2. REDUCED IMPACT LOGGING (RIL)

In most cases, non-coniferous tropical forests (NCTF) are managed under polycyclic silvicultural systems. Unfortunately, selective cutting (i.e., high grading) and not `true' selection cutting is most often practiced. According to Johns (1992), the most effective management of most tropical forests entails the protection and encouragement of advanced growth in optimally sized canopy gaps created during logging, with planting of gaps where no advanced growth exists. Critical for the sustained management of these forests is the implementation of reduced impact logging (RIL) techniques (Nicholson 1965, Putz 1994, ISTF 1995, Marsh et al. 1996, Weidelt 1996, Stokes et al. 1997). Palmer and Synnott (1992) state: "while the merits of various forest management systems are being debated, tropical silviculturalists are of one voice in advocating the use of RIL techniques."

Various authors (Armstrong and Inglis 2000; Dykstra and Heinrich (1996), Elias 2000, Van der Hout 1999, Reid and Rice 1997, Ruslim et al. 1999, Sist et al. 1998, Sist 2000, Vanuatu Department of Forests 1999, Webb 1997) have proposed definitions or aspects of reduced impact logging. They are fully described in Appendix 1. Summarizing the work of these authors, RIL is defined as:

`Intensively planned and carefully controlled implementation of harvesting operations to minimise the impact on forest stands and soils, usually in individual tree selection cutting.'

RIL is generally characterized (Table 1) by having stand entries only at a predetermined cutting cycle, which generally should be no shorter than 20 years. No more than one-third of the basal area should be removed at one entry and a pre-harvest operational inventory is strongly recommended. Access road construction should be done well in advance of harvesting, and climber cutting, if required, should be done up to two years before harvest. Planning should consist of tree marking, location mapping and planned felling direction, and this should be linked with the layout of a minimal number of extraction trails. Once the logs are removed, they should be placed on landings of minimal size. The logging operations should only be conducted under favourable conditions (e.g. when soils are dry). The forest workers and supervisors should be well trained so that they can ensure minimal negative impacts on the site; maximum utilization of the trees felled; minimum damage to residual trees and advanced regeneration; and rehabilitation of negative impacts that may have occurred on the site. Finally they should be well qualified to conduct a post-harvest assessment.

Table 1. Some major characteristics of RIL techniques

RIL techniques are not difficult to implement. At the operational scale, the savings due to more efficient operations (when compared to conventional logging practices) will generally offset any additional costs in planning, layout and control, and make it at least cost neutral (Andel 1978, Mattsson-Marn and Jonkers 1981, Tabudar 1984, DeBonis 1986, Hendrison 1989, Pinard et al. 1995, Sayer et al. 1995, Bruenig 1996, Moura-Costa 1997). However, the implementation of RIL has been sporadic in practice and sustainable management of tropical forests is rare (FAO 1989a, Buenaflor 1990, Jonsson and Lindgren 1990, Tuomela et al. 1996). Where RIL techniques are not implemented, the volumes extracted in second and third cuts will be much reduced from those of the first cut. This is reflected in the logging intensities from natural (previously unlogged) and semi-natural (previously logged) forests (FAO 1997).