Support for reevaluation of policy prohibiting logging operations in the wet season for the Brazilian Amazon.

In the Brazilian Amazon, logging is primarily restricted to the driest months of the year by law. Even so, the dry season in the humid tropics is susceptible to considerable rain events, with rain occurring monthly. Therefore, an experiment was established in unentered Central Amazonian old-growth forest to compare skid trail use in the wet season, when logging operations are not permitted, as well as in the dry season. This was done to investigate the differences in soil compaction for the season closed to logging versus the season open to logging. A randomized complete block design (RCBD) was utilized with three blocks composed of seven sub-blocks each, which contained a control, 1, 3 and 12 tractor cycles in both the wet and dry seasons. A Caterpillar track-type tractor model D6D was used for experimental skid trail establishment. Regardless of season the initial machine cycle caused the greatest increase in soil bulk density (BD) and penetration resistance (PR), as well as the greatest decrease in macroporosity. In fact, the initial dry season cycle caused more severe compaction than the wet season. Nevertheless, after 3 cycles, increases to BD and PR were similar for both seasons, with the end result after 12 cycles nearly identical. To the contrary, macroporosity was substantially reduced in the dry season versus the wet season. Overall, the site impacts were similar in both seasons. Thus, skidding operations could be permissible during the wet season with similar impacts caused in the dry season. [ABSTRACT FROM AUTHOR]