Publications
Including large and small scale harvesting systems and operations including harvesting, extraction, environmental protection, operator health and safety, and value adding operations such as sawmilling. Available in the following formats:
Project results including background detail, summarised study data and description of work.
Originally produced for delegates attending the respective workshops.
Summary results from extensive trials or publication related to smaller project.
Brief document relating to minor investigation or summary of longer document.
Summaries are given on this page. Depending on the status or the reports, additional information may be made available on request to the contact name shown against the respective summary.
Agri-forest tractors: Forestry Commission Project Report 25
Choosing the appropriate scale of machinery for forest operations is a significant factor in achieving management objectives. While large scale, purpose-built machinery (Ireland 2008) usually gives the highest outputs and ergonomic benefits to operators there are still significant benefits of agri-forest tractors at the appropriate operational scale. Agri-forest tractors are machines modified or purpose-built for forestry with high versatility for a wide range of work activities.
This report describes the range of attributes of agri-forest tractors and ancillary equipment and their suitability and safety requirements for forestry work. All tractors must have safety features appropriate to the tasks undertaken, to protect the operator from roll over, falling and penetrating objects. Information on tractor safety in forestry is available and comprehensive, however, guidance is not currently conveniently gathered in one place. This report itemises safety standards that tractor operators and forestry works managers should be familiar with.
Cableway extraction A82: Forestry Commission Project Report 24
The trial has shown that the Mulholland Cableking 230 18T winch was capable of extracting the timber from the study site. An assessment of previously extracted material showed that the largest log extracted was 3.86 m³ OB. However, the ability of the system to extract larger material over longer distances is not known and it is thought a newer and larger system may be required. The study identifies “wait lights” and this element represents the time needed for the A82 safety traffic control system. This safety requirement accounts for 15% of total productive time which would reduce output by about 1.00 m³/shr.
The average load volume extracted was 1.1 m³ OB with loads ranging from 0.70 m³ to 2.36 m³ and the average extraction distance was 116 m. Using a charge of £60/hr for the winch and two men and an output of 6.4 m3 OB/shr, the cost to extract the felled timber would be in the region of £9.50/m³. To obtain a full working cost for the operation you would need to include all management time, surveying, road building, felling, processing and stacking.
Careful planning and organisation of the cableway extraction system must be carried out to ensure effective and safe operation for all tasks. Due to the proximity of the public highway, a defined working system has to be in place to ensure fail-safe communication between the cableway and traffic control operators.
A literature search has identified larger capacity cableway systems that may be suitable for GB conditions.
Fibre-gen Hitman Acoustic Tool evaluation: Forestry Commission Project Report 49
The Fibre-gen Hitman Acoustic Tool is a harvester-head mounted device for measuring wood density, as an aid to timber grading. This report describes field trials to retrofit the tool to a Ponsse harvester head to evaluate performance. The fitting and positioning of the components of the acoustic system onto the existing Ponsse H75 harvester head was well planned by the engineers. The components were well guarded by additional steel fabrications.
No problems were encountered with the actual hammer and receiver unit. A minor problem was noted with the electrical cable of the acoustic tool being strapped to hydraulic hoses inside the harvester head housing. As the hose heated and expanded, the tie strap tightened around the cable prohibiting the electrical connection.
There was no time difference between the production of acoustic quality (QA) and non-acoustic (NAQ) sawlogs when using the acoustic tool.
The acoustic tool identified logs, suitable as sawlog material that otherwise would have been downgraded due to stem straightness, buttressing, number of knots, knot size and stem roughness as per Forestry Commission Fieldbook 9: Classification and presentation of softwood sawlogs.
Forest operations in steep terrain – Evaluation of Silvatec Sleipner 8266 TH purpose-built 8-wheeled harvester: Forestry Commission Project Report 22
A Silvatec Sleipner TH8266 8-wheeled harvester fitted with a Silvatec 560 harvester head was evaluated working on a conifer thinning operation in Ewinhope plantation, Dumfries and Borders Forest District.
The Silvatec Sleipner 8266TH was a well constructed machine with adequate power and ergonomics to harvest timber on the trial site. This machine is fit for purpose especially when considering felling operations on sloping ground.
The tilting cab improved operator ergonomics when working on slopes because a level working position can be maintained on slopes up to 55%. The BOSS, (Bogie Optimisation Stabilising System) hydraulic ram actuated system helped to maintain stability and traction when harvesting and moving on site. The machine was observed harvesting on slopes up to 47% and travelled on slopes up to 53% and no problems with stability were noted.
Forest operations in steep terrain – Evaluation of Tigercat LH845C tracked tilting base harvester: Forestry Commission Project Report 21
A Tigercat LH845C tracked base harvester fitted with a Logmax 6000 harvester head was evaluated on a conifer clearfell operation in Ardross, Dingwall. The operator had 20 years of experience in mechanised harvesting.
The studied Tigercat has been a reliable machine (3000 hours use) with adequate power and responsive ergonomic control systems. Operator access was good for cab entry and machine maintenance. Visibility from the cab was less than optimum but still judged to be fit for purpose. The machine appeared to be of strong rugged construction.
Harvesting was seen on slopes of up to 57% and the machine travelled a slope of 61% to 67%, all travel taking place up and down the hill with no diagonal working. The harvester head with a large saw could fell buttressed trees and 92% of sawlog products were cut within tolerance.
Standard outputs of 7.56 m3/hour (0.27 m3 tree size, level ground) and 14.66 m3/hour (0.65 m3 tree size, sloping ground) were recorded in a Sitka spruce crop. A machine cost of £75/hour gives felling costs of £9.92/m3 and £5.11/m3. The study data suggest conversion losses of over 30% for each study, when comparing whole tree and end product volumes. Technical Development measured whole tree volumes using inventory plots and end product using length and top diameter.
Tractor based mechanised harvesting in sweet chestnut coppice: Forestry Commission Project Report 40
Increasing the use of wood as fuel and the proportion of woodlands under management are both Forestry Commission objectives for Great Britain. Coppice woodlands are a common stand type in southeast England and a large proportion are undermanaged.
Coppicing has historically been carried out using manual and motor manual methods. The use of a harvester presents an alternative to declining manual working.
A Valtra T160 tractor fitted with a roof-mounted crane and Keto 51 felling head was studied in neglected coppice stands. The sweet chestnut (Castanea sativa) stands had been coppiced 17 and 27 years previously. Mean diameter and stems per hectare >7 cm were 8.2 cm and 4333 for the younger stand, and 12.0 cm and 3800 for the older stand. Three products were cut from the stands; 4 m woodchip poles, 7 foot firewood logs and 1.5 m signposts. Volume yield was 202 m3/ha for the younger stand and 305 m3/ha for the older. Machine costs and outputs for the older and younger stands were 2.00 m3/shr and £21.22/m3, and 1.67 m3/shr and £26.08/m3 respectively. The machine coped well with coppice working although a greater than normal number of chainsaw malfunctions were experienced due to the tendency for the densely packed stems to pinch the saw. The delays associated with this lead to a suggestion of a greater allowance to be made for this. The conversion factor of 1.416 that is normally used for grapple harvesters would be increased for this harvester and operation to 1.664 to allow for 41% of other work.
Wind farm non-commercial tree clearance: Forestry Commission Project Report 3
As part of clearance of crops for wind farm development, felling is to take place in a wide range of crops, many of which are likely to prove uneconomic. Technical Development (TD) was asked by the Forestry Commission Wales Wind Energy Programme (WEP) to provide information on, and approaches to, removing non-commercial crops.
This work firstly characterises the crops to be cleared for wind farm construction and then discusses the effect of crop and site characteristics on harvesting and clearance choices. Felling, site clearance and woody biomass handling options then are discussed, providing outline outputs and costs as a reference in future decision-making.
Woodfuel harvesting from coppice restoration: Forestry Commission Project Report 27
This report presents the results of a coppice restoration with motor-manual felling and forwarder extraction in an oak (Quercus robur) and ash (Fraxinus excelsior) stand of c. 75 years of age. The mean diameter at breast height (dbh)1 and volumes were respectively 20 cm and 0.282 m3 for the ash and 20 cm and 0.299 m3 for the oak. The operation consisted of cutting all trees and understorey and only keeping selected standards at a density of approximately 40 stems/ha. A shortwood system was adopted where 2.2 m length firewood products were cut in majority.
The observed outputs were 0.67 m3/shr for motor-manual felling corresponding to a £24.28/m3 felling cost, and 2.22 m3/shr/100 m extraction distance with a tractor based forwarder, corresponding to a cost of £22.28/m3/100 m extraction distance.
The substantial amount of unmarketable material contributed greatly to the felling costs, and the forwarding costs were affected by the relatively small size of the loads.
A low-impact extraction system, the Iron Horse, was also evaluated as part of this study. It showed a good ability to travel creating a minimal impact, but its full potential could not be evaluated as the forwarding configuration, as well as the products’ specification, limited the load size.
Careful consideration of harvesting systems and equipment best suited to a given operation will help to achieve the best quality work and minimise costs.
* These publications were produced by Technical Development.
Some (mainly older) publications are not available online. If you do not find what you are looking for, please contact Bill Jones.