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Appropriate technologies

"Appropriate technology" can best be defined as fulfilling two essential criteria: 1) it must be sustainable; and 2) it must be locally accepted and adapted. Sustainability implies that whatever implement, tool or machine is added to a system to improve efficiency should be locally available, or can be produced locally. Sustainability also refers to the possible damage to, or disturbance of, the environment (e.g., to biodiversity).

The traditional forest harvesting technologies used in the Philippines were generally environmentally sound but they were inefficient. Many accidents occurred using these technologies and they led to an enormous amount of wood waste. In the natural forest, the felling and crosscutting losses were often more than one cubic meter per tree felled - a financial loss of between US$500 and US$1,500 per ha at today's market values. The wood waste in plantation forests was equal to US$20 per ha - as much as the price of a new two-man handsaw for each hectare harvested.

The problems and deficiencies of using water buffaloes and traditional sleds are easy to overcome by replacing the sleds with animal sulkies (small log arch) or animal-drawn log trailers. The trailers may be equipped with a mechanical loading crane, or even with a hydraulic knuckle-boom loader powered by a chainsaw engine or a similar small petrol or diesel engine.

In the Philippines, improvements in technology and efficiency proved difficult to achieve. The traditional ways of doing things, and faith in "Filipino ingenuity," hindered attempts to change things between the years 1976 and 1992.

Tree farmers, especially those of the older generations, seem to have difficulty understanding the concepts of "depreciation" and "cost-efficiency." Thus, they only tend to look at the speed with which chainsaws cut wood. They do not fully consider the time and cost of going to the nearest town to buy fuel and lubricants for their chainsaws. When the farmers are questioned about this, they say that the chainsaws give them a good excuse to go to town for other shopping or diversions. The repair and down time of the chainsaws are often not of great concern.

Under the ILO/Finland project, felling operations were developed to become as efficient as possible, without the use of chainsaws. Early research showed that chainsaws were three times more costly to use (per cubic meter harvested) compared with manual saws. This ratio has not changed since the initial studies were made 20 years ago. Yet farmers still have difficulties believing that chainsaws, which cut wood three to five times faster than handsaws, are two to three times more expensive to use per cubic meter. If economic efficiency is a main concern, then farmers should not be using chainsaws. However, this message is a difficult one for farmers to accept.

If properly trained, both manual-saw and chainsaw operators can work safely in the forest. The chainsaw is a dangerous tool if misused, but the ax can also be extremely dangerous. To ensure the safety of fellers and to minimize damage to residual trees, appropriate felling operations are required, particularly directional felling. This means that the actual felling procedure is but one small part of a well-planned operation, where the routes for the land transport of wood are carefully planned during pre-felling operations. Successful operations therefore require that all trees in the stand be felled in a pre-determined direction, without being tangled up with, or damaging, other trees, agricultural crops, or other objects. The skills involved in directional felling are very important on tree farms, since many other agricultural crops are growing under and among the trees. Farmers are quickly discouraged from planting more trees if their coffee bushes and other crops are damaged during tree felling activities.

This is where the importance of quality training comes in. It is necessary to know how to change the center of gravity of trees to be felled. This is done by removing a portion of the tree at its base, called the "felling sink," "notch," or "front cut." After this, the "felling cut" or "back cut" is started from the opposite side of the trunk, slightly above the level of notch. The difference ratio depends on the diameter of the tree (e.g., for a 20 cm tree - 2 cm above; for a 70 cm tree - 7 cm above, etc.). The felling cut continues exactly opposite from the desired felling direction, until an even, uncut portion of wood remains in the center. This "hinge" of uncut wood is intentionally left in the center, and is the cutter's life insurance! If this hinge is damaged in the cutting process, then the tree may fall in any direction, and the cutter's life could be in danger.

Trees seldom grow uniformly, nor is the ground in the forest always level. Therefore, additional tools are often necessary to achieve the desired felling direction. The most simple, inexpensive and reliable of all helping tools is the felling wedge. The cheapest manual saw is the two-man crosscut saw, which is very durable. Its use is now quickly spreading into all plantation forests in the southern Philippines. New two-man crosscut saws are different from the old two-man raker tooth saws, in that they are of the so-called "peg-tooth" or "triangular tooth" type. This newer version is much easier to maintain compared to the older model.

Crosscutting with a bow saw

The bow saw (shaped like a reversed bow) with a thin blade would be the most efficient harvesting tool, but high-quality bow saws are no longer available. The small hobby saws, common in most developing countries, have frames that are too weak for professional felling or crosscutting of trees. The tension of the blade is not sufficient for stems larger than 10 cm in diameter. The professional bow saw has to be able to maintain a tension of 200 kg; the small hobby saw can only manage 40-70 kg.

For felling leaning trees, or trees growing at the edge of riverbanks, gullies, steep slopes, or near electrical installations or houses, a special tool, the "felling tongs," is recommended. The tongs can be attached to a long wooden pole, which then is clamped onto the stem 6-8 m3 above the ground. The tongs are spring loaded and are attached to the tree while being anchored to the ground. A rope, 1.5 times the length of the tree (35-45 m3), is attached to the tongs. When a team of people pull the rope, the tree can easily be maneuvered against its lean. The tongs provide up to two tons of pulling force. They are particularly effective for felling trees away from coffee and fruit trees grown under timber trees.

Another harvesting operation is debarking. This activity depends very much on the end-use of the wood. The most important reasons for debarking are to allow easy assessment of the quality of the wood and to minimize the risk of insect damage. In pulp and paper manufacturing, the bark is not desired. In the southern Philippines, more than half of all plantation-grown wood is debarked. If, however, the bark is to be used as fuel for boilers or for wood fibers, then the bark is not removed until the wood reaches the mill. The same applies to veneer or peeler logs, which are protected by the bark during transport.

Tree felling with a bow saw

Traditionally, debarking was done with a machete. Although very cheap, the machete has one big disadvantage in that it is not designed for debarking. It forces its user to "work on four legs," an ergonomically very uncomfortable position. Limited by the short handle, the wielder is forced to work with his back bent. Likewise, the jungle knife, used for turning the logs, also forces the worker to debark in difficult positions, with the blade often pointing toward the body or leg, causing frequent injuries.

The improved tool is called the debarking "spud" or "spade." It consists of a blade shaped like a spade, attached to a long handle. Also attached to the side of the blade is small hook for turning the logs. The additional weight of the handle, in combination with the upright working position, allows for a more comfortable working condition compared to the machete. The correct debarking sequence also minimizes the incidence of accidents since the log, placed in front of the worker, diverts the tool away from workers' legs. Nevertheless, it is obvious that efficient training in the use of the debarking spud and all other tools is essential.

Traditional debarking by boys using machetes

Training farmers in the use of debarking spuds

In transporting logs overland, the felled trees or crosscut logs are conveyed to the nearest road, landing or waterway. In the southern Philippines, this job has traditionally been carried out by water buffalo, also known as carabao. A major limiting factor for using carabao, however, is the availability of water in the harvesting area. The carabao, or swamp-water buffalo, is different from the common water buffalo found elsewhere in Asia. This animal has to bathe every two hours or so, to cool down its body. It lacks pores in the skin to control excessive heat through sweating. Therefore, the water buffalo may suffer from sun stroke unless it can cool its skin.

During muddy conditions after rains, the hoof of the carabao spreads like a snowshoe, allowing this stocky animal to walk across soft mud, whereas most other animals would sink. However, during dry spells, the carabao is much less effective. Studies in the southeastern Philippines indicate that Brahman oxen fare much better than carabaos when the soil has hardened (as soon as 2-4 hours after rain). Farmers therefore have begun to switch from carabaos to white Brahman oxen for domestic transport, including that of wood. Brahman oxen are not sensitive to heat, and have no problems surviving dry working conditions. In fact, the use of Brahman oxen is spreading throughout the Philippines.

The main problem, whether using carabaos or Brahman oxen for wood transport, is that the pulling and loading device, or the skidding sled consumes too much of the animal's pulling energy. In 1992, a research team measured the required pulling force for skidding timber. It was found that under average soil conditions, the maximum pulling force of a carabao with traditional yoke and sled is 150 kg. Out of this, 35-50 kg is the weight of the sled alone. Accordingly, the net load pulling force is only around 100 kg. In practical terms this means that the maximum load in flat terrain can not exceed 200 kg, since the resistance of the log with one end uplifted is half the total weight of the log.

Carabao with traditional yoke and 4-wheeled trailer

Table 2. Dragging Resistance in Relation to Soil Moisture and Skidding Implements

Skidding (Pulling a log along the ground)

Soil Moisture (percent)

Dragging Resistance Coefficient







Carabao Sledge



Wheeled Implement



The maximum pulling capacity of a prime carabao bull ranges between 150 and 450 kg, depending on the weight of the animal itself. The maximum continuous pulling power of the carabao/sled combination is 100-120 kg. In comparison, a carabao with a harness/four-wheel trailer can average 250 kg (measured max. 350 kg). The best solution for wood transport in southeastern Philippines therefore appears to be a combination of full harness for the carabao together with a four-wheeled or six-wheeled log trailer.

The resistance for a log trailer is only between 10-28 percent of its total weight, depending on how many wheels it has. If the harness, thill shafts, and trailer are weighed together, their weight is between 120-280 kg, depending on the operator's seat, mesh protection and the number of wheels. The fully loaded trailer described above would require a pulling force of 100-300 kg.

Imported 6-wheeled carabao trailer and full harness

Semi-mechanized loading of freshly cut wood onto a carabao trailer

Table 3. Study Results of Carabao Skidding Alternatives

Skidding alternatives

Average load size (m3)

Skidding Distance

100 m

500 m

Daily production (m3)

Yoke and traditional wooden sledge




Yoke and local wooden two-wheel cart (car axle/tires)




Harness and imported four-wheel log trailer of steel




The data indicate that, on average, one carabao pulling a four-wheel log trailer can transport 11 to 15.5 m3 of Paraserianthes falcataria during a full work day (a work day consists of 9½ hours with 6 hours of work and 3½ hours of resting periods), depending on the distance and conditions of the terrain over which the wood is hauled. With the traditional sled, this level of work is impossible.

Production can also be increased with the use of other equipment such as a sulky. The use of the sulky, or "logging arch," was abandoned in Europe around 1920. Originally, sulkies were drawn by horses to transport tree-length logs over flat terrain. These arches were too heavy for manual use, and the narrow tires with rubber treads limited their carrying capacity.

An arch suitable for manual use was developed in Tanzania in the early 1970s. It resembled the sulky used in horse racing, and thus was named the "logging sulky." This sulky was initially only intended for pulling down trees that lodged among the conifers grown in plantations, but it was soon discovered that it could also be used to manual skid small logs over short distances of up to 50 m.

Releasing a lodged log using a sulky

Transporting wood with the help of a sulky

While logging sulkies seemed promising for log skidding, actual adoption was disappointing. The early sulkies made from water-pipes were too heavy, and the wooden bearings were not strong enough. In 1980, logging sulkies were also tested in the southern Philippines, but were unsuccessful. One of the drawbacks encountered was that the 2-wheel sulky had very low carrying capacity on soft soil. Likewise, the sudden twisting motion of the sulky handle added an unnecessary strain to the people pulling the sulky.

The Forestry Training Programme (FTP) of Finland made a final attempt to develop a more appropriate sulky in the early 1990s. The new design, equipped with two bogies and four wheels, called the "new Bogie-Sulky," became a success in the southern Philippines by 1992. This version, also known as the "U-model," has a carrying capacity of 300 kg and the logs (or bundle of pulpwood or fence posts) are lifted completely off the ground for conveyance to the road. Since the logs are not dragged along the ground, much less effort is needed to pull and push the sulky by the three-person work team.

A final sulky model, named the "H-sulky," after the shape of its frame, was also developed. Although this sulky is capable of carrying a 1,050 kg load, a 500 kg load size is recommended for continuous work. Studies indicate that production rates using the H-sulky range from 1.2 to 2.8 m3/hr, depending on distance, terrain, and conditions under which wood is being transported (up to a maximum of 250 m).

The entire procedure of harvesting plantation-grown wood requires extensive training and numerous high-quality tools. Table 4 shows the most common tools and equipment required. The list and number of items needed will depend on the financial resources of the farmer or tree grower, and on the scale of operation. It is obvious that a harvest of only 100 m3 (½ ha) does not justify a high initial investment, whereas 2,000 m3 (10 ha) can warrant a larger investment.

Parts of a sulky

Table 4. Animals, Tools and Implements Used in Harvesting Plantation-grown Wood

Description of Animal, Tool or Implement

Purpose of Animal, Tool or Implement

Estimated Price (US$)

Water buffalo (Carabao)

Transport of wood


Wooden sled, yoke and rope

Transport of wood


4-wheel sulky, of bogie type

Manual or animal transport of wood


Imported 4-wheel log trailer

Animal transport of wood


Imported full buffalo harness

Attachment of log trailer


2-man crosscut saw (5-6')

Wood cutting


Professional bow saw, 36" imported

Wood cutting


Logging ax, imported

Cutting of wood


Whetstone (carborundum)

Metal sharpening


Machete (bolo)

Clearing of biomass


Wooden jointer

Equalizing of saw teeth


Setting iron

Setting the saw teeth


Setting cat

Measuring gauge for saw teeth


Pulpwood pick

Lifting and stacking of wood


Debarking spud

Debarking of wood


Two-man tong

Dragging and loading of wood


Felling tongs and 50 m's of rope

Forced felling of leaning trees


Felling wedge

Felling and bucking of trees


Cant hook

Turning of logs


Debarking spike

Keeping log in place while debarking


Metal file, 6-10"

Saw and other sharpening


Safety helmet

Head protection


Steel toed safety boots

Leg and feet protection


First aid kit

First aid


Pair of working gloves

Protection of hands


New technologies are appropriate only if they are locally available at reasonable prices. However, this alone is not sufficient to sustain their adoption and continuous use. The quality of the tools and implements has to be guaranteed - at a standard not less than 80 percent of an equivalent well-made imported tool. Fortunately, the Philippines has a multitude of skilled local inventors, designers and technicians. The modification of thousands of old military vehicles into passenger "jeepneys" after the Second World War has earned the country a solid reputation for ingenuity. The necessary skills for auto-engineering are therefore available in the country. However, a basic problem lies in the appreciation and valuation of goods or products made in the Philippines, many of which are of inferior quality. One reason is that the raw materials that are used are often already "worn out" (e.g., steel is "tired" or full of micro-cracks). Another factor is the local system of bidding or canvassing, where less concern is placed on the quality of the product than on the cost. Fortunately, in forestry, this attitude is changing, chiefly because of the strenuous and dangerous nature of work, for which quality tools are clearly advantageous.

In the Philippines, tool manufacturing was started in three locations, all with long traditions of local blacksmith technology. Many people were interested in participating in trial tool manufacturing, but few were willing to invest in additional quality raw materials. Numerous workshops and small factories tried to fabricate copies of the imported tools and implements, but the generally poor quality of the tools resulted in failure.

It was not until 1981 that the first promising signs emerged. Of some 50 workshops involved in the trials, one in particular realized that the required quality could only be obtained by correcting the prevailing haphazard heat treatment in the manufacturing process. This manufacturer (Vergsons Industries, located in San Fernando, Pampanga) was brought to the UNIDO-supported Metal Industries and Research Development Center (MIRDC) in Taguig, Rizal. The owner of Vergsons Industries discovered his mistakes in heat treating the tools without proper furnaces and temperature gauges. With help from MIRDC, he managed to solve these problems, finally resulting in the local production of consistently high-quality tools.

The development of appropriate technologies involves numerous challenges. One challenge is to establish local manufacturing capabilities for high-quality tools. To motivate manufacturers to produce high-quality tools locally, a market for the tools is needed. But to develop a sizable local market, a critical mass of people who accept and value the new product or technology must exist. In practical terms, this viscous circle means that between the time a new technology is introduced and it is widely accepted, 10-20 years may sometimes elapse. This was the case in the Philippines.

An additional factor needed to encourage acceptance and application of new technologies is that there has to be a local distributor of the tools and technologies in the major areas where potential users are located. To accelerate adoption, there should also be local credit facilities to enable farmers to buy tools before harvesting trees. Thus, when farmers receive their harvest payments, the price of the tools can be deducted from their proceeds. If this arrangement is not possible, then farmers may be forced to contract harvesting services, leading to a situation where they may finally stop planting trees altogether because of the low financial returns. Until 1992, this was often what happened in the plantation forests throughout the southern Philippines.

By overcoming these constraints and providing adequate incentives and support for the adoption of high-quality tools for forestry, technological innovations eventually made their mark in the Philippines. No less than 18,000 pieces of high-quality tools were produced and distributed (many of them free of charge) in the southern Philippines by 1992. Another 25,500 high-quality tools were exported to Fiji, Indonesia, Mozambique, Sri Lanka, Thailand, Tanzania, and Zimbabwe.

Local tool manufacturing

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