Changes in soil fungal communities following anthropogenic disturbance are linked to decreased lodgepole pine seedling performance

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.

Soil transfers from intact to disturbed boreal forests neither alter ectomycorrhizal fungal communities nor improve pine seedling performance

“…Despite evidence of higher EMF abundance and shifts in community composition in soils of late‐successional forests compared to disturbed sites (Rodriguez‐Ramos et al, 2021), and that these soils influenced seedling performance in the greenhouse when used as inoculum (Beck et al, 2020), soil transfer volumes did not change the soil and root EMF communities. Wubs et al (2016) observed shifts in fungal community composition in grassland restoration using 2.51 L/m 2 .…”

“…Soil volumes of 150 ml have previously been used in field settings to enhance mycorrhizal formation in conifer seedlings (Amaranthus & Perry, 1987). In a simultaneous greenhouse study, we tested the inoculum potential of soils (15 ml of inoculum added to 350 ml of soil) from the same disturbed and late‐successional stands and found that root‐associated EMF communities differed by inoculuem origin demonstrating: (a) viable propagules were present, and (b) the inoculum differed by site (Beck et al, 2020). In this latter study, seedlings inoculated with soils from late‐successional forests were colonized by EMF from the genera Wilcoxina , Suillus , Rhizopogon , Tuber and Piloderma .…”

“…Soil microbial communities from late‐stage successional ecosystems to recipient recovering sites may benefit target plant species (Wubs et al, 2016). In boreal forests, evidence from greenhouse studies suggests that EMF from late‐successional conspecific forests can enhance pine seedling growth, and that disturbances can reduce pine growth by modifying EMF communities (Beck et al, 2020; Karst et al, 2015). Thus, late‐succession forests are logical soil sources for any in‐situ restoration.…”

Do Bioinoculants Affect Resident Microbial Communities? A Meta-Analysis

“…Additionally, faster growth rates and larger populations sizes of bacteria compared to fungi mean there may be more opportunity for novel mutations able to quickly adapt to changes to the environment (Hibbing et al, 2010). As well, soil fungal communities tend to be more closely aligned with plant communities both for mutualists (Cassman et al, 2016;Zhang et al, 2021) and saprobes (Francioli et al, 2020), thus we may expect less change in their communities without concurrent changes to vegetation (van der Heijden et al, 1998;Beck et al, 2020).…”

Resilience impacts of a secondary disturbance: Meta‐analysis of salvage logging effects on tree regeneration

“…Beyond its direct effects on seedling or sapling survival, salvage logging can also impact tree regeneration by increasing microclimatic stress (Marañón‐Jiménez et al, 2013) and reducing mutualistic interactions such as mycorrhization (Beck et al, 2020) and seed dispersal (Leverkus & Castro, 2017). However, salvage logging could also enhance regeneration through mechanisms such as soil scarification, increased irradiance and seed dissemination during logging operations (Peterson et al, 2009; Royo et al, 2016).…”