Vijender Persad Ram Jiwan


It was generally assumed that tropical moist forest ecosystems perpetually renewed themselves and represented as inexhaustible wood potential. However, with the expansion of harvesting, this was quickly found to be otherwise (Bertault et. al., 1992).

Unsystematic logging does not ensure sustainable timber yields as it damages a disproportionately high percentage of future crop trees and emerging regeneration. It is usually characterized by inadequate planning of logging roads, landings and skid trails, insufficient care for the residual stand, poor felling techniques and use of inappropriate and often outdated equipment; resulting irreversible forest or degraded forest as the harvested valuable trees species do not necessarily regenerate successfully. Similarly, intensive logging of natural forests also has a negative impact on the social and natural environments (water resources, air and water quality) in the long run. With time, it also became apparent that logged-over forests would become degraded unless silvicultural treatments are applied to maintain or increase the growth and regeneration abilities of such valuable trees species.

As silvicultural practices or regimes varies with trees species, site (terrain and soil), and climate; foresters did face problem in sustaining the wood yields of a few economically desirable trees species due to the considerable variations in diversity (species mix) and complexity of the native forest.The sustainable management of our native forest did evolve with time. In the early 1920s Regeneration Improvement Felling and Commercial Regeneration Felling systems were applied depending on location and demand. It was aimed to improve the existing growing stock through removal of inferior trees species either by tree-girdling or felling in several stages to promote the development of trees species with potential value. However, it was found that both the systems were not feasible and it was discontinued and replaced by Malaysian Uniform System.  This system aims at converting the virgin lowland forest to a more or less even-aged forest with greater proportion of commercial trees species in the forest stands since it was observed that in certain clear-felled areas advanced seedlings regeneration on the forest floors were adequate under proper silvicultural practices. In areas where natural regeneration is insufficient prior to logging especially hilly and mountainous areas, Selective Management System (SMS) is practiced. This involves the selection of management or logging regimes based on inventory data instead of assumptions (Hooi, 1987). The system promotes natural regeneration through selective felling (based on diameter) to open the crown allowing light to reach the ground to trigger the germination of seeds as well as to stimulate the growth of already established seedlings that were suppressed prior canopy opening. The systems do prescribe carrying out of silviculture treatments and continuation of maintenance, especially creeper cutting, to ensure the survival of seedlings up to sapling stage.

Today, harvesting of the production forest in the Permanent Reserve Forest is based on the principles of Sustainable Forest Management (SFM), following a prescribed forest management and harvesting plans in order to ensure sustainable log production with minimal damage to forest stands and environmental quality in maintaining the biodiversity and ecological system. In fact, Malaysia is committed to SFM, since it has developed Malaysian Criteria and Indicators (MC&I) for the management of its native forest which is in line with ITTO’s criteria and indicators in monitoring and assessing SFM for the purpose of forest management certification.  



The initial research on native forest began in the early 1900. Establishments of experimental plots were done independently without common guidelines. Often the research carried out suffered from successive changes in financing and policy. Thus, much of the information on native forest silviculture was incomplete for field applications. 

However, establishment of experimental plots especially Permanent Sample Plots (PSP) based on series of simple principles focusing on stand dynamics and the usually applied silviculture activities (e.g., logging) and treatments to promote tree growth, regeneration and increase yield is beneficial. A number of sizeable plots stratified according the forest types and usage of statistical means to interpret data is necessary. With the information gained on technical concept, its application to larger areas on trials basis or forest management projects is utmost important in evaluating the methods.  

During measurement of PSP, it is impossible to access all tree sizes and trees species, and it is not wise to measure all seedlings and saplings since most will die. All trees species exceeding 10 cm diameter at breast height (dbh) be measured (Synnott, 1979) for all parameters of importance and accounted, inclusive of lesser known species. The re-measurement for native forest PSP can be done with an interval that ranges between 3 to 5 years (Vanclay, 1991).    

Nowadays, Sustainable Forest Management (SFM) not only involves sustained yield management but also fuller range of environmental, social and economic issues (Lanly, 1995). In Malaysia, Environmental Impact Assessment (EIA) is prepared prior harvesting for concession areas with more than 500 ha, to look into the significant impact of logging on environment. The EIA procedures and mitigation process are outlined by the Department of Environment.

Broadly the silviculture and management of native forest comprises the silviculture, yield regulations, and logging.


2.1 Silviculture and Yield regulations 

Native forest yield estimation involves felling cycle period, trees species increment or growth data, and estimation existing growing stock of the forest. Field data of trees species increment or trees species growth equations and net stocking are pluck into the forest estate model (if available) to determine the felling cycle, if not, manually estimated. A simulation run of the available data is necessary to determine allowable cut for various felling cycle. Therefore, felling cycle and allowable cut will vary depending on forest stands to avoid over-cutting which may cause degradation. 

The establishment of harvesting goals and limits according to principles of SFM is very important requirement for managing native forest. The limits should be based on allowable cut calculations for the area to be harvested and environmental constraints in individual compartments (or blocks) of the harvesting area.


2.2 Harvesting System

The logging and the silvicutural techniques applied using the Selection System intended to provide at least 50 first class trees per hectare (Bertault et. al. 1992) through stand improvement of natural forest (examples, canopy opening by harvesting and girdling) and enrichment planting. Silviculturally, the application of pre-felling vine/creeper cutting is also prescribed where creepers bind tree crowns that increase damage on residual stands during felling (Appanah and Putz, 1984). To ensure that the vine stems and creepers have weakened substantially, it is recommended that the operation is made one year prior to logging (Putz, 1994).     

In moist tropical forest selective logging using bulldozers, generally about half the damage to residual stands is cause during felling, and the remainder is as the result of yarding or log extraction (Nicholson, 1958; Redhead, 1960). Improper planning and machinery usage during logging do cause:

  • negative impacts on forest stands that will further slow down the already slow recouping growth rate of native forest;
  • affects forest dependent people livelihoods;
  • reduced water retention capacity and increased erosion polluting water; and
  • damages to the residual forest stands and wildlife habitats. 

Thus, felling damages need to be minimized by adopting directional felling to avoid destroying regenerated saplings when carrying out log yarding especially skidding.

Tree felling and yarding need great deal of attention. Although variety of options are available for yarding (examples, oxen, elephants, farm tractors, articulated skidders, crawler tractors, high-lead and skyline cable systems, cable yarder, helicopters, and balloons), the most common yarding tool is bulldozer that is actually designed for road building and not for log skidding. However, bulldozer cause damage can be reduced by restricting machine movements to the design skid trails and maximizing log winching distances (Putz, 1994).

However, even with the best silviculture management practices based on the best available research information pertaining to sustainable management of native forest, it still seems inappropriate if poor harvesting techniques are practice by the loggers.

2.2.1 Protection Measures in Selective Management System of Production Forest 

To properly implement the Selective Management System in Malaysia a guideline on protective measures has been developed by foresters. Amongst the measures taken during implementation are (Mohd Paiz and Wan Mohd Shukri, 2003):

§  A limit on the extent of forest areas to be logged yearly based on approved annual coupe.

§  Production of forest harvesting plan detailing the harvesting blocks, the road system along with its alignment and construction, and the forest stands rehabilitation methods. These will help in minimizing the negative impact on environment and degradation of forest as it is a prerequisite requirement by law before approval of any logging operations.

§  Cutting limits for trees to be felled (dbh) is based on the Pre-logging Inventory carried out. The standards for cutting limits are as follows:

o The cutting limit prescribed for dipterocarp species is not less than 50 cm dbh, except Neobalanocarpus heimii (Chengal) whereby the cutting limit is not less than 60 cm dbh;

o   The cutting limit for group of non-dipterocarp species should not be less than 45 cm dbh;

o   The residual stands should have at least 32 sound commercial trees with dbh ranging between 30-45 cm;

o   The percentage of dipterocarp species of residual stands for trees with dbh more than 30 cm should not be less than the original stand (prior harvest); and

o   The retention of mother trees (at least 4 trees per hectare) and certain wild fruit trees for fauna conservation. 

§  All trees that are above the cutting limits are marked with felling direction and tagged for felling to control the production from the forest.

§  During logging, the following are taken into account:

o   Directional felling is properly implemented to ensure minimal damage to existing stands;

o   Forest roads, skid trails, and landings are constructed according to the standards prescribed to ensure minimal detrimental environmental impact. Thus, road alignment, road density, and skid trails need Forestry Department approval prior construction.

§  The buffer zones along rivers and streams are delineated on topographic map and on ground to mitigate soil erosion.

§  After logging, a post-logging inventory is carried out. Based on the outcome, silviculture treatments such as girdling of defective trees, creeper or climber cutting, and/or enrichment planting for areas with poor natural regeneration are applied. A similar inventory is conducted at year 10 to assess the status of regenerated forest.  

2.2.2 Reduced Impact Logging (RIL) 

In recent decades, it has been recognized that proper planning of harvesting operations and application of appropriate technologies can considerably reduce the damage caused on native forest. Intensively planned and carefully monitored on ground application of forest harvesting techniques lowers the level of damage to the residual stand, soil, water and wildlife so that the productive capacity of the forest is sustained even after logging, besides maintaining the ecological system. These are collectively referred to as Reduced Impact Logging (RIL).

The application of RIL is based on two goals. One is to harvest marketable trees as economically and safely as possible to support economic development and local livelihoods in developing countries. The other is to achieve desirable characteristics of the residual forest as they derive from ecological and, to a certain extent, social requirements. Examples of the latter are to maintain the possibility of harvesting non-timber forest products, the continued availability of unpolluted water and a carbon reservoir to ameliorate global climate change.

The main objectives of RIL are:

1.     minimize impact on the environment (including wildlife) and related social aspects;

2.     minimize damage to potential future crop trees (including regeneration);

3.     improve logged forest stands for recovery and maximizing yield of the forest. 

RIL comprises the entire activities of forest harvesting operations that is pre-harvest forest inventory; selection of merchantable trees species; designing of infrastructure; planning of forest roads, skid trails and log landings; construction of forest roads, log landings and skid trails; use of appropriate felling and bucking techniques; winching of logs to planned skid trails; and an assessment of the logged forest through post-felling forest inventory. It is important that the trees to be harvested are carefully selected.

The guidelines used for the implementation of RIL entitled “Guidelines for Reduced Impact Logging” are based on the following (Mohd Paiz and Wan Mohd Shukri, 2003):

1.     Field guide for Pre-felling Forest Inventory;

2.     Guidelines for the Implementation of Tree Marking using Timber Tagging;

3.     Guidelines for the preparation of a Forest Harvesting Plan as documented in the Code of practice for harvesting of Natural Inland Forest, 1997; and

4.     Field Guide for Post-Felling Forest Inventory.

However, moving to RIL requires comprehensive training of managers, supervisors and workers at all levels of forest operations, as well as operational changes on the ground. It success most importantly, requires commitment towards SFM by politicians, land owners, managers of logging companies, forestry staff, licensee, logging contractors and forest workers. Hence, RIL can be seen as one important step toward SFM. 

With a view of increasing acceptance to develop sound Forest Estate Model under SFM principles the application of proper and complete RIL procedures and technologies is a very important, for example the usage of high-lead yarding and skyline cable system. The later harvesting technique has been found to be successful in the Dermakot Forest, Sabah. In addition, it is also implemented in Forest Management Unit under Sustainable Forest Management License Agreement.

In general, the application of RIL does not comprehensively consider social issues such as land and customary rights. Additional steps are required to produce timber from sustainably managed forests as defined by forest certification systems such as Malaysian Criteria and Indicators (MC&I). RIL needs to operate within policy and legislative frameworks and technical forest management considerations not only on sustained yield planning but also environmental and social considerations. Reduced Impact Logging (RIL) in Compliance to Malaysian Criteria and Indicator (MC&I)

The forest certification MC&I is formulated based on ITTO’s criteria and indicators of SFM involves evaluation of forest management operations in compliance to a set of ecological, environmental, economic and social criteria, indicators, activities and management specifications. It covers forest and trees species inventories, forest management plan, logging plan inclusive of forest engineering activities, silviculture and management of forest stands, and other related forest management activities example, forest health and fire prevention. Since, harvesting activities monitoring and assessment are included in MC&I, the proper on ground implementation of RIL is an approach towards SFM and forest certification (Figure 1).




 Figure 1: Flowchart describes the relationship between RIL, SMS, MC&I and SFM (source: Mohd Paiz and Wan Mohd Shukri, 2003)

 Financial Implications of RIL

The application of RIL depends to a considerable extent on its cost-effectiveness. Some studies have shown RIL practices can be less costly than conventional practices on a long term basis and some studies have indicated the opposite. The results of cost-benefit analysis are very location-specific and cannot be generalized. But, some common conclusions can be drawn. Inventory and planning costs are higher for RIL. On the other hand, operating costs are generally lower as a result of proper planning and reduced equipment wear. Wood recovery is usually higher with RIL, because of better procedures for locating and marking commercial trees within the forest, reduced felling damage and a reduced incidence of leaving felled logs in the forest.



Primarily, proper yield regulation is achieved through establishment of PSPs. It is the basis for growth modeling, yield prediction, sustained yield management, and other aspects of forest management (pricing logs, cash flow analysis, etc.). Hence, the reliability of the raw data from the field is vital which directly depend on the measuring crew technical knowledge and the know-how. The information gained with regard to stand dynamics and silviculture of natural forest will be effective practical tools for managing native forest sustainably.

To sustainably manage our native forest, technically sound and proper implementation of silviculture management of native forest (logging, treatments, etc.) laid out by the Forestry Department especially the practice of proper yield regulation technique and logging (i.e. RIL in compliance to MC&I)  are necessary towards achieving SFM. It is important that those involve in logging to take up the challenge to implement the concept of SFM and should not deviate from RIL guidelines in all forest operations.



Appanah, S. and Putz, F.E., 1984. Climber abundance in virgin dipterocarp forest and the effect of pre-felling climber cutting on logging damage. Malayan Forester 47: 335-342.

Bertault, J.A., Dupuy, B. and Maitre, H.F., 1992. Silviculture for sustainable management of tropical moist forest. Paper prepared for ‘Tropical Silvicultural Workshop at the Centennial Conference of the International Union Of Forestry Research Organizations (IUFRO), Berlin. 7pp.

Hooi, C.T., 1987. Forest management systems for tropical high forest, with special reference to Peninsular Malaysia. Forest Ecology and Management 21 (1-2): 3-20.

Lanly, J.P., 1995. Sustainable forest management: lessons of history and recent developments. Unasylva 46 (182): 38-45. 

Mohd Paiz, K. and Wan Mohd Shukri, W.A., 2003. Forest harvesting practices towards achieving sustainable forest management in Peninsular Malaysia. Paper submitted during International Expert Meeting on The Development and Implementation of National Codes of Practice for Harvesting – Issues and Options. 10pp.

Nicholson, D.I., 1958. An analysis of logging damage in tropical rain forest, North Borneo. Malayan Forester 21: 235-245.

Putz, F.E., 1994. Approaches to sustainable Forest Management. Working paper No 4: 7pp; Centre for International Forestry Research, Jakarta. 

Redhead, 1960, J.F., 1960. An analysis of logging damage in lowland rain forest, Western Nigeria. Nigerian Forest Information Bulletin No 10: 5-16. 

Synnott, T.J., 1979. A manual of permanent plot procedures for tropical rain forest. Tropical Forestry Papers 14, Commomwealth Forestry Institute, Oxford.

Vanclay, J.K., 1991. Data requirements for developing growth models for tropical moist forest. Commonwealth Forestry Review 70(4): 248-271.



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