Predicting climate change impacts on maritime Antarctic soils: a space-for-time substitution study

Horrocks, Claire; Newsham, Kevin K.; Cox, Filipa; Garnett, Mark H.; Robinson, Clare H.; Dungait, Jennifer A. J.

doi:10.1016/j.soilbio.2019.107682

Cited by 15 publications

(10 citation statements)

References 64 publications

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“…In the former setting, the growth of the fungus was only suppressed by temperatures cycling daily to >20°C when water was freely available, and, in the field, only in irrigated soils to which organic C and N had been applied. Together, these observations broadly suggest that further warming of maritime Antarctica, in combination with organic C and N inputs from expanding plant populations (Amesbury et al, 2017;Cannone et al, 2016;Horrocks et al, 2020) and enhanced water availability arising from increased precipitation, snow melt or localized flooding (Adams et al, 2009;Fox & Cooper, 1998;Medley & Thomas, 2019;Robinson et al, 2020), is likely to inhibit the growth of P. roseus in soil. Given that soil surface temperatures at Mars Oasis already reach 19°C during summer, the observations suggest that surface warming of only a few degrees Celsius, equivalent to that anticipated in the maritime Antarctic over the next few decades under moderate greenhouse gas emission scenarios (Bracegirdle et al, 2008;Bracegirdle & Stephenson, 2012), will elicit these effects at the study site.…”

Section: Discussionmentioning

confidence: 95%

Inhibitory effects of climate change on the growth and extracellular enzyme activities of a widespread Antarctic soil fungus

Misiak

Goodall‐Copestake

Sparks

et al. 2020

Global Change Biology

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Temperatures approaching or exceeding 20°C have been measured during summer in polar regions at the surfaces of barren fellfield soils under cloudless skies around solar noon. However, despite the upper temperature limit for the growth of cold-adapted microbes-which are abundant in polar soils and have pivotal roles in nutrient cyclingtypically being close to this temperature, previous studies have not addressed the consequences of climate change for the metabolism of these organisms in the natural environment. Here in a 5-year field experiment on Alexander Island in the southern maritime Antarctic, we show that the abundance of Pseudogymnoascus roseus, the most widespread decomposer fungus in maritime Antarctic fellfield soils, is reduced by 1-2 orders of magnitude when irrigated and nutrient-amended soils are warmed to >20°C during summer. Laboratory experiments under conditions mimicking those during midsummer in the natural environment indicated that the hyphal extension rates of P. roseus isolates and the activities of five extracellular enzymes are reduced by 54%-96% at high water availability after exposure to temperatures cycling daily from 2 to 21°C and 2 to 24°C, relative to temperatures cycling from 2 to 18°C. Given that the temperatures of surface soils at the study site already reach 19°C during midsummer, the observations reported here suggest that, at predicted rates of warming arising from moderate greenhouse gas emissions, inhibitory effects of climate change on the metabolism of P. roseus could manifest themselves within the next few decades. Furthermore, with peak temperatures at the surfaces of fellfield soils at other maritime Antarctic locations and in High Arctic and alpine regions already exceeding 20°C during summer, the observations suggest that climate warming has the potential to inhibit the growth of other cold-adapted microbes, with negative effects on soils as the Earth's climate continues to warm.

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Section: Discussionmentioning

confidence: 95%

Inhibitory effects of climate change on the growth and extracellular enzyme activities of a widespread Antarctic soil fungus

Misiak

Goodall‐Copestake

Sparks

et al. 2020

Global Change Biology

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“…Previous studies have examined the effects of depth on Antarctic soil bacterial communities ( Herbold et al, 2014 ). Nevertheless, this heterogeneous distribution of the microbial communities has not been as widely studied on a wide geographical scale ( Horrocks et al, 2020 ), where cryoturbation and other physical process can alter the biotope.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity of Microbial Communities in Soils From the Antarctic Peninsula Region

2021

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Ice-free areas represent less than 1% of the Antarctic surface. However, climate change models predict a significant increase in temperatures in the coming decades, triggering a relevant reduction of the ice-covered surface. Microorganisms, adapted to the extreme and fluctuating conditions, are the dominant biota. In this article we analyze the diversity and composition of soil bacterial communities in 52 soil samples on three scales: (i) fine scale, where we compare the differences in the microbial community between top-stratum soils (0–2 cm) and deeper-stratum soils (5–10 cm) at the same sampling point; (ii) medium scale, in which we compare the composition of the microbial community of top-stratum soils from different sampling points within the same sampling location; and (iii) coarse scale, where we compare communities between comparable ecosystems located hundreds of kilometers apart along the Antarctic Peninsula. The results suggest that in ice-free soils exposed for longer periods of time (millennia) microbial communities are significantly different along the soil profiles. However, in recently (decades) deglaciated soils the communities are not different along the soil profile. Furthermore, the microbial communities found in soils at the different sampling locations show a high degree of heterogeneity, with a relevant proportion of unique amplicon sequence variants (ASV) that appeared mainly in low abundance, and only at a single sampling location. The Core90 community, defined as the ASVs shared by 90% of the soils from the 4 sampling locations, was composed of 26 ASVs, representing a small percentage of the total sequences. Nevertheless, the taxonomic composition of the Core80 (ASVs shared by 80% of sampling points per location) of the different sampling locations, was very similar, as they were mostly defined by 20 common taxa, representing up to 75.7% of the sequences of the Core80 communities, suggesting a greater homogeneity of soil bacterial taxa among distant locations.

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“…with maximum hyphal extension rate being recorded here at a water potential of −0.66 MPa. However, we cannot discount the possibility that the positive association between the relative abundances of the fungus in DNA and RNA communities and soil 13 C value may have arisen from 13 C enrichment at increased soil depth (Horrocks et al, 2020), possibly arising from isotopic fractionation or the addition of 13 C-enriched microbially-derived C during decomposition (Schweizer et al, 1999;Boström et al, 2007), or from the depletion of the 13 C content of plant material entering soil over the previous 150 years (Leavitt and Lara, 1994;Royles et al, 2013).…”

Section: Discussionmentioning

confidence: 98%

“…In agreement with previous studies showing significant effects of depth on the frequencies of distinct fungal guilds and taxa in soil (Dickie et al, 2002;Lindahl et al, 2006), the fungus reported here was more abundant and active in deeper soils, with, as depth increased from 2 to 8 cm, a doubling in its relative abundance in the DNA community at Signy Island, and a threefold increase in its abundance in the RNA community at Léonie Island. The preference of the fungus for deeper, and hence older (Horrocks et al, 2020), soils resulted in its relative abundance in both nucleic acid communities being negatively associated with soil 14 C enrichment, with peak abundances of DNA and RNA reads in soils with MRT of C of 1,000-1,200 years BP. The increased relative abundance of the fungus in soils with enriched 13 C values, derived from plants growing under wetter conditions (Wasley et al, 2006), also agrees with its preference for growth at increased water availability, FIGURE 5 | Radial extension rate of the fungus in response to (A) pH values between 3.9 and 6.1, (B) temperatures between -2 and 25 • C, and (C) water potentials between -0.66 and -8.24 MPa.…”

Section: Discussionmentioning

confidence: 99%

“…Following convention (Stuiver and Polach, 1977), 14 C results were normalized to δ 13 C = −25 and expressed as % modern and conventional radiocarbon ages (in years BP, where 0 BP = AD1950). Mean residence time (MRT) of C in soil was determined from 14 C concentration using a bomb-14 C soil carbon turnover model (the Meathop Model; Harkness et al, 1986), as described by Horrocks et al (2020). For samples that showed no clear evidence of bomb-14 C incorporation (i.e., < 97%Modern), the conventional radiocarbon age was used as the MRT (Bol et al, 1999).…”

Section: And 13 C Determinationsmentioning

confidence: 99%

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A Previously Undescribed Helotialean Fungus That Is Superabundant in Soil Under Maritime Antarctic Higher Plants

et al. 2020

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We report a previously undescribed member of the Helotiales that is superabundant in soils at two maritime Antarctic islands under Antarctic Hairgrass (Deschampsia antarctica Desv.). High throughput sequencing showed that up to 92% of DNA reads, and 68% of RNA reads, in soils from the islands were accounted for by the fungus. Sequencing of the large subunit region of ribosomal (r)DNA places the fungus close to the Pezizellaceae, Porodiplodiaceae, and Sclerotiniaceae, with analyses of internal transcribed spacer regions of rDNA indicating that it has affinities to previously unnamed soil and root fungi from alpine, cool temperate and Low Arctic regions. The fungus was found to be most frequent in soils containing C aged to 1,000–1,200 years before present. The relative abundances of its DNA and RNA reads were positively associated with soil carbon and nitrogen concentrations and δ13C values, with the relative abundance of its DNA being negatively associated with soil pH value. An isolate of the fungus produces flask-shaped phialides with a pronounced venter bearing masses of conidia measuring 4.5–6(7) × 1.8–2.5 μm, suggestive of anamorphic Chalara. Enzymatic studies indicate that the isolate strongly synthesizes the extracellular enzyme acid phosphatase, and also exhibits alkaline phosphatase and naphthol-AS-BI-phosphohydrolase activities. Ecophysiological measurements indicate optimal hyphal growth of the isolate at a pH of 4.2–4.5 and a water potential of −0.66 MPa. The isolate is a psychrotroph, exhibiting measureable hyphal growth at −2°C, optimal hyphal extension rate at 15°C and negligible growth at 25°C. It is proposed that the rising temperatures that are predicted to occur in maritime Antarctica later this century will increase the growth rate of the fungus, with the potential loss of ancient C from soils. Analyses using the GlobalFungi Database indicate that the fungus is present in cold, acidic soils on all continents. We advocate further studies to identify whether it is superabundant in soils under D. antarctica elsewhere in maritime Antarctica, and for further isolates to be obtained so that the species can be formally described.

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Predicting climate change impacts on maritime Antarctic soils: a space-for-time substitution study

Cited by 15 publications

References 64 publications

Inhibitory effects of climate change on the growth and extracellular enzyme activities of a widespread Antarctic soil fungus

Inhibitory effects of climate change on the growth and extracellular enzyme activities of a widespread Antarctic soil fungus

Heterogeneity of Microbial Communities in Soils From the Antarctic Peninsula Region

A Previously Undescribed Helotialean Fungus That Is Superabundant in Soil Under Maritime Antarctic Higher Plants

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