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27 March, 2019

The 2018 Research Experience Placements

Investigating the relationship between tree root biomass and soil hydraulic properties across soil types

Based: Bangor University

Project objectives:

Increased frequency of flood events and a failure of hard-engineered solutions to prevent damage to infrastructure from extreme events has resulted in a surge of interest in natural approaches to flood risk management. Afforestation of the uplands has been suggested as an approach to mitigate against flooding, yet the evidence base supporting the role trees have in altering landscape hydrology is weak and species specific impact on hydrology is poorly understood. Recent research at Bangor University has established a strong relationship between root biomass and soil hydraulic properties from trials conducted at the BangorDIVERSE experimental plots. Soil pore size distribution varies significantly across tree species with larger pore sizes likely to facilitate the movement of water during periods of high rainfall, reducing fast overland flow and the likelihood of flooding. However, the trial was limited to one soil type and further investigation as to whether this relationship is replicated across the landscape is required. Thus, the objective of this project is:

To investigate the relationship between total tree root biomass and hydraulic conductivity across four different soil types.

Project outcomes:

We now have data describing the relationship between Ash tree roots and hydraulic function of soil, across a spectrum of soil types. We already know that the removal of Ash trees through felling or disease will have a greater impact on hydraulic function and therefore downstream flooding than removal of other tree species. But this phenomena has only been evidenced on one soil type. As a result of the REP project, we can now describe the relationship between Ash and hydraulic function across the majority of the UK and parts of Europe. The research adds to that already conducted as part of the Multiland project and will be written up in a paper this year.

The student has benefited from the project through exposure to the research process at PhD level. they now understand the process of doing a PhD as well as the highs and lows that it entails. They have gained considerable knowledge in a subject which they were previously unfamiliar with and gained experience in both fieldwork and lab work. Difficulties in the field are an inevitable consequence of fieldwork and we have been able to work together to overcome them. Although much of the fieldwork was done as a team, the student has had to process the samples almost entirely alone. As such, they have developed excellent lone working and problem solving skills. Laboratory tasks associated with the project were also entirely new to the student, and they became proficient in both root and soil analysis. Finally, they have also developed their own data entry and spreadsheet manipulation skills and understand the importance of the data collected.

Functional screening for plant growth promoting traits in the rhizosphere of ancestral and domesticated wheats grown in different soil managements

Based: Rothamsted Research

Project Objectives:

Rothamsted research holds a bacterial culture collection of Pseudomonas fluorescens, isolated from the rhizosphere of ancestral and domesticated wheat species grown in soils sampled from differing land managements (permanent grassland, arable and bare fallow from the Highfield experiment at Rothamsted Research). P.fluorescens is a model example of a plant growth promoting rhizobacteria (PGPR) and can promote crop growth and health through interaction with a crop via its root zone. PGPRs have various beneficial traits, including biotic stress tolerance (e.g. compete and actively reduce soil pathogens) and nutrient solubilisation (release nutrients in the soil making them available for plant uptake). The objectives of this project were to study the functional ability of the bacteria in this collection for traits associated with crop growth or health promotion and to identify if crop genotype or soil management can influence Pseudomonas community structure and function.

The main objectives are summarised as follows:

* To screen the culture collection for several PGPR functional traits through plate assays (siderophore production, anti-fungal activity against the wheat pathogen G.graminis and phosphate solubilsation) to determine any differences in Pseudomonas community function across the differing land managements and wheat genotypes

*To amplify and sequence the housekeeping gene gyrB for isolates followed by creation of a phylogenetic tree to compare and determine Pseudomonas community structure across the differing land managements and wheat genotype

Project outcomes:

The results yielded by the student’s work show the diverse nature of the Pseudomonas genus. Although it appears from these results that land management in addition to comparing a modern hexaploidy wheat to an ancestral tetraploid relative does not impact or shape major differences in functional and structural ability of the associated Pseudomonad communities, it does highlight the functional diversity of this ubiquitous bacterial genus. This has proved a good starting point looking at anthropogenic impacts on plant beneficial Pseudomonads, further experiments will focus on expanding soil managements to different soil types in addition to exploring a larger range of domesticated and ancestral species- not just wheat. These results did not show an obvious impact on beneficial Pseudomonad communities, but it’s important to remember that other soil bacterial species may be affected by these agricultural inputs.
Overall the student seemed to enjoy their time within the team. They found the concepts and theories of great interest but disliked that there wasn’t a definitive, easy answer at the end of the project- although  did understand that 8 weeks is a short period of time to cover a broad complex research question. The work and results to which the student contributed is a good achievement given the time frame and the fact that they had no prior training in a laboratory or experience of molecular microbiology.

Resilience of UK agricultural soils to extreme flooding events and the impacts on greenhouse gas fluxes

Based: Centre for Ecology and Hydrology

Project Objectives:

Resilience of UK agricultural soils to extreme flooding events and the impacts on greenhouse gas fluxes

Project outcomes:

Training was provided in numerous field and laboratory techniques allowing analysis of greenhouse gas samples, plant biomass and soil sampling. The main outcome produced a complex R script which built on previous work done by another REP student allowing rapid calculation and quality control of greenhouse gas flux data from experimental samples analysed through gas chromatographs. This output was led and completed by the student to a very high standard, and provided the initial analysis of a very large and complex dataset. The code that the student has produced will also be utilized by numerous other members of our group allowing faster flux calculation and data visualization.

The student was able to learn in a state of the art laboratory setting how basic ecological data is collected, and then use their knowledge to produce faster and more user-friendly code for calculations.

During this placement the student was able to be involved in all aspects of an ecological research experiment, from initial sample preparations and numerous field sampling techniques, through to sample processing and analysis. The complete cycle was completed when they were able to develop R code for data visualization.

Overall, this was an excellent student who provided a considerable input into our group, which will have a lasting impact on the processing of data.