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A Time and Motion Study on Thinning Farm Sawlog Plantations for Firewood and Chip

Philippa Noble DPI, Wangaratta,
Rhodey Bowman DPI, Tatura
2009

ISBN 978-1-74217-466-2

Acknowledgments

We wish to thank:-

Andrew Lang, plantation owner at Lismore and member of the SMARTimbers cooperative for his valuable assistance in developing the project, allowing us access to thin his sugar gum plantation and organising contractors for the Lismore site; Central Victorian Farm Plantations Committee for their funding assistance; Sue Harris from DPI Colac for meticulous measurements, filming and observations during the Lismore trial; and Simon Noble from Rutherglen for making the Gripper Snipper available and driving the tractors at both the Lismore and Yarrawonga sites.

For the Yarrawonga site we thank Peter Smith for allowing us to drive over his newly sprouting wheat crop to access his red gum plantation at Yarrawonga; Bruce Sonogan DPI Benalla for his chainsaw work in felling trees; and Heath Doyle from Tree Solutions in Shepparton for agreeing to be timed falling trees and providing the chipper and skid steer.

The Department of Primary Industries Plantation Incentive Strategy provided initial funding for this project.

Contents

Contents
Summary
Background

The Plantation Industry in Victoria
Sawlog Plantation Silviculture
Markets for Thinnings
Harvesting Systems
In-field Wood Chipping Options

Project Aim
Methods

The Sites
The Treatments
The Harvesting Equipment Systems
The Product Processing Systems
The Measurements

Results

Harvesting Component data
Amalgamated Harvest System Plot Results
Operator Variation
Trial Data
Processing Systems
Bark and Wood Measurements

Discussion

Selection and Travel Time
Chemical Thinning
Tree Felling
Pole and billet production
Processing systems
Example of thinning operations using the results from this trial

Conclusion
References
Appendix 1. Comments on grapple arm chipper
Appendix 2. Billet size class
Appendix 3. Width of bark, sapwood and heartwood
Appendix 4. Billet aggregation time feasibility study

Summary

Currently the harvesting systems for small trees and plantations, particularly first thinnings, generally use manual labour and chainsaws. There is potential for expansion of farm plantations to provide firewood and biomass, but for this to happen, cost effective mechanised harvesting is needed. As the costs of harvesting these smaller plantations are related more to the time to handle the number of pieces and are less dependant on the size of each piece, this project investigated the time and motion efficiency of the various harvest options currently available for first thinning of hardwood plantations in Victoria.

The report provides information to assist plantation growers determine which system is most cost effective for their plantation by providing a detailed analysis of the times taken for each of the individual elements within the harvest operations. Chemical thinning to waste took the least amount of time. Manual falling and processing was generally still the quickest way to handle the trees, but mechanically falling with a Gripper Snipper was comparable in some situations. For further processing of logs once harvested, using a chipper with a grapple arm to process whole trees was much quicker than manual loading of trees cut into billets. Occupational health and safety was found to be an issue with using manual labour for this type of work.

Background

The Plantation Industry in Victoria

The plantation industry in Victoria is continually expanding whilst access to native forest timber is reduced. The plantation industry has developed on the basis of industrial-scale plantations of pine for sawlogs and eucalypts for pulp but interest in the production of eucalypt sawlogs, firewood and woody biomass is increasing.

The growth of eucalypt plantations for hardwood sawlogs is a relatively new industry in Victoria. The sawlog industry has largely been based on native forest hardwoods and pine plantations. Less than 200 hectares of eucalypt plantations for sawlogs in Victoria were established in the early 1990s. A large proportion of the current plantations were planted under a government incentive scheme which ran from 1996 – 1999 when 1600 ha of mainly Blue Gum (Eucalyptus globulus) and Shinning Gum (E. nitens), with some Sydney Blue Gum (E. saligna) and Rose Gum (E. grandis) were established in North East Victoria. A further 1000 ha of sawlog plantations have been established on private farms of a range of other species, including the more durable species such as Sugar Gum (E. caldocaylx), River Red Gum (E. camaldulensis), and Ironbark ( E. tricarpa).

The fact that the plantation eucalypt sawlog industry is still in its infancy in Australia is illustrated in Tasmania where the company Forest Enterprises Australia (FEA http://www.fealtd.com) has only started processing small-diameter E. nitens logs with a hewsaw commercially in the past three years. Most mills currently processing eucalypt sawlogs are based on the native forest sawlog resource where quarter-sawing requires large logs with a minimum size of 40 cm diameter to achieve acceptable recovery rates.

Sawlog Plantation Silviculture

Standard silviculture regimes for producing plantation-grown sawlogs currently require high initial stocking rates of around 1000 sph (stems per hectare) to be planted with two or three thinnings over the life of the plantation to achieve a final stocking rate of between 100 – 250 sph which is capable of growing acceptable sawlogs.

Due to the growth characteristics of eucalypts, hardwood plantations require thinning fairly early in the rotation if growth is not to be compromised and trees moisture stressed. The first thinning is undertaken between three and seven years and the second usually before ten years.

Stressed eucalypts are produce more tension wood, which can affect their sawing ability and reduce recovery rates of quality timber, as well as being more prone to insect attack, particularly borers.

Markets for Thinnings

To profitably harvest the small log volumes taken from first thinnings of sawlog plantations requires a high-value product or a low cost of operation and preferably both.

Pulp is generally a low-value product requiring high volumes of debarked log of specific species, with E. globulus being the preferred species and E. nitens being acceptable. Species with coloured wood fibres are generally not acceptable.

Poles for fencing or construction can be obtained from some plantation thinnings, although the fact that thinnings can often be poorly formed, weak trees makes this market fairly limited. Many species are also non-durable or at a young age are dominated by sapwood, necessitating a highly durable species or timber preservation treatments be used.

Fuelwood is another potential product from small-diameter logs. Climate change and global concern for the increases in CO₂ have increased the focus on the potential for wood as an alternative energy source to fossil fuels. There has also been increasing pressures for conservation on our native forests, leading to a reduction in the amount of firewood available. This has meant that the focus on utilisation of first thinnings as a source of biomass energy has attracted attention, with potential for increased values. The development of plantations of more durable species in lower rainfall zones for fuelwood further points to the need for harvest systems that can efficiently handle smaller-diameter logs.

Many overseas countries use fuelwood in the form of chips, as they are easily stored, do not require drying before use and supplies of feedstock to boilers can be automated with little manual handling. There are many heaters available on overseas markets that cater for this form of fuelwood, but these are not currently being used to a great extent in Australia . Solid firewood heaters are more common in Australia and currently use around 6 - 10 million tonnes of timber per year.

Harvesting Systems

The hardwood industry needs a cost-effective thinning and handling systems of small logs to make hardwood plantations a more financially viable proposition by providing some early returns from the thinning operations. The system needs to include the following factors;

• cost-effective conversion of standing trees into short (often split) and dried lengths or into chips
• relatively low capital cost (less than $100,000 including felling head and processors)
• relatively high work rate
• low fatigue level ( operator able to work effectively for a normal 8 hr shift
• high level of operator comfort
• high level of safety
• ideally leaving bark and leaves spread over the woodlot.

A number of options for harvesting and extracting wood products from first thinnings have been investigated and tested.

Chemical thinning

Chemical thinning of plantations has been undertaken successfully where the trees are thinned to waste. Chemical thinning kills the standing trees, which can still be harvested after death for products such as fuelwood if required. Kerruish and Noble undertook a trial using varying rates of a number of chemicals in 1999 (unpublished). Further studies on this form of thinning are being carried out by the Central Victorian Plantations Committee.

Machine harvesting

Commercial machines capable of harvesting over 100 trees per hour or 40 tonnes per hour are currently used in pine and native forest logging and some pulpwood plantation harvesting. The capital cost of these machines is generally over $300,000.

These large machines are well suited to clear falling as they need room to swing and grab trees. Pines are thinned at a much later age than eucalypts and their establishment rate of around 1300 sph allows for a clearfall-outrow thinning, giving room to reach into the neighbouring two rows for thinning without damaging the remaining trees. Eucalypts are not suited to such an out-row system as they have a faster initial growth period and are not as tolerant to competition and shading as pines, so need thinning earlier to reduce competition. Tension wood can also develop if eucalypts are left unthinned and grow too tall and thin, reducing the recovery rates of quality sawn timber (Washusen 2002). Early thinning, can lead to the development of larger branches in response to increased light after thinning (Volker 2007) and this uneven growth can also result in tension wood developing,

A Churchill Fellowship study by Jon Lambert in 2003 into small-scale harvesters used overseas in Scandinavian countries found that small shear heads with or without bunching, stroke delimbers or multi-processing heads- fitted to purpose-built tractors or larger excavators, were being used but had minimum capital costs of $250,000.

Andrew Lang also undertook a Churchill Fellowship in Scandinavia to investigate thinning procedures and found that first thinning is normally cost neutral, through costs being reduced by high work rate for harvesters and forwarders and product returns increased by log sales from the landing, a number of buyers competing for products and a legislative framework encouraging the use of biomass.

Investigations by Lambert (2007) assessed two common types of harvesters currently in use in Victoria to determine under what conditions mechanical harvesting technology currently available could be used to economically harvest small-diameter 13.5 year old Blue Gum plantation thinnings. Lambert demonstrated that a purpose-built rubber-tyred harvester with a telescopic boom achieved up to 100 percent higher productivity in first thinning and 80 percent in second thinning with very little retained-stem damage despite no out-rows being removed, compared to the tracked excavator with a harvesting head attached. The productivity was most influenced by the average piece size of the trees being removed. He concluded that excavator-based harvesters were only really suited to thinning operations where an out-row is removed. The use of these currently available machines in younger, smaller-diameter eucalypt sawlog plantations for first thinnings, where the volume of product from first thinning of around 5 – 15 m³/ha, is a long way from being economic in relation to the capital values of these machines.

One way to reduce costs of mechanical harvesting is to adapt a harvesting machine to a conventional tractor available on most Australian farms, obviating the need for a purpose-built tractor. The development of such a machine was undertaken by an engineering student from RMIT, designing a 'Farm Tree Gripper Snipper” that can be fitted to the front-end loader of a 70 hp tractor. Following development of designs, a prototype was built by Burder Engineering in Wangaratta in North East Victoria. This machine weighs around 600 kg and is capable of cutting through a stem diameter of up to 20 cm using a shear mechanism. Clamps have been fitted to hold the tree in place and enable transport if required. The whole gripping and cutting mechanism is worked out to one side of the tractor and can be extended out to 1.5 m beyond the tractor. The lifting aspect of the front-end loader means that a cut can be carried out at a height of 3 m, enabling the top of trees to be fallen separately to the log. No productivity rates are currently available for this machine.

Manual Harvesting

Manual harvest investigations have been undertaken by Sonogan (2006) and Bulman (2006).

Bulman (2006) investigated six small-scale harvesting and processing systems in an eighteen-year-old sugar gum plantation. The systems were a Scandinavian firewood mill, a traditional saw bench, a low-cost sled system, an at-stump processing system, cutting blocks at the stump with a chainsaw and snigging logs to a log dump for processing. All these trials involved manual chainsaw felling. Bulman notes that the chainsaw felling, crosscutting and manual loading was suitable for any terrain and only required one manual lift. Productivity rates were 0.71 m³ per man hour for small trees of 16 cm diameter under bark (DUB) at stump and 0.81m³ per man hour for large trees of around 19 cm DUB at stump. Using a sled to transport billets of 1.8 m from the plantation was the most productive method of firewood extraction, as they only required a single lift and multiple logs could be crosscut at one time. Productivity rates for the whole process of fall and sled were 0.85 – 1.2 m³ per man hour. Issues with the sled causing high soil disturbance and debris build up and bogging were raised, as well as billets greater than 20 cm diameter being too heavy to manually lift onto the sled.

Sonogan (2006) estimated the cost of manually thinning a plantation from 1000 sph to 500 sph to be around $300 per hectare and concluded that manual harvesting and processing of logs with a small-end diameter of less than 10 cm is unlikely to be profitable. With the requirement for sawlog plantations to be pruned (to ensure a minimum size defect core in the final crop) when stems are from 9 – 14 cm diameter at breast height (DBH) and the fact that once crop trees are pruned, the un-pruned trees need to be removed, there will generally be few harvested trees greater than 10 cm SED. To make this first thinning economic, or at least cost-neutral, is a problem recognised world-wide.

Sonogan also found that for small diameter logs, 63 percent of total air-dry weight of wood was contained in the section of the log that was over 10 cm. He concluded it was more efficient to concentrate on the larger portion of the log with a diameter over 10 cm, than the rest of the top of the tree.

Further studies by Sonogan (June 2006) in an eight-year-old blue gum plantation investigated manually harvesting, delimbing and billeting logs into 2.5 m lengths and extracting these billets using a sled. He found that this process can be a viable activity if efficient practices are used. Some of the factors to improve these efficiencies were the orientation of fallen trees such that two rows were fallen into the space between them, leaving the docked logs visibly exposed to aid extraction and every second space left clear of debris for easy access. The productivity of the faller to fall, dock and billet each row of trees ranged from 0.51 – 0.71 tonnes per hour of air-dry wood (15 percent moisture). Sonogan found processing billets with a large-end diameter (LED) greater than 12 cm improved productivity (tonnes/hr) by 18 percent over those billets with a LED less than 12 cm. He notes that these Blue Gum billets still had their bark on, and after one year this bark was still firmly attached, with the bark forming around 15 percent of the total weight of the wood. He also adds a word of caution that when billets had a LED nearing 25 cm, they became too heavy for manual loading and a mechanised lifting system would need to be considered.

Bowman undertook a time and motion billet aggregation time study in 2007 to determine the time required to aggregate timber billets into small piles in a plantation. He also concluded that the amount of slash required to drag the billets over could double the time taken, and the larger the billets, the more efficient in aggregation but the issue of weight of billets for safe handling will determine the size used.
His report is in Appendix 3.

Bulman (2008) carried out further work evaluating manual small-scale harvest thinning and an industrial-scale excavator-based harvester in a number of eucalypt species plantations for the production of firewood. The small-scale harvest system manually felled the trees, tractor winched them to a log dump and used a forklift to load logs onto a tractor-driven processor, producing short split blocks. The industrial scale harvest system thinned using a fifth-row out-row, debarking the logs and leaving them in piles which were collected with a forestry forwarder to carry them to the road and load onto trucks. He found that initial reservations about the high operational and floating costs associated with engaging the industrial-scale harvest systems were unfounded as the cost of industrial-scale tree harvest per hour was equivalent to the cost of four chainsaw operators, but the productivity of the industrial equipment was much higher. For 0.2 m³ sized trees, manual falling productivity was 2.2 m³/hr and the industrial scale harvester achieved 8.8 m³/hr while also debarking, cross cutting and stacking the logs.

In-field Wood Chipping Options

Preliminary studies of in-field chippers by Quayle (2008) in farm plantations found that mulch and chip production from thinning material may indeed be profitable. Two studies were undertaken. An initial study in a clear-fall chipping of a mixed durable species 13 to 20-year-old plantation (including River Red Gum and Ironbark) with diameters from 15 – 25 cm, found that and 18 inch chipper and a bob-cat feed using two workers, could process 105 m³ of mulch a day (15 m³ mulch per hour) for a cost of $15 per cubic metre. A further study chipping 7 year old Ironbark thinnings with a 9 inch chipper and three men manually falling and feeding, cost around $11 per cubic metre (20 m³ of mulch per hour).

Project Aim

This project aims to investigate the time and motion efficiency of the various harvest options currently available for first thinning of hardwood sawlog plantations in Victoria. This will enable provision of information to assist plantation growers to determine which system is most cost-effective for their plantations, by providing a detailed analysis of the times taken for each of the individual elements within the harvest operations.

Methods

The Sites

Two sites were harvested, one of 6-year-old Sugar Gum at Lismore and one of 10-year-old River Red Gum near Yarrawonga.

Lismore site

This site was located in south west Victoria, 10 km west of Lismore on the property “Titanga” of Andrew Lang. It was in a flat area on the basalt plains, which had been previously cropped and ideally suited to Sugar gum growth. The six-year-old Sugar Gums (E. cladocalyx) were of 'ERP' provenance stock with rows aligned north-south. The trees were just reaching canopy closure, with foliage reaching to within one metre of the ground. This made access to the stem and visibility of its form difficult. Their form was generally good, but a number of multi-stems were present. This plantation required half the trees removed i.e. 50 percent thinned.

Yarrawonga site

This site in North East Victoria was approximately 10 km south-east of Yarrawonga in a slight depression in the generally flat landscape making it ideal for River Red Gum growth. The 10-year-old trees were mostly single-stemmed, but very few were straight. With foliage in the top third of the tree only, visibility and access to the stem were easy.

The Treatments

Three harvesting systems and four processing systems were investigated.

The harvesting systems were the use of a

1. manual chainsaw,
2. tractor-mounted Farm Tree Gripper Snipper, and
3. chemical axe to kill the standing tree.

The processing systems investigated were;

1. harvest of whole trees,
2. in-field production of poles (trees cut at base and with top foliage removed),
3. in-field production of billets,(trees cut into sizes suitable for manual handling), and
4. in-field production of chips.

The Harvesting Equipment Systems

Manual Chainsaw

Two trained and experienced chainsaw operators were used to select and hand-fall approximately 50 percent of the trees in the plantations. Their chainsaws were a 95 Husqkvarna with an 18 inch bar and a 020T Stihl with a 14 inch bar.

Tractor Mounted Gripper Snipper

This machine was designed to fit onto the front-end loader of a medium-sized tractor. In the first Lismore trial an 80 hp Fiat tractor was used, and in the Yarrawonga trial site a 75 hp Massey Ferguson tractor was used. The same person operated both of these tractors with the gripper sniper attached.

The gripper-snipper required two hydraulic fittings, one to operate the shear cutting blades and the tree gripping mechanism mounted above the blades, and the other to push the frame, on which the blades and grippers were mounted, out to the side. This side-working mechanism enabled the tractor to stay straight along the row and work on the tree to the side of the tractor: this facilitated better visibility of the tree to be harvested. The front-end loader hydraulics of the tractor could then be used to position the shears at the appropriate height on the tree: either at full height (approximately 3 meters), or anywhere down to the base of the tree. Once the tree was held by the grippers and cut, it could be tilted using the front-end loader hydraulics, and transported.

In the trial the whole tree was laid down in the row adjacent to the tractor, whereas the poles were laid in the row the tractor was working in parallel to the row. The tractor-mounted gripper snipper could only work on one row at a time, the row to the left of the tractor, so the tractor would needed to move up and down the same row to harvest the trees either side of the alley.

Stem diameters up to a maximum of 20 cm were able to be cut with this machine. Stems in the Yarrawonga trial had been planted with guards and wire stakes. These had to be removed prior to any chainsaw harvest but the Gripper Snipper with the shear blades was able to harvest without their removal; the wires falling out once the tree was cut.

Chemical Thinning

A chemical thinning axe (known as the 'Woody Weeder') designed by Bill Kerruish was used to undertake the chemical thinnings. This device is shaped like a hammer with a blade at the tip which is used to make a slit by striking into the tree and through the bark. It then injects a measured dose of chemical into the sapwood of the tree. The operator was required to select the trees for thinning then inject them. Only water was used in this case, as the time taken for the job was the information required. Other trials have been undertaken to determine chemical rates for successful tree death without causing flashback to the remaining trees.

The Product Processing Systems

Whole Trees

Trees were cut off at the base approximately 10 cm from the ground. They were directionally fallen out of the working row, so they laid in the adjacent row. This left fallen trees in every second row, with alternate rows clear of debris. When a chainsaw was used, very small trees were felled using a back-cut only, but a scarf-cut used as well as a back-cut to fall larger trees.

Poles

Using the chainsaw, trees were fallen, into the adjacent row, branches removed and the top crown foliage cut off at approximately 7.5 cm diameter.

The Gripper Snipper was able to cut the crown top off either at 7.5 cm or at the full extent of the tractor reach (whichever was lower). These tree tops were placed in the adjacent row. Some branches were broken off as the open blades were lowered (thus the pole was not fully delimbed) to cut the base with the pole then laid in the working row beside the tractor.

Billets

Billet production for the Lismore site was to provide firewood in 1.2 m lengths for a specific market. This specification was just able to be handled manually in the first site where trees were younger and smaller. In the Yarrawonga site the billets were cross-cut according to approximate weight able to be man-handled, which resulted in some being shorter than 1.2 m.

Billets were cut using a chainsaw, preparing the tree in the same way as for poles, then undertaking further cross-cutting as required.

Billets were cut with the Gripper Snipper in the feasibility study only. The arc trajectory of the front-end loader as it is lowered required the tractor to be moved back then forward for each cut, making this system relatively difficult without an automatically geared tractor.

Chips

The processing of chips was tested using an infield chipper working within the rows.

A 9 inch chipper was used which was able to be towed down the row by a small truck into which the chips were discharged and transported. Whole trees were fed into the chipper either by using a mechanical grapple log grab on a 3 metre arm attached to the chipper, using a skid steer machine, or manually lifted once cut into manageable billets. Poles were fed into the chipper either manually or with the Skid Steer. Billets were fed into the machine manually, using two men and a truck driver.

At the Lismore site a Bandit Brush model 90 XP chipper was used for the manual loading treatments and a Skyrider mechanical grapple-fed 210 HP Bandit Intimidator Model 1990 drum chipper was used for the self-loading treatment. The Bandit Chipper is a disc chipper of a common type and size used by shires and many tree- lopping services.

There are about four main brands of chipper used by commercial operators of this sort and all are made in the USA . The Bandit chipper was bought second-hand for about $25,000 and chosen for its weight and size, allowing it to be towed relatively easily, if necessary by a heavy utility, and manoeuvred readily in confined spaces like gardens and streets. Similarly the truck at the Lismore site was a relatively small-wheelbase tipper with about a 6 tonne capacity, and holding about 11 m³ of chip fully loaded.

The grapple arm of the Skyrider chipper could only swing through 110 degrees and reach was strictly limited to about 3 m from the edge of the feed throat, out about 2 m on the left side and 1.5 m to the right. To enable the arm to reach the trees from four rows at one pass, some trees were manually aligned to make them accessible to the grapple arm, requiring an extra labour unit for the process.

At the Yarrawonga site, tree handling was undertaken using a compact Vermeer skid steer with a 26 hp Kubota diesel engine with a large log grab fitted on the front, capable of lifting 600 kg. This skid steer could fit easily onto a trailer for transport and was worth around $30,000 new. The chipper at Yarrawonga was a 9 inch Rivett Chipper 86 hp Hask motor, adjusted to a 2 cm chip. The truck at Yarrawonga was fairly small with a 6 m³ holding capacity. Whole trees from the Yarrawonga site were easily fed into the chipper using the skid steer, with the truck and chipper backing down the row containing the felled trees.

Poles from the Gripper Snipper were aligned along each side of the row, and the tree tops placed in the adjacent row. This enabled the chipping process to be streamlined to two operators and reduced the risk of tripping over foliage. During this process one person drove so the truck was constantly moving. The person feeding the logs into the chipper would wait at the feed bar control until the main part of the butt was being processed and then proceed to pick up the next pole. Manually lifted poles were only chipped at the Lismore site as the Red Gum poles at the Yarrawonga site were too heavy. The Skid steer was used to transport these Red Gum poles.

The chips were dumped into piles at the edge of the plantation. Samples were taken from both the whole tree chips, which included wood, bark and leaves, or from the pole and billet chips, which were just bark and wood. These can be separate products in the garden mulch market as too many long twigs/stems in the mulch reduce its quality for the domestic garden mulch market.

The Measurements

A homogenous section from within each plantation was selected for the trial. The size of this trial area is given in Table 1.

Measurements of times of each harvest system were taken along at least one whole row. These were called the TRIAL measurements.

Within the Trial area, a micro-measurement PLOT was marked through the centre of the trial for detailed measurements of each task. Within this plot each tree height and diameter measured.

The treatments were conducted in formative steps:

1. Feasibility Tests – outside the trial areas these were conducted to test the practicality of performing each task and further developing it as appropriate
2. Micro Measurement Plots– to time and study the smaller elements of a task so that variations could be modelled
3. Trial Runs – to perform selected harvest and processing systems along a whole plantation row to gauge the impact of work conditions e.g. fatigue, equipment maintenance and the time to undertake the harvest.

The harvesting system tasks were:

1. Manual fall
2. Chemical thin
3. Manual pole-production
4. Manual billet-production
5. Gripper Snipper (GS) fall
6. Gripper snipper (GS) pole–production.

The Components studied and timed within each of the harvesting tasks were:

1. Select the tree to thin and travel to the tree (Select and Travel)
2. Chemical thin the tree with the axe (Chemical Thin)
3. Fall the whole tree into a predetermined row (Fall Whole Tree)
4. Remove the crown of the tree; this included some trimming of branches for access and pole production The Gripper Sniper was not able to undertake any branch trimming but was able to place the crown of the tree in a separate row to the pole if required. (Top)
5. Remove the crown of the tree and cut the stem into billets (Billet).

A number of product processing components were measured for timing. These were:

1. Chip whole trees – mechanically handled
2. Chip whole trees – as billets and heads – manually handled
3. Chip billets – manually handled
4. Chip crown (Lismore only)
5. Chip poles from Gripper Snipper- manually handled
6. Bulk poles from Gripper Snipper – mechanical skid steer
7. Load poles onto trailer – skid steer.

To give an indication of the sizes and weights of the trees being handled in the trials, a few whole trees were weighed for foliage and stem proportions.

Where a forked final crop tree was 'form pruned' (one stem removed only), it was treated as a harvested tree, as the cut stem was processed in the same manner as the rest of the harvested stems in the trial. This was more of an issue in the Lismore site, where 3 percent of trees were forked.

Results

All trial results are given either as plot data obtained from micro measurements in the plots, or as trial data obtained when the whole rows was measured.

Table 1. Plantation Data

Plantation Information	Lismore site		Yarrawonga site
	Pre Harvest	Post Harvest	Pre Harvest	Post Harvest
Species	Eucalyptus cladocalyx		Eucalyptus camaldulensis
Age (years)	6		10
Row spacing (m)	4		4
Inter-row spacing (m)	2.5		3
Mean diameter (DBH) over bark (cm)	10.1	9.9	14.1	15.8
Diameter range, over bark (cm)	5.5-13.6	6.9-12.5	3.0-22.9	9.8-22.9
Mean height (m)	6.6	6.7	8.9	9.5
Actual stocking (sph)	969	538	777	425
Basal area (m2/ha)	7.6	4.1	13.0	8.6
Diameter : basal area ratio	1.3:1	2.4:1	1.1:1	1.8:1
Total estimated volume of stems on site (m3/ha)	16.9	9.4	41.5	28.2
Estimated volume of trees removed (m3/ha)		6.5		13.3
Multiple leaders at base (%)	7	0	4	2
Multiple leaders at breast height (%)	19	0	20	12
Outstanding specimen trees (%)	3	3	1	1
Dead, missing trees or removed (%)	10	56	3	48
Actual percentage of stems harvested from standing density (%)		46		45
No. of rows in trial	19		12
Trial row length (m)	175		120 (rows 1-12) 80 (rows 14-17)
Micro-measurement Plot length (m)	25		30
Micro-measurement Plot stocking (sph)	945	525	806	438
Heartwood radius (cm)		NA		2.5 – 6.5
Sapwood radius (cm)		NA		2-3.5
Bark width (cm)		NA		1.5-3

The volume of stems harvested varied between sites due to the Lismore trees being younger and more even, as some selection had gone into the planting stock, whereas at Yarrawonga the Red Gums were older with a number of larger trees, but a lot more variability was found as seed for this plantation was collected from native forests with no genetic selection.

Whilst it might be assumed that thinning takes out smaller trees, the reality is that the spatial distribution of trees in the plantation is more important in the selection process than the diameter. This is illustrated in the results as post thinning, little difference in the diameter was found, particularly in the more uniform Sugar Gum.

According to Rowan Reid (2001), the diameter to basal-area ratio of a plantation should be greater than two in order to allow free growth of the trees. These plantations had a ratio less than this, indicating that both the plantation sites needed thinning. The Yarrawonga site should still be thinned further to allow free growth.

Table 2. Whole Tree Measurements.

Species	Whole tree Weight range (kg)	Large End Diameter (LED) (cm)	% wt of tree as Stem (%)	Weight of a 16 cm LED tree (kg)
Sugar Gum (6 year old)	47-109	13.5-16.4	30-52	90
Red Gum (10 year old)	45-161	16.0-24.0	63-77	65

Measurements of a sample of whole trees (Table 2) showed a wide variation in weight range, with the Red Gum at Yarrawonga having a high proportion of weight in the stem whereas the Sugar Gum at Lismore had more weight in the foliage and seed capsules.

Harvesting Component data

Micro Measurement Plots

The time taken for the various work components within each harvest system has been presented as either 'Select and Travel' time, 'Fall' time or 'Post Harvest Processors'. In a few instances, unusual times were recorded due to difficulties with equipment or trees (for examples a tree sitting on the saw). Due to the relatively small sample size within the plots, these outlier figures could affect the results markedly so these particular times have been excluded in most analyses; however bracketed figures in the following tables include these outliers. Comparison of Plot measurements with Trial measurements will reflect the appropriateness of removing these outliers from the results.

Table 3. Plot times for 'Select and Travel' time component within each harvest system

(The figures in brackets show times including difficult trees which took an unusually long select and travel time)

Site	Lismore				Yarrawonga
Harvest System	Mean (sec/ tree)	Range (sec/ tree)	st. dev (sec/ tree)	Number of trees thinned	Mean (Sec/ tree)	Range (sec/ tree)	St. dev (sec/ tree)		Number of trees thinned
Manual fall	4.8	2-7	1.7	11	5.9	4-9	1.6		9
Chemical thin	5.8	4-11	1.8	11	-	-	-		-
Manual pole production	7.1	3-12	3.3	9	7.3	5-12	2.1		8
Manual billet production	6.7	3-10	2.3	19	Y1 6.8	4-11	2.1		9
					Y212.9	3-19	4.9		10
Gripper Snipper fall	9.3 (11.6)	7-11 (7-28)	1.5 (6.8)	7 (8)	11.6	8-20	3.9		10
Gripper Snipper pole production	9.3	4-18	4.3	10	10.4 (12.9)	6-14 (6-30)	2.9 (7.4)		7 (8)

Y1 is operator number 1 at the Yarrawonga site
Y2 is operator number 2 at the Yarrawonga site

Table 4. Plot times for 'fall' tree component within each harvest system(Outlier tree times are included in brackets)

Site	Lismore				Yarrawonga
Harvest System	Mean (sec/ tree)	Range (sec/ tree)	St. dev (sec/ tree)	Number of trees thinned	Mean (Sec/ tree)	Range (sec/ tree)	St. dev (sec/ tree)	Number of trees thinned
Manual fall	11.5	4-21	5.9	11	22.0	7-34	10.1	9
Chemical thin	-	-	-	-	-	-	-	-
Manual pole production	10.7	6-21	4.3	9	14.8	6-23	5.3	8
Manual billet production	8.1	5-13	2.1	11	Y1 27.1 (51.0)	13-73 (13-159)	21.1 (52.2)	7 (9)
					Y2 21.0	10-44	9.4	10
Gripper Snipper fall	31.4	24-40	6.4	8	14.5	9-26	5.4	10
Gripper Snipper pole production	49.1	19-59	12.0	9	37.6	11-83	29.0	8

Y1 is operator number 1 at the Yarrawonga site
Y2 is operator number 2 at the Yarrawonga site.

There was a lot of variation in time to 'fall' trees within all the treatments. At the Lismore site, the Gripper Snipper took longer to fall the Sugar Gum than the 'Manual Falling', but this was not necessarily the case in the Red Gums at Yarrawonga.

The variation between the sites was mainly a results of the larger and less-balanced growth of the Red Gum trees at the Yarrawonga site needing most to be felled using a scarf and back-cut, whereas the smaller trees at Lismore were more balanced and lighter in the base so the faller generally used a straight back-cut and tended to push the trees over once they were almost cut through.

More trees were hung-up in the 'Manual Felling' process at Yarrawonga than Lismore and this was reflected in the larger range and standard deviation in the results (particularly when the outlier tree values are included).

Table 5. Plot times of 'Chemical Injection', 'Pole' and 'Billet' production harvesting system components.
(Outlier tree times are included in brackets)

Site	Lismore				Yarrawonga
Harvest System	Mean (sec/ tree)	Range (sec/ tree)	St. dev (sec/ tree)	Number of trees thinned	Mean (sec/ tree)	Range (sec/ tree)	St. dev (sec/ tree)	Number of trees thinned
Chemical thin	9.0	6-15	2.5	11	-	-	-	-
Manual pole production	23.2	11-32	5.7	9	16.0	5-29	9.5	7
Manual billet production	21.7	13-33	6.8	11	Y1 56.5 (72.9)	7-90 (7-204)	29.4 (56.3)	8 (9)
					Y2 34.9 (45.3)	8-51 (18-129)	10.1 (32.8)	8 (9)
Gripper Snipper pole production*	34.6	17-69	16.6	9	18.2	9-25	6.1	5

* Different product – poles maximum length 3 m and not pruned
Y1 is operator number 1 at the Yarrawonga site
Y2 is operator number 2 at the Yarrawonga site

Note: Both the pole and billet production trees were also delimbed but not all trees in the plot were necessarily processed, if they were too small to get a pole or billet, they were just felled. The figures shown in this table only include those trees that were processed.

There was a wide variation in the times taken for most processing task at both sites.

The 'Chemical Thinning' was the exception to this as this process was mainly affected by the amount of branches impeding access to the stem by the chemical axe operator.

Amalgamated Harvest System Plot Results.

Representative times for each component were determined by taking the average of all the treatments that included each component, including all operators but excluding outlier trees.

Table 6. Amalgamated time taken for each component within each Harvesting System in the plots, showing mean range and standard deviation. (Outlier trees removed)

Site	Lismore						Yarrawonga
	Manual			Gripper Snipper			Manual			Gripper Snipper
Harvesting Elements	Mean	Range	Std Dev	Mean	Range	Std Dev	Mean	Range	Std Dev	Mean	Range	Std Dev
Select and Travel	6.0	2-12	2.4	9.3	4-18	3.4	8.4	4-19	4.1	11.1	6-20	3.5
Chemical Injection	9.0	6-15	2.5	-	-	-	-	-	-	-	-
Whole Tree Fall	9.9	3-21	4.3	40.8	19-59	13.1	21.1	6-73	12.4	24.8	9-80	22.4
Top Tree Pole Prod'n	23.2	14-32	5.7	34.6*	17-69	16.6	16.0	5-29	9.5	18.2*	9-25*	6.1*
Billet – Manual	21.7	13-33	6.8				44.8	7-90	24.3

* Different product – poles maximum length 3 m and not pruned

Figure 1. Times of plot results for each component within the various harvesting systems (Outlier trees removed)

Operator Variation

At the Yarrawonga site, two fallers were available so a comparison was between their times for the billet production harvest system.

Table 7. Variation between different operators at the Yarrawonga site

Harvest element task time		Operator Y1	Operator Y2
Travel time		6.8	12.9
No of trees		9	10
Falling time	Including all trees	51.0	21.0
	Excluding tree hang-ups	27.1	21.0
Billeting and pruning	Including all trees	72.9	43.7
	Excluding tree hang-ups	56.5	34.9

Operator Y 1 was less experienced in falling but more experienced in tree selection and used a smaller chainsaw than Operator Y 2. Hung-up trees added substantial time to the harvest system. They could add an extra 24 seconds to fall a tree.

Trial Data

Comparisons between whole- row trial time measurements were also undertaken in the study and these proved to be generally consistent with the plot measurements.

To enable a fair comparison between the plot data and the trial data, all outlier trees from the plot data were included in the results, as the whole row measurements were not able to distinguish outlier trees.

To enable comparison between the rows, the results were normalised to a standard number of initial trees per row (35 trees per row for Lismore and 20 and 13.3 trees per row for Yarrawonga).

Table 8. Total time taken for each harvesting system from plots and whole row trial data (Numbers in square brackets represent items with outliers removed)

	Lismore		Yarrawonga
Harvest System	Plot sec/tree	Trial sec/tree	Plot sec/tree	Trial sec/tree
Manual fall	16.3	18.2	27.9	32.6
Chemical thin	14.8	16.4	-	-
Manual pole production	43.2 [41.0]	40.7	38.1	50.0
Manual billet production	38.7 [36.5]	36.1	101.2 [Y1- 90.4 & Y2- 68.8]	97.3 Y1-117.4 & Y2- 76.4
Gripper Snipper fall	43.0 [40.7]	42.2	26.1	30.0
Gripper Snipper pole production	93.0	88.0	68.7 [66.2]	61.9

Figure 2. Harvest system comparison in timing at both sites (including all trees)

Note:
1. For items with *, the plot times have had outliers removed whereas the corresponding trial time includes those outliers.
2. Fallers Y1 and Y2 at the Yarrawonga site have been included in this graph to illustrate the type of variation that can occur in the same trees with different operators.

Processing Systems

The results of using various combinations of processing systems are given below as a graph format for ease of comparison, and in detail for use if the results are used to analyse the cost effectiveness of each system.

Figure 3. Processing system comparison at both sites

Table 9. Trial results of time and volume of chip produced from various processing treatments (plot results given in brackets.)

Process	Species	Time Hours: mins/ hectare	Time seconds/ tree	Volume of chip m3/ha	Volume of chip m3/tree	Chip density (oven-dried) kg/m3
Chip whole trees – mechanically handled skid steer	River Red Gum	5:49 (6:48)	52.4 (61.2)	61.9	0.155	209
Chip whole trees – mechanically handled grapple arm	Sugar Gum	5:12 (4:40)	37.4 (33.6)	100.4	0.201	194
Chip whole trees – as billets and heads – manually loaded	Sugar Gum	7:50 (7:48)	56.4 (56.2)	86.6	0.173	194
Chip billets – manual load- Lismore	Sugar Gum	3:17 (3:59)	23.6 (28.7)	31.9	0.064	267
Chip billets – manual load Yarrawonga	River Red Gum	2:52 (3:28)	25.8 (31.2)	35.2	0.088	257
Chip crown – Manually loaded	Sugar Gum	13:58 (8:08)	100.6 (58.6)	80.7	0.161	164
Chip poles from Gripper Snipper- manually loaded	Sugar Gum	3:13 (3:09)	23.2 (22.7)	15.0	0.030	267
Bulk poles from Gripper Snipper into piles– mechanical skid steer	River Red Gum	3:28	31.2	(Poles)
Load poles onto trailer – skid steer	River Red Gum	5:33	50.0	(Poles)

Note: Times have been normalised to 500 trees/ha for Sugar gums at the Lismore site and 400 trees/ha for Red gums at the Yarrawonga site.

The number of people varied between the different systems. Using the skid steer, there was a chipper driver, a skid steer driver and a person to direct the logs into the chipper.

The grapple arm needed one to drive the chipper and grapple arm and another in the plantation ensure the logs were accessible by the grapple arm.

In the manual handling of billets, the Yarrawonga site collected four rows at once using two people collecting and a driver. The Lismore site used one man to feed and a driver but did only two rows at a time collecting from rows without heads in the way as these had already been collected.

The chipper at Yarrawonga produced much smaller sized chips than the Lismore site chipper. This did not seem to affect the chip density as the billets chips from both sites were of similar density. The inclusion of leaves in the chip produces from whole tree processing had a much greater affect on reducing chip density and increasing chip volume. The chip to stem volume was calculated to be 2.6:1 at Yarrawonga and 4.9:1 for Lismore.

The Gripper Snipper pole collection took a similar time to the billets but produced less volume of chips as often the poles were shorter than the manually harvested poles. Poles were placed easily within the row by the Gripper Snipper harvesting, but billets were collected from rows without crowns so they were also easy to collect.

At the Yarrawonga site, the collection of Gripper Snipper poles into piles by the skid steer was undertaken by picking one pole up and taking it to the next pole, dropping it and picking up both poles and so on until the bundle was too large or difficult to carry further. This process was repeated from the other direction until a large pile was produced.

Although not replicated, this could be compared to the process of picking each pole up with the skid steer at Yarrawonga and loading onto a trailer. This took nearly as long again, but did have the advantage of improved transport of logs out of the plantation.

Chipper and trucks were moved 10 – 15 metres once the two rows either side of the travelling row were clear. The manual feeder operators carried products up to 15 m to the chipper after stepping over remaining trees and tops on the ground. Time was also spent breaking off branches when cleaning of billets by the chainsaw operator was incomplete. This extra time also meant that the chipper was only actually working less that half the time when being fed manually with foliage.

Bark and Wood Measurements

The opportunity was taken to measure the width of bark, sapwood and heartwood of the Red Gums at Yarrawonga. The bark ranged from 1.5 – 2.5 cm in width, increasing with the larger trees, the sapwood ranged from 2 – 3.5 cm wide, again increasing with increasing tree diameter and the heartwood ranged from 2 to 6.5 cm in radius. The results are in Appendix 2.

Discussion

This trial has provided evidence to improve the ability of plantation growers to differentiate the time requirements for each task in thinning operation. The results provide some basic information for calculating the labour time requirements and therefore costs for various plantation thinning operations.

Overall the similarity of results from both the plot and trial results gives confidence in the figures produced.

The manual harvesting system trial-row results tended to take slightly longer than the plot- row results, and the Gripper Snipper trial row timings were generally slightly quicker than the plots. Fatigue and experience could play a role in this, with the tractor machine harvesting being less tiring and quicker with experience than manual chain-sawing. Trialling over a whole day would be expected to accentuate this difference.

Selection and Travel Time

Selection and travel times are a minor component of the harvest operation, irrespective of whether a tractor or manual chainsaw is used.

Manual falling took less time to 'Select and Travel' to each tree than the Gripper Snipper, although differences in time were observed between the two sites, these were not significant. Any processing following falling by manual-fallers increased the time taken to select and travel to the next tree.

Manual falling only entailed harvesting whole trees into the adjacent row and walking up a clear row, whereas those trees which required further processing took longer to 'Select and Travel' and 'Fall' for the pole and billet production at both sites due to the extra time taken to step over the poles, billets and crown. This walking over trash resulting from further processing would also be more tiring that walking up a clear row with potential to trip over while holding a chainsaw, increasing the safety risks.

The greater variability in 'Select and Travel' time for Manual Pole and Billet production would be due to the differences in the amount of branching and shape of the fallen tree. Whether billets and branches were cut from the stump end of the log first or from the top of the log first, affected the amount of foliage that was stepped over and therefore the time to travel between trees.

Between-site differences in time taken to 'Select and Travel' to the next tree may be partly attributed to the difference in stocking rate of the sites. Different operators between the sites could account also for some variation, as the Chemical Thin 'Select and Travel' at Lismore was a different operator to the manual faller and did take slightly longer than the Manual Fall operator. This longer time to 'Select and Travel' for the Chemical Thin operation could also be due to the need to part branches higher up the stem to get clear access to it for the axe.

An operator unused to selecting trees will take longer, as evidenced by Operator 2 (Y2) at Yarrawonga, but this would soon be improved with experience and training.

When using a tractor for thinning, the foliage can restrict the ease of view of the stem for appraisal, with more time needed to ensure a good view for the selection process.

Chemical Thinning

Chemical thinning in this trial was the quickest and easiest form of thinning to waste, where no product is required. Results of further studies are needed to ensure rates of chemical effectively kill the selected trees without causing flashback of adjoining trees. There was less trash on the ground, reducing the safety risk from tripping, but the need for the operator to get close to the stem does introduce the risk of eye injury from branches. Protective glasses are necessary for this type of thinning. There would also be an increased risk from falling dead limbs and trees in the future, especially if chemical thinning is used to kill larger trees.

Chemical thinning could be considered as a prior step to any other harvesting system. The condition of the killed trees may positively or negatively affect time and motion aspects such as chain-sawing rates and visibility, but also has the advantage in the case of firewood of being instantly ready for market.

Chemical thinning may also be required as a follow up to the chosen harvesting system where coppice regrowth warrants treatment but rates would differ greatly from those measured here.

Tree Felling

The time taken to chainsaw fell a tree was generally twice as long as it took to select and walk to each tree, if no scarf-cut was needed in the falling process. Chainsaw felling the Sugar Gums at Lismore did not require a scarf-cut as the trees were able to be manually pushed over once nearly cut through. To ensure control of a falling tree, particularly larger ones, a scarf-cut is required. When this method of falling is used, as in the Yarrawonga site, the falling time can increase to three times the select and travel time, making this process around 30 seconds per tree.

The time taken for the tractor mounted Gripper Snipper to fell a tree is dependant on the speed of closing of the shears, which is more related to the hydraulic pump capacity of the tractor than the diameter or density of the tree. The tractor at Yarrawonga was able to close the shear blades quicker than the Lismore tractor, and thus time to fall the trees with the Gripper Snipper at Yarrawonga was quicker than at Lismore.

With visibility of each stem easier at Yarrawonga, the time taken for the Gripper Snipper to select and fall was comparable to the manual chainsaw falling at Lismore and quicker than the manual falling at Yarrawonga when a scarf- cut was used.

Occasionally at the Lismore site a stem got jammed in the Gripper Snipper blades due to foliage and this added to the time taken for machine harvesting there.

Pole and billet production

Once further processing of the felled tree is required, times for the harvest system can be at least doubled again. Removing the top and side branches of the tree to produce a pole can add a further 20 seconds per tree onto the job, with the extent of delimbing needed on the log only altering this by a few seconds.

Pole production by the Gripper Snipper doubled the time to thin each tree compared with only falling the tree with the machine. Much of this time was in waiting for the hydraulics to lower the machine on the front-end-loader arms from the top of the stem after it had cut the crown off to the bottom. As the arms are lowered in an arc, the blades have to be slid sideways in and out for both the top and bottom cut, so the speed of the hydraulic system had a major influence on timing. This hydraulic action took more time that actually moving the tractor from tree to tree. Further the length of poles is limited to the lift height of the front-end-loader.

Billeting of logs into 1.2 m lengths was only undertaken by the manual system, although the Gripper Snipper was able to do this if branches were small enough to be knocked off with the blade and if an automatic tractor was able to drive back and forth as the front-end-loader arms were lowered in an arc, cutting the billets on the way down the stem.

Manual cross cutting logs into billets of generally 2-3 per log in the young Sugar Gum plantation took around 22 seconds per tree, which was a similar time to pole production. The Sugar Gum stems were generally fairly even, whereas the Red Gums at Yarrawonga took a lot longer to process into billets as the shape of the trees was more variable and larger branches required removing. The actual number of billets from the different sites could not account for all of this variation, as 1025 per hectare were cut from the Lismore rows and 1500 per hectare from the Yarrawonga rows.

Processing systems

The time taken to process the fallen logs in various ways for chip, billet or pole production, varied substantially if heads were manually handled.

Where chipping whole trees is needed, manual loading of an in field chipper took over two hours longer than using a machine. This manual loading took between 30 and 60 seconds per tree. This was due to picking up numerous branch pieces as well as having to walk over a lot of fallen trees.

The manual loading of crowns was not included in the Yarrawonga site, but at the Lismore site, when this was included, the time taken for whole tree loading into the chipper was more that doubled, both when done as part of the whole tree process or as a process on its own after the billets were removed from the row. Manhandling of whole trees took over two hours longer per hectare than using the grapple arm at Lismore.

There was a difference in the volume of chip from these two treatments with the grapple producing higher volumes, even though the manual handlers tended take more time picking up bundles of smaller sticks and leaves to include the whole tree. The large percentage of foliage and seed pods in relation to stem weight on the Sugar Gums (50 - 80 percent of the weight of the tree) meant that a large volume of chips were produced (more than double the volume of the log chips per tree). The density of this foliage-only chip was a lot lower that the stem chip, but the unit of sale used for the chip product, whether it is determined by a volume or weight basis, will influence whether foliage is included in the chipped product. Nutrient recycling within the plantation from retaining the crown foliage should also be carefully considered with respect to sustainable growth, before taking the foliage off- site.

Chipping machine hire rates are generally based on the whole system (per hour). The chipping system may include three people (one to drive the chipper and two to load manually load, or one to drive the chipper, one to drive the skid steer and one to operate the chipper), or two people (one to drive the chipper and grapple arm and one in the plantation to ensure access of logs by the grapple arm). The results obtained in this trial will give a guide to the time difference needed to assist in deciding which system is best suited to each plantation.

One aspect not measured in the trial was the fatigue factor - particularly in the manual loading. Continually picking up wood from the ground was found to be a fatiguing process and by the end of the third set of rows, workers were significantly slower in all movement.

Comments from a contractor operating a manual feed chipper system included;

• Picking up heads was very labour intensive and he and his workers wouldn't be interested in the work.
• Picking up heavy billets was tiring and some were at the limit of what the chipper could handle so a manual feed bar was required, and some large branches were still attached to the billets and needed removing, slowing the operation.
• Safety issues that could lead to accidents included walking over branches, tripping, repetitive work, boredom, fatigue, heavy manual labour, heat stress, insect and snake bites and vehicle accidents from backing down the rows with the chipper and truck.
• The fact that the trial was undertaken on a cool day could not be underestimated as productivity would be much decreased on a hot day.

The grapple-arm chipper at Lismore was able to load and process four rows of whole trees in one pass, although some manhandling of the Sugar Gums was needed to present the trees in an accessible way for the grapple to access. Trees needed to be felled so that they lay in correct orientation for the grapple to pick up the butt of tree rather than head. Working across two rows, layout of the fallen trees was hardly an issue, but across four rows it became more of a problem, with more trees needing to be dragged into correct position. Using a longer grapple arm may obviate the need for this extra person when working across four rows, but the issue of damage to retained trees could become significant. A longer arm was not trailed in this study.

The skid steer at Yarrawonga was only able to pick up two rows of trees and feed them into a chipper during each pass as it had difficulty crossing over the mounds along the rows and trees were carried across the front of the grab, making them too wide to fit between the retained trees. The Skid Steer harvesting two rows took almost twice as long per tree as the grapple arm harvesting four rows.

If a grapple-arm chipper loader had been used in the River Red Gums at Yarrawonga, harvesting four rows at once would have been difficult as their size would have made manhandling to align them for machine access almost impossible. If the grapple arm had proceeded along only two rows at once, this manhandling in the Sugar Gums would have been eliminated but the grapple arm operating times would have been increased to some extent.

The 9 inch throat manual-feed chipping machines were powerful enough to process only the smaller diameter butts without having one man remain at the control bar which was used to stop the feed and even to reverse feed. Once the first metre of butt was through that operator would go and collect more feed.

The only sign of any damage to standing trees during processing came from the chipper truck scraping on an occasional stem. This is despite the truck and chipper being both the full 2.4 metres wide.

The need to precisely place the trees in to the chipper took extra time with the Skid Steer and this was reflected in the skid steer loading poles onto a trailer, which took about the same time; almost 50 seconds per tree.

Amalgamating the Red Gum poles with the skid steer was only marginally slower than that manually loading billets or poles into a chipper. As the majority of costs relating to harvest are determined by the number of pieces and the returns are determined usually by the size of the pieces, it is useful to be able to identify the cheapest harvest option and then relate this to the predicted returns

Example of thinning operations using the results from this trial

Below are two worked examples using the figures produced by this trial with the aim to determine the most cost effective way of chipping thinnings on site.

Costs used in this example

Chipper $120/hr including two people
Skid Steer $20/hr extra
Grapple arm $20/hr extra
Manual labour $80/hr
Gripper Snipper $75/hr

Example 1. Thinning 6-year-old Sugar Gum plantation

Thin from 900 to 500 = 400 sph thinned (Using Lismore trial data where possible)

	Cost ($ /hr)	Time for task per tree (sec)	Time for task per ha (hrs)	Cost / ha ($/ha)	System cost ($/ha)
Manual fall	80	18.2	2	160
Chemical thin	80	16.4	1.8	144
Gripper Snipper fall	75	42.2	4.6	351
Manual pole production- poles left in plantation	80	40.7	4.5	360
Gripper Snipper pole production	75	88	9.7	727
Manual fall & billet	80	36.1	4	320
Chip whole trees with grapple arm + hand fallen OR +Gripper Snipper fall	80 + 140	37.4	4.1	902	902+ 160 = $ 1062 902+351 = $ 1253
*Chip whole trees mechanically handled -skid steer + Hand fall OR + Gripper Snipper Fall	140	52.4	5.8	812	812+160 = $ 972 812+ 351 = $ 1163
Chip manual load of billets + manual fall & billet OR + Gripper Snipper pole	80 + 120 ( with 2 people)	23.6	2.6	520	520+320 = $ 840 520+727 = $ 1240

*figures from Yarrawonga site used.

For pole production in this plantation, where poles can be manually loaded it may be cheaper to harvest using manual labour at $360 /ha, but for chipping whole trees, hand fall and skid steer fed chipper is the least cost of $972 /ha. Where billets only are used for chip, manual billeting and loading is marginally cheaper, but the ability to work continuously on loading billets manually needs to be considered. If the system is to be mechanised using the Gripper Snipper to fall the trees, costs would increase to $1163 /ha. If trees were more accessible, as in the River Red Gum trial, the cost of using the Gripper Snipper to fall the trees would be lowered to $166 /hr, and the cost of a chipping system using the skid steer to load would be $978 /ha, $138 more than the $840 using all manual labour for falling and loading.

To determine returns, the volume of tree products can be calculated prior to harvest by measuring the trees. The Sugar Gum in this trial produced approximately 90 m³/ha from chipping whole trees, so if these chips are valued at $35 /m³, this would give sales of $3150 /ha. With the costs calculated above, a mechanised system would still be viable with this price of chips. If only poles were harvested, a greatly reduced chip volume would result, 15-31 m³/ha, at $35 /m³ = $525 - $1085 /ha. In this case the final returns from manual loading of poles would be viable, whereas machine loading would barely be cost neutral.

Example 2. Thinning 10-year-old Red Gum Plantation

Thin from 800 to 450 = 350 sph thinned (Using Yarrawonga data where possible)

	Cost ($ / hr)	Time for task per tree (sec)	Time for task per ha (hrs)	Cost ($/ha)	System cost ($/ha)
Manual fall	80	32.6	3.2	256
Chemical thin	80	16.4	1.8	144
Gripper snipper fall	75	26.1	2.5	187
Manual pole production- Poles left in plantation	80	38.1	3.7	296
Gripper Snipper pole production	75	66.2	6.4	480
Manual fall & billet	80	68.8	6.6	528
*Chip whole trees with grapple arm + hand fallen OR +Gripper Snipper Fall	80+140	37.4	3.6	798	798+ 256 = $ 1054 798+187 = $ 985
Chip whole trees mechanically handled -skid steer + Hand fall OR + Gripper Snipper Fall	140	52.4	5.1	711	711+ 256 = $ 967 711 + 187 = $ 898
Chip manual load of billets + manual fall + manual billet	80 + 120 ( with 2 people)	25.8	2.5	500	500 500+ 528 = $ 1028
Bulk Pole from Gripper Snipper into piles with skid steer+ falling	140	31.2	3	420	420 420+187 = $ 607

* Figures from Sugar Gum Lismore site used as none available from River Red Gum.

The River Red Gum plantation poles were larger and older so the potential for manual handling is reduced; they were also more difficult to fall, requiring a scarf-cut and with more hang-ups. These costs show that the cheapest option is to use a Gripper Snipper to fall the trees and a skid steer to load them. The grapple arm harvesting four rows in this plantation would need to omit the use of manual labour to align the trees as they were too heavy, so either more care would be needed in placement of every tree when fallen so it is accessible to the grapple arm or only collect from two rows at a time- this timing was not available in this trial.

Chip volumes from the River Red Gum whole trees were 61 m³/ha, at $35 /m³ = $2135, giving a final return of $2135 - $898 = $1237. Volume of chips from poles was 35m³ giving a return of only $222 /ha after harvest costs.

Conclusion

This trial shows that alternative harvesting methods to manual chainsaw harvesting and processing can be comparable in time and efficiency. The figures allow the relative cost of each system per hectare to be developed once cost per hour of the equipment and labour are known. It also raises the issue of fatigue and safety, with the ability of manual labour to keep up a continued high work rate being limited. The risk of accidents also increases with fatigue. The ability to find people willing to undertake hard physical work for days on end in Australia for a long term job is also very limited.

This trial demonstrates that on smaller trees (less than 10 cm DBH) manual falling is more efficient in terms of cost and processing rate. As tree diameter increases (e.g. 14 cm DBH), the Gripper Snipper becomes comparatively time and cost efficient and safer with less fatigue and safety issues. Where whole tree harvest and chipping is required, manual handling is not a reasonable option. The use of a grapple-feed chipper is ideal, whilst use of a skid steer could be comparable depending on the cost per hour of the different machines and the layout and accessibility of the fallen trees.

References

Lambert, Jon. 2003, Investigation of economically viable systems that have been specifically developed for the harvest of small plantation resources. Churchill Fellowship report.

Volker, P. 2008 Management of hardwood sawlog species. Conference proceedings Plantation eucalypts for high value timber, Moorabbin, Melbourne.

Poynter, M., Borschman, R. (2002) An investigation of the commercial viability of producing plantation grown eucalypt firewood in the Mount Lofty Ranges, SA.

Bulman, P. 2006 Viable small scale firewood harvesting systems, Mt Lofty ranges Private Forestry.

Sonogan, B. January 2006, Small-scale Mechanical Harvesting Project report. DPI. Benalla.

Sonogan, B. June 2006 Manual Harvesting Project – Report for the Box Ironbark Project DPI. Benalla.

Reid, R., (2006) Diameter–basal area ratio as a practical stand density measure for pruned plantations. Forest Ecology and Management 233 pp 375-382.

Washusen, R., (2002) Silvicultural effects on tension wood occurrence in Eucalyptus globulus CSIRO Client Report 1075.

Appendix 1. Comments on grapple arm chipper

Other comments regarding the Grapple arm chipper by Andrew Lang and Sue Harris.

• Often up to 6 - 8 trees were taken in at one point with three being manually fed or positioned. Occasionally accessing a tree within reach of the grapple required carefully extracting it from between two adjacent standing trees without damaging them.
• This system used one man in the cab at all times, moving forward in small moves of about 5m on signal to start and stop from man on ground. Stop point had to allow swing out grapple control panel to fully open so man on control could see as far as possible round to other side of chipper, and also to allow best possible access of grapple to stems and butts on both sides. Trees were normally fed in butt first, though it was possible to feed in head first. Often one tree was being inserted while the first had only just started. The capacity of this machine was more than enough for this size of tree, even if two at once. Occasionally two trees would be picked up head to toe and fed in from one end. Mostly with one tree the grapple would bring it in and rest the butt on the feed throat apron, take a second grip a metre along from the first grip and feed it in.
• The work rate was relatively high both because the chipper fed faster and the trees were whole, and because of dealing with four rows simultaneously. This meant that the inefficient part of the process (closing the control screen, moving the truck and re- opening the screen) took relatively less time overall.
• The grapple was clearly able to dig up dirt when it picked up a tree. However there was no sign of any going into the chipper. This is apparently less of an issue with drum chippers, though the blades were obviously quite chipped at the start of work, with most of this being taken off with a hand sharpener before commencing.
• The chipper blades are reversible and last up to 50 hours of use before they need turning around. With dirty wood the blades may need to be reversed in as little as 20 hours. This process is quite fast but the catch is that any blade can only be sharpened up to five times before replacement. Cost of sharpening is relatively low, but new blades may cost up to $500, so the cost of chipper blades can be $1-2 per working hour.

One serious issue with a drum chipper is that for best quality chip the position of the anvil along the bottom of the chipper drum has to be set at optimum point. This anvil to blade clearance issue was pointed out toward the end of the trial, and resulted in the chip sample having too much unchipped stick. The ideal is for a chipper to be running a number of sets of blades that are all wearing equally, so that the anvil can be adjusted to suit, and give the best job over time. Apparently the anvil also wears on its leading edge and becomes rounded giving a gradually less well-cut chip.

Appendix 2. Billet size class

Graph illustrating the number of billets in each size class for the two trial sites

Appendix 3. Width of bark, sapwood and heartwood

Relationship of width of bark, sapwood and heartwood to stump diameter of Red gums at the Yarrawonga site.

Appendix 4. Billet aggregation time feasibility study

Rhodey Bowman, DPI Tatura

Purpose: to determine the time required to aggregate timber billets into small piles in a plantation.

Assumptions:

• Dry billets of 1-3 metres in length and 10-20 cm mid-diameter (5-30 kg)
• Use of billet grab
• Walk and drag billets up to 10m

The task can be broken up into 3 components, thus;

• walking to billet
• dragging billet to aggregation point
• picking up and dropping billet (with dragging in between)

Task	Time issues	Motion issues	Time range	Comments
walking to billet	distance, terrain	tripping, slipping	0.75-1.5m/sec depending on harvesting slash
drag billet to aggregation point	distance, terrain, weight, entanglement	weight, entanglement, tripping, slipping	0.5-1.0m/sec depending on harvesting slash and billet weight (5-30kg)	weight made no difference til over 20 kg, entanglement could add lots
pick-up and put-down billet	bark, billet congestion, drop and re-grab	weight, entanglement, bending	4-6sec/billet depending on billet congestion at pick-up	entanglement adds to weight, bark main cause of billet drop
all tasks (5m walk & drag, 15kg billet)	as above	as above	~(4+6.5+4.5)= 15sec/billet	light-med slash

The following example based on 1ha and sensitivity analysis shows the likely variation and uses the following base assumptions:

• 4 x 2.5 m planting layout
• thinned trees fallen into every second row
• aggregate 1000 2.5 m billets
• aggregate into piles every 2^nd or 4^th row
• billets weigh 10-15 kg (e.g. dry 10-12.5 cm mid-diameter)
• moderate ground slash (obviously heavier & lighter in alternate rows)

Time taken per ha (billets per pile)	Number of billets per hectare
	500 (½ x yield)	1000	1500 (1½ x yield)	2000 (½ billet length)	3000 (½ length & 1½ x yield)
Time per billet	12 seconds (light slash & 4.8m drag)	1.7 hrs (5)	3.3 hrs (10)	5.0 hrs (15)	6.7 hrs (20)	10.0 hrs (30)
	16 seconds (moderate slash & 4.8m drag)	2.2 hrs (5)	4.4 hrs (10)	6.7 hrs (15)	8.9 hrs (20)	13.3 hrs (30)
	22 seconds (heavy slash & 4.8m drag)	3.1 hrs (5)	6.1 hrs (10)	9.2 hrs (15)	12.2 hrs (20)	18.3 hrs (30)
	14 seconds (light slash & 6.0m drag)	1.9 hrs (10)	3.9 hrs (20)	5.8 hrs (30)	7.8 hrs (40)	11.7 hrs (60)
	19 seconds (moderate slash & 6.0m drag)	2.6 hrs (10)	5.3 hrs (20)	7.9 hrs (30)	10.6 hrs (40)	15.8 hrs (60)
	26 seconds (heavy slash & 6.0m drag)	3.6 hrs (10)	7.2 hrs (20)	10.8 hrs (30)	14.4 hrs (40)	21.7 hrs (60)

Comments

• Whilst the further you walk and drag billets the longer it takes, this must be weighed up against the time taken to extract the piles. That is, the further you drag billets the fewer piles there are and perhaps the fewer rows you will need to travel down (e.g. every 4^th row instead of every 2^nd). There will be practical minimum and maximum limits to the number of billets in a pile.
• A long billet generally doesn't take any longer to drag than a short billet and so it is much more efficient to work with longer lengths. The limit on this for length is that which you can reasonably move between trees and between rows. From a weight perspective it is that which you can reasonably drag throughout a day's work which will vary with a person's strength but likely in the order of 15-20kg. If the billets are short and fairly light, two billets could be dragged at a time but unless they are picked up next to each other this will still be less efficient than a longer length.
• Under current first thinning recommendations, the maximum billet mid-diameter should be around 15cm. If we are talking 2.4m lengths then this will weigh in the order of 40kg, too high for manual work. With air-drying this will reduce to 20-30kg, and given these are the largest billets, quite within limitations for manual work. And so allowing drying is preferable unless this is not suitable for the targeted thinning product.
• With second thinnings or final harvest for firewood, the increased diameter may require shorter billets to keep the weight down, and may take longer to aggregate with more billets involved.