Mechanism of Frost Crack Formation in Trees—A Review and Synthesis

Frost cracks, as separations in the radial-longitudinal plane of tree stems, result obviously from tension stress in the tangential direction of wood's annual rings. The main cause is "frost-shrinkage" due to freezing-out of cell well moisture into lumens of wood cells. Other causes are the more rapid cooling of the stem's outer wood, expansion of freezing water in cell lumens, and formation of ice lenses in wood. It is shown how healed wounds in stems function as stress raisers and trigger the cracking. Forest Sci. 29:559-568.