In the eastern Amazon, the use of RIL resulted in about half to one-third the ground damage (roads + skid trails + log decks) when compared to conventional logging (CL). Canopy damage was also about half in RIL compared with CL treatments (Pereira et al. 2002). At this same site in Brazil, a comparison of costs and revenues for typical RIL and CL operations included estimations of productivity, harvest volume, wasted wood, and damage to the residual stand. The major conclusion of the study was that RIL was less costly and more profitable than CL under the conditions observed in the eastern Amazon site. The largest gain to RIL was provided by savings on the otherwise wasted wood. Large gains attributable to RIL technology were also observed in skidding and log deck efficiency. In addition, investment in RIL yielded an environmental dividend in terms of reduced damage to trees in the residual stand and reduction of the amount of ground area disturbed by heavy machinery (Holmes et al. 2002). The authors concluded that monetizing the value of the environmental dividend remains a major challenge in the promotion of sustainable forestry in the tropics.
RIL can also lead to economic savings. For example, in the Celos system in Surinam, the increased costs of planning with the use of RIL were found to pay off in increased efficiency (especially in skidding), reduced wastage, as well as reduced environmental damage. Savings in skidding costs with the use of RIL have also been reported in Sarawak (Higman et al. 1999). However, some studies have found higher costs in RIL than in conventional logging, due to the need for extra training, higher standings for road building, and higher costs of supervision. The fact that RIL is still of limited use throughout the tropics suggests that either it is more expensive or potential financial advantages are outweighed by other considerations (Leslie et al. 2002).
Logging impact alone is not always a good measure of the quality of forests that remain after logging (Wadsworth 1999). If better forest conservation is to result from low impact logging, it may require additional practices to those generally embodied in RIL. For example, directional felling could significantly reduce logging impacts if its purpose, in addition to ease of skidding, was also to avoid damage to immature trees. In sum, there is more to RIL than just guidelines on how to reduce logging damage. RIL should always be used in the broader context of sustainable forest management. RIL on its own may help reduce logging damage, but in isolation it will not ensure better forests.
A key aspect in sustainability of forest management is logging frequency. Logging intensity can be characterized by two aspects: static intensity (onetime logging) and dynamic intensity (frequency, i.e., cutting cycle). The regulation of frequency of timber removal (implementation of a cutting cycle) requires a management unit large enough to accommodate a reasonable cutting cycle, generally taken to be between 20 and 30 years, and at the same time large enough annual compartments so that the static harvest intensity can be kept reasonably low. As a result, sustainable management depends upon an adequate formulation of management units for which appropriate long-range management plans must be developed, specifying the manner in which logging intensity will be regulated, and the means by which productivity can be enhanced through silvicultural practices (Vincent 2002).
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