Mimicking climate warming effects on Alaskan soil microbial communities via gradual temperature increase

Abstract

Climate change can trigger shifts in community structure and may therefore pose a severe threat to soil microbial communities, especially in high northern latitudes such as the Arctic. Arctic soils are covered by snow and ice throughout most of the year. This insulation shields them from high temperature variability and low surface temperatures. If this protective layer thaws, these soils are predicted to warm up at 1.5x to 4x the rate of other terrestrial biomes. In this study, we sampled arctic soils from sites with different elevations in Alaska, incubated them for 5 months with a simulated, gradual or abrupt temperature increase of +5 °C, and compared bacterial and fungal community compositions after the incubation. We hypothesized that the microbial communities would not significantly change with a gradual temperature treatment, whereas an abrupt temperature increase would decrease microbial diversity and shift community composition. The only differences in community composition that we observed were, however, related to the two elevations. The abrupt and gradual temperature increase treatments did not change the microbial community composition as compared to the control indicating resistance of the microbial community to changes in temperature. This points to the potential importance of microbial dormancy and resting stages in the formation of a "buffer" against elevated temperatures. Microbial resting stages might heavily contribute to microbial biomass and thus drive the responsiveness of arctic ecosystems to climate change.

Responses of Cyanobacterial Crusts and Microbial Communities to Extreme Environments of the Stratosphere

“…At the RNA level, microbial community composition results showed that Chloroflexi and Gemmatimonadetes were more resistant to the extreme stratospheric environment than Cyanobacteria, especially Kallotenue and Longimicrobium (Figure 4). Chloroflexi is a dominant bacterial phylum in many extreme environments, such as alkaline hot springs, deep lakes, and arctic soils [59][60][61]. Chloroflexi can be photoautotrophic, chemoautotrophic, or mixotrophic, and they can adapt their metabolic strategy depending on the prevailing environmental conditions [62,63].…”

Impact of long-term fertilizer and summer warming treatments on bulk soil and birch rhizosphere microbial communities in mesic arctic tundra

“…Some long-term warming studies on microbial communities have shown alterations of both soil bacterial and fungal communities (Deslippe et al 2012). However, other studies have demonstrated a decrease in soil microbial growth or no significant changes (Lamb et al 2011;Rinnan, Michelsen, and Bååth 2011;Ballhausen et al 2020), with still others showing increased microbial nutrient mobilization only if competing plants are eliminated (Schmidt et al 2002). It is likely that both abiotic and biotic factors play a role in explaining these variable responses.…”

“…It would be interesting to continue monitoring these warmed plots in the future because significant impact of warming on soil communities may require longer experimental treatment time than a dozen years, although it is noted that not all researchers support longer-term experiments (Ballhausen et al 2020). Alternatively, because temperatures in the greenhouses on rare extremely warm days can rise as much as 13°C above ambient (Zamin and Grogan 2012), combined with rising background climate change-associated increases, future warming experiments could provide unrealistic conditions for arctic soil communities and unduly stress the plants.…”

“…Changes in tundra soil fertility resulting from increased seasonal temperatures are likely to be slow and cumulative (Ballhausen et al 2020;Hobbie, Nadelhoffer, and Högberg 2002), which points to the importance of extended experiments to evaluate the effect of warming on soil communities. Long-term greenhouse experiments, as well as nutrient addition plots, were established in moist acidic tundra soils near Toolik Lake, Alaska, in 1988 as part of the Arctic Long-Term Ecological Research experiments to simulate aspects of prolonged climate change.…”

Warming alters cascading effects of a dominant arthropod predator on microbial community composition in the Arctic

“…The soil microbial community can be structured by warming via three main pathways: 1) direct abiotic effects of temperature, and indirect biotic interactions mediated by 2) plants and 3) higher level consumers. Microbial community structure may not be sensitive to a few degrees of Celsius warming in a short term (~ a few months) as demonstrated in lab incubations (11,12) but see (13). On the other hand, microbial communities may be structured by indirect effects mediated by plants which can instantly respond to warming (14).…”