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Regardless of the type of logging equipment used in a particular ground-skidding system, the extraction of logs is a difficult, often hazardous operation that can inflict substantial damage on forest ecosystems (Dykstra & Heinrich 1996). Therefore, in order to carry out extraction operations efficiently and safely, as well as in an environmentally sound way the following are considered:


· appropriate size and power configuration of logging equipment, adjusted to the actual needs of the system applied and with respect to stand and terrain conditions;


· appropriate equipment with respect to technical and safety standards, as well as ergonomic principles and requirements;


· machine operators should undergo skill testing before field work after adequate training;


· well planned skid trail layout 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;


· clear instruction to and close supervision of the extraction crew by the forest engineer responsible for all harvesting operations.


Following these guiding principles, the ground-skidding equipment stated below is used for the extraction of logs in the environmentally sound forest harvesting system as carried out in the F2M project of Precious Woods.


machine type






Caterpillar D4H TSK crawler tractor

70 kW

10.4 t

2.2 m

skid trail opening and

pre-skidding of logs


Caterpillar 518C (4x4) wheeled skidder

117 kW

11.5 t

2.7 m

skidding of concentrated



The D4 crawler tractor is used to open skid trails prior to extraction, to drag logs to skid trails by means of cable during the pre-skidding phase, and in road maintenance operations.

Unlike the crawler tractor, which is a general-purpose machine, the Cat wheeled skidder is designed, like all skidders, explicitly for log extraction. In the environmentally sound forest harvesting system each log is winched to the skid trail and the skidder is driven as close as possible to every log. The wheeled skidder is equipped with a grapple to provide high skidding productivity.

The company-owned Cat wheeled skidders were also used for skidding in cutting unit B/F09 where the traditional logging system was applied. Information was obtained on production rates, costs, and environmental impacts of timber harvesting as generally done in the Amazon-region of Brazil.

In cutting unit B/F09 the skidder-mounted winch was used for the skidding of logs, since the use of a grapple is to be considered as an exception due to the higher investment costs of this equipment. Even the use of a skidder instead of a general-purpose machine like a D6 crawler tractor is still not very common in the traditional logging system as described in chapter 6.

Photo 13. Heavy loads - a challenge to the skidder operator

Photo 14. Lack of planning - timber logging during wet season, extensive landing

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