Disturbances have altered community dynamics in boreal forests with unknown consequences for belowground ecological processes. Soil fungi are particularly sensitive to such disturbances; however, the individual response of fungal guilds to different disturbance types is poorly understood. Here, we profiled soil fungal communities in lodgepole pine forests following a bark beetle outbreak, wildfire, clear-cut logging, and salvage-logging. Using Illumina MiSeq to sequence ITS1 and SSU rDNA, we characterized communities of ectomycorrhizal, arbuscular mycorrhizal, saprotrophic, and pathogenic fungi in sites representing each disturbance type paired with intact forests. We also quantified soil fungal biomass by measuring ergosterol. Abiotic disturbances changed the community composition of ectomycorrhizal fungi and shifted the dominance from ectomycorrhizal to saprotrophic fungi compared to intact forests. The disruption of the soil organic layer with disturbances correlated with the decline of ectomycorrhizal and the increase of arbuscular mycorrhizal fungi. Wildfire changed the community composition of pathogenic fungi but did not affect their proportion and diversity. Fungal biomass declined with disturbances that disrupted the forest floor. Our results suggest that the disruption of the forest floor with disturbances, and the changes in C and nutrient dynamics it may promote, structure the fungal community with implications for fungal biomass-C.

No abstract

Disturbances are frequent events across the Canadian boreal forest and can affect both below‐ and above‐ground ecosystem processes. How disturbances change below‐ground soil fungal communities and in‐turn affect pine establishment and performance is poorly understood. Such understanding has become increasingly important in light of observed changes in disturbance regimes in recent years due to climate change. We used a greenhouse experiment to determine how soil inoculum collected from lodgepole pine stands undisturbed (control) or disturbed by fire, mountain pine beetle outbreak, logging and salvage logging affect pine seedling performance in western Canada. We first characterized whether fungal communities of seedling roots change as a function of inoculum source, and then determined whether changes in fungal community composition impact pine seedling performance (biomass and height). Root fungal communities of pine seedlings from logged and salvage logged disturbances differed from their respective paired controls, while soils from natural disturbances (fire and beetle outbreak) did not. Among disturbances, the pine root fungal communities of fire and salvage logged disturbances differed. In parallel to the root fungal communities, seedling performance also decreased when comparing logging and salvage logging disturbances to paired controls. Among disturbance treatments, seedlings from the salvage logged disturbance did not grow as big as seedlings inoculated with soils from burned forests. Synthesis and application. Our findings indicate that anthropogenic disturbances (logging and salvage logging) can have cross‐generational impacts on pine seedling performance, through functional shifts in seedling root fungal community structure. Furthermore, the impacts of soil fungi on pine seedlings appear to be pronounced following salvage logging, stressing the importance of compound disturbance events. These findings may be important to land managers considering clear‐cut logging or salvage logging in pine forests, particularly where soil biotic communities are likely to be one of the predominate factors in pine establishment.

No abstract

No abstract