Monocyclic Methods

The Malayan Uniform System (MUS) is one of the oldest and most widely known management system of natural forests in Southeast Asia. It was designed for forests that are relatively uniform and rich in commercial species of the Shorea genus in the Dipterocarpaceae family. The genesis and nature of the system have been described by Wyatt-Smith and Panton (1963). All trees of commercial size are harvested in a single operation, followed by poison-girdling of all unwanted stems (non-commercial species, or commercial species with defective stems). Three to five years after the initial harvest, diagnostic sampling is conducted to determine the status of regeneration and to prescribe treatments that will ensure good regeneration. Silvicultural treatments to promote regrowth include climber cutting (liberation) and poison girdling of unwanted trees competing with the more desirable species. These practices are applied at 10, 20, 40, and 60 years and the area is harvested again after 70 years.

In the MUS, regeneration was generally good on lowlands with fertile soils and the system was commonly used until the mid-1960s (Dawkins and Philip 1998). The low cost of mechanical extraction and making and maintaining roads and the lack of demand of other species created an ideal situation for the MUS in the lowland areas. However, competition with other land uses such as rubber and oil palm led to a displacement of this management system to more hilly terrain where conditions were not so favorable for natural regeneration (Buschbacher 1990). Another factor that contributed to the decline of the MUS was the increasing use of wood preservatives which permits the utilization of more species.

By the late 1980s, a selective management system (SMS), similar to one being used in the Philippines, was suggested as a more flexible and appropriate approach to suit the changing conditions of forest management in Malaysia. The new SMS required a pre-felling inventory where permanent sample plots are defined and used to determine growth rates by diameter classes and species groups, mortality, regeneration, and felling damage. The felling regime is then designed based on minimum diameter limits (MDL) for cutting that are defined for each species, so as to conserve the resource, ensure sus-tainability, reduce damage to the remaining forest, and optimize utilization. Yields of 30-40 m3/ha were expected in 25- to 30-year cutting cycles, thus transforming the system into a polycyclic method. The system has yet to be tested over time and success greatly depends on the efficacy of the control of logging (Dawkins and Philip 1998).

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