Long‐term increase in snow depth leads to compositional changes in arctic ectomycorrhizal fungal communities

Abstract

Many arctic ecological processes are regulated by soil temperature that is tightly interconnected with snow cover distribution and persistence. Recently, various climate-induced changes have been observed in arctic tundra ecosystems, e.g. shrub expansion, resulting in reduction in albedo and greater C fixation in aboveground vegetation as well as increased rates of soil C mobilization by microbes. Importantly, the net effects of these shifts are unknown, in part because our understanding of belowground processes is limited. Here, we focus on the effects of increased snow depth, and as a consequence, increased winter soil temperature on ectomycorrhizal (ECM) fungal communities in dry and moist tundra. We analyzed deep DNA sequence data from soil samples taken at a long-term snow fence experiment in Northern Alaska. Our results indicate that, in contrast with previously observed responses of plants to increased snow depth at the same experimental site, the ECM fungal community of the dry tundra was more affected by deeper snow than the moist tundra community. In the dry tundra, both community richness and composition were significantly altered while in the moist tundra, only community composition changed significantly while richness did not. We observed a decrease in richness of Tomentella, Inocybe and other taxa adapted to scavenge the soil for labile N forms. On the other hand, richness of Cortinarius, and species with the ability to scavenge the soil for recalcitrant N forms, did not change. We further link ECM fungal traits with C soil pools. If future warmer atmospheric conditions lead to greater winter snow fall, changes in the ECM fungal community will likely influence C emissions and C fixation through altering N plant availability, fungal biomass and soil-plant C-N dynamics, ultimately determining important future interactions between the tundra biosphere and atmosphere.

Abrupt changes in the composition and function of fungal communities along an environmental gradient in the high Arctic

“…Several studies have experimentally demonstrated that the composition and function of fungal communities shift in response to increased snow accumulation or temperature (Deslippe, Hartmann, Simard, & Mohn, ; Geml et al., , ; Morgado et al., , ; Mundra et al., ; Semenova et al., , ). However, further investigations are needed, since complex interactions may occur with habitat type (Morgado et al., ), changes in N deposition (Lilleskov et al., ), date of snowmelt (Schmidt et al., ), microbial activity in winter (Aanderud, Jones, Schoolmaster, Fierer, & Lennon, ; Buckeridge & Grogan, ; Schimel, Bilbrough, & Welker, ; Semenchuk et al., ), floristic composition or climatic variability.…”

“…Several studies have experimentally demonstrated that the composition and function of fungal communities shift in response to increased snow accumulation or temperature (Deslippe, Hartmann, Simard, & Mohn, 2012;Geml et al, 2015Geml et al, , 2016Morgado et al, 2015Morgado et al, , 2016Mundra et al, 2016;Semenova et al, 2015Semenova et al, , 2016.…”

“…Unlike plants and animals, fungi do not decrease in richness from the Low to the high Arctic (Bjorbækmo et al., ; Timling & Taylor, ). Nonetheless, clear shifts in fungal composition have been observed across gradients of bioclimates, primary succession and nitrogen (N) deposition (Bjorbækmo et al., ; Blaalid et al., ; Fujimura & Egger, ; Lilleskov, Hobbie, & Horton, ; Timling et al., ), in response to varying soil chemical properties (Siciliano et al., ), or amongst habitats and rhizospheres of contrasting plant species in the Arctic (Morgado et al., ; Shi et al., ; Timling, Walker, Nusbaum, Lennon, & Taylor, ; Wallenstein, McMahon, & Schimel, ). Fungi are essential for the functioning of arctic ecosystems and control much of the carbon (C) balance (Dahlberg & Bültmann, ).…”

Tundra is a consistent source of CO2 at a site with progressive permafrost thaw during 6 years of chamber and eddy covariance measurements

“…Biological drivers potentially tied to fluxes are improved species performance [ Chapin and Shaver , ; Oberbauer et al, ], shift in plant communities [ Walker et al , ; Schuur et al , ; Myers‐Smith et al , ; Hollister et al , ], and herbivory [ Welker et al , ; Kelsey et al , ]. The warming of soils and thawing of permafrost stimulate soil organic matter decomposition [ Mackelprang et al , ; Schädel et al , ; Xue et al , ] and increase heterotrophic respiration from soils result in a positive feedback to the atmospheric CO 2 concentration but will depend on snow accumulation [ Nowinski et al , ; Blanc‐Betes et al , ] and changes in soil community abundance and composition [ Mohan et al , ; Morgado et al , ; Parker et al , ; Semenova et al , ; Geml et al , ; Morgado et al , ]. Increased CO 2 loss may, however, be counteracted by increases in net primary production (NPP) as plant productivity increases [ Epstein et al , ] and the plant community shifts from graminoid to shrub dominance [ Sturm et al , ; Walker et al , ; Myers‐Smith et al , ; Pearson et al , ; Hollister et al , ].…”

The effects of increased snow depth on plant and microbial biomass and community composition along a precipitation gradient in temperate steppes

“…Together these mechanisms can increase water and nutrient supply for soil microbes and plants (Groffman et al, 2006;Buckeridge et al, 2010). In addition, greater snow accumulation could also alter both plant and microbial community compositions (Zinger et al, 2009;Kreyling et al, 2012;Bokhorst et al, 2013;Morgado et al, 2016;Semenova et al, 2016).…”