Survey of Damages after Storm Events

Objectives of the rough survey:

• Overview of size and extent of storm damages, i.e. amount of storm damaged timber and windthrown area
• nformation to policy makers to initiate supporting measures / relief programs (e.g. subsidy program, ordinance to the forest damage compensation law)
• Information of public (PR)
• First informational basis for coping with storm damages, definition of strategy (logging stop, first adjustments between work volume and work capacity as well as storage capacity)

Parameters to be collected at the forest district level during the rough survey:

• Timber quantity in solid cubic meters total and separated in hard / soft wood as well as forest owners, as far as possible
• Area damaged in ha

The first rough surveys of damages / damaged timber are just estimations due to the urgency of immediate recovery measures (assistance, clearing of roads), which do not leave much time for surveys. Experiences after "Lothar" have shown that long serving forest rangers can estimate the situation relatively well. Although a delay in first estimations is possible, due to serious damages and corresponding workload, a rough estimation from forest management data is helpful. The stand volume (cubic meters standing) and area allow a rough estimation of the damages.

For non-accessible or non-visible areas it may be possible to get an overview by helicopter.

Objectives of the exact survey:

• The exact survey helps on-site personnel to plan the processing of storm damaged timber. Therefore it’s important to survey, in addition to the amount of damaged timber and the dimension of the affected area, further parameters for every storm area including tree species, type of damage (area damage/single throws, breakage/throw), terrain and urgency of processing (e.g. valuable assortments, forest protection situation, opening-up).

Parameters to be surveyed at detailed inventory of damaged area stage:

• Amount of timber in solid cubic meters per damaged area, separated into tree species
• Expected assortments
• Area damaged in ha
• Type of damage
• Terrain and opening-up (roads etc.)
• Forest protection situation, urgency of processing
• Type of processing
• Contractors / own labour
• Capacity requirement
• Miscellaneous (regeneration, harvesting methods, application of technique)

Detailed planning further approaches and measures to cope with storm damages and determining strategies (order of processing and method, assortments, kind of storage and storage possibilities, effects on the timber market or sale price as well as predictions of subsequent forest protection problems) at both the forest district and management/federal state level.

Information for policy makers to initiate supporting measures / relief programs (e.g. support program, ordinance to the forest damage compensation law)

It has been found helpful to mark the storm areas on ranger district maps showing the extent and amount of storm damaged timber (e.g. basic forest map with a scale of 1:10 000). Furthermore it’s possible to mark storage areas and conversion sites on the maps.

Besides the necessary terrestrial survey and estimation of damages by forest enterprise personnel in the first days after the event, which is very important for further internal approaches, surveys by helicopters (or small planes) can be helpful,

• to gain a overall impression of the situation
• to survey damages at remote or non or difficult to access forest areas (e.g. plateaus, large areas)

• For a contemporary aerial survey the assistance of other administrations (e.g. police) should be sought, but private flight can also be chartered.
• Allow sufficient time to fly over forest districts as well as damaged areas and to survey several areas in more detailed.
• Flights have to be prepared by forestry office personnel in advance. It’s more efficient and allows for important areas to be surveyed in detail, if the flight route is defined before take-off.
• Cameras and/or video cameras should be used to document the storm damaged areas. Experience proved that photos or videotapes, which can be evaluated afterwards, are helpful for further planning.
• Basic forest maps with a scale of 1:25 000 or older aerial photographs are helpful for orientation. Damaged areas can be marked on the maps/photographs.

The use of flights for an exact mapping or survey of damages is restricted as there is less time for precise orientation, it is difficult to delimitate areas on a map and single throws are difficult to identify or not visible at all.

Aerial surveying doesn’t replace terrestrial inspections, but complements them. Flights provide an overview of the situation and have a powerful psychological and emotional effect on those who can’t get into the forests. Flights can bridge information gaps if a fast survey with remote sensing is not possible (see below).

Results of the project "Sturmmon" by the University of Freiburg, Department of Remote Sensing and Land Information Systems (Issue 2003):

• Landesforstverwaltung Baden-Württemberg (Hrsg.): Schriftenreihe der Landesforstverwaltung, Baden-Württemberg Bd. 83: Orkan "Lothar" – Bewältigung der Sturmschäden in den Wäldern Baden-Württembergs, S. 113-123.
• Steinmeier, C.; Schwarz, M.; Holecz, F.; Stebler, O.; Wagner, S., (2002): Evaluation moderner Fernerkundungsmethoden zur Sturmschadenerkennung im Wald. Birmensdorf, Eidg. Forschungsanstalt WSL. 194 S.

• Erhebung der Sturmschäden/Grobschätzung der Sturmholzmenge B-W (47 KB)
• Erhebung der Sturmschäden/Grobschätzung der Sturmholzmenge Rh-Pf (46 KB)
• "Feinerhebung der Sturmholzflächen" (82 KB)

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Back to the article overview in the: Storm Topic Collection – Coping with Storm Damaged Timber