Cross-season legacy effects of climate extremes on alpine soil microbial communities: resilience, regimes shifts and biogeochemical cycles

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences

Abstract

Soil contains a vast diversity of microbial that is an important driver of the biogeochemical cycles on which the functioning of earth depends. These soil microbial communities are vulnerable to environmental changes caused by human actions, including land use and climate change. However, our understanding of how shifts in microbial communities resulting from environmental change influences the global biogeochemical cycles they support is poor. This lack of knowledge is exacerbated by most studies investigating only one facet of environmental change: in the real world, human actions are causing multiple and simultaneous changes to the environment, including climate extremes that are expected to become more intense and frequent with on-going climate change. This is what this proposal is about: understanding how seasonally distinct climate extremes combine to impact soil microbial communities and the crucial biogeochemical cycles that they support. We do this in high mountain ecosystems, which cover a large part of the Earth's land surface, support high levels of biodiversity, and provide a host of services for humankind, including the storage of vast amounts of carbon, nutrients and water. Moreover, mountains are under considerable threat from climate and land use change. Climate change, for example, has been taking place in the mountains at almost double the rate of the northern hemisphere average, leading to less snow in winter, which reduces insulation of the ground and increases freeze-thaw activity, and less rain in summer, which causes prolonged drought. Yet, how these two factors combine to affect soil microbial communities, and is poorly understood. Furthermore, farming in mountains is also changing, with traditional grazing practices being abandoned in many mountains areas, which is causing encroachment of dwarf shrubs into the alpine zone. Put simply, mountain areas are at the front line of global change, but the consequences for microbial communities and the biogeochemical processes that they perform remain poorly understood.

Whilst soil microbes can often resist or recover from individual environmental perturbations, they may not be able to withstand multiple shocks happening in quick succession. Reduced snow in winter, followed immediately by severe summer droughts may tip soil microbial communities, and the nutrient cycling functions they perform, into alternative states. When such a shift occurs, the structure of the soil microbial community, and its capacity to cycle key nutrients will be permanently altered. Alarmingly, we do not know under which conditions such regimes shifts in microbial communities will occur, or whether changes in land-use practices will affect the outcome. Nor do we know what it will mean for global biogeochemical cycles, which is surprising considering the vast amounts of carbon stored in alpine soils, and the importance of nitrogen cycling for agricultural activities. This proposal tackles this issue head on, testing how reduced snow cover and summer drought affects the diversity and function of soil microbial communities and the consequences for biogeochemical cycles in these understudied ecosystems. We will tackle the following so far unexplored questions. Does one type of climate extreme impair the ability of soil microbial communities, and the biogeochemical cycles they support, to resist and recover from further perturbations? At what frequencies and severities of summer drought do microbial communities tip into an alternative state? Does encroachment of shrubs dampen the combined effect of seasonally distinct climate extremes on soil microbial communities? By testing these questions, we will gain novel, transformative understanding of the structure, function, and dynamics of microbial communities, and how this links to biogeochemical cycling, and we will do so in situ in the context of ongoing and rapid environment change in an understudied and vulnerable natural ecosystem.

Planned Impact

(a) Who will benefit from our research?

The main beneficiaries of our research will be the academic community, via the generation of new fundamental knowledge on the consequences of climate extremes for soil microbial communities and major biogeochemical cycles in fragile alpine grasslands, and how effects are moderated by vegetation change. Our research, however, will also be of direct relevance to land managers and policy makers with interests in ecosystem service management in alpine regions and their resilience to climate extremes, which are expected to increase in their intensity and frequency with climate change. These key stakeholders include regional national park authorities in mountain regions and government environmental and conservation agencies, such as the environmental office of the Provincial Government of Tyrol, and farmers and landowners with interests in the management of alpine areas. Our project will also benefit the general public with interests in mountain ecosystems and threats to their biodiversity, including the large number of tourists who visit this region of Austria in both winter and summer.

(b) How will these benefits be realised?

Dissemination of research findings to international audience: This will be achieved through the publication of research findings in leading international journals, and via presentations by PDRA's and PI's at conferences and workshops. Given the novel and timely nature of our proposed research, and our track record of publishing high profile papers, we envisage that this proposal will yield several high impact publications. The PDRA will be encouraged to present at international conferences and workshops, and to be actively involved in research networks, such as the British Ecological Society (BES) Plants, Soils, and Ecosystems Special Interest Group (SIG) to disseminate research findings.

To engage with and promote knowledge transfer to stakeholders: We already have links with relevant stakeholders, including policymakers, land managers, farmers and landowners and the local and regional tourist office, via our NERC funded research in this regions. We plan to hold a one-day workshop for these stakeholders in autumn 2022, which will involve a series of presentations and discussions based on our findings. We also plan to involve a student intern in making a short film for the general public about threats of climate extremes in mountain ecosystems and potential solutions or mitigation strategies.

To raise public awareness of our research: the PI, Co-I and project partners have a strong track record of being actively involved in outreach activities, promoting public awareness of our science through local and national media interviews, and by presenting our results at science communication events. Here, a major focus will be on a public exhibition, during the winter ski season of 2021 in nearby Obergurgl, a popular ski resort, using artwork and instillations to inform the general public on the potential threats to ecosystem services of climate extremes in alpine regions. We will also take part in specific educational events at the Alpine Research Centre, Obergurgl (e.g. Summer School on Alpine Field Ecology) and public engagement meetings (e.g. University of Innsbruck "Open Science Days").

Transferable skills training: An important outcome of this project will be the delivery of a highly trained early career researcher and technician with training in multi-disciplinary approaches to the study of the soil microbiome, including cutting edge genomic tools and links to biogeochemical cycles. All staff will also receive training in advanced statistical approaches for analysing large datasets including network analysis, Bayesian modelling, and structural equation modelling. The Researcher Co-I will undertake public engagement training via NERC.

Publications

10 25 50
 
Description The work on this project was significantly disrupted and delayed by the Covid-19 pandemic during the first year of the project in 2020. Field work was delayed by 12 months due to lack of access to sites, although much work has been done since then as outlined below. Soil microbial communities regulate key biogeochemical cycles that underpin plant productivity and determine the inputs and outputs of carbon (C) in the atmosphere, thereby amplifying or mitigating climate warming, respectively. Yet, how resistant soil microbial communities are to sequential extreme climatic events, such as freeze-thaw events and summer droughts caused by reduced snowfall in winter and reduced rainfall in summer, respectively, is unclear. Whether the functions performed by these important belowground communities eventually recover from extreme climatic events is also unknown. In this work we are addressing important unknowns about the resilience of soil microbial communities and their functioning to co-occurring climate extreme events, and of the factors that render them vulnerable to regime shifts to alternative states. To do this, we are using a field experiment in the Austrian Alps to test how recurring cycles of seasonal climate extremes, namely winter freeze-thaw cycles and summer drought, individually and in combination, affect soil microbial communities and biogeochemical cycling. We have imposed three years (2021, 2022 and 2023) of sequential climate extreme events (i.e., winter snow removal and summer drought) and have sampled soils annually in 2021, 2022 and 2023 to detect microbial responses to treatments. We have also completed a laboratory manipulation experiment using soils from the field experiment treatments collected in 2023. This will allow us to determine how multiple years of extreme climatic events in the field affect the resilience of soil microbial communities and their functioning to subsequent climate extremes, and whether they have become more vulnerable to regimes shifts to alternative states. Laboratory analyses is complete and data analysis is ongoing. Second, we are testing how recurring inter-annual cycles of winter freeze-thaw and summer drought affect plant and microbial C transfers. During the summer of 2022 we performed a pulse labelling experiment using CO2 that is enriched in a stable isotope of carbon, 13C, which can be traced and measured as it is transferred through plants and into soil microbes. Laboratory analysis is now complete and data analyses are ongoing. Finally, we are testing how cross-season legacy effects of seasonal climate extremes modify the vulnerability of soil microbial communities to regime shifts to alternative states with altered biogeochemical cycles. To do this we have conducted a tightly controlled lab manipulation experiment, by implemented freeze-thaw treatments varying in frequency combined with drought treatments varying in intensity. Data collection and laboratory analyses are completed, and statistical analyses are ongoing.
Exploitation Route Our research outputs will be of interest to a range of academic groups, including soil scientists with interests on controls on nutrient and carbon cycling, and climate change scientists interested in the impacts of multiple global change drivers of ecosystem processes and greenhouse gas emissions. Our research will also be of interest to alpine ecologists concerned with understanding how global change impacts mountain ecosystems. More specifically, we will provide novel insight into the resistance and resilience of soil microbial communities, and the crucial functions they perform, to co-occurring extreme climatic events. There is an increasing drive towards understanding functional relationships between microbial diversity and ecosystem processes in the real world, and our research should provide new insights into this issue. Finally, there is growing interest in the potential for multiple global change drivers, including extreme climatic events, to have synergistic effects on ecosystem processes. Our study will be among the first to inform on the potential for such interactions, in our case between reduced winter snow cover, summer drought and vegetation change, to tip ecosystems into alternative stable states, which permanently altered functioning. This will have important implications for the delivery of ecosystem services that support human populations.
Sectors Agriculture

Food and Drink

Environment

Leisure Activities

including Sports

Recreation and Tourism

 
Description The project is ongoing, with economic and societal impacts still in the very early stages. However, preliminary results from the work have featured in presentations by the lead investigator and PDRA, and Professor Bardgett talked about the research we are doing in this project, and in a previous grant, in a series of BBC World Service "The Underworld: Life in Soil. He was interviewed at a high altitude site near Innsbruck where he talked about the research and impacts of changing snow cover on soil microbes (https://www.bbc.co.uk/programmes/w3ct43cp).
First Year Of Impact 2022
Sector Environment
Impact Types Cultural

Societal

 
Description Belowground microbial responses to global change in alpine ecosystems, International Mountain Conference, Innsbruck, Sept 2022. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Plenary lecture on belowground microbial responses to global change in alpine ecosystems, International Mountain Conference, Innsbruck, Sept 2022, which sparked questions and discussion afterwards.
Year(s) Of Engagement Activity 2022
URL https://www.uibk.ac.at/congress/imc2022/index.html.en
 
Description Focus session at the International Mountain Conference in Innsbruck, Austria. Topic: Snow cover change and mountain ecology. 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A focus session was organised at the International Mountain Conference in Innsbruck, Austria. Broadbent and Bardgett organised and chaired 12 talks that were given on snow cover change impacts on mountain ecosystems.
Year(s) Of Engagement Activity 2022
 
Description Invited lecture University Bern, Ecology Lecture Series, Oct 2022 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Invited talk at the University of Bern, Switzerland, as part of their Ecology Lecture Series, October 2022. The presentation was mainly to undergraduate and postgraduate students, but also to research and academic staff at the University. The talk generated discussions and potential future collaborations.
Year(s) Of Engagement Activity 2022
 
Description Invited seminar in the Plants, Photosynthesis and Soil seminar series at the University of Sheffield. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact 60 members of the Department of BioSciences at the University of Sheffield attended, ranging from faculty to undergraduate students. The talk sparked interesting questions and led to further discussions with faculty and PGR students.
Year(s) Of Engagement Activity 2023
 
Description Invited talk, University of Estonia, January 2023 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Invited talk at the University of Estonia on below ground responses to climate extremes, which generated discussions and potential future collaborations.
Year(s) Of Engagement Activity 2023
 
Description Keynote presentation on below ground responses to climate change in mountain ecosystems at International Mountain Congress, Innsbruck 2022 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Findings from our research were presented to an international audience of scientists and stakeholders with interests in different aspects of mountain ecosystems.
Year(s) Of Engagement Activity 2022
URL https://www.imc2022.info/sessions/belowground-microbial-responses-to-global-change-in-alpine-ecosyst...
 
Description Keynote talk on soil microbial community responses to climate extremes: resistance, resilience and transitions to alternative states, Soil Ecology Lecture Series, China, 2022 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Presentation on soil microbial community responses to climate extremes: resistance, resilience and transitions to alternative states to the Chinese Soil Ecology Lecture Series, which provoked a series of questions and some future collaborations.
Year(s) Of Engagement Activity 2022
 
Description Plenary Lecture British Ecological Society Annual Meeting, Belfast, 2019. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Plenary Lecture, The hidden majority: soil biodiversity, ecosystem processes, and global change. Celebrating Global Ecology, British Ecological Society Annual Meeting, Belfast, Dec 2019. The talk generated discussions and debate, and helped to raise awareness of the importance of soil biodiversity for ecological processes.
Year(s) Of Engagement Activity 2019
 
Description Presentation at the European Geosciences Union General Assembly in Vienna, Austria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 70 scientists attended the presentation, ranging from PGR to Professors. The talk elicited interesting questions and led to requests for collaboration.
Year(s) Of Engagement Activity 2022
URL https://meetingorganizer.copernicus.org/EGU22/EGU22-8723.html
 
Description Presentation at the International Mountain Conference in Innsbruck, Austria. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 75 scientists attended the talk, which stimulated interesting questions and discussion afterwards
Year(s) Of Engagement Activity 2022