Reservoir wood
As a reservoir timber which is wood from trees referred to by a dam were flooded. The dead tree trunks standing in the water are well preserved due to the lack of contact with the air and can be harvested with special saws and used as timber even after decades under water . The term reservoir wood denotes a commercial range in the international timber trade and includes many mostly tropical types of wood.
Worldwide occurrence
Worldwide there are over 45,000 reservoirs with a depth of at least 15 meters. Many of them are dammed up over forested areas; it is estimated that there are around 35,000 km² of forest in reservoirs. The possible harvest volume of the flooded forests is estimated at around 500 million m³ of wood. The Brokopondo Reservoir in Suriname is an important reservoir for the harvest of reservoir wood . It has an area of approx. 1,560 km² and its usable wood volume is estimated at over 10 million m³.
harvest
The harvest of reservoir wood is expensive because the felling and recovery of the trunks is very time-consuming. Usually this is done manually by a motor by divers with hydraulic chainsaws . The trunk is provided with floats and secured with ropes so that it does not sink to the bottom of the lake. In the murky water many meters below the surface, visibility conditions are extremely poor, even with diving lamps. In addition to the very adventurous felling method, divers are exposed to other dangers from alligators and snakes .
In addition to the motor-manual underwater wood harvest, there are mechanical harvesting methods in which submersible robots and floating cranes are used.
Special trees of a certain species are often selectively harvested in the tropics. When harvesting wood in the reservoir, on the other hand, hardly any attention is paid to the type of tree when it is felled and rather the area is harvested. The sorting by type of wood then takes place when the sawmill is cut. Harvesting often counteracts excessive organic pollution in the lakes. The aim is to improve the water quality sustainably and to contain the ecological damage of the reservoir.
processing
incision
The cutting of the wood should be done soon after the harvest. As a rule, this is done directly on the bank of the reservoir in order to avoid long transport routes for the heavy timber.
The sawmill at the Brokopondo reservoir was founded especially for cutting the reservoir wood. There the wood is cut with band saws of older design. Highly technical machines are not used so that the workers on site can carry out maintenance work and repairs independently.
Drying
The long immersion in water, the reservoir timber can be faster and easier to dry than fresh cut wood. Drying cracks occur less often in dammed timber than in freshly felled wood due to the loss of tension during storage in water.
Products
Reservoir wood can be used in many ways. Depending on the type of wood, it is well suited for outdoor use and can be used e.g. B. be used for decking and garden furniture. In interior construction, for example, it is used as parquet and solid wood floorboards. In principle, any conventional area of application for wood is also conceivable for reservoir wood.
Wood quality
The wood quality of reservoir wood can be compared with the wood quality of the same type of wood from natural forests. Several studies have shown that the original properties of the wood species are largely preserved in the case of reservoir wood. Improvements in the staying power ( dimensional stability ) and the drying behavior were even observed. This can be explained by the decades of freshwater storage, during which the natural growth tensions have been reduced over the years.
trade
Reservoir wood is not subject to any trade restrictions, regardless of the type of wood. This offers the trade an attractive opportunity to trade in types of wood that are no longer or can only be traded to a limited extent due to the Washington Convention on the Protection of Species . Wood types traded as reservoir wood are for example Pakoeli, Garapa , Massaranduba , Andiroba , Greenheart, Walaba or teak .
Environmental influences
Reservoirs are often created without considering the existing vegetation . In the 20th century, huge areas of the tropical rainforest were flooded without first harvesting the wood. Today there is great potential in this existing, well-preserved wood supply in the reservoirs for protecting natural forests. Underwater harvesting has several advantages over conventional timber harvesting in the tropics. There are no logging paths and forest roads, there is no felling damage to the existing trees, wild animals living in the countryside are not disturbed, hunting grounds of the indigenous population are not injured, and there is no soil compaction by heavy machinery. Not to be forgotten, however, are the ecological changes and impairments of nature, the landscape and the indigenous population that the reservoir created earlier had already caused. Another argument in favor of the use of reservoir wood is that the decomposition of wood in the water produces fermentation gases that are harmful to the climate, such as methane . In the long term, these can have a negative impact not only on the atmosphere , but also on the flora and fauna of the water body.
See also
literature
- Trade journal wall floor ceiling. April 4, 2009
- Parquet magazine. June 2008
- Forest Finest. Issue 1, 2011
- Wooden central sheet. No. 48, November 28, 2008.
- Klaus Sieg: Forest workers under water: The goods made of reservoir wood . In: Badische Zeitung . Freiburg im Breisgau July 12, 2014 ( online [accessed January 12, 2015]).
Web links
Individual evidence
- ^ A b c d E. Wildermuth: Whether Greenheart or Andira - everything is "Kappes". In: Holzzentralblatt 48, p. 1365 f, November 28, 2008 ( PDF ( Memento of the original from February 5, 2015 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to instructions and then remove this notice. )
- ↑ Katharina Beckmann (2014): Out into the green. Planet Wissen Extra, broadcast on May 26, 2014 video library
- ↑ Lucian Haas: The tree fellers on the reservoir bottom. In: Hamburger Abendblatt from February 14, 2006
- ^ A b Klaus Sieg: Forest workers under water. Badische Zeitung edition July 12, 2014 accessed online on February 5, 2015
- ↑ a b c d The wood that came out of the water. In: Forest Finest. Issue 1, 2011, p. 26 ( PDF )
- ↑ Almut Bruschke-Reimer: Felling wood in the reservoir - new robot makes it possible . In: Image of Science. on August 10, 2001; accessed on February 13, 2015.
- ^ Tropical wood from the Bayano reservoir www.tropicalhardwood.de
- ↑ a b c Walter Pitt: multi-layer parquet, solid wood and terrace boards made of dammed wood. In: wall floor ceiling. Edition April 4, 2009.
