Soil microbiome feedbacks during disturbance-driven forest ecosystem conversion

Abstract

Disturbances cause rapid changes to forests, with different disturbance types and severities creating unique ecosystem trajectories that can impact the underlying soil microbiome. Pile burning – the combustion of logging residue on the forest floor – is a common fuel reduction practice that can have impacts on forest soils analogous to those following high severity wildfire. Further, pile burning following clear-cut harvesting can create persistent openings dominated by non-woody plants surrounded by dense regenerating conifer forest. A paired 60-year chronosequence of burn scar openings and surrounding regenerating forest after clear-cut harvesting provides a unique opportunity to assess whether belowground microbial processes mirror aboveground vegetation during disturbance-induced ecosystem shifts. Soil ectomycorrhizal fungal diversity was reduced the first decade after pile burning, which could explain poor tree seedling establishment and subsequent persistence of herbaceous species within the openings. Fine-scale changes in the soil microbiome mirrored aboveground shifts in vegetation, with short-term changes to microbial carbon cycling functions resembling a post-fire microbiome (e.g., enrichment of aromatic degradation genes) and respiration in burn scars decoupled from substrate quantity and quality. Broadly, however, soil microbiome composition and function within burn scar soils converged with that of the surrounding regenerating forest six decades after the disturbances, indicating potential microbial resilience that was disconnected from aboveground vegetation shifts. This work begins to unravel the belowground microbial processes that underlie disturbance-induced ecosystem changes, which are increasing in frequency tied to climate change.

Effects of Substrate Composition on the Growth Traits of Grafted Seedling in Macadamia (Macadamia integrifolia) Nuts

“…Our results also showed that after 13 months, the substrate composition changed dramatically compared to that at 0 months. These may be related to microbiome feedback during macadamia plant growth in these substrates [ 40 ]. Tropical peat soils are generally defined as soils formed by the accumulation of partially decayed woody plant materials under waterlogged condition [ 41 ].…”