The main operations for the tree interface of a mature forest include sanitation, thinning, pruning and removing the cuttings and the tree waste. Additional interface operations executed in order to reduce the quantity of flammable matter are the creation and maintenance of firebreaks and grazing lines. Treatment of the forest requires preparation of a program for the forest interface, which would include prioritization of the necessary tasks according to their level of urgency as dictated by the physical state of the forest, section or grove, primarily by considering the risk level of a fire starting and spreading.
This work includes creating barriers along principal roads that serve hikers and visitors (for example in recreation areas), along main ridge lines and, with especially high priority, where the forest borders on residential communities and other facilities.
The following are the details of the operations performed by KKL JNF in order to reduce fire damage in mature forests:
Sanitation – Continuous work done throughout the lifecycle of the forest, which includes removal of dead/desiccated/sick trees from the forest, whether they are upright or prone. Trees that cannot be removed due to problematic conditions are sawed into stumps around 1m long, which are left scattered in that section.
Thinning – Ideally, thinning should be done every seven to ten years. This entails removing the less developed trees and the withering trees. Thinning in conifer forests is done in accordance with the density charts that define the number of trees left while taking the age of the forest into consideration and the quality of the habitat. Some of the trees are removed by thinning, and the normal density level for proper development of the trees is thereby retained. In the process of thinning, a high enough level of shade is maintained for preventing massive development of sub-forest brush.
Pruning – Pruning includes the lower branches of a tree up to a third of its height, 2.5m from the ground at most. In recreation areas and along trails (where there is a higher risk for fires), pruning might be done as high as 4m. This is in order to remove the lower branches of the tree so that the treetop is separated from the ground. The lower branches tend to be very dry, and they conduct the fire upward. In the process of pruning, vines on the trees that could conduct fire up to the treetop are also removed.
Removing the Cuttings and the Tree Waste – The cuttings and waste are transported from the forest area to the side of the road, where they get chopped up and then removed from the forest for various uses or, alternatively, scattered on the ground. KKL JNF is careful about keeping a strip of forest along the roads free of cuttings and tree waste, for at least 30m from the roadside, and encourages the residents of nearby communities to use cuttings and tree waste for heating and other uses.
Burning the Cuttings – This is an interface operation of great importance for the management of cuttings, and it is customary in various forested countries as a routine treatment. After sanitation, thinning and pruning, the cuttings must be dealt with, and in places where the forest is on a steep slope or far from the road, the cuttings are burned in a glade. Spot treatments (such as felling a single tree) that do not justify or facilitate chopping up the cuttings, include burning.