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

Max-Bernhard Ballhausen,Matthias C Rillig,Rebecca Hewitt

doi:10.1038/s41598-020-65329-x

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.

Highlights

Climate change can trigger shifts in community structure and may pose a severe threat to soil microbial communities, especially in high northern latitudes such as the Arctic
Per sample, six independent PCR reactions consisting of 16.25 μl water, 5 μl KAPA HiFi Fidelity Buffer, 0.75 μl dNTPs, 0.75 μl of primers 515 f and 806r targeting theV4 region of the 16 S rDNA, 0.5 μl KAPA HiFi DNA Polymerase, and 1 μl template DNA were run in a 25 μl reaction volume with the following conditions: 95 °C for 30 sec, followed by 30 steps of 98 °C for 30 sec, 55 °C for 30 sec, and 72 °C for 30 sec, and a elongation at 72 °C for 5 min
This translated into a total of 2,888 fungal and 19,298 bacterial Exact Sequence Variants (ESVs)

Summary

Introduction

Climate change can trigger shifts in community structure and may pose a severe threat to soil microbial communities, especially in high northern latitudes such as the Arctic. Even though the short growing season leaves only a short time window for reproduction, fungi in this biome have a long lifespan and slow population growth, which results in lower population turnover as compared to more temperate climates[6] It has, been reported that the slow and steady fungal growth can produce 10 times more fungal than bacterial biomass in arctic soils. Microbial diversity has been shown to be negatively correlated with elevation[15], positively influenced by elevation[16], and to rather be dependent on abiotic soil parameters like pH or snow cover, or biotic factors like plant community composition[17,18]. Kotas et al.[19] find no significant shifts in abundance or community composition of fungi or bacteria associated with elevation

Methods

Results

Conclusion