Saturday 5 February 2005
How Sunlight Ruins Your Trees
This may come as a surprise, but excessive exposure to sunlight can ruin your trees. Before you rush out to the yard with a backpack full of sun block, consider the following; competition for sunlight is the primary agent that shapes trees in the forest. Without this evolutionary pressure, trees may not have developed into tall, stately plants. Growing tall is energy-intensive business. When competition for sunlight is removed, trees may grow horizontally with large spreading limbs. The tree’s lower branches may touch the ground, looking like the legs of a stool. This appearance is sometimes called stooling. The name actually refers to a method of propagation where some branches may root when they come in contact with the ground. If this appearance appeals to you, you have a unique eye for landscapes. Large lateral limbs on trees may be weakly attached to the main trunk and prone to failure when heavily weighted with snow or ice. What are the solutions to this potentially devastating problem? Timely corrective pruning of young trees is the best approach. Trees grown in landscapes can be trained early, through careful pruning, to limit the growth of large, low limbs. Another option for prevention is to design tree plantings in groups to shade each other, mimicking the natural processes that keep trees growing upright. Unfortunately, these processes can't be implemented on large existing trees. Large cuts on the lower trunks of mature trees usual leads to extensive decay. This decay may cause the trees to fail at the points where the limbs were removed. Careful reduction of large lateral limbs can lessen the impact of eventually removing these large branches. Cabling and bracing, the installation of support rods, and cables or props can reduce, but will not eliminate the risk of limb failure. Put the sun block away and reach for a modern book on tree pruning. If you have a mature tree that has large low limbs that require removal, consult an ISA certified arborist. A small fee paid for a consultation will certainly pay off in the long run.