FOREST HARVESTING CASE STUDY 19
Environmentally sound forest harvesting in Brazil
Assessment of regeneration and environmentalimpacts four years after harvesting
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This case study is one of a series of publications produced by the Forest Harvesting, Trade and Marketing Branch of FAO in an effort to promote environmentally sound forest harvesting and engineering practices. The purpose of these studies is to highlight both the promise of environmentally sound forest harvesting technologies as a component of sustainable forest management, and the constraints that must be overcome in order to assure widespread adoption of those technologies.
The FAO Forest Products Department wishes to express its appreciation to Precious Woods AG (Zurich, Switzerland) and to Precious Woods Amazon (MIL Madeireira Itacoatiara Ltda., Itacoatiara, Amazonas, Brazil) for their encouragement and cooperation in the preparation of this case study as well as the original 1996 study, which was documented by Norbert Winkler in report no. 8 of this series of case-study publications. For the present study, special thanks are due to João Cruz Rodrigues, forest director of MIL Madeireira, and Marcelo Argüelles de Souza, forest staff member of MIL Madeireira, for their assistance and collaboration throughout the period of field work.
The field studies and analyses described out in this report were carried out by Stefan Wellhöfer, a consultant for FAO, who also prepared the written report. FAO Forestry Officer Joachim Lorbach managed the preparation of the report for publication in the FAO Forest Harvesting Case-Study Series. Editing and final layout for publication were done by Dennis Dykstra.
The study reported in this document was carried out as a follow-up to a previous study in this series, which was documented by Winkler (1997). Both studies were undertaken in a managed natural forest near Itacoatiara, about 230 km west of Manaus, in the Amazon region of Brazil. The two studies were conducted in collaboration with Precious Woods Amazon (PWA), the Brazilian subsidiary of Precious Woods AG located in Zurich, Switzerland.
Like the study of Winkler, the re-examination reported here was conducted in Block 312/9668 of Compartment B of the PWA Project. Two plots, B/F09 (which was treated with “conventional” logging) and B/G09 (treated with PWA's “environmentally sound” harvesting system), were harvested in 1996. Since then, no further treatments have been applied.
The purpose of this re-examination was to assess the condition of the forest four years after logging had been completed. For this purpose, assessments were undertaken of regeneration within felling gaps and on skidtrails, water infiltration rates on skidtrails, the current status of potential crop trees (PCTs), and the condition of residual trees of commercial species.
Regeneration in felling gaps was measured by establishing five, 2 m × 2 m sample plots in each of four felling gaps located within each of the two treated areas. All seedlings, saplings, and poles within each sample plot were counted and identified, and the diameter of each stem 10 cm above the ground was recorded. On the basis of this assessment it was established that regeneration of both commercial and non-commercial tree species is generally satisfactory and appears adequate to permit full recovery of the forest ecosystem over time. In addition, there is no significant difference in the numbers or sizes of tree regeneration, or in the numbers of tree species regenerating, between the two treatment areas.
Regeneration on skidtrails was assessed to give an impression of the influence on regeneration of heavy soil compaction by harvesting machines in the yellow latosol soils that are common in the part of the Amazon Basin where PWA's operations are located. The assessment was conducted by establishing 20, 2 m × 2 m sample plots on skidtrails in each of the treatment areas. Procedures followed were the same as those in the felling gaps except that regeneration in ruts was recorded separately from regeneration growing in other parts of the skidtrail. The evaluation showed, not surprisingly, that there is significantly less regeneration in skidtrail ruts than in the less deeply disturbed side strips or centre strips of the skidtrails. There was no significant difference between regeneration on skidtrails in the two treatment areas. However, the plot treated with conventional logging was much more heavily covered with skidtrails than the plot treated with environmentally sound harvesting. Winkler (1997) showed that almost 20% of the area logged conventionally was in skidtrails, compared to only 4.5% of the area harvested with improved techniques. In the long run this difference is likely to have a significant effect on overall regeneration of the respective areas.
Water infiltration rates on skidtrails were assessed by using an infiltrometer produced locally with simple pipes. The test was somewhat inconclusive because it was conducted after 10 days of rain and infiltration rates were generally low. There was no significant difference in infiltration rates between the two treatment areas, but the test did suggest that the ruts of skidtrails were heavily compacted, even on secondary skidtrails used for only one or two trees. As with regeneration on skidtrails, this implies that a much higher fraction of the total area was heavily compacted on the conventionally logged area than on the area treated with environmentally sound logging. This is due to the fact that the former has four times as much area in skidtrails as the latter. Even though regeneration occurs at approximately the same rate on the two areas, the long-term survival and growth of seedlings therefore seems likely to be much lower on the conventionally logged area.
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, © FAO 2002
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SYMBOLS AND ACRONYMS
2. DESCRIPTION OF THE STUDY AREA
2.1 The PWA project area
2.2 Climatic conditions
2.3 Soil conditions
2.4 Forest composition
2.5 Description of the study plots
3. LOGGING SYSTEMS USED IN THE STUDY AREAS
3.1 Conventional logging in the Amazon region
3.2 Environmentally sound harvesting as implemented by PWA
3.2.1 Harvest planning
3.3 Felling system
3.4 Extraction operations
3.4.3 Operations at the landing
3.6 Description of the logging equipment
3.7 Forest road construction
3.8 Operational costs
4. LABOUR FORCE AND COMPENSATION OF WORKERS
5. STUDY METHODOLOGY AND ANALYSIS OF DATA
5.1 Assessment of regeneration
5.1.1 Assessment of regeneration in canopy gaps
5.1.2 Assessment of regeneration on skidtrails
5.2 Assessment of PCTs and other harvestable trees
6. CONCLUSION AND RECOMMENDATIONS
6.1 General development of PWA
6.1.1 Development of the forestry sector
6.1.2 Development of the processing sector
|DBH||diameter at breast height|
|PCT||potential crop tree (a tree of commercial species that is expected to be harvested during a subsequent harvesting operation)|
|PWA||Precious Woods Amazon, Itacoatiara, Amazonas, Brazil|