How can repeated freezing and thawing damage trees and other plants?

Repeated freezing and thawing can cause significant structural and physiological damage to trees and other plants. This phenomenon often leads to the following issues:

• Mechanical Stress and Frost Cracks: When temperatures fluctuate rapidly—such as during cold nights following warm winter days—the water within a tree's sap and vascular tissues can freeze and expand. Simultaneously, the outer bark contracts faster than the inner tissues, building internal mechanical stress. When this pressure becomes excessive, it is released as sudden "frost cracks" or splits in the trunk and branches, often accompanied by loud popping sounds.12
• Sunscald: In thin-barked trees, intense winter sunlight can heat the bark and underlying cambium layer, particularly on the south or southwest sides in the Northern Hemisphere. When the temperature drops suddenly due to cloud cover or sunset, these tissues freeze, shrink, and crack. This injury, known as sunscald, can kill bark and expose underlying tissue.3
• Increased Vulnerability: These cracks and dead patches create entry points for insects, bacteria, and fungi, which can lead to further plant disease.31
• Soil and Root Damage: For low-growing plants like alfalfa, clover, and strawberries, alternate freezing and thawing can cause soil heaving, which damages roots and splits plant crowns, leaving them susceptible to decay-forming fungi.2