Surface soil recovery occurs within 25 years for skid trails in the Brazilian Amazon

Abstract

Each year, thousands of km2 of humid tropical forest are logged in the Brazilian Amazon. Many of these areas are underlain by clay soils dominated by non-expansive kaolinite. Logging operations often entail the use of heavy machinery to drag logs through the forest on skid trails, which causes substantial soil disturbance. Therefore, the objective of this study was to investigate if soil recovery occurs over time in the studied Ferralsol. The hypothesis is that soil recovery has indeed occurred and that the trend of recovery is observable. In this endeavor, a chronosequence was established composed of four logging units that were logged 13, 19, 23, and 26 years ago, as well as a control in undisturbed old-growth forest. Samples in the upper topsoil were collected for soil bulk density (BD), fine root biomass (FRB) and various soil chemical properties. Results indicated a sequential recovery. Prior to the study period of 13–26 years after logging operations, FRB recovered. The predicted recovery of the cation exchange capacity was at approximately 15 years, which was followed by soil organic carbon at 20 years. Lastly, BD was recovered within 25 years. Overall, soil organic carbon demonstrated the greatest associations with recovery variables as it accumulated over time. Although surface soils in skid trails did indeed recover, it was a lengthy process that occurred over several decades. In this context, skid trails should be planned to minimize soil disturbance in the logging area to the greatest extent feasible.