Avaliação dos efeitos físicos no solo após exploração florestal em grande escala na Amazonia central

Abstract

In the tropical forests of the Amazon, there are still few studies on soil compaction caused by logging activities. Therefore, this study sought to increase the knowledge of the impacts to soil resources caused by legal logging operations in the Central Amazon. The evaluated operation was located on the property of a timber company using techniques and strategies based on the CELOS Harvesting System. The aim of implementing these methods is to minimize the potential impacts to the forest stand and the associated resources of the forest environment. Some of these strategies include the reduction of ground disturbance through fewer skid trails and the winching of logs. Systematic sampling was conducted in areas of ground disturbance caused by skid trail construction, log winching and machine traffic of 1, 2, 3, 5 and >10 cycles. The soil of the study site was classified as a Xanthic Ferralsol. The soil physical properties that were quantified up to 20 cm in depth were: soil bulk density and soil penetration resistance. Soil samples were taken with 100 cm 3 metal rings, and soil strength was determined with a Stolf impact penetrometer with a cone angle of 30°. The only difference between the control and areas of log winching were encountered in the 0-5 cm depth (p<0.05) and were generally not growth limiting. The skid trail construction had significant differences (p<0.05) with the control under the tracks after one cycle in all 4 depths, but between the tracks, there was only a difference (p<0.05) in the surface layer of 0-5 cm, and this was not growth limiting. In the evaluation of machine traffic, the greatest increase in compaction occurred under the tracks of the D6M tractor after the 1rst cycle. The critical values for growth limitation did not occur between the tracks until after the 2nd cycle of the 525B Skidder, which was the 3rd total cycle when combined with trail construction and log skidding. The conclusion of this study was that the use of the techniques based on the CELOS Harvest Sistem such as log winching and minimal skid trail construction reduced the impact of soil compaction in the area studied.