Soil communities following harvest have different early successional dynamics compared with post-wildfire patterns

Abstract

Abstract Stand-replacing wildfire is the primary natural disturbance in jack pine-dominated boreal forests; but clearcut harvest also emulates this natural renewal process. We used a 60-year clearcut harvest chronosequence to assess whether soil communities became more similar to those in wildfire-origin stands over time. We assessed convergence across disturbance types at each stand development stage and recovery compared to the wildfire mature stand development stage (~ 85 years). To evaluate cumulative effects, we also assessed a 20-year salvage harvest chronosequence where wildfire was followed by salvage logging of fire-killed trees. Beta diversity analyses showed different recovery times among soil taxa. Following clearcut harvest, bacteria converged to wildfire reference conditions more quickly, followed by arthropods, whereas fungi did not converge within the study period. Soil communities in salvage-logged sites diverged from clearcut harvest and wildfire references suggesting compounded disturbance effects. This work showcases how highly-scalable DNA metabarcoding and bioinformatic tools can be applied to simultaneously monitor a diverse array of soil biota. In future work, tracking fungal and arthropod soil communities may provide more insights into the longer-term effects of current forest management practices and provide guidance when comparing alternative approaches.