strong winds, snow, and ice. 

Excess rainfall can impact trees, especially those close to your home, posing a potential risk of damage. This article will discuss the effects of saturated soil on trees and offer some solutions for protecting them.

The Effects of Saturated Soil on Trees

When soil becomes supersaturated, water displaces the oxygen it contains, stressing the tree since its roots need oxygen to function properly. Waterlogged soil can have both short-term and long-term impacts on trees.

Short-Term Impact

The short-term impact of saturated soil involves the tree’s roots, which act as anchors. When the soil becomes waterlogged and loses its strength, the roots can slip through the soil more easily. This can lead to tree failure during strong winds after or during heavy rainfall or when the tree is imbalanced due to a lean or asymmetric canopy.

Long-Term Impact

If a tree experiences excessive soil moisture over a longer period, an ISA Certified Arborist® will look for specific signs to determine its impact. These signs may include soil buckling on one side of a leaning tree, indicating a shifting root plate, or root death and decay. Decay may manifest as a sparse canopy, dead or dying limbs, or mushroom growth at the tree’s base.

Recognizing Trees at Risk from Saturated Soil

Healthy trees may not display many visible problems caused by excess water. However, trees in waterlogged soil may suffer from oxygen deprivation and exhibit signs of poor health, such as:

  • Thinning, yellowing, wilted, or brown leaves
  • Reduced leaf size
  • Dying back sections of the tree canopy
  • Cracked or heaving soil
  • Exposed roots
  • Changes in the tree’s lean
  • Cavities, discolorations, or fungi on trunks
  • Root rot (soft, mushy, or black roots)

Addressing Soil Issues in Soggy Ground

If you have concerns about trees in waterlogged soil, you can take steps to improve the situation.

Enrich the soil: Adding organic matter can improve heavy clay soil drainage and help sandy soil hold together better while retaining moisture and nutrients. Mixing 2 inches of compost per foot of soil depth can be beneficial.

Improve yard drainage: Enhancing drainage can prevent water from accumulating around your trees. Sandy soils typically drain the fastest, followed by silt-based and clay soils. Compacted soil from construction can cause poor drainage. Installing French drains, vertical mulching, drainage tiles, rain gardens, or bioswales can help divert water away from trees and improve overall drainage.

Choose native plants or trees: Selecting native plants or trees that thrive in moist soil can create a landscape capable of withstanding various weather conditions.

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