Recultivation/ renaturation of wet storage sites
Pic. 1: The timber is gone – what now?
Recultivation of proposed wet storage sites should be considered in advance, before commencing to build the site. Costs and effort can vary widely depending on initial situation (e.g. sealed surface or grassland,…), prior and future land use and agreements in the contract of lease etc.
Bark needs to be cleared away and disposed of, usually in landfills for ground excavation (subject to charges). It might be possible to sell good quality bark residues to gardening companies. Removal of roads turned out to be expensive. To save some of the costs for disposal of the material, it could be used otherwise in the enterprise. Check in advance whether material is needed e.g. to upgrade or repair forest roads.
The humus layer should be cleared away when building the site and stored separately. It can then be used later for recultivation. Losses of topsoil are inevitable. Keep an eye out for opportunities to gather additional topsoil from elsewhere. Experiences after “Lothar” showed that additional costs for recultivation amounted to, on average, 0.15 – 1.00 € per m³ timber.
Document the initial situation elaborately (photos if necessary) before commencing storage to help plan recultivation and avoid conflicts.
Experience backup
Wet storage is an appropriate method to conserve large amounts of timber after storm calamities. Broad information on how to set up and maintain a wet storage site should be made available to all members of staff (every forest district).
A few (2-3 for Baden-Wuerttemberg) selected long-term operated sites will help maintain today’s standard of knowledge and gain new experience. Specialists from these sites can act as information multipliers in the event of future storms. Training can be provided by the specialists, and they can be consulted by site operators if problems arise during the storage period. Discussion forums can be used to exchange experiences, discuss current problems, and present innovative, customised solutions.
Securing sites
A comprehensive list of potential wet storage sites should be compiled and revised and updated regularly. This will help in the event of future calamities. Sites should be evaluated regarding suitability for use after calamities. Permanent operation permissions for a few selected sites can help gather long-term know-how.
Problems arising outside the storage
Conflicts of interests: Fishing clubs, operators of campsites and swimming pools fear their activities might be impaired (e.g. water pollution). Residents might complain about the noise of engines during rolling in and out and a possible rise in mosquito populations.
Wet storage of short wood
Wet storage is a suitable standard storing method for long logs. Wet storage of short wood is possible in principle, but more complex and cost-intensive:
- Time and effort for irrigation higher (more cross sections per cubic metre).
- More space required (max. spacing of roads approx. 12 metres when timber is stored on both sides, thus higher establishment costs).
- Higher risk of quality deterioration (run in) at both face ends, relative higher degradation compared to long logs.
- Water demand higher (more sprinklers, hoses, connectors etc.)
- Ideal irrigation is more difficult to organise because the range of the sprinklers is 12-15 m. For the irrigation of face ends, sprinklers might have to be modified.
Wet storage of hardwood
Wet conservation of beech is possible in principle, but should only be realised by request of a customer, after the sale contract (which stipulates the period of storage) was signed.
Max. time of storage: Sliced veneer: 5 months
Peeled veneer: 12-14 months
Irrigation of beech requires 20% more water to preserve timber quality (compared to softwood).
Operation by irrigation companies
- Compiling a positive list of companies which can be recommended.
- Consider stipulating in the service contract that costs arising from operating errors have to be covered by the operating company.
- Standardised invitations to tender help to get comparable offers by different companies.
Wet storage and pollution of waterbodies
A literature study was conducted on behalf of the Forest Authority and the regional authority (fishery office) of Freiburg in 2001. It deals with the impacts of wet storage sites for the conservation of windthrown spruce and fir logs on the biocenosis of flowing waters. Special attention is turned on the impacts on fish in open waters and ponds. (Forest Authority Freiburg, 2001, unpublished).
The authors arrive at the conclusion that wet storage has only minor sustained negative impacts on the biocenosis of flowing waters if the legal requirements are complied with (in Baden-Wuerttemberg, this is the Verwaltungsvorschrift Nasslagerung, administrative regulations on wet storage). Wet storage can be considered comparatively environment friendly as no pesticides are used. However, concentrated washout from over 2,000 m³ stored timber is a substantial load. This can have negative impacts on aquatic biocenoses. Receiving waters play an important neutralising role here. A minimum amount of water should therefore be available in both extraction and discharging waters at all times. The state office for water supply and distribution Rhineland-Palatinate published recommendations for wet storage after "Wiebke" and "Vivian" (Ittle-Reinlassöder, 1991). These were based on values measured in the vicinity of several wet storage sites. Results of toxicity tests did not show any indication of negative impacts resulting from wet storage.
Downloads (in german)
Sources
- Graf Kanitz, Beregnungstechnik im Bereich der Forstdirektion Koblenz, AFZ 5/1991, 245-247.
- Ittel-Reinlassöder, I. (1991): Überwachung der Wasserqualität an Nasslagerplätzen. AFZ 5/1991, S. 248-251.
- Willmann, R. /Forstdirektion Freiburg (2000): Merkblätter Nasslagerung.
- Waldschadenshandbuch, S. 12 BUWAL, Eidg. Forstdirektion und Sektion Holz (Hrsg.), Bern, 1993.
Forest Crises Management Advisory Guide
Back to the main page of the Forestry Crisis Management Advisor Guide: Overview of the different topic collections
Back to the article overview in the: Storm Topic Collection – Coping with Storm Damaged Timber