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Current harvesting practice in Suriname has considerable potential for improvement both in terms of efficiency of harvesting operations and in terms of environmental impact of logging activities. Whiteman (1999b) identifies skidding and long-distance transport as the two most important aspects of current practices in terms of their impact on production costs. The absence of proper harvest planning in the majority of concessions further contributes a low level of inefficiency and productivity.

3.1 Planning of harvesting operations

Planning of timber harvests is one part of overall forest management planning, which is itself a component of comprehensive land-use planning (Dykstra & Heinrich 1996). To be effective, harvest planning must be based on a general forest inventory for the concession area and a comprehensive pre-harvest survey including terrain reconnaissance of each cutting unit prior to harvesting. This permits the development of accurate plans, which in turn will permit operators to improve operational control, optimise harvesting production rates, and reduce environmental impacts. All planning of harvesting operations should be guided by the consideration that unless the forest is left in a condition that will permit the attainment of a desired future condition, sustainability cannot be assured.

As far as forest inventory requirements are concerned, the Forest Management Act of 1992 (FMA) requires that inventories be conducted on newly granted concessions. However, implementation of FMA has been very limited to date (Eckelmann 1999). Before an application for a new concession can be submitted, FMA requires that an exploration inventory be conducted on the area. This first assessment is meant to serve as a basis for determining the AAC and for subsequent zoning of the concession into operating classes. However, the AAC is more commonly based on the number of years of the concession agreement and local experience from the past.

Mitchell (1998) found that the majority of forest operations in Suriname are managed either by small to medium-sized sawmills or by some of the larger independent logging companies. Most of the concessions operated by these companies were granted before FMA 1992 came into force. The area on these older concessions, many of which are still being operated, averages about 12,000 ha. For a cutting cycle of 25 years, this suggests that on a "typical" forest concession in Suriname, the area logged averages about 480 ha per year.

However, according to Mitchell (1998) it is believed that many concessionaires repeatedly cut over a much smaller area, focusing only on the more accessible portions of their concessions. Discussions with forest managers confirmed that generally only small areas are harvested each year. Mitchell (1998) finally used in his analysis an annual cutting area of only 220 ha per concession. This was the annual area harvested as determined by Hendrison (1990) for a large and relatively well-equipped forest concession in Suriname.

Results from the CELOS experiments suggest that a yield of 20-30 m/ha on a cutting cycle of 20-25 years may be possible, although this depends in part on the application of silvicultural measures that appear to be completely unapplied in Suriname at present. Mitchell (1998) therefore used in his analysis a harvesting intensity of 17.5 m/ha based on observations made by Hendrison (1990) regarding the yields that can be expected without silvicultural interventions.

Multiplying this average harvesting intensity by 136 ha, the estimated annual cutting area of Concession 387, suggests that the current level of production in Mr Doerga's concession might be around 2,380 m/year. Results from the field study, however, suggest that the harvesting intensity may be lower-perhaps only three-quarters of the average level used by Mitchell (see Table 5). The average level of production estimated by Mitchell (1998) of around 3,850 m/year for a "typical" forest concession in Suriname of about 12,000 ha also suggests that the actual annual level of timber production is probably much lower than the above-mentioned value for Concession 387. According to old LBB records available for the concession, annual production of roundwood averaged only about 1,000 m during the period 1978-88. This is probably driven more by markets and operating considerations than by the productivity of the forest, which appears capable of sustaining higher annual levels of harvest.

New concession agreements issued under FMA 1992 not only require forest inventories but also include conservation clauses that prescribe species to be harvested (or protected) and mandate the delineation of conservation zones. Thus the first steps are being taken towards comprehensive forest planning, an essential component of sustainable forest management.

In general, harvest plans are of two types (Dykstra & Heinrich 1996): long-term (strategic) and short-term (tactical), with the latter always to be based on the strategic plan to ensure coherence throughout the whole planning and implementation process.

The strategic harvest plan for an operating area demarcates non-harvest zones such as preservation blocks and non-forest areas; divides the production forest into annual operating areas, often referred to as "coupes"; and shows both the existing and proposed transportation systems. A coupe is not necessarily a single, contiguous block, as areas to be harvested within a given year may be dispersed throughout the concession for various reasons.

The tactical plan provides details of operations that are to be carried out during a period of one year and is therefore associated with the annual coupe. However, at present only one company in Suriname is known to demarcate annual cutting blocks (Eckelmann 1999). It is SBB's policy to define management units of 100-500 ha which will then be divided into 12.5-ha plots, referred to as "cutting units", which are the smallest administrative units. Under favourable terrain conditions where only one harvesting system is used (e.g., ground skidding) and the cutting units are contiguous, planning the layout of landings and skidtrails for all cutting units within a management unit can be done simultaneously.

In order to draw up a tactical plan for selection harvesting in a tropical forest, a pre-harvest inventory, often referred to as stock survey, has to be carried out and each cutting unit must be mapped individually. The boundaries of the cutting unit and all features that may influence harvest planning (water courses, swampy areas, slopes, or other problem sites) should be shown on this map, for which the recommended scale is between 1:1,000 and 1:10,000. Furthermore, the location of each individual tree that might be harvestable is marked on the map (see Figures 3 and 4). In forests with a high density of climbing vines, it is generally recommended that the pre-harvest survey be done well in advance of harvesting and that climber cutting be done at the same time as the trees are being marked for felling. The climbers, which tend to bridge across tree crowns, will then die and become brittle, reducing the chance that a felled tree will pull over neighbouring trees as it falls (Dykstra & Heinrich 1996).

The new concession agreements issued under FMA 1992 require that pre-harvest inventories be conducted, but only one concession holder at present is known to carry out such surveys (Eckelmann 1999). Other licensees only undertake conventional prospecting, often referred to as "tree spotting", which involves identifying potential trees but not mapping their locations.

All information about each harvestable tree that is recorded on inventory sheets in the field should then ideally be entered into a database for the concession. This would facilitate harvest planning by permitting the concession holder to evaluate silvicultural alternatives and use information about market acceptance of various tree species to plan the cut. It would also assist in determining which species are locally rare or regenerate poorly under current harvesting regimes.

All trees to be harvested are to be marked on the tree location map (stock map) for the cutting unit. The spatial distribution of the harvest can then be adjusted as necessary to avoid large canopy openings that would be caused by felling several neighbouring trees. The final map of the cutting unit, which shows terrain features as well the location of harvestable trees, future crop trees, and each tree to be felled, should finally serve as the basis for the layout of skidtrails and landings. The logging supervisor can then use the map, together with field checking, to ensure that the harvesting plan is feasible and that the operation can be undertaken safely, efficiently, and economically.

A copy of the harvest map and accompanying information about the trees to be harvested should be provided to the felling crew. This will reduce or eliminate time spent searching for the trees to be felled (see Section 6.1.1). In order to detect hidden internal decay, an investigative cut with the chainsaw blade should be made into each tree selected when the presence of decay is suspected. This helps avoid unnecessarily felling trees that cannot be utilised, improving felling productivity and reducing needless canopy opening.

All trees cut during felling operations should be marked on the map. Each log cut from the tree should be tagged and recorded in order to ensure that it is not missed by the skidding crew. An updated map of the cutting unit showing the location of the felled trees and the associated log numbers should then be provided to the skidding crew. Actual locations of skidtrails and landings should also be drawn on the map after they have been established in the field. This will facilitate their reuse during future harvest entries.

According to a recently introduced system, licensees are required to keep logging registers and fix tags with bar-coded information to each log (Photo 3). Corresponding tags are also to be attached to tree stumps so that each log's origin can be traced if necessary (personal communication with SBB). Log movement by truck is monitored by SBB/LBB during scaling, which occurs during the transit of logs from the forest to the sawmill (Eckelmann 1999).

3.2 Forest road planning

The concept of opening up forests by a permanent road network, as a precondition for forest management and sustainable utilisation, is widely accepted both to specialists and to the public at large, but it is a difficult concept to put into effect. From the environmental point of view, forest roads are unquestionably the most problematic features of timber harvesting operations. They are complex engineering structures upon which transport efficiency depend and are essential to reliable access to the forest for management and monitoring purposes (Dykstra & Heinrich 1996).

Therefore, comprehensive planning is required for proper location, design, construction, and maintenance of forest roads and subsidiary structures, in order to meet environmental and economic objectives. Another important fact to be considered in road planning activities in remote areas of Suriname is that, as in the case of the Bruynzeel Road, forest roads not only serve timber harvesting purposes but are also an integral part of the local development infrastructure.

The general layout of the forest road network as the basic component of the transport system varies considerably due to many factors such as:

Sample unit

 

 Types of trees located and measured

 

 Production rate






Plot/01

 

 commercial species with dbh > 40 cm and

 

 2.5 person-days/ha

   

 commercial species with dbh 25-40 cm

   
         

Plot/02

 

 principal tree species with dbh > 40 cm and

 

 1.5 person-days/ha

   

 principal tree species with dbh 25-40 cm

   

Felling crew

 

Equipment used

     

1 chainsaw operator

 

1 Stihl AV 070 chainsaw

1 assistant

 

1 maintenance toolkit

   

1 machete

Objectives

Recommended measures

Achieve a high standard of felling safety

hire personnel fully qualified for the work task, in good health, able to recognise hazardous situations, and with personal responsibility

provide appropriate safety gear and properly maintained equipment

 provide training in proper felling techniques

provide training in maintenance of equipment

require climber cutting prior to harvesting

supervise operations closely

Minimise damage to residual trees and stand

require directional felling

require climber cutting sufficiently in advance of harvesting (perhaps 6-18 months) to ensure that the vines become brittle and break easily

ensure that a tree location map is provided to the felling crew

Maximise volume of wood utilised from each felled tree

ensure the use of proper felling and crosscutting techniques

require climber cutting sufficiently in advance of harvesting

ensure that operators follow bucking and grading rules

supervise operations closely

Facilitate efficient extraction

provide a tree location map to the felling crew that shows skidtrails

require the use of directional felling

supervise operations closely


Photo 5. Filing the cutting chain, using techniques that violate all safety instructions in the chainsaw manual.


 

3.6 Extraction system

The skidding operation is normally planned to begin several days after completion of felling operations. However, due to the time constraints in carrying out this study, extraction of logs started immediately after the felling crew had left sample unit Plot/01 to commence felling on Plot/02. Starting from the existing forest road, the skidder operator opened a short road up to 8 m in width to provide access to the harvest area. Clearing vegetation and moving soil was done by means of the skidder's blade. At the end of this short access road, a landing was established on both sides of the road to serve as a collection point for logs extracted from the sample units.

On Plot/01, skidding was done in the conventional way. Having established the landing, the skidder operator got off the skidder and walked the area in the vicinity of the landing, searching for logs in order to decide how to arrange the work. The skidder operator then drove the skidder into the stand in the general direction of the felled trees.

In the conventional logging system, the skidder operator drives to each felled tree. The winch line is then wrapped directly around the log to be skidded. To enable the skidding assistant to push the winch line under the log, the skidder operator often uses the skidder's blade to raise the log by pushing it against nearby trees. As a consequence, the neighbouring trees are often bent or broken, or their bark is stripped off. In some cases, more than one log may be skidded at a time. To accomplish this, the logs are manoeuvred into alignment by the skidder, an activity that may cause extensive soil disturbance and damage to residual vegetation in the vicinity of the felled tree. This could be avoided by attaching a choker cable to each log and then gathering the choker cables with the winch line, a technique that is commonly used in industrialized countries.

Another procedure that was observed on the study area to have a significant negative impact on the residual stand is the fact the skidder operator often followed a different route to the landing than the one followed to reach the felled tree. This practice results in substantially more soil disturbance and damage to residual vegetation than if designated skidtrails were used. In addition, the skidder operator sometimes searched for felled trees by driving the skidder through the forest, rather than by walking. In the aggregate, these unplanned searching and skidding activities contributed to a dense criss-crossing network of skidtrails, some of which even led to natural canopy gaps in which no tree was felled.

On both sample plots, extraction was carried out by means of wheeled skidders. After about two-thirds of the logs had been extracted from Plot/01, the Caterpillar skidder being used on that study plot broke down and replacement parts had to be ordered from abroad. Skidding was therefore shifted to a smaller Franklin skidder that was available nearby. This necessitated a change in the skidding crew as well. Details of the skidding crews and equipment used during the study are as follows:

Study Plot

Skidder

Skidding Crew

Plot/01

First 2/3 of area

Caterpillar 528C wheeled skidder with winch

1 skidder operator (Crew A)

1 assistant (Crew A)

Final 1/3 of area

Plot/02

Franklin 170 wheeled skidder with winch

1 skidder operator (Crew B)

1 assistant (Crew B)

In contrast to the conventional skidding system used in Plot/01, skidding on Plot/02 was carried out in the manner of planned harvesting supported by use of the tree location map that had been prepared during the pre-harvest survey. All trees felled in Plot/02 were marked on the map, including their approximate direction of fall. Using this information, a skidtrail system was designed and drawn on the map, utilising old skidtrails where appropriate.

After receiving instructions from the person carrying out the work and time studies, the skidder operator moved from the landing into the stand, opening the designated and pre-marked skidtrails and using the skidder's blade as needed to clear obstacles. Logs lying across the skidtrail were skidded to the landing before opening of the trails continued.

Turning at the end of the opened skidtrail, the skidder moved to the first stop for attaching logs as determined by the assistant. The assistant's decision was based on the tree location map and an inspection of the field situation, considering the location of future crop trees, regeneration, understory vegetation, and obstacles.

The planned procedure was for the assistant to pull the winch line to the log and attach it while the wheeled skidder remained on the designated skidtrail. The log would then be winched to the skidder. Normally, in easy terrain where the recommendation of straight alignment of skidtrails is followed, the distance between adjacent skidtrails would be planned at 100 m and the winching distance would be a maximum of 50 m. A chainsaw would be available to crosscut logs too heavy to be winched, to trim branches from improperly topped trees, or to remove smaller trees from the cableway when necessary. However, due to the unplanned use of the Franklin skidder, which was equipped with a badly frayed winch line so that only a short section could be used, the planned extraction procedure had to be altered. Instead, the skidder operator reversed the skidder to the felled tree along the planned cableway. Only the final eight trees could be skidded in the planned way, due to the arrival of a new winch line for the skidder.

3.7 Operations at the landing

Landings are collection areas to which logs are delivered during the extraction process and represent the interface between extraction and transport of logs (Dykstra & Heinrich 1996). The location and design of landings should be done during harvest planning, at the same time that the forest roads are located and designed. At the landing the logs may be sorted, possibly stored temporarily, and then assembled for transport to the processing facility or other final destination. Temporary storage of logs should be considered in case of:



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