PhD Studentship - Plant-Microbe interactions in a changing climate

PhD Description:

Peatlands are important ecosystems in the global C cycle as they lock away about one-third of the global terrestrial carbon (Yu 2012). There is, however, growing concern that peatland carbon dynamics will be affected by global climate change. These effects can be direct, but also indirect through changes in plant species richness or plant community composition and associated functional responses. As an example of a direct effect, repeated extreme events (extreme temperature and/or prolonged drought) strongly decreased productivity and enhanced the release of carbon (Kuiper et al. 2014; Bragazza et al. 2016), resulting in a positive climate feedback. Whilst the effects of climate warming on microbial respiration are well understood, recent research has shown that mixotrophic microorganisms (i.e. micro-organisms that can switch between heterotrophy and autotrophy (depending on the presence of carbon resource) play an important role in the uptake of carbon in peatlands, and that their loss, which could be associated with enhanced warming, is linked to a significant loss in net ecosystem carbon uptake (Jassey et al. 2015). 

In addition to increases in temperature, other recent changes in environmental conditions, such as enhanced nitrogen deposition, are known to impact plant species richness negatively (Duprè et al. 2009). Such a decrease in species richness has often been linked to eroded ecosystem function (Isbell et al. 2011). Nonetheless, a large scale survey across UK systems highlighted that whilst environmental change negatively impacted species richness in a range of ecosystems, peatlands seemed to be least affected (Field et al. 2014). Recent observations from a cross-European peatland survey have shown the effects of environmental change on peatland species richness are indeed marginal (Robroek et al. 2017). Moreover, environmental change seems to result in a reshuffling of the plant community composition, but species that are lost seem to be replaced by functionally ‘alike’ species. These results would suggest a self-regulating mechanism by which the effects of environmental change on ecosystem functioning is moderated through the specific replacement of species which maintains functionality at the ecosystem level. Indeed, the effects of warming on peatland carbon fluxes have been shown to be moderated by alterations in the composition of the main plant groups (Ward et al. 2013). Over much longer time-scales, peatland vegetation has been shown to recover from extreme disturbance (Swindles et al. 2016). Despite a potential self-regulating mechanism in peatland plant communities there is growing evidence that shifts in species composition cascade to the function of ecosystems (Bardgett & Van der Putten 2014), most likely through specific relationships between plant and microbial communities (Robroek et al. 2015). Yet, the consequences of microbial shifts on ecosystem functioning remain relatively unexplored (Classen et al. 2015). To advance our understanding of the consequences of climate change on ecosystem functioning we need to better understand the relationships between above and below ground components of ecosystems. 

Project aims

The aim of this studentship is to identify specific plant-microbe interactions and to study if apparent plant-microbe relationships are affected by climate and environmental change. To achieve these aims, we will first (challenge 1) make use of eight-year plant removal experiment which will allow us to test the proof-of-principle that plant communities select for a specific microbiome. We will next (challenge 2) test the robustness of apparent plant-microbial links along environmental gradients (e.g. temperature, annual precipitation, nitrogen deposition). Palaeoecological approaches can be of great use to further understand the role of climate and environmental change on plant-microbe interaction, and subsequent processes such as carbon sequestration, including the resistance of these plant-microbe interactions to climatic change. Hence, we will (challenge 3) use the palaeorecord (500 years b.p) to identify relations on plant and microbial compositions and link shifts therein to historical climate records.

Expectations

The three challenges form the basis of this PhD studentship. 

After an in-depth review of the literature, we expect the student to understand the wider context of the field and to be able to link contemporary and palaeoecological studies (milestone 1: review paper). The student will then be well prepared to tackle the first challenge with the objective to find links between plant and microbial communities (milestone 2). This knowledge should feed into site selection to tackle challenge 2, with the objective to identify the role of environmental change on the robustness of apparent plant-microbe links (milestone 3). Results from the environmental gradient study (challenge 2) will then be compared with the results from the palaeorecord study, which should further inform on the effects of environmental change on plant-microbe links (milestone 4).   

Training

A comprehensive personal and professional development training plan will be in place, besides extensive opportunities expand the student’s multi-disciplinary outlook through interactions with a wide network of academic and industrial/policy partners. Specific training will include: 

– an initial literature review/meta-analysis. 

– setting-up experiments and analyzing results in the R statistical environment.

– using molecular approaches for studying microbial diversity, including techniques for sedaDNA extraction.

– Gas flux measurement techniques. 

– training in ecophysiological profiling to study the functionality of microbial communities.

We further expect the student to maintain existing collaborations with the staff of the Store Mosse National Park, and to exchange results and translate them to conservation practice. 

The project is funded for 3 years and welcomes applicants from the UK and EU who have or expect to obtain at least an upper second class degree in Biological Sciences or allied subjects. Funding will cover fees and a stipend at current research council rates of £ 14,777 per annum for 2018/19. 

Due to funding restrictions this position is only open to UK/EU applicants

Applications for an MPhil/PhD in Biological Sciences should be submitted online at:

https://studentrecords.soton.ac.uk/BNNRPROD/bzsksrch.P_Login?pos=4973&majr=4973&term=201819  

Please place Dr Bjorn Robroek’s name in the field for proposed supervisor.

General enquiries should be made bjorn.robroek@soton.ac.ukAny queries on the application process should be made to pgafnes@soton.ac.uk

Applications will be considered in the order that they are received, and the position will be considered filled when a suitable candidate has been identified.

The University of Southampton and Biological Sciences both hold an Athena Swan Silver & Bronze Award, respectively, demonstrating their commitment to provide equal opportunities and to advance the representation of women in STEM/M subjects: science, technology, engineering, mathematics and medicine.   Due consideration will be given to applicants who have taken a career break.  University benefits include onsite childcare facilities, state-of-the-art on-campus sports, arts and culture facilities, a full programme of events and a range of staff discounts.