The study was carried out in a tropical natural forest of the Guyana Shield in the Forest Belt of Suriname close to Kabo, district of Para. One of the numerous small concession holders serving the local timber market was identified and proved willing to host this study, which required the application of "planned" harvesting on the co-operator's timber concession, number 387. The objective was to provide a comprehensive analysis of planned harvesting as an alternative to the conventional way of logging as usually carried out in Suriname.
The study documents each phase of the conventional logging system, which is used almost exclusively in Suriname's small timber concessions and was applied on one sample plot at the study site. The productivity and environmental impacts associated with this system are compared with those of planned harvesting as applied on the other sample plot in Concession 387.
Data on the two harvesting operations were collected under almost identical conditions. Work and time studies on harvesting activities in both systems, and post-harvest assessments of environmental impacts, were carried out in the adjacent sample plots at the study site.
Felling in the conventional system was done by unskilled workers hired by the concessionaire and using the concessionaire's equipment. The same chainsaw operator was employed for felling in planned harvesting, but this time guided by the team leader of the inventory crew using the tree location map for the sample plot.
For the timber extraction phase, the skidders and skidding crew of a logging contractor employed by the concessionaire were used in both systems. In planned harvesting, however, the skidding crew was guided by the team leader of the inventory crew using the tree location map.
The average time required to fell a single tree was greater in the conventional logging system (8.67 min) than in planned harvesting (7.92 min) due to the time spent by the chainsaw operator (almost 10% of total time) searching for harvestable trees under the conventional system. Expressed in terms of volume recovered, felling productivity averaged 12.74 m³/h of workplace time under planned logging as compared to only 9.25 m³/h of workplace time under conventional logging.
Skidding time for a single log under the conventional system, due to the time spent by the skidder operator searching for logs (again about 10% of total time), was significantly greater (23.87 min) than under planned harvesting (17.83 min). A similar result was found when comparing the productivity of the two harvesting systems with similar average log volumes per tree extracted. For skidding under planned harvesting, productivity averaged 8.15 m³/h of workplace time, whereas skidding productivity under conventional logging averaged only 5.91 m³/h of workplace time.
If the labour cost per cubic metre of logs delivered to the landing under conventional logging is assigned an index value of 100%, then the comparable cost under planned harvesting would amount to only 77.5%, despite the additional labour cost required for pre-harvest inventory under planned harvesting. The substantially higher felling and skidding productivity under planned harvesting not only offsets the additional cost of the pre-harvest inventory but reduces the overall labour cost by more than 20%.
Investigation of timber losses revealed considerable potential for improvement. Timber wastage ranged between 11.7% and 15.7% on the sample plots. In applying planned harvesting, timber losses related to missed trees could be avoided, which, by contrast, amounted to about 5% under the conventional system. However, the main timber losses observed during the study resulted from improper felling techniques.
The superiority of planned forest harvesting over the conventional logging system is also underscored by the assessment of environmental impacts for both systems.
Since the estimate of damage to residual trees was restricted to principal tree species (about 15 species), the percentages of residual trees found damaged on both sample plots were extremely low: 5.5% for conventional logging and 2.5% for planned harvesting. However, for the latter no damage was registered during skidding operations, whereas skidding damage was observed on the conventional logging operation.
For the planned harvesting system an average of about 5.4% of the area harvested was affected by primary skidtrails, whereas in conventional logging the corresponding value more than twice as high-12.4%. In addition, conventional logging utilized secondary skidtrails, thus disturbing an additional area of soil which is not included in this figure.
Canopy opening by tree felling ranged from 6.5% to 7.7% of the area for the two sample plots. Through directional felling, gap size could theoretically be controlled. However, chainsaw operators capable of applying directional felling techniques were not available during the time of this study. This highlights an important training need if logging practices are to be improved in the future.
Perhaps the most important finding of this study is that planned timber harvesting can reduce costs significantly by comparison with conventional logging, in contrast to the strongly held belief that "reduced-impact" logging must necessarily cost more than "high-impact" logging. The results of this study suggest a labour-cost advantage of more than 20% for planned harvesting as compared to conventional logging. This result is of course specific to the conditions under which this study was conducted and cannot easily be generalized. In particular, the relative wages of operators, assistants and members of the inventory crew, as well as conditions of timber, climate, and topography, should be considered carefully when comparing cost estimates for the two systems considered in this report with those for other countries or even other areas within Suriname.
There is widespread agreement that the rapid and extensive adoption of environmentally sound forest harvesting is perhaps the highest single priority in the effort to promote sustainable forest management. Harvesting systems that reduce costs while at the same time reducing environmental impacts have the potential to permit the production of tropical forest products in ways that will simultaneously benefit timber producers, consumers, society at large, and the environment. The results of this and further case studies that might be undertaken in the region could serve as a basis for developing regional and national codes of forest harvesting practice. An important goal of such codes of practices is to improve standards of utilisation while at the same time substantially reducing environmental impacts associated with timber harvesting.