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CATASTROPHIC STORMS HIT EUROPE’S FORESTS: DANGERS OF AFTERSHOCKS!

Published: 30 December 1999

Tempestuous winds ravaged forests in Europe on 26 December and again on 28 December 1999 leaving a morbid trail of fallen and broken trees. "The tempests will have disastrous effects not only on forest but also on the timber markets as well as on wildlife" says Edward Pepke, Forest Officer at the United Nations Economic Commission for Europe (UN/ECE), "but aftershocks may even be more disastrous. In particular there is a risk of insect infestation which may further harm forests."

The windthrow was accentuated by the preceding weeks of heavy rainfall and unseasonably warm temperatures. Soils in many mid-European forests as well as urban and cultivated areas were unfrozen and waterlogged rendering the root systems inefficient against the high winds. Deep-rooted pines and hardwood species were often broken while shallow-rooted species like fir and spruce were more frequently uprooted. However many trees found little resistance in the muddy soils and succumbed to the two successive storms.

At this time soon after the storms, it is impossible to accurately assess the magnitude of the damage. However early reports indicate record levels of damages. In Switzerland, for example, the Office fédéral de l’environnement, des forêts et du paysage has estimated that approximately 8.4 million cubic metres (m3) of timber has been downed. This is twice that felled by the disastrous storms in 1990 (4.3 million m3).

Estimates for damages in other countries have not yet been received because of inaccessibility of mountain forests due to road closures by fallen trunks, branches and deep snow, combined with the end-of-year holiday period. It is known that in addition to Switzerland forests in France, Germany and Belgium sustained considerable damage.

Unfortunately many mountain forests, which were destroyed, were planted and managed specifically for avalanche control. These forests on steep slopes and thin soils will take decades to re-establish. Already avalanches have occurred from the heavy snows at altitude and the loss of these protective forests could aggravate the hazardous situation.

All forests have a protective watershed protection function too. However the ability of mountain forests to absorb and regulate water flow can be disrupted by the windblow, potentially leading to rapid water runoff.

Wildlife habitat has been ravaged in certain areas and wildlife biologists will be assessing the impacts and damages to populations of birds and animals. Current forest management practices prescribe leaving some quantities of dead trees in harvested sites. These trees are nesting sites for birds and animals as well as important sources of biodiversity. However the vast quantities of dead and dying trees could have negative consequences.

Following the 1990 windblow there were incidents of insect infestation on the dead and dying timber. Worm holes and associated stain from fungal and bacterial attack can render structural- and furniture-grade wood useless. Not only are the fallen trees at risk, but also the adjacent trees which can be hosts for the parasites too. Therefore many dead trees must be removed to avoid a breeding ground for unwanted infestations.

Clean-up of windthrown timber depends on access to the forest stands. Therefore massive sanitation cuttings will commence as soon as forest soils support heavy equipment. Clean-up operations are not easy and safety of forest workers is a prime consideration due to the danger of broken and leaning trees and spring poles, i.e. trapped trees which whip upwards when released.

The 8.4 million m3 which were felled in Switzerland by the storms in 2 days are equivalent to 2 years’ of normal harvest. The forest products markets have barely reached an equilibrium between supply and demand. Now the surplus roundwood on an already fragile market could destabilize Europe’s timber markets.

The ramifications of the 1990 storms lasted 2 to 3 years. In 1991 and 1992 following the last storms, Germany stocked logs in forests to reduce the immediate effects of an oversupply. Nevertheless prices of roundwood plummeted and forest managers faced difficulties in paying for their management operations. Governments will be called upon to assist in financing the resulting forest operations.

Wood from wind-felled trees can be of lower quality and subject to lower value uses. Rather than sound structural or furniture wood, some of the windthrown timber will be of value for agglomerated particle board and fibreboard, pulpwood or for energy production. The surplus of available virgin fibre could have a negative effect on the recycled fibre market.

Meanwhile the public which depends on forests for recreation will be faced with a changed landscape. Immediately access roads to ski stations and crosscountry ski trails and alpine ski slopes were blocked. In the spring and summer hikers, mountain bike riders and others who seek recreational opportunities in European forests will be faced with obstacles and sometimes dangers from leaning and dying trees. Many of the public will already be shocked at the damage to their urban trees and forests and will be disappointed to find the countryside has been similarly affected.

"While it is too early to assess the extent of the damage to Europe’s forests by the storms at Christmastime, the precedent from the 1990 storms indicates that years will be necessary to bring forests and markets back to a stable situation. However the destruction of century old forests will take an equal time to return to their former state," concludes Edward Pepke.

For further information please contact:

Information Unit

United Nations Economic Commission
for Europe (UN/ECE)
Palais des Nations, Room 356
CH - 1211 Geneva 10, Switzerland
Tel: +41 (22) 917 44 44
Fax: +41 (22) 917 05 05
E-mail: info.ece@unece.org
Website: http://www.unece.org


United Nations Economic Commission for Europe

Information Unit

Palais des Nations, 

CH-1211 Geneva 10, Switzerland

Tel.: +41 (0) 22 917 44 44

Fax: +41 (0) 22 917 05 05