Previous PageTable of ContentsNext Page


1. Introduction

A portable sawmill, called the Wokabout Somil in Melanesian pidgin and the mobile sawmill or the Wokabout Sawmill in this report was developed and manufactured in Papua New Guinea. The introduction of the sawmill in 1983 was a result of a joint-venture project of the South Pacific Appropriate Technology Foundation and a Papua New Guinean national engineering company.

To date about 400 mobile sawmills have been produced and put into operation in PNG, Solomon Islands, Vanuatu, Cook Islands and Niue.

The basic idea behind increasing sawmill capacity was to give rural communities the possibility of producing their own lumber for housing purposes. The mobile sawmill converts logs into lumber at sites where there are no hauling or yarding machines available or where the site is inaccessible because of the lack of roads. To meet requirements the sawmill is made light and portable, with simple technology and maintenance needs.

The sawmills are bought by rural clans which seldom have previous experience in sawmilling or logging. Although the delivery of the sawmill includes a compulsory three week training for the users of the sawmill, the level of skills to take care of logging and sawing is very low. This, added to the great number of sawmills, has raised questions about the effects that sawmilling might have on forests in PNG, and whether there exist needs and possibilities for directing the activities toward more rational use of raw material.

The common way in which the sawmill is used is to take it to a site in a forest near a road and clearcut an area surrounding the sawmill. The radius of the clearcut area is normally about 50 metres, depending on the ability of the crew to roll logs at the sawing site. This way of doing clearcuts can cause problems if reforestation of the clearcut is neglected. Clearcut areas are normally situated in places where there are good quality logs available. Anyhow, the Wokabout Sawmill does not have technical properties to produce sawn timber of highest quality and therefore the raw material for the sawmill should be of rather low quality; high quality logs should be channelled to sawmills that have a higher quality of end product.

Little information has been collected about the use of the mobile sawmill in PNG. The information on productivity, need for manpower and the quality of lumber, as well as the level of skills among sawmillers are based mainly on opinions instead of proper studies. The Forest Harvesting and Transport Branch of FAO therefore carried out this study to evaluate the role of the mobile sawmill in forestry and to outline the needs and ways to improve usage of them. The main objective was to determine ways to reduce waste from logging and to increase the utilisation of reject logs from commercial logging operations by using mobile sawmills. The increased participation of rural communities in harvesting and wood processing was also examined.

2. Location of the case study

The study took place in May 1990 in Papua New Guinea. Field studies were carried out in the Kui logging area in Morobe province, about 120 km southeast of Lae.

The arrangements for the study were made together with the UNDP/FAO project PNG/86/009 and the Forest Research Institute in Lae. The Provincial Forestry Department in Morobe provided the Wokabout Sawmill and the work crew for the study. The Philippine logging company Timber Producers and Marketing Corporation (TPMC) provided the timber for sawing, as well as accommodation and living facilities during the field study.

3. Study methodology and data collected

The sawing at the Kui logging operation was studied as a case example and complementary information was obtained by interviewing people and collecting inventory data concerning other logging operations.

The time study consisted of sawing 11 reject logs chosen at random from a log pile in the export harbour of the logging area. The measurements and defects of the logs were registered and are shown in Appendix 1. The preparation and sawing time of every log were recorded to an accuracy of 0.1 second. The sawing process was divided into four work phases: adjusting the vertical and horizontal positions of the sawing carrier, sawing the length of a log, returning the carrier, and adjusting the vertical position.

The number and length of timber pieces sawn were recorded and are shown in Appendix II. The dimensions of the timber were measured from sample timber.

The level of skill and productivity among sawmillers varies considerably. Therefore to obtain a reliable overall picture of an operation one has to collect a large amount of data. In this case that was not possible because of the limited manpower and time. The results of this case study thus give just one example of a sawmill operation; other sawmills operating in PNG might deviate significantly from the figures given in this study. The sawmilling team studied was a very skilled one. Therefore the productivity and working habits of the group is supposed to be among the best with this equipment. The team had been trained by the Provincial Forestry Department, where a Philippine sawmilling specialist, Mr. Art Padua, did the training.

For the above reasons the figures given about production represent the maximum estimated capacity of the Wokabout Sawmill rather than the average production by sawmillers.

4. Description of the sawmill studied

The portable sawmill was developed and is being manufactured in Papua New Guinea. It is made under the Wokabout Somil Programme of the South Pacific Appropriate Technology Foundation (SPATF) in cooperation with a PNG National Engineering Company, the Wokabout Workshop.

The portable sawmill is a small scale sawmill designed for village use. It is used at the logging site to manufacture sawn timber straight from the felled logs. The machine itself consists of separate parts that can be hand carried to the site without any transportation equipment.

The sawmill produces dimensioned timber. The maximum dimensions of the timber are 250 x 100 mm in section. The maximum length of the logs to be sawn is 6.5 m.

The sawmill consists of an 8 m long track, an engine and circular saw unit mounted on a carrier, a hand winch to operate the saw and an 8 m x 4 m frame made out of steel tube. The frame provides a stand for the track on which the carrier is driven with the winch. The layout of the sawmill is seen in Photo 1.

Photo 1. The layout of the Wokabout Sawmill in operation.

Photo 2. The engine unit and track of the Wokabout Somil

Photo 3. The blades are mounted at an angle of 90 degrees to one another.

Photo 4. The sawing unit is driven by a hand winch.

Photo 5. The height of the sawing unit is adjusted manually with the help of wooden measure ticks.

The engine of the sawmill is an 18 horsepower Briggs & Stratton four stroke petrol engine. Its fuel consumption is about 20 litres in an 8 hour shift and oil consumption is about 4 litres per week. The engine uses regular gasoline. In normal sawmilling use the engine runs at 1800 revolutions/min.

The sawmill has two circular saws mounted at 90 degrees to one another. The diameter of the vertical saw is 32 inches and that of the horizontal saw is 12 inches. The circular saws have 6 removable teeth each. A tooth is tightened in the blade with a shank. The blades are belt driven with a normal working speed of about 600 r/min.

The frame supporting the track is made of steel tube with diameter of 10 cm. The frame is used also for gauging the saw.

For transportation the sawmill can be dismantled into smaller parts. The total weight of the sawmill is 500 kg consisting of 100 kg for the frame, 200 kg for the track and 200 kg for the engine and circular saws mounted on the carrier.

Photo 6. The engine unit being transported by four workers.

5. Logging in PNG

5.1. Logging operations in PNG

The total land area of PNG is 46 million ha. The area of closed forest is 36 million ha, of which 15 million ha are regarded as operable forest.

The Papua New Guinea forest resource is evenly distributed throughout the country. Approximately half the forest cover is formed by lowland rainforest less than 1000 m in altitude.

Commercial logging operations started in PNG in the 1950s. The annual cuttings have been growing year by year so that by the late 1980s the yearly production was about 5 million m3 from an area of 80 000 ha.

The forest are owned by rural clans. Each clan is allowed to use its own forests and sell wood locally. Sales outside the local market and for export are controlled by Timber Licences that are controlled by the Government Forest Department. In some cases the government has purchased Timber Rights from landowners and for these areas it can grant Timber Licences to timber companies. Timber Rights are valid for up to 40 years, while Timber Licences are normally valid for 10 years.

Every timber company having a Timber Licence has to prepare a working plan for each 5 year cycle. This plan has to contain an overall schedule of activities concerning the working area. Companies are also asked to prepare a one year plan for details of logging operations such as movements of machines and felling of trees. However, most of companies are not preparing these plans properly. They are mostly based on map data without an on-site survey and therefore they often do not match the reality.

The government has acquired 6 million ha under Timber Rights. So far, about 2 million ha of this area has been logged and about 4 million ha are still to be logged. The remaining sawlog volume on this unlogged area is about 125 million m3.

In 1990 a total area of 4.4 million ha containing a total volume of about 32 million m3 of wood was under Timber Permits. The annual maximum cut was 3.7 million m3 and the maximum annual export volume was 3.5 million m3.

5.2. Selective logging method

The selective logging method has been introduced in the tropical rainforests partly because of the sensitivity of such forests to clearcutting and partly because of the need to harvest only the logs that are big enough in size to make processing them profitable.

This means that a logger is allowed to take out from the forest only permitted species and stems having a breast height diameter (BHD) greater than a specified limit.

In PNG the minimum BHD is 50 cm. Companies exporting logs normally use a minimum BHD of 60 cm.

The selective logging method is meant to give a sustainable yield of wood out from the forest. By taking out only mature trees, leaving behind younger generations, the future growth of the forest will be assured. In well planned and managed operations this goal can be achieved.

Depending on the logging operation, selective logging leaves behind various amounts of secondary class logs and defective trees which are under the minimum BHD size. These trees might have some value if taken out of the forest at the same time when they are found to be defective. If they are left in the forest to wait for a next logging operation their value will most likely be lost.

5.3. Raw material content of logging site after logging

Logging operations are very seldom done so that the maximum number of trees fulfilling the minimum BHD demand are logged. Therefore there are mature trees in the forest that can still be used as raw material without contravening forest management or threatening sustainability of the forest.

The evaluation of the raw material content of the logging site after an operation needs a detailed inventory on the site. The limited time for this case study did not allow that kind of examination.

In the Forest Working Plans of PNG there is a requirement to make a post-harvesting inventory on 5 % of the harvested area. This information can be used to determine the average raw material content in PNG forests. For the Kui logging project these inventories have not yet been done.

Buenaflor has made detailed inventories in his study on the Vanimo logging operations in PNG. He studied two logging sites in West Sepik in northwestern PNG. The following results were given in Working Document No. 15 FAO:DP/PNG/84/003.

Area A, containing 15.5 ha of forest, was logged in the normal manner used in PNG. That means logging without proper planning before the operation. Area B, containing 16 ha of forest, was logged with careful planning and supervision.

The distribution of trees in areas A and B before and after logging were as summarized in Table 1.

Table 1. The commercial and residual stands in areas A and B before and after logging operations at West Sepik, Papua New Guinea. Source: Working Document No. 15, FAO:DP/PNG/84/003.

Diameter class, cm







Before logging: number of trees > 20 cm BHD

Area A







Area B





















Before logging: number of trees/ha > 20 cm BHD

Area A







Area B







Before logging: number of trees > 50 cm BHD

Location of trees

50-59 cm

60+ cm


Area A

Area B

Area A

Area B

Area A

Area B

Forest road







Skid roads







Log landings





















Logs removed







After logging: trees remaining > 50 cm BHD

Total trees














The differences between logging operations in areas A and B were mainly in the number of defective trees in size classes less than 50 cm BHD.

In the Buenaflor study about 22 mature trees per hectare having BHD above 50 cm were left on site after logging. Of these about 16 were in the size classes between 50 and 60 cm BHD.

The volume table for standing trees in PNG gives the volumes shown in Table 2 for different merchantable height classes.

Table 2. Standard volume table for commercial timber species in Papua New Guinea. Source: PNG Government Forest Department.

BHD, cm

Height classes, m







Volume, m3











































From the above information it can be calculated that after logging operations more than 60 m3/ha merchantable sized mature trees are left in the forest. Of these about 45 m3/ha are in BHD classes between 50 and 59 cm.

The value of the trees damaged during a logging operation will be lost if they are not used before they become affected by tree diseases. So the damaged trees, although not fulfilling the minimum BHD, should also be used as raw material in order to obtain the maximum advantage from the operation.

Buenaflor also studied the damage to the residual trees which resulted from the felling and extraction operations. The damage study was conducted on a 10.8 hectare sample plot that was situated in logging area B. The results of the study are summarized in Table 3.

Table 3. Logging damage in a commercial operation in area A at West Sepik, Papua New Guinea. Source: Working Document No. 15, FAO:DP/PNG/84/003.


Diameter class, cm






Before logging: number of trees > 20 cm BHD

Total trees












Removed for roads and landings












After logging: number of damaged trees > 20 cm BHD

Crown broken






Stem injuries






Lost and/or destroyed






Total trees damaged






Trees/ha damaged






The total number of damaged trees in the forest after the operation was about 21 trees/ha in BHD classes from 20 cm to 50 cm. Most of the trees are in the smaller classes in that there are about 8 trees/ha in both 20 cm and 30 cm BHD classes. In the larger classes the number of damaged trees was smaller. In BHD classes above 50 cm there are not normally many damaged trees, because they are mostly logged and extracted from the forest to landings.

Based on the data in Table 3 and the estimated volumes from Table 2 it can be calculated that about 15 m3/ha in BHD classes between 20 cm and 50 cm were damaged and left in the forest at the conclusion of the logging operation.

6. Portable sawmilling operation


6.1. Productivity in relation to time

The productivity of the sawmill was examined by conducting a detailed time study. Ten sample logs were sawn and detailed times were recorded during the operation. The measurements and descriptions of the sample logs are presented in Appendix 1.

This type of time study gives information about production in relation to effective working time. However, the results cannot be used to estimate the daily or weekly production of the sawmill.

The raw material consumption of the sawmill in effective working time was studied in the time study. The dimensions of the raw material were measured crosswise at both ends of the sample logs. The volume of the log, V, was calculated from the formula V = (D1 + D2 + D3 + D4)/(8piL), where D1, D2, D3 and D4 are the crosswise diameters at the ends of the log in metres, L is the length of the log in metres, and pi is 3.14159, the ratio of a circle's circumference to its diameter.

The time required to process a log includes the setting of the log for sawing, sawing time, horizontal and vertical adjusting of the sawing unit during the sawing operation and minor servicing and repairs not exceeding 15 minutes. Data recorded during the time study give the following consumption per working hour according to log size.

Figure 1. The roundwood consumption of the sawmill in effective working time. Descriptions of the 10 sample logs for which data were recorded can be found in Appendix 1.

The rate of roundwood consumption by the sawmill varied between 0.5 and 2.5 m3/hour of effective time. The roundwood consumption per unit of effective time does not seem to have a straight dependence on the volume of the log. In total operating time including all the setting up and moving of the logs, the volume of the log has a straight effect on the productivity. The length of the log is an important criterion on effective time as longer logs necessitate less adjustment of the sawing unit compared to the volume of timber sawn.

Figure 2. The effective time consumption per m3 of roundwood processed in relation to the volume of the log.

In Figures 3 and 4 the time required for sawing each log is related to the amount of timber recovered from the log. For this calculation, recovery rate information from Section 6.3 has been used.

Figure 3. Production of sawn timber per hour of effective working time.

Figure 4. Processing time required per cubic metre of sawn timber recovered from the logs.

6.2. Overall productivity

The term "overall productivity" in this report means the average productivity of the sawmill over a longer period of time, for example the average production, measured in m3/day, during the months of March and April 1990. This productivity includes all the side works, repairs and moving etc. of the sawmill in the working time; it is not merely the productive time in the sense of producing sawn timber.

The basic idea of using a mobile sawmill is to take it to the logging site and do the sawmilling there. The sawmill must therefore be installed on each sawing area before operation. The set-up time for the sawmill on a new area is normally about two hours covering the time taken to clear an area for the sawmill, to adjust the basement for the logs to be sawn and to install the sawmilling equipment.

The dismantling time is about 0.5 hours. The re-installation of the sawmill on the same site without transporting the sawmill over a longer distance takes normally about one hour.

On average two trees are sawn at a site. The average size tree used in a Wokabout operation in PNG gives three logs.

The sawmilling crew spends about two hours arranging the logs for sawing.

The overall production of the sawmill depends very much on the skills of the sawmilling group as well as on the maintenance of the equipment. The manufacturer of the Wokabout Sawmill estimates that a new group will achieve a production level of 0.8 m3/day of sawn timber in the first year of operation. In the second year production will be 1.0 m3/day and in the third year 1.25 m3/day.

The Morobe Province Forestry Department has found from their studies that the average production of the sawn timber with Wokabout sawmills varies between 1.0 and 2.0 m3/day. The maximum overall production for one crew over a longer period has been 4. 0 m3/day.

6.3. Recovery rate of the Wokabout Somil

The volume of timber recovered from each sample log was measured. The dimensions of each log were measured crosswise at both ends of the log and log volumes were calculated from the formula given on page 12 of this report.

The volume of sawn timber produced from each log was determined by measuring the length, width, and thickness of each piece sawn from the logs, multiplying these dimensions (in metres) to calculate the cubic volume, and summing for all pieces cut from the log.

On average the recovery rate of the sawmill during the study was slightly more than 50 %. The recovery rate for a specific log depends primarily on the sawing pattern used. Figure 5 should be studied together with the information in Appendix 2 describing the sawing patterns of the sample log in the study.

The kerf of the sawmill is 7 mm.

Figure 5. Recovery rate for the sawn sample logs, with the volume of timber recovered expressed as a percentage of the volume of logs consumed during the operation.

The recovery rate for the ten logs varied between 44 % and 56 %. The most important factor affecting the recovery rate was the sawing pattern. The volume of the log does not seem to have an important effect on the recovery rate.

The sawmill cannot process the whole log and after normal sawing a 10 cm thick slice is left. This slice can be utilised in order to raise the recovery rate by edging and thinning it on top of another log, thus producing a wide plate of timber. The plate is normally 25 mm thick and from 300 to 500 mm wide. The time consumed in utilizing the slice is rather high because it requires additional adjustments of the sawmill.

Photo 7. The bottom slice of the log is sawn on top of another log into a wide timber plate.

6.4. Quality of products

The accuracy of sawing by the sawmill was estimated by measuring the width and thickness of sample pieces of sawn timber at one-metre intervals along their length. The results are summarized in Figures 6 and 7.

Figure 6. The accuracy of the width dimension as measured along the length of 100 x 50 mm timber sample pieces. Differences between vertical and horizontal sawing are not shown. Note that the greatest accuracy was achieved near the top of each piece.

The sample logs in this study were sawn with blades and teeth in good condition. Variations in the dimensions were mainly caused by the mechanical structure of the sawmill.

As a mobile unit, the Wokabout Somil has been designed to minimize the weight of the components. This results in reduced rigidity of the main beam and supporting frames, which affects the accuracy of sawing due to vibrations.

The quality of sawing with the Wokabout Sawmill varies considerably, depending on the skills of the crew and the maintenance of the saw blades and other equipment. With good maintenance the Wokabout Somil is able to produce timber the quality of which is reasonable for building purposes. However, on average the saw blades are poorly maintained which causes big variations in dimensions and very uneven surface of the timber.

Figure 7. The accuracy of the thickness dimension as measured along the length of the 100 x 50 mm timber sample pieces. Differences between vertical and horizontal sawing are not shown. Note that the greatest accuracy was achieved at both the top and the bottom of the pieces.

In PNG the sawn timber should be treated with dip diffusion preservatives before use or sale. To be successful the treatment should be done 8 hours after sawing because the surface of the timber cannot absorb preservative when it is too dry. The Wokabout sawmilling crews do not normally have a proper tank for dip diffusion and therefore the treatment is not done. Untreated timber is not allowed to be exported although it might technically be high quality timber. As a result of the treatment problem there is no export of timber from mobile sawmills.

At the moment the demand for sawn timber in PNG exceeds the production, so quality is not rated as a very important factor among the sawmillers because even the poorest quality of timber can be sold.

6.5. Costs

Costing of the sawmill is highly dependent on the overall costs in the area where the operation is done. A very high proportion of the cost consists of the cost of labour, gasoline, lubricants and spare parts etc., the prices of which are related to the overall cost in the country.

For this study, the consumption assumptions of a Wokabout Sawmill are assumed to be as follows:

Gasoline consumption by the engine is 20 litres in an 8 hour shift and the oil consumption is 4 litres per week, assuming a weekly oil change.

The circular saws are assumed to last about 6 months if good care is taken of them. The price for the larger blade is about 700 - 1000 K and the smaller one, 200 K. There are 6 teeth and shanks in each plates. The lifetime of a tooth is two weeks and that of a shank is 6 months. The price for a tooth is 5.4 K and for a Shank 11 K.

The blades are run by 4 belts which need to be changed every 3 months. The cost of the 4 belts is 34 K.

The air filter costs 4 K and lasts about three months. Spark plugs (2), about 2 K per each, should be changed every third month. The bearings in the plates and rail cost 150 K per year.

The sawmilling crew consists of five men: 1 operator, 2 siters and 2 utility men. Wages amount to about 40 K per week for the operator, and 35 per week for each siter and each utility man.

Establishment costs are estimated to be as follows:

Wokabout Somil

K 7000


K 750

Dip treatment tank

K 300

Dip diffusion salts

K 550

Petrol, oil, tools

K 200

Transport to site

K 150

Total establishment cost

K 8950

The detailed cost estimate summarized in Table 4 has been derived from the information above plus estimates provided by the manufacturer and by experienced users.

Table 4. Estimated cost of operating a Wokabout Sawmill for three years.

Costing assumptions

1. Consumables


K 19/m3

Petrol and oil

K 11/m3

Chainsaw operator

K 15/m3

Dip diffusion salts

K 15/m3

2. Operators

Manager (1)

K 71.0/week

Labourers (5)

K 182.5/week

Operators are paid for 29 weeks/year

3. Production

0.8 m3/day year 1

K 200/m3

1.0 m3/day year 2

K 220/m3

1.25 m3/day year 3

K 250/m3

4. Loan

Assume a K 5000 establishment loan at 15 % interest for 18 months

5. Depreciation

Based on 24 months, 50 % per year

6. Inflation

Assume a 10 % increase per year after year 1

Annual revenue generation

Year 1

Year 2

Year 3

Operating days












Price, K/m3




Total income, K




Annual costs (all amounts in Kinas)

Wages, manager




Wages, labourers








Petrol + oil












Dip salts








Loan interest




Total cost




Average cost, K/m3




Annual profit, K




The calculations in Table 4 give an estimated production cost of 181.5 K/m3 in the first year of operation. The calculations for the second and third year of production are based on assumptions that cannot be stated to be very reliable and therefore they can only be taken as possible developments in the process.

6.6. Observations on the sawmilling operations

The efficiency, quality and productivity of the sawmilling operations vary a lot depending on the sawmilling crew. It seems that most crews suffer from a lack of technical maintenance skills as well as from a lack of ability to manage the economy of the operations. A typical Wokabout sawmill experiences significant delays because of poor maintenance.

The main problem with crew skills is in sawdoctoring. The teeth of the circular saws are not sharpened often enough and sharpening is often done with poor accuracy. Sawing with blunt saws causes problems with the tensioning of the blades and without skills to tension the blades they are driven very soon to a condition in which they can not been used any more without professional help from outside. To get the blades tensioned and sharpened outside takes time, and meanwhile the sawmill is often stopped to wait for the blades to be tensioned and sharpened. Moreover the quality of the timber cannot be kept when the blades are not kept in stable condition.

The Timber Training College provides saw blade servicing in Lae for the Wokabout sawmilling crews.

The poor knowledge of overall technical matters also causes problems with the maintenance of the engine and other equipment. All too often the engine oil is neglected and parts needing grease are worn out due to lack of proper lubrication.

The sawmillers often have only limited knowledge of business economics and they are commonly without any former experience in taking care of investments, funding or cashflow. The sawmilling operation is normally started with just enough capital but without enough capital to operate the mill; i.e., to buy spare parts or pay wages. Often the sawmilling crews are overstaffed and therefore wage costs compared to revenues are too high.

7. Timber usage improvement with portable sawmills


7.1. Combining the logging operations and the mobile sawmilling

There appear three main possibilities for improving timber utilization in PNG: the use of reject logs, damaged residual trees and non-commercial standing trees. In general there are trees which do not have a sufficiently high processing value to justify transporting them to full-scale sawmills. Processing them on the site and transporting only the products, or using the products locally, offers a possibility for obtaining a profit from such trees.

As there are few ways to process wood on site mobile sawmilling is the most obvious way to use the available timber. Charcoal making is another possibility, but in the PNG society construction timber is much more needed than fuelwood.

There are some things which make the logging operations attractive for mobile sawmillers. Wokabout crews prefer to process bigger amounts of wood on one spot in order to avoid long setup and shutdown times, as well as to increase production by standardizing the operations and movements with logs and timber on the same familiar spot. As a semi-stationary sawmill the Wokabout is never located deep in the forest, because the crews prefer to transport the sawmill and sawn timber using vehicles.

Apart from the main roads, the roads in the forested areas of PNG are mainly in areas that are being or have been logged. It is not possible for rural clans t present to build roads for the transport of timber. Nor do the rural clans have machines for the transportation of logs or sawn timber. Expensive machines for log handling are, however, owned by logging companies operating in PNG.

Regarding the needs of the Wokabout sawmillers as well as the roundwood flow in the logging operations and the existing infrastructure in logging areas, it seems logical to link Wokabout sawmilling with commercial logging operations. At present, however, there is little cooperation between loggers and mobile sawmillers.

7.2. Timber usage improvement

Possibilities for improving timber utilization depend on the difference between the maximum cutting limit of the forest management plan and the amount actually taken out during logging, as well as on the fraction of reject logs without any processing in the forest.

As was shown in section 5.3., Buenaflor found in his sample plots that about 60 m3 of merchantable sized mature trees per hectare are left on the logging site after an operation. This amount varies depending on the number of species in the forest and on the number of commercial species that are to be logged. In PNG there are about 400 species which are known to have commercial value but only about 70 of them are regularly logged and marketed. The logged species are the most common ones in PNG and therefore the relation between the volumes of logged and left trees are not the same as it is with the number of the species.

According to the PNG Forestry Department, from 5 to 8 stems or about 30 m3 per hectare, are logged. On average about 30 m3/ha of mature trees are left behind in non-commercial species. In areas with only a few commercial species growing, the drain is nearly the maximum and no mature trees are left in the forest.

The non-commercial species, if not over-mature, are not definitely lost if not logged, because they can be left as a reservoir waiting for future logging and possible changes in marketed species. Over-mature trees with rotten heart or other defects will be probably lost because the time between logging operations is normally tens of years.

During the logging operations standing trees are always damaged when big stems fall down. Damaged trees of commercial species that fulfill the minimum BHD for selective logging are normally felled and taken out of the forest. Damaged trees in BHD classes from 20 to 50 are most often left in the forest. Buenaflor found in his studies that an average of 15 m3/ha of damaged trees not fulfilling the minimum BHD 50 cm are left in the forest.

The logs that are extracted but found then unsuitable for export are considered export rejects. The difference between the scaling volume of logs harvested and the volume exported is the export falldown. The fraction of export falldown depends upon the market for export logs. According to the Forestry Department, under normal market conditions the export falldown can be as high as 35 % of the scaling volume. When the markets are "tighter" logging tends to be done more carefully and selectively in relation to certain species and then the export falldown can drop to 10 % of the scaling volume.

Depending on the location of the export harbour, reject logs are used for producing sawn timber on the spot, left on the side of the harbour or in some cases burned because of the lack of storage areas.

Most reject logs are rated unexportable because of defects like splitting or heart rot. In raw material for sawmilling these defects reduce the conversion rate of the sawmill, but if processed without further transport they do not have a very significant effect on the productivity of the sawmill. In most cases the reject logs are suitable raw material to be processed with a mobile sawmill.

7.3. Logging waste as raw material for sawmillers

The timber that is left standing in the forest can be acquired for use by making the required royalty payment. This is normally 4 K/m3, of which 75 % goes to the forest owner and 25 % to the Government. Besides the royalty there is also a Forest Industry Levy of 0.215 K/m3 for Government and 3.0 K/m3 for locally processed timber for the forest owner. Altogether these costs total 7.215 K/m3.

If the timber is in the export harbour or somewhere else out of the forest it contains also the harvesting and transporting costs and besides the logging company has already paid the royalties to the forest owner. To get this raw material for their own use the sawmillers have to buy this timber from the logging company and cover the costs that have been paid by the company. According to a sawmilling specialist in PNG the prices for reject logs in export harbours are from 20 to 42 K/m3. The price the logging company is asking from the sawmillers depends a lot on the other processing possibilities in the harbour as well as on the use of the timber. If the timber is marketed or used by the logging company the payment paid by the company is just to cover the sawmilling work.

One of the most important things for the sawmillers in cooperation with the logging company is the possibility to get the help of machines in moving and piling the logs as well as to get the logging work done by machines. This can be arranged easily if the sawmilling is done at the same time as the logging operation. Otherwise the sawmilling should be planned beforehand and the logs to be sawn can be piled with the machines to be ready for sawmillers.

The logging company normally charges the sawmillers for the use of machines according to the running costs of the machine. In the Kui logging operation there was a Caterpillar 966E loader which was used to help the sawmilling operation. The hourly cost for that loader was 15 K. However, according to the operations manager the cost of piling the sawmilling logs for the mobile sawmill was so small that the company was not interested in charging anything for the loader.

8. End use of sawn timber

Most timber produced with Wokabout sawmills is used for construction purposes by local people. Another major end use for timber is in pallet making for industry and a very small fraction in some special cases can be exported. About 30-40 % of the total production is bought and marketed by timber retailers.

Commercial timber is graded into three classes, A, B and C. The price per cubic metre for each class is always fixed and the prices per linear metre are calculated from that basic price. Grade A is used for construction and grades B and C for timber in pallet making and other purposes. There is a lack of construction timber in PNG because of low production by domestic sawmills and thus the quality of timber is not an important factor in the market. In addition the lowest quality timber is normally bought for construction purposes. Pallet making sets further low criteria for the quality than construction because dull-edged timber is also approved for that use.

According to the Timber Industry Training College (TITC), the average price for sawn timber in grade A from sawmills is calculated by using the price of 450 K per m3, and the retailers are selling construction timber at a price based on 550 K per m3. The price difference between different grades is about 40-50 K/m3. However it was found that the Wokabout sawmillers were selling timber at a price based on 220 K/m3 for grade A, and at a price based on 160 K/m3 for grades B and C. In pallet making the selling price is set per pallet.

When making pallets the sawmiller always has a contract for the pallets before operations begin so that sawmillers are not producing them for stock. This is also quite often the case with construction timber.

Currently in Morobe province there are about 10 companies buying pallets and five companies buying sawn timber. Of the latter, three are buying timber for their own use and two of them are retailers. The companies have their own graders to do the grading. The Provincial Forestry Department has proposed to establish a marketing arm to help and train mobile sawmillers in marketing their timber.

The lack of proper preservation of sawn timber is a problem for the products of mobile sawmillers. Without preservation sawn timber last only about 6 years in the climate of PNG. If the production of bigger sawmillers grow to match the markets, local sawmillers might face some difficulties if they are not able to produce treatment for their timber. At the moment TITC is providing treatment for timber on at a price based on 100 K/m3.

9. Socioeconomic impacts of the logging-sawmillmg combination

Society in PNG is moving rapidly towards an actively developing country. It is important to find ways for rural communities to become involved in this development.

Commercial logging operations, which are using natural resources owned by clans, are mostly run by foreign companies or companies coming from outside the clan area without having any previous contact with the clan. For many rural communities these logging operations are the first real economic activities they have had with the outside world. The involvement of the rural communities in these operations is slight, apart the royalty that they receive as owners of the forest. In some operations local people are employed as chainsaw men or as helpers for the skidding machines.

There is a need to find ways for rural communities to develop businesses using their own resources. In this regard the mobile sawmilling is seen as a very promising form of action.

Combining the mobile sawmilling with commercial logging in order to do salvage logging and sawing of rejects can benefit both rural communities and logging companies. For communities it gives the possibility of getting employment and thus income; in addition it gives them access to the economical use of their own resources. Sawmilling combined with logging operations help the sawmillers work in a more professional manner raising the effectiveness of production through assistance in transport and marketing that the logging company can provide.

Learning to work outside the home and the transfer of know-how from the company to the local people should also be taken in consideration when evaluating the involvement of rural people.

10. Environmental impacts of the logging-sawmilling combination

Forestry officials in PNG are aiming to get all logging done according to the rules of selective logging with an acceptable level of damage for the remaining forest. Therefore to be suitable for use, all new methods of working in the forest must be in accordance with these rules.

The level of knowledge of forest harvesting among the mobile sawmillers is low, although some training has been provided by the sawmill manufacturer and the Forestry Department. Besides knowledge, one big problem is the sawmillers' attitude, in that they do not think they are affecting the forest through their operations. The amount of wood logged by one Wokabout crew per year is only about 400-500 m3, but if the total number of sawmillers is taken into consideration the total forest area affected by the sawmilling groups is already significant. Due to the large number and the various locations of sawmilling crews they are difficult to reach for control or consultation during their logging operations. Therefore any change in logging habits that will more effectively control the sawmilling crews can be regarded as an improvement.

The calculations on improving timber usage presented earlier in this report are based either on the selective logging method or the use of damaged or waste timber, thus representing the possibilities of using timber along rules that are environmentally sustainable. In order to extract the total amount of wood that is available in the forest as recounted earlier, one must make an assumption that no new damage is done to the remaining stand, which is not very often the case. Therefore, if logging operations are to be environmentally sound and sustainable they should not attempt to extract the maximum available cut, unless that is calculated taking into account the damage.

The method described of combining mobile sawmilling with commercial logging operations promotes the practise of getting the sawmillers to work with operations that are under official control. Commercial loggings are, or at least should be, following the forest management rules laid down by the Forestry Department.

It can be assumed that sawmillers working in cooperation with controlled logging will work within the framework of environmentally accepted logging rules, thus benefitting the sustainable management of PNG forests.

Photo 8. The site after a sawmilling operation in forest in Morobe Province in PNG.

11. Conclusions and recommendations

Mobile sawmilling seems to fit well with commercial logging operations in enhancing the usage of wood and the reduction of waste. But it was observed that there is still a need to modify opinions among logging companies as well as sawmillers to make this kind of cooperation known and to get it implemented. Loggers find mobile sawmilling promising and an interesting way to get the local people involved in the operations, but it seems that further advice is needed to find better ways of cooperating.

Wokabout sawmillers normally have no previous experience in sawmilling. When purchasing a sawmill a three weeks course on running the sawmill and some training is given by Forestry Department and other organizations. However, the level of skills on technical questions and their knowledge of business administration are at a poor level.

There is a need to evaluate existing training and on the basis of that evaluation to develop an overall plan for training in mobile sawmilling in PNG.

Specific training needs exist in sawdoctoring and maintenance of the engine. Wrongly maintained circular saws are a reason for the low quality of the sawn timber as well as for low productivity. The lack of proper maintenance of the engine causes a lot of time consuming stoppages in sawmilling. When short of money the sawmillers forego oil and filter changes without fully appreciating the damage that this can cause in the engine. Understanding the importance of good maintenance and its effects on the economy of sawmilling would benefit the sawmillers immediately.

Timber markets and are expanding rapidly and become more competitive in PNG, and in order to stay in business the mobile sawmillers must acquire some knowledge of marketing and business management. The cash flow in mobile sawmilling is rather small and that makes it very sensitive to mistakes in the planning of operations. The sawmillers should get training in basic planning of business activities, control of cash flow, bookkeeping and financing of investments.

It can be foreseen that retailers will be increasingly involved in the timber markets in PNG. These retailers are interested in taking a share of the mobile sawmilling production to be marketed to end users. If the retailers get too strong they can endanger the income level of the sawmillers and the rural people will no longer be the ones to benefit from the sawmilling industry. To avoid problems the sawmillers should get some training in marketing and timber delivery in order to take care of their own customers and to be able to negotiate with the retailers more effectively.

A further technical evaluation in the Wokabout Somil itself is needed. At present it is not really used as a mobile "bush- mill" as was the idea behind it. Instead it is most often used as a semi-stationery sawmill. Anyhow, it is a lightweight unit and therefore not rigid and productive in the way a stationary mill should be. On the other hand the sawmill is a bit too heavy to be transported manually in a forest. The transport of the sawmill and sawn timber is done along the roads, and very often with the help of a vehicle. Thus the sawmill is mobile only as long as a road exists. Therefore, a village-level stationary sawmill as well as a truly portable mobile sawmill should be developed. If possible these should be based on the same basic construction, which can also be a Wokabout Somil, to make it easier to standardize servicing and the delivering of spare parts.

Preservative treatment for the sawn timber can present rather serious environmental problems if done in the forest without suitable dipping basins and careful handling of the preservative liquids after operation. A standardized dip diffusion method which would be suitable for field operations should be developed.

Previous PageTop Of PageTable of ContentsNext Page