Soil fungal responses to warming in polar regions

Misiak, Marta. 2018 Soil fungal responses to warming in polar regions. Cardiff University and British Antarctic Survey, PhD Thesis, 176pp.

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Abstract/Summary

Polar regions are subjected to rapid climate change, with increased air temperatures and precipitation being predicted during future decades. Rising temperatures and precipitation will have an effect on saprotrophic soil fungi, microbes key to nutrient cycling and decomposition processes that are dominant in polar soils owing to their abilities of remaining physiologically active at low temperatures and water availabilities. Here, a combination of field warming experiments and laboratory experiments are used to investigate the effects of warming, water and nutrient availability on the abundance, growth and enzyme activities (cellulase, chitinase, acid and alkaline phosphatase and leucine aminopeptidase) of a range of saprotrophic fungi in Arctic and Antarctic soils. In a five-year-long maritime Antarctic field experiment, the abundance of Pseudogymnoascus pannorum DNA was reduced in soil warmed with open top chambers (OTCs) that had been enriched with nutrients. Laboratory experiments confirmed the inhibitory effect of warming to > 21 °C on the growth and enzyme activities of P. pannorum, but only when water was not a limiting factor. In contrast, in an Arctic field experiment, OTCs and watering had no effects on the abundance of DNA of seven Arctic soil fungal taxa after three years of treatment. The growth of five Arctic taxa (Acremonium sp., Isaria sp., Leptosphaeria sp., Phialocephala sp. and Mortierella spp.) was increased by warming to > 21 °C, with only that of P. pannorum being inhibited by warming to 24 °C. Warming did not affect the enzyme activities of Arctic fungi, with activities mainly being influenced by changes in water potential. The research here suggests that the growth and enzyme activities of Antarctic P. pannorum may be inhibited by future warming arising from continued greenhouse gas emissions to the atmosphere, but that Arctic saprotrophic soil fungi appear to be more resilient to environmental changes.