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Competence Network Climate Change, Risk Management and Transformation in Forest Ecosystems

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Forest Research Institut Baden-Württemberg (FVA)
Department of forest economics

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D-79100 Freiburg

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Article

Author(s): Jutta Odenthal-Kahabka
Editorial office: FVA, Germany
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Chipper Application when coping with Storm Damages

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Restholz im Wald
Does the chipper application pay off?

Even during the first stage of coping with damages the following questions might arise:

  • Can storm damaged timber be placed on the market as fuelwood?
  • Is chipping of (remaining) timber a reasonable alternative to processing as stem wood or industrial roundwood or not processing at all?
  • Do processed areas need to be cleared up or can they be abandoned?

To answer these questions the following should be taken into consideration.

Chip output and demand

Calculation of the theoretical benefits

  • It can be assumed, that 20 % of the thrown coniferous wood and approx. 40 % of the thrown hard wood can not be used as round wood and is therefore theoretical available as fuelwood.
  • Depending on geography, only the proportion of accessible areas should be taken into consideration.
  • Further influencing factors are the allocation of self-cutting contracts and the amount of timber used as fuelwood.
  • After "Lothar" in 1999 it was assumed that 3 million solid cubic meters, of the initially estimated 25 million solid cubic meters of storm damaged timber, would be available as fuelwood in Baden-Wuerttemberg.

Demand

The demand for woodchips differs regionally and rises with the amount of mainly communally owned wood heat plants. An overview is available from local authorities; the upper forest authorities could possibly provide this information on the region’s demand. After calamities it should be remembered that higher production at saw mills increases the amount of offcuts This leads to a further supply pulse, which might not be compensated for by higher demands. After "Lothar" in 1999, the theoretical supply of chips in Baden-Wuerttemberg was far higher than the demand. Therefore selling was a problem. However, due to the increasing number of wood heat plants this might not necessarily be an issue following future storm events.

Need for ground clearing / slash removal

Silvicultural

Generally the silvicultural need for ground clearing is not necessary, even if removal/ clearing is obligatory, e.g. for afforestation. Due to ensuing trafficking damage, clearing should only take place locally and not over the entire site. In general it’s enough to retain the remains in piles on site.

Forest protection

During the storm year chipping does not often occur because of the excess supply of material providing breeding grounds for beetles. Chipping can not efficiently decrease the beetle population. In the following year the remaining material is no longer suitable for beetle breeding. Only where, through a removal of all breeding material before the juvenile beetle flight stage, the beetle threat to neighbouring stands can be prevented, and where insecticide treatment can not be considered, is chipping recommended for forest protection reasons.

Miscellaneous

It is reasonable to chip along roads during full-tree harvesting under the following circumstances:

  • the sale of wood chips is assured
  • a cost-efficient processing is possible
  • forest protection or silvicultural reasons make clearance necessary

Processes and costs of chip production

Basically two main techniques in the forest are distinguished:

  • Chipping with a chipper truck on truck roads
  • Chipping with a forwarder-chassis mounted chipper on skid roads

The following remarks relate to the processing of spruce-tops by contractors. Expenses vary considerably depending on operating conditions and the type of chipper used.

The high costs of skidding the chip material arise from skid road distances of more then 20 m. Expenses can be reduced if the material is brought into crane range during logging or when chipping on truck roads if the material is brought into the range of the chipper by the tractors when bringing the stem wood to the truck road. Chipping in stands beyond skid roads should not be performed to avoid driving across the area/stand.

Chipping with a chipper truck on truck roads/ central sites

Cost-efficient chip production is possible where large quantities of wood material are accessible within the crane reach of large scale chippers. This mainly occurs near roads and conversion sites. The material needs to be skidded from the skid road to the truck road by a forwarder then gathered together.

Costs (incl. value added tax)

Chipper use is often accounted by hourly rates.

Costs (2000) Output
€/Fm**** €/srm****
Chipper truck (130,-- to 180,--€/h) 12-16 5-9 20-40 srm/h
Pre-concentration with forwarder along truck road 18-13 4-6
Pre-skidding into crane range along skid road1 (only at 40 m skid road distances) 26-40** 5-9**/
3-4***

Chipping with forwarder-chassis mounted chippers on skid roads

The wood chipper drives on the skid road and chips the material within crane range. Depending on the mounted crane type, the range is 8 -10 m. Because of its comparatively large weight, use is possible on slopes up to a max. slope gradient of 20 %.

Costs (2000) Output
€/Fm**** €/srm****
Chipper forwarder (use of chips) 18-23 7-9 20-30 srm/h
Chipper forwarder (chipping and blowing on site) 16-21 6-8 25-35 srm/h
Pre-skidding into crane range along skid road 26-40** 5-9**/
3-4***

* If skid roads are 40 m apart; it’s preferable if pre-skidding takes place during the logging of the main assortments.
** Referring to pre-skidded timber
*** Referring to total chipping volume
**** Fm: solid cubic meter, srm: loose cubic meter

Due to the high amount of wood in windthrown areas, the hectare-related clearing costs add up to more then 2,500€ (2000 figures).

Chip transportation to heat plant

For the chip transport to the heat plant an additional 2.50 –4.50 € per SRm3 (loose cubic meter, 2000 figures) has to be calculated.

Temporary storage

For organisational reasons and due to the limited capacity of the wood chip market, temporary storage will be necessary in many cases. Basically storage as roundwood and as wood chips is distinguished. Roundwood storage is simpler and less expensive. Therefore, if storage capacity is available, timber with a high volume of compact wood should be stored in high stacks, ideally with same end first - storage so that the wood doesn’t wedge. For long term storage it is possible to cover the stack with a special fleece (WISA-WRAP, a special bitumen treated paper, which later on can be chipped along with the wood). Always try to keep costs down.

Wood chip storage is remarkable time-consuming, hence should be restricted to just the best material. Therefore small-sized compact wood with a large amount of soft or highly soiled wood should be withdrawn. The desirable roofing is cost-intensive. These additional costs can not be compensated with higher prices for better chip quality. If chips are stored in buildings, good ventilation is necessary due to moisture evaporation. Outdoor storage is possible for a period of 1 year, if consideration is given to the following:

  • Fortified ground to avoid the mixture of soil and stones
  • High bulk stacks with steep sides
  • No depressions which trap water
  • Preferably high material compaction
  • Covering with special paper after approx. 8-10 weeks can help to increase the heating value.
  • Preferably no tree foliage which accelerates the decomposition process

For the temporary storage of wood chips calculate additional costs of approx. 1,50 - 4,-- €/SRm3/a (per loose cubic meter and year). Furthermore add costs for the discontinuous transport of approx. 3,-- €/SRm3 (per loose cubic meter).

Economic Rating

Costs, depending on the process, range between 7,-- and 24,-- €/SRm3 (per loose cubic meter) ‘free on factory’ face maximum revenues of approx. 10,-- €. The wood chip marketing has to be clarified in advance. Potential costumers are mainly communal wood heat plants.

Additional savings can be realised in other work fields but its only acceptable to include them when the saved treatments are absolutely necessary. Possible fields include:

  • Lower risk through beetle removal (doesn’t apply if an excess supply of material provide breeding grounds)
  • Replacement of motor-manual industrial timber processing with own workers
  • Avoidance of cutting tree tops into small pieces
  • No area clearing required
  • Forest in recreation areas "cleaned up"

More economically interesting would be the use of wood chip by the forest owning community for its own communal heat systems (kindergarten, communal facilities etc.)

Information