Regardless of the type of logging equipment used, the extraction of logs is a difficult, often hazardous operation that can inflict substantial damage on forest ecosystems (Dykstra & Heinrich 1996). This is perhaps especially true with ground skidding. In order to facilitate the extraction operations to be carried out efficiently and safely, as well as in an environmentally sound way, the following should be considered:
· logging equipment should be of an appropriate size and power configuration for the local stand and terrain conditions;
· the equipment should adhere to technical and safety standards, as well as ergonomic principles and requirements;
· machine operators should undergo skill testing and training before field work;
· layout of the skidtrail network should be carefully planned, followed by a correct alignment of tree stems with respect to extraction routes to facilitate extraction without major problems for the extraction crew and machines;
· the extraction crew should receive clear instructions and close supervision by the authorities responsible for harvesting operations.
Unfortunately, none of the above-mentioned considerations seem to be fully applied in the majority of extraction operations in Suriname's forest concessions. For purposes of this study, planned harvesting was applied on sample unit Plot/02. This involved laying out a skidtrail network based on the tree location map, and supervising the operation throughout. The ground-skidding equipment listed below was used for the extraction of logs. See also Figure 5.
Machine type |
Power |
Weight |
Width |
Activities |
Caterpillar 528C |
130 kW |
14.0 t |
2.9 m |
skidtrail opening and skidding of logs |
Franklin 170 |
115 kW |
9.9 t |
2.4 m |
skidtrail opening and skidding of logs |
Crawler tractors, which are general-purpose machines, are seldom used in extraction operations in Suriname due to easy terrain and stand conditions compared to what can be found in many tropical countries. Both of the wheeled skidders listed above were explicitly for log extraction. The Cat wheeled skidder was hired by the concessionaire from Mr. Morguul who runs a logging business.
The Cat skidder was intended to be used for log extraction from both sample units during the study. However, after about two-thirds of Plot/01 had been harvested, the skidder broke down and work and time studies on extraction operations had to be continued with the smaller Franklin skidder which was available on the concession. The Franklin skidder, also hired from a logging contractor, was used to skid logs from the remaining part of Plot/01 (the conventionally harvested plot) and the whole area of sample unit Plot/02 where the planned harvesting was carried out.
In the planned harvesting on Plot/02, it was intended to use the skidder-mounted winch for pulling logs to the skidtrails so that the skidder could remain on the designated skidtrail at all times. The capacity of the winch drum on the Cat 528 would have permitted a winching distance of up to 50 m. Even the lower drum capacity of the Franklin skidder would have facilitated winching logs to the skidtrails as planned on Plot/02. However, due to the poor condition of the winch line on the Franklin skidder, the winching distance was limited to 15 m and the skidder had to move backwards into the stand along the anticipated cableway until the logs could be reached. Only the last eight trees extracted on Plot/02 could be winched to the skidtrail as planned, after a replacement cable had been delivered.