Soil microbial community dynamics and biogeochemical cycles under global change: effects of climate and vegetation change in alpine ecosystems

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

Abstract

Scientists are becoming increasingly aware that that highly diverse microbial communities in soil play major roles in driving the biogeochemical cycles on which the functioning of Earth depends. It is also becoming clear that this belowground microbial diversity is highly sensitive to land use and climate change, but the consequences of this for biogeochemical cycling are poorly understood. This is what this proposal is about: understanding how both land use and climate change work together to influence soil microbial communities and their functioning, and to experimentally test the consequences of this for major biogeochemical cycles. Uniquely, we do this in high mountain ecosystems, which cover a large part of the Earth's land surface and provide a host of services for mankind, including the storage of vast amounts of carbon, nutrients and water. Moreover, mountains are under considerable threat from climate and land use change, but the consequences of this for biogeochemical cycles is largely unknown. Climate change, for example, has been taking place in the mountains at almost double the rate of the northern hemisphere average. Also, there is considerable concern that land use change, especially the collapse of traditional farming, will have major impacts on how mountain ecosystems function. Given all this, coupled with new knowledge nutrient cycles of mountain ecosystems rely on tight coupling between soil microbial and plant communities, it is all the more surprising that the consequences of global change for soil microbial diversity and the functioning of mountain ecosystems remains largely unexplored.

One of the most noticeable impacts of climate change in mountain areas is less snow, especially in spring. This reduction in snow is happening at an alarming rate, and there is concern that it will accelerate in future years, potentially reducing snow cover by around 50% at the end of this century. On top of climate change, the way that mountains are farmed is also changing, with traditional grazing practices being abandoned in many mountains areas of the world. A consequence of this, which is compounded by climate change, is the encroachment of dwarf shrubs into the alpine zone. New research shows that both of these changes, namely reductions in snow cover and the encroachment of dwarf shrubs, can have dramatic affects on the way that mountain ecosystems function. But the concern is that when they happen together, the impacts are magnified. This proposal tackles this issue head on, testing how shrub encroachment and reduced snow cover simultaneously affect the diversity and activity of soil microbial communities and the consequences for biogeochemical cycles in these understudied ecosystems. We will tackle the following so far unexplored questions. Do reductions in snow cover disrupt the growth and activity of soil microbial communities across the year, both in summer and winter, and does this alter the cycling of carbon and nutrients, and supply of nutrients to plants? Do these changes in soil microbial communities have legacy effects in the future, reducing their ability to deal with other affects of climate change, such as summer drought, which is also increasing in alpine areas? Finally, does the encroachment of shrubs dampen, or amplify, the effects of reduced snow cover on ecosystem processes by altering microclimate and promoting the growth of more resilient fungi in soil? By testing these questions, we will not only yield novel, transformative understanding of the structure, function, and dynamics of microbial communities, and how this links to biogeochemical cycling, but we will do so in situ in the context of ongoing and rapid environment change in an understudied and vulnerable natural ecosystem. Our studies will also provide policy makers and land managers with guidance on how best to manage mountain ecosystems to maintain their integrity in the face of rapid climate and land use change.

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 likely impacts of reduced snow cover and shrub encroachment on the functioning of fragile alpine ecosystems. Our research, however, will also be of direct relevance to land managers and policy makers with interests in ecosystem service management in alpine regions under on going climate change, such as 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 many 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 BES Plants, Soils, and Ecosystems Special Interest Group and the to disseminate research findings.

To engage with and promote knowledge transfer to stakeholders: We will directly engage with stakeholders, including policymakers, land managers, farmers and landowners and the local and regional tourist office, through two workshops. The first will be a one day meeting to be held at the start of the project in Autumn 2016 at the Alpine Research Centre, with the aim of informing of stakeholders of our research goals and engaging with them to develop the most effective mechanisms for translation of our findings into policy and land use decisions. The second workshop will be held in the final year of the project, in Autumn 2018, and will involve a series of presentations and discussions based our findings, and a field excursion to observe impacts of reduced snow cover and shrub encroachment in the field, and to identify mitigation strategies. Key outputs will be a policy brief on future research priorities for integrating research knowledge on climate change impacts on mountain ecosystems into police, and a short film on threats of climate and vegetation in mountain ecosystems and potential solutions or mitigation strategies.

To raise public awareness of our research: the PI has 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. The PI and PDRA will engage in similar activities for this project, including involvement in specific educational events at the Alpine Research Centre, Obergurgl (e.g. Summer School on Alpine Field Ecology and public engagement meetings (e.g. Alpine Research Centre / University of Innsbruck "Open Science Days" and "Night of Science", and established events at The University of Manchester's, such as the Faculty of Life Sciences Community Open Day and Science Star and Discover Days for year 8 and 9 pupils, and year 12 pupils respectively.

Transferable skills training: An important outcome of this project will be the delivery of a highly trained PDRA and technician with training in multi-disciplinary approaches to the study of plant-soil-microbial interactions using the most sophisticated techniques. The PDRA will undertake public engagement training via NERC.

Publications

10 25 50
 
Description This project aims to investigate the response of alpine grassland soils to climate change, specifically testing how the structure and function of soil microbial communities is altered by reduced snow cover and whether this response is moderated by the presence of shrubs. To achieve this, we set up various field experiments in the Austrian Alps in partnership with Innsbruck University and Helmholtz Zentrum, Munich. These field experiments range from local to regional scales, and use snow and vegetation manipulations to determine how changes in snow cover and vegetation affect soil microbial communities and their functioning. Our project has generated a number of key findings and publications as detailed below.

Key finding 1. Snowmelt timing and soil microbial communities. We used a field experiment located at Hohe Mut (2650 m.a.s.l.), Obergurgl in the Austrian Alps to test how differences in snow cover, via snow addition and snow removal, affected soil microbial communities and their functioning in alpine grassland. We found that spring snowmelt triggers an abrupt transition in the composition of soil microbial communities of alpine grassland that is closely linked to shifts in soil microbial functioning and biogeochemical pools and fluxes. Further, by experimentally manipulating snow cover we show that this abrupt seasonal transition in wide- ranging microbial and biogeochemical soil properties is advanced by earlier snowmelt. Preceding winter conditions did not change the processes that take place during snowmelt. Our findings emphasise the importance of seasonal dynamics for soil microbial communities and the biogeochemical cycles that they regulate. Moreover, our findings suggest that earlier spring snowmelt due to climate change will have far reaching consequences for microbial communities and nutrient cycling in these globally widespread alpine ecosystems. This work was published in The ISME Journal (Broadbent et al. 2021).

Key finding 2. Snow cover change and shrub expansion effects on soil microbial community composition, functioning and soil biogeochemistry. We established two complementary field experiments, including a landscape-scale experiment spanning three geographically distinct alpine valleys in Austria, and a snow manipulation experiment at one site. We found that shrub expansion modulated the impacts of snow cover change on belowground ecosystem functioning in both our experiments. Shrub expansion also had a stronger influence on soil microbial community composition and functioning than changes in snow cover. Moreover, shrub-associated shifts in microbial communities were closely linked to changes in soil biogeochemistry. Our study reveals the microbial mechanisms by which shifting vegetation patterns and winter climate change influence biogeochemical cycling and C and N retention in mountain ecosystems. This study is almost ready for submission to an international journal.

Key finding 3. Climate change impacts on diurnal cycles of microbial community composition and functioning. This study involves sampling throughout a 24 hour period in winter and summer in order to discover whether microbial communities show diurnal cycles in composition and functioning in alpine grasslands. We measured the metagenomes and metatranscriptomes of the soil microbial community during a diurnal cycle on snow removal and control plots in winter and summer. We are currently analysing the metatranscriptomic datasets with our international collaborators.
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, but more generally, we will provide novel insight into functional relationships between microbial community change and ecosystem processes. 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 snow cover and vegetation change, to amplify or dampen rates of ecosystem change.
Sectors Agriculture, Food and Drink,Environment

URL https://www.manchester.ac.uk/discover/news/climate-change-driven-snowmelt-in-alps-triggers-abrupt-seasonal-change/
 
Description Our recently published findings in The ISME Journal are already attracting much attention online. According to Altmetric, our article "is in the 98th percentile (ranked 2,725th) of the 148,549 tracked articles of a similar age in all journals and the 99th percentile (ranked 1st) of the 63 tracked articles of a similar age in The ISME Journal", in regard to online attention. Given the project has only very recently been completed, the economic and social impacts will only increase. We have had interest from members of the public and policy organisations following various talks and workshops. The PDRA on the project has also been invited to present a talk about the project to a local science interest group, The Didsbury SciBar, which is scheduled for October 2021. Moreover, with climate change impacts increasing globally, and reduced snow in alpine regions leading to much media coverage, albeit primarily due to ski resort closures, we expect media coverage and further interest from the public. Especially following the anticipated open-access publication of our further findings in leading scientific journals.
First Year Of Impact 2021
Sector Environment
Impact Types Societal

 
Description International symposium on Above- and Below-Ground Biodiversity for Sustainable Ecosystems, AgrosScope 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Keynote lecture on soil microbial community responses to climate extremes: resistance, resilience and transitions to alternative states. Symposium on Above- and Below-Ground Biodiversity for Sustainable Ecosystems, AgrosScope, Zurich, Nov 2019.
Year(s) Of Engagement Activity 2019
 
Description Keynote lecture, NERC STARS Annual Conference, Windermere 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Keynote talk at STARS annual conference, Windermere, Jan 2019
Year(s) Of Engagement Activity 2019
 
Description PhD Workshop Alpine Biology and Global Change, University of Innsbruck 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Plenary lecture on soil microbial community responses to climate extremes: resistance, resilience and transitions to alternative states, PhD Workshop Alpine Biology and Global Change, University of Innsburck, Jan 2020.
Year(s) Of Engagement Activity 2020
 
Description Presentation at the British Ecological Society Annual Meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact 50-100 researchers and students attended the talk in which I presented our findings regarding climate change impacts on soil microbial communtities. The talk sparked interesting questions and discussions afterwards with researchers from other research organisations
Year(s) Of Engagement Activity 2019
 
Description Round table discussion Chinese Academy of Science, Max Plank Institute Round Table, Shanghai, Nov 2019. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Invited member and international expert with presentation on research challenges related to soil biodiversity and ecosystem functioning under global change: resistance and resilience to climate extremes. Chinese Acedemy of Science, Max Plank Institute Round Table, Shanghai, Nov 2019.
Year(s) Of Engagement Activity 2019
 
Description Workshop at International Mountain Conference in Innsbruck, Austria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact 51-100 international researchers, students and members of policy organisations attended the workshop to discuss climate change impacts on alpine grasslands. I presented findings from our research that highlighted impacts on soil microbial communities and processes. Key areas for future research were debated and routes to fund such research discussed.
Year(s) Of Engagement Activity 2019