Temporal variation of Bistorta vivipara‐associated ectomycorrhizal fungal communities in the High Arctic

Abstract

Ectomycorrhizal (ECM) fungi are important for efficient nutrient uptake of several widespread arctic plant species. Knowledge of temporal variation of ECM fungi, and the relationship of these patterns to environmental variables, is essential to understand energy and nutrient cycling in Arctic ecosystems. We sampled roots of Bistorta vivipara ten times over two years; three times during the growing-season (June, July and September) and twice during winter (November and April) of both years. We found 668 ECM OTUs belonging to 25 different ECM lineages, whereof 157 OTUs persisted throughout all sampling time-points. Overall, ECM fungal richness peaked in winter and species belonging to Cortinarius, Serendipita and Sebacina were more frequent in winter than during summer. Structure of ECM fungal communities was primarily affected by spatial factors. However, after accounting for spatial effects, significant seasonal variation was evident revealing correspondence with seasonal changes in environmental conditions. We demonstrate that arctic ECM richness and community structure differ between summer (growing-season) and winter, possibly due to reduced activity of the core community, and addition of fungi adapted for winter conditions forming a winter-active fungal community. Significant month × year interactions were observed both for fungal richness and community composition, indicating unpredictable between-year variation. Our study indicates that addressing seasonal changes requires replication over several years.

Community structure and functional group of root‐associated Fungi of Pinus sylvestris var. mongolica across stand ages in the Mu Us Desert

“…The proportion of RAF genera showed strong heterogeneity in the different age groups, even though the top genera were similar in fungal community composition, and this evenness decreased with increasing stand age. In each age group, there were more than 130 genera which distributed unequally, confirming the results of previous research on intraspecific compositional diversity, even at fine‐scales (Bahram, Polme, Koljalg, & Tedersoo, ; Mundra et al, ). The nonuniformity in fungal distribution derived from stand age can be explained by vegetative growth, root growth, and root exudates.…”

Biogeography of plant root‐associated fungal communities in the North Atlantic region mirrors climatic variability

“…Although community structure was clearly linked to climatic variables, the plant roots were not sampled at the same time for the different sites in this study, and temporal variation in the fungal communities could in theory affect some of the difference observed. Temporal variation has been observed in RAF in the High Arctic, however, spatial factors were found to be the more important in shaping the community assembly (Mundra et al, ). In this study, we had two independent datasets from mainland Norway sampled at different time points, and they cluster close together in the ordination, indicating again the importance of geography and climate.…”

Can root-associated fungi mediate the impact of abiotic conditions on the growth of a High Arctic herb?

“…To test our hypotheses, we selected alpine bistort Bistorta vivipara (L.) Delarbre ( Polygonaceae ), a model plant to study root-associated microbial communities in alpine 6,[31][32][33][34][35] and arctic habitats 7,19,[36][37][38][39][40] . Bistorta vivipara is a common, long-lived perennial herb in the northern hemisphere.…”

“…The following edaphic parameters, representing critical properties of the abiotic environment, were measured in all datasets: pH, soil nitrogen concentration (N) and carbon to nitrogen ratio (C/N; used as an indicator for soil nitrogen availability or soil fertility). Edaphic variables were obtained in the same way for all datasets (described in detail in 7,19,40 ).…”