Girdling

Girdling, also called ring barking or ring-barking, is the process of completely removing a strip of bark (consisting of Secondary Phloem tissue, cork cambium, and cork) around a tree's outer circumference, causing its death. Girdling occurs by deliberate human action (forestry and vandalism), accidentally (as in the case of new saplings tethered to a supporting stake), or by the feeding actions of some herbivores (who feed on bark at their height). It is most commonly used as a deliberate method of clearing forests for agricultural purposes and by fruit farmers to yield larger fruits.

Girdling in forestry and horticulture

Like all plants, trees use two vascular tissues for transportation of water and nutrients: the xylem (also known as the wood), and the phloem. Girdling results in the removal of the phloem, and death occurs from the inability of the leaves to transport sugars (primarily sucrose) to the roots. In this process, the xylem is left untouched, and the tree can usually still temporarily transport water and minerals from the roots to the leaves until the roots die. Death occurs when the roots can no longer produce ATP and transport nutrients upwards through the xylem.

Girdling is a slow process compared to felling and is often used only when necessary— such as removing an individual tree from an ecologically protected area without damaging surrounding growth.

Accidental girdling is also possible and some activities must be performed with care. Saplings which are tied to a supporting stake may be girdled as they grow, due to friction caused by contact with the tie. If ropes are tied frequently to a tree (e.g. to tether an animal or moor a boat), the friction of the rope can also lead to the removal of bark.

Girdling in agriculture

Girdling is also used as a technique to force a fruit-bearing plant to bear larger fruit. A farmer would place a girdle at base of a large branch, and remove all but one fruit from that branch. Thus, all sugars manufactured by leaves on that branch have no sinks to go to but the one fruit, which thus grows to many times normal size.

External links

* A South African [http://psybergate.com/wetfix/WetlandFix/WetlandFix6/wfPart6.htm Alien plant control guide] describing ringbarking in the context of available methods for controlling infestations of foreign plants.
* A [http://simplyaustralia.net/issue8/thebush-2.html description of the Australian bush] , with an illustration of ring-barking in progress.