Relating fungal functional diversity to C-cycling in sub- and Maritime Antarctic soils

Lead Research Organisation: Rothamsted Research
Department Name: Sustainable Soils and Grassland Systems

Abstract

The decomposition of organic matter is a critical process to the functioning of terrestrial ecosystems. This process is largely driven by saprotrophic (decomposer) fungi in soil and plant litter. Saprotrophic fungi therefore have pivotal roles in the release of carbon (C) from terrestrial ecosystems, in the form of CO2 (a climate-forcing gas), to the atmosphere. Currently, little is known of the specific roles of individual fungal species, i.e. functional diversity, in the degradation of particular C components in the sub- and Maritime Antarctic. The first step in characterising functional diversity is to identify the soil C components (fractions, particle sizes and ages) with which decomposer fungi in soil are associated. Establishing baseline fungal taxonomic and functional diversity and characterizing the soil C components - central aims of this proposal - are fundamental to understand the impacts of environmental change on Antarctic ecosystems. Why the sub- and Maritime Antarctic? Soils in these regions have relatively high stocks of C because of the slow decomposition of organic matter and the tundra vegetation present. For example, soils from South Georgia and Signy Island contain 30 to 40% C. The potential temperature responses of these soils and the C fractions they contain are also important to understand because the terrestrial Maritime Antarctic has been warming rapidly, at c. 0.2-0.4 degrees C per decade over the past 50-100 years, one of the fastest rates of warming recorded. The temperature sensitivity of young and older C fractions in releasing CO2 to the atmosphere is much debated, particularly for peatlands and permafrost soils, such as those that occur in the sub- and Maritime Antarctic. We will determine the associations of specific fungal taxa with specific organic fractions in the field at three sites in the sub- and Maritime Antarctic, and characterise by age and organic geochemistry, the C components of these fractions. In the laboratory, the specific C fractions mineralised by 'key' species of fungi will be determined, together with responses to temperature increases and freeze-thaw cycles. The outcomes of the project will be: (1) a better understanding of the roles of particular groups of fungi in the C cycle, (2) a benchmark for future studies (e.g. in arctic or temperate soils) of the functional roles of fungal mycelia in relation to C mineralisation will have been obtained, and (3) the effects of temperature increases / freeze-thaw on C mineralisation will have been determined.

Publications

10 25 50
 
Description Results from soils collected from the three Antarctic Islands on a latitudinal gradient show differences in total soil C and N concentrations likely to be driven by differences in climate leading to increased C input further north and reduced N uptake further south, leading to soils having distinctly different C:N ratios. The lower soil N concentrations at depth in the low maritime Antarctic (Signy Island) compared with the other study sites and the highly 15N enriched soils observed in the high maritime Antarctic (Léonie Island) indicate potentially significant losses of old accumulated ornithogenic N may have occurred because of warming over the last approximately 100 years on Signy Island, a possibility that requires further research. The differences in stable carbon isotopes and bacterial (PLFA) and fungal (ergosterol) biomarkers across the island transect show how differences in climatic stress lead to the development of distinct plant and microbial communities across the three islands. With the prediction of several degrees of warming over the next 100 years for the region, the response of the communities in these C and N rich soils could have consequences for the the local ecosystems but also have global implications driven by net changes in greenhouse gas emissions.
Exploitation Route Our findings suggest that the impact of warming on soil and C availability has progressed further than expected on Leonie Island.
Sectors Environment

 
Description Presentation to the British Society of Soil Science# Applications of compound-specific mass spectrometry to investigate microbial dynamics in Antarctic soils Claire A. Horrocks, Jennifer A. J. Dungait, Filipa Cox, Kevin K. Newsham, Roland Bol, Mark H. Garnett, Clare H. Robinson
First Year Of Impact 2014
Sector Environment
 
Description Visit to BAS, October 2016 
Organisation British Antarctic Survey
Country United Kingdom 
Sector Academic/University 
PI Contribution Visited collaborator to discuss manuscript progress.
Collaborator Contribution Co-authors.
Impact Papers and talks.
Start Year 2014
 
Description Oral Presentation SWESDiG 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact South West England Soil Discussion Group presentation by Dr Claire Horrocks 'Biogeochemical markers for microbial dynamics in Antarctic soils', May 2014
Year(s) Of Engagement Activity 2014
 
Description Oral presentation BSSS, Manchester 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Offered oral presentation at the British Society of Soil Science (BSSS) Annual Meeting by Dr Claire Horrocks, Manchester, Sept 2014.
Year(s) Of Engagement Activity 2014
URL http://soils.org.uk/event/230
 
Description School Visit to Teign School Kingsteignton 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Gave a talk on science careers and the different projects I have worked on and the different countries scientists get to travel to
Year(s) Of Engagement Activity 2014
 
Description talk to RAU MSc student visit 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Gave a presentation highlighting the varied applications of soil biochemical analysis: Entitled "The UK to Antarctica; global applications of soil Biochemistry"
Year(s) Of Engagement Activity 2015