Wind Pruning

Large Wind Pruned Tree

When you walk on the trail at the top of Shell Ridge, notice how the trees are leaning away from the direction of the wind. There is almost always a wind up here and model sail plane enthusiasts use this to great advantage. The trees, however, are subject to two kinds of pressure - wind and desiccation, or drying. Winds add pressure to the tree canopy and actually force the tree to lean away from this force. Desiccation, however, is another, more subtle force. If, on some calm day, a branch "decides" to grow in a westerly direction, it will be subject to drying conditions as the wind starts again. The wind will dry this new branch and it will soon wither and die. Branches that grow within the canopy of other branches (which affords protection) have less pressure on them and can grow more easily.

Most people would think it is only the force of the wind that makes these trees bend away, but it is this combination of wind and drying that causes it. Therefore, watch for these two forces and their result as you hike along the top of Shell Ridge and other windblown areas - seaside trees come to mind.

Jerry Fritzke
June 21, 2003