Technodiversity Glossary

Pre-skidding of full trees from the felling site to the strip road with a winch that is mounted or attached to a tractor. 

Functiogram

Advantages

• extraction over long distance without driving on the ground 
• extracting in steep terrain (uphill)
• bringing trees to a site where machines for delimbing and cross-cutting can operate

Limitations, threshold

• distance limited by the length of the cable, often more than 100 m
• distance limited by the weight of the cable that must be pulled by the worker, so on flat terrain not more than 50 m, downhill wider distances are possible
• cable cannot be pulled uphill, therefore no downhill extraction over longer distance 

Main use

• in stands where fully mechanized methods are not applicable due to ground conditions, tree species (large broadleaf trees, e.g.)
• with wider distance of trails, where trees must be pulled into the reach of the crane of a machine
• in combination with extraction by means of a tractor 

Economic suitability

Winching performance depends on many factors, but mostly on extraction distance and tree size.

However, extraction distance and tree size have the strongest effect on cycle time, productivity and pre-skidding cost.

• When pre-skidding distance increases from 20 to 60 m (i.e. triples), then productivity decreases between 40 and 70% and pre-skidding cost increases up to 2.5 times. The effect of pre-skidding distance is stronger with smaller tree volumes.
• When tree volume increases from 0.1 to 1 m³ (i.e. factor 10), then productivity increases between 50 and 180% and pre-skidding cost  decreases between 33 and 66%. The effect of tree volume is stronger on shorter distances.

• machine costs without personal costs: 10,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 2
• in total: 80,00 Euro/h
• regression line minutes per tree
  • b₀ = 1
  • b₁ (depending on tree volume) = 3
  • b₂ (depending on pre-skidding distance) = 0,15

Since winch pre-skidding is extremely sensitive to distance, it should be used on very short distances, only. If tree volume is large enough, then one can obtain acceptable results also on medium distances, up to 50 m.

Ecological suitability

Ecograms

Social suitability

• S-class: no contact with forest road -> S5
• E-class: simple machine work, heavy and dangerous -> E3

Dekking J. 1984 Goliat, a small tractor with tracks. IEA/FE/CPC7 Report, 17 pp.

Dunnigan J. 1993 Braided Kevlar^TM Cable: Trials in Skidding Wood With an ATV. Field Note FN-022. FERIC. Pointe Claire, Quebec, Canada.

Ewing R. 2001 Use of a portable capstan winch and associated hand tools in manual thinning. FERIC Advantage Reports, 28: 4 p.

Ewing R. 2003 Harvesting riparian zones using cable skidders equipped with Spectra synthetic-fibre mainlines. FERIC Advantage Reports, 20: 6 p.

Harstela P., Tervo L. 1981 Bunching of timber by winches and horse. Folia Forestalia 466, 20 pp. In Finnish.

Hill S. 1991 D4H tractor and towed arch in radiate clearfell. LIRA Report 16, 8. 4 p.

Horvat D, Spinelli R, Šušnjar M. 2005 Resistance coefficients on ground-based winching of timber. Croatian Journal of Forest Engineering 30: 3-11

Leek N. 1976 Bunching with Radiotir 740 in thinnings. Nederlands Bosbouw Tijdschrift 48: 151-157.

Magagnotti N., Spinelli R. 2012 Replacing steel cable with synthetic rope to reduce operator workload during log winching operations. Small Scale Forestry 11: 223-236.

Picchio R., Magagnotti N., Sirna A., Spinelli R. 2012 Improved winching technique to reduce logging damage. Ecological Engineering 47: 83-86.

Prebble R. 1986. Evaluation of the Logquip smart arch. LIRA Report 11, 5. 4 p.

Pritchard N. 1986. The Logquip smart arch for small crawler tractors. LIRA Report 8. 4 p.

Ryans M. 1980 Evaluation of the Agri-Winch: a farm tractor-mounted logging winch. FERIC Tech. Rep. TR41. 18 p.

Spinelli R, Magagnotti N 2012 Wood extraction with farm tractor and sulky: estimating productivity, cost and energy consumption. Small-scale Forestry 11: 73-85.

TDB 2002 ATC timber sulky. Information Note ODW 9.04, Ae Village, UK. 5 p.

 Turner T., Huyler N. Bousquet D. 1988 Farm Tractor Skidding Costs in Relation to Profitability of a Fuelwood Harvesting System. Nort.h J Appli For 5: 207-210

Vaughan L. 1988 Thinning with small crawler tractors. LIRA Report 13, 26. 6 p.

Zeĉić Z., Krpan A., Vukuŝić S. 2005 Productivity of Holder 870 tractor with double drum winch Igland 4002 in thinning beech stands. Croatian J For Eng 26: 49-56.

Felled trees are pulled to a trail by means of a tractor winch and collected; when some full trees are collected, the tractor extracts them to the forest road and unloads alongside the road.

Functiogram

Advantages

• due to the cable, the area from which full trees can be extracted, is large
• capable for steep terrain (pre-skidding uphill)

Limitations. thresholds

• extraction length of the cable limited by the human power, maximum 50 m
• damage caused by the full trees

Main use

• small scale forestry with own tractors

Economic suitability

Example:

• machine costs without personal costs: 65,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 2
• in total: 135,00 Euro/h
• regression line minutes per tree
  • b₀ = 4,0
  • b₁ (tree volume) = 2,0
  • b₂ (skidding distance) = 0,005

Ecological suitability:

Ecograms

Social suitability:

• S-class: unloading full trees on forest road -> S3
• E-class: simple machine work, heavy and dangerous -> E3

Functiogram

• capable of working in steep terrain
• less soil disturbance than for ground-based
• capable of pre-skidding loads (drop line)
• can work with limited road network

• Relatively long set-up and dismantle time
• Fixed set-up and dismantle time require relative intensive removal (ca. 0.5-1 m3/ m line)
• High planning effort
• Requires high operator skill

• Mountain operations
• Alpine forestry
• Developing on soft terrain as reduced-impact alternative to ground-based extraction

Economic suitability

Example:

• machine costs without personal costs: 100,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 3
• in total: 205,00 Euro/h
• regression line minutes per tree
  • b₀ = 1,0
  • b₁ (load volume) = 0,5
  • b₂ (logging distance) = 0,015
• plus costs for installation and dismantle of the cable system

Ecological suitability

Ecogram

Social suitability

• S-class: unloading full trees on forest road -> S3
• E-class: simple machine work, heavy and dangerous -> E3

Spinelli R.,  Marchi E., Visser R., Harrill H., Gallo R., Cambi M., Neri F., Lombardini C., Magagnotti N. (2017) The effect of carraige type on yarding productivity and cost. International Journal of Forest Engineering - Accepted paper.

Spinelli R., Magagnotti N., Visser R. (2015) Productivity models for cable yarding in Alpine forests. European Journal of Forest Engineering 1, p. 9-14.

Spinelli, R., Magagnotti, N. (2011) The effects of introducing modern technology on the financial, labour and energy performance of forest operations in the Italian Alps. Forest Policy and Economics, 13 (7), pp. 520-524.

Huyler, N., LeDoux, C., 1997. Cycle-time equation for the Koller K300 cable yarder operating on steep slopes in the Northeast. Res. Pap. NE-705, USDA Forest Service, Northeastern Forest Experiment Station 4 p.

Senturk, N., Ozturk, T., Demir, M., 2007. Productivity and costs in the course of timber transportation with the Koller K300 cable system in Turkey. Building and Environment 42: 2107-2113.

Stampfer, K., Visser, R., Kanzian, C., 2006. Cable corridor installation times for European yarders. International Journal of Forest Engineering 17: 71-77.

Zimbalatti, G., Proto, A., 2009. Cable logging opportunities for firewood in Calabrian forests. Biosystems Engineering 102: 63-68.

see SP-x2-x3 cross-cutting

After felling, delimbing, and topping, tree lengths are pre-skidded to a strip road using animals, and most commonly draught horses. Different breeds are available in different regions, but the most popular are heavy breeds like French Percherons, Belgian Ardennes, or Italian TPR.

Functiogram:

Advantages

• Capacity to work in dense stands and narrow corridors, inaccessible to mechanical vehicles.
• Capacity to handle soft or steep terrain (provided extraction proceeds downhill).
• Very low soil and stand impacts, because the animal has neither the size nor the power of a machine, and therefore it can never resort to brute force against an obstacle, but it must rather use brains and technique.
• Safety for the operator, who can control the horse at a distance through voice commands.
• Comfort for the operator, who is spared noise, vibration, exhaust gases, heavy cable pulls and tiresome walks on uphill grades (since he can ride the horse if the walk is too hard).
• Competitive cost on intermediate pulls (between 50 and 100 m), which are too long for direct winching and too short for cost-effective cable yarding.

Limitations, thresholds:

• The system is suitable for young trees only, as obtained from first and second thinnings, or to coppice harvesting operations. The size of older trees is generally too large for an animal to move them without preliminary crosscutting
• Distance must not exceed 200 m. Best results are obtained on shorter distances, between 25 and 100 m.
• Extraction must proceed on flat terrain or downhill slopes, with a maximum gradient of 50%. Experienced animals and drivers can safely handle steep terrain.
• Draught animals can only work 5 to 6 hours a day.  Operators working longer hours generally keep two animals and rotate them.

Main use

• Animal pre-skidding is still competitive with other mechanized pre-skidding systems (winches, mini-skidders etc.), but it is rarely used in industrialized countries, where it remains a specialist niche. The reason is in the small numbers of horse loggers, ready to accept the constant commitment imposed by animal care.

Economic suitability

Example:

• machine costs without personal costs: 10,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 1
• in total: 45,00 Euro/h
• regression line minutes pre log
  • b₀ = 3,0
  • b₁ (tree volume) = 8,0
  • b₂ (skidding distance) = 0,025

Ecological suitability:

• Ecogram 

Social suitability:

• S-class: no contact with forest road -> S5
• E-class: manual work, very heavy and dangerous -> E1

Felled and delimbed tree lengths are pulled to the trail with a cable winch that is mounted or attached to a tractor. 

Functiogram

Advantages

• extraction over long distance without driving on the ground 
• extracting in steep terrain (uphill)
• bringing trees to a site where machines for delimbing and cross-cutting can operate
• Compared with full trees, tree-lengths offer less resistance to drag and are easier to move within the stand
  
• Compared with full trees, no nutrient removal

Limitations, threshold

• distance limited by the length of the cable, often more than 100 m
• distance limited by the weight of the cable that must be pulled by the worker, so on flat terrain not more than 50 m, downhill wider distances are possible
• cable cannot be pulled uphill, therefore no downhill extraction over longer distance 

Main use

• in stands where fully mechanized methods are not applicable due to ground conditions, tree species (large broadleaf trees, e.g.)
• with wider distance of trails, where trees must be pulled into the reach of the crane of a machine
• in combination with extraction by means of a tractor 

Economic suitability

Example:

• machine costs without personal costs: 60,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 2
• in total: 130,00 Euro/h
• regression line time per tree
  • b₀ = 4,0
  • b₁ (tree volume) = 2,0
  • b₂ (skidding distance) = 0,1

Ecological suitability

Ecograms 

Social suitability

• S-class: no contact with forest road -> S5
• E-class: simple machine work, heavy and dangerous -> E3

Tree-lengths are dragged to the landing by a tractor equipped with a single or double-drum winch. The winch is used for assembling the load and for pre-skidding the tree-lengths to the skid trail if necessary.

Functiogram

• Independent pre-skidding and extraction capacity in one unit
• Can operate on steep terrain, if skid trails are available at a suitable spacing
• Can work in small lots if skidder is road legal

• Slow (pre-skidding)
• Need an assistant (chokerman) and/or the driver needs to leave the cab (uncomfortable)
• Limited load capacity

• Mountain operations
• Small-scale forestry
• Traditional extraction method when crosscutting should not be done before reaching the forest road (or the customer)

Economic suitability

Example:

• machine costs without personal costs: 65,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 2
• in total: 135,00 Euro/h
• regression line minutes per tree
  • b₀ = 4,0
  • b₁ (tree volume) = 2,0
  • b₂ (skidding distance) = 0,005

Ecological suitability

Ecograms 

Social suitability:

• S-class: unloading tree length on the road -> S3
• E-class: simple machine work, heavy and dangerous -> E3

Logging arch study for farm tractors - Merlo study etc.

Functiogram

• capable of working in steep terrain
• less soil disturbance than for ground-based
• capable of pre-skidding loads (drop line)
• can work with limited road network
• minimum of operations on the working site (safety)

• Relatively long set-up and dismantle time
• Fixed set-up and dismantle time require relative intensive removal (ca. 0.5-1 m3/ m line)
• High planning effort
• Requires high operator skill

• Mountain operations
• Alpine forestry
• Developing on soft terrain as reduced-impact alternative to ground-based extraction

Economic suitability

Example:

• machine costs without personal costs: 100,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 3
• in total: 205,00 Euro/h
• regression line minutes per tree
  • b₀ = 1,0
  • b₁ (tree volume) = 0,5
  • b₂ (skidding distance) = 0,015
• plus time for set-up and dismantle

Ecological suitability

Ecogram 

Social suitability

• S-class: unloading tree length on the road -> S3
  
• E-class: simple machine work, heavy and dangerous -> E3

Functiogram

• Capacity to deal with almost any terrain conditions 
  
• Limited impact

• Short distance only
• Animals need training and constant care
• Low productivity
• Only works with relatively small and short logs that are within the weight capacity of animal power

• Small scale forestry

Economic suitability

Example:

• machine costs without personal costs: 10,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 1
• in total: 45,00 Euro/h
• max. 0,4 m³ per log
• regression line minutes per tree
  • b₀ = 3,0
  • b₁ (tree volume) = 8,0
  • b₂ (skidding distance) = 0,025

Ecological suitability

Ecogram 

Social suitability:

• S-class: no contact with forest road -> S5
• E-class: manual work, very heavy and dangerous -> E1

Functiogram

Advantages

• Limited (or no) investment for manual sliding
• Capacity to deal with almost any terrain conditions 
• Limited impact

• Short distance only
• Downhill if sliding or throwing 
• Very low productivity
• Only works with relatively small and short logs that are within the weight capacity of human power

• Small scale forestry 

Economic suitability

Example:

• machine costs without personal costs: 0,00 Euro/h
• personal costs per person: 35,00 Euro/h
• number of persons: 1
• in total: 35,00 Euro/h
• regression line minutes per tree
  • max. load per cycle 0,1
    
  • b₀ = 2,0
  • b₁ (tree volume) = 1,0 
  • b₂ (skidding distance) = 0,025

Ecological suitability

Ecogram 

Social suitability:

• S-class: no contact with forest road -> S5
• E-class: manual work, very heavy and dangerous -> E1