Damage to trees by electrical discharges

Damage to trees by electrical discharges.

Electrical discharge damage is generally quite rare. However, they most often occur in old and tall trees, superior to other neighboring trees. The frequency of collecting electrical discharges is highest in poplars, elm and oaks as well as conifers in spruces and pines. The reason for this may be the presence of various chemical compounds that increase the electrical conductivity of the tree. The quality of the root system is also of great importance. Trees with deep and numerous roots are much more frequently discharged. Infested beeches are generally less common, birches and chestnut trees. The severity of the paralysis may depend, except for the tree species and its size, on the quality of the geological substrate, ground moisture level, etc.. Trees growing in soils with a high level of groundwater draw lightning more often than those growing in dry soils.

The size of the damage is directly proportional to the force of the discharge. Very strong discharges cause the top of the tree to shatter and the trunk to crack and split over a considerable length. In many cases, the tree catches fire, which is more common in conifers and old deciduous trees, over a large area of ​​decayed. It doesn't take long to burn; they are hindered by too high humidity of the tree tissues. Much more often the discharge tears the bark with a thin layer of wood over a considerable length of the limb or trunk (drawing).

Drawing. Poplar trunk damaged by a strong electric discharge.

An electric discharge can kill or electrocute living cells. There are known cases of killing young roots. In all cases, electrical discharges result in the formation of large-surface wounds. Their treatment does not differ from that applied to other bark and wood lesions, however, due to the size and location of these wounds on the tree, it requires a greater amount of work and the overcoming of many technical difficulties. For these reasons, most often no one deals with such damage. In trees with softwood, e.g.. in poplars or maples, rapid infectious damage may occur, due to the high availability of tissues of the damaged tree for many fungi.

In cases of damage to low-value trees, undertaking maintenance treatments may be unjustified after comparing the value of the tree with the required expenditure. Assessing the tree, its plastic value should be taken into account, age, ability to heal wounds, general health condition, safety for the environment, etc.. The decision to carry out nursing treatments or to refrain from them should be made as soon as possible. Leaving a valuable tree with open wounds can be risky. It is very difficult to prevent damage by electrical discharges. The only way is to install a lightning protection system on trees with a potential threat. Such an installation consists of a lightning arrester at the top of a tree, a line led from it attached to quite long ones (20—30 cm) hooks, split and attached to those stuck in 3-4 metal rods outside the perpendicular projection of the crown (drawing).

Drawing. Scheme of establishing a lightning protection system in a tree.

This prevents the infection of numerous roots located in the area of ​​the crown's reach. From the trunk to the driven metal bars, the line should run below the surface of the ground.