Project Description
Project Overview
This PhD will investigate how above and belowground biodiversity interact to confer resilience to agricultural systems in the face of climate change. Improved agricultural grasslands dominate our agricultural landscapes, are species poor and are themselves dominated by perennial ryegrass with a focus on maximising agriculture production. As the climate changes, these production systems are increasingly prone to the vagaries of climatic extremes (drought and flooding), resulting in increased uncertainties over fodder production and yield. Multispecies swards consist of mixtures of three key functional groups, grasses, legumes and herbs, and have potential advantages over conventional perennial ryegrass systems being able to exploit resources in complementary ways. For example, variation in rooting depth confers drought resistance, nitrogen (N) fixing legumes reduce inorganic N requirements, and herbs can have medicinal benefits for grazing livestock (anthelmintic properties). Deeper roots and diverse root traits from multispecies swards may also improve carbon sequestration and its associated positive impacts to soils.
How multispecies swards interact with below ground soil communities to alter the structure of soil food webs, and their ecological functioning and stability in the face of climate change is the focus on this PhD. The capacity of soil food webs to absorb, recover and adapt to climatic shocks and perturbations, and the extent to which this capacity is altered across a gradient of multispecies sward biodiversity will be studied in this project. In particular, we will impose experimental droughts across a gradient of multispecies sward diversity, and will quantify the response in terms of soil food web structure and stability (multiple stabilities: resistance, recovery, variability and persistence), soil physical structure, and capacity to sequester carbon. The project will focus on soil micro-arthropods including mites, collembolans and nematodes, as well as earthworms. It will improve our understanding of the linkages between these below ground communities and above ground parameters of agronomic and economic importance such as biomass production and nutritive value for grazing livestock.
This project will take a dual approach to the investigation of research hypotheses undertaking a combination of field research and experiments, complemented by mesocosm investigations of drought and flood stress reflecting seasonal climate extremes. The project is a CASE studentship in collaboration with AFBI in Northern Ireland being the CASE partner. The project will experimentally quantify and assess the relative merits of different measures of ecological resilience and multiple measures of ecological stability (Donohue et al. 2013). The project, therefore, offers the opportunity to evaluate the mechanisms that underpin variation in ecological stability and will attempt to quantify empirically species-specific contributions to multiple measures of stability including variability, resistance and recovery (engineering resilience). Emphasis will be placed on soil invertebrate food web and community structure, with a focus on quantifying species interactions, and both functional (e.g. body mass, trophic level and trophic role) and structural properties (e.g. abundances and richness) to support a fundamental exploration of different stability concepts and their relevance in applied agricultural management.
The overall aim is to assess the relative value and efficiency of implementation of these different approaches in the context of soil health and agricultural management. The project will involve a mixture of experiments and survey work. The successful candidate will avail of a range of multispecies sward platforms available through the AFBI experimental farms at Hillsborough and Loughgall, as well as co-research farms through AgriSearch’s Beacon farm network. Queen’s University Belfast and AFBI have a strategic alliance and the successful candidate will be exposed to the different research cultures and environments in both organisations.
Modelling of ecological stability will be assessed using data from the project describing predator-prey interactions and consequently food web structure in the soils at different multispecies sward sites. This is important as ecological network structure is known to determine the stability of ecological communities. Lotka-Volterra models will be used with varying functional responses informed by body mass and allometric relationships quantified from the literature to determine parameterisation of these models for the theoretical assessment of different types of stability.
Essential & desirable candidate skills
Essential: Full and clean driving license. Experience of experimental design, use of R, degree (BSc or MSc) in a relevant discipline, e.g. ecology, zoology, conservation.
Desirable: Experience of soil systems, agricultural ecology, food webs and/or biodiversity functioning experiments. Experience working with the identification of terrestrial invertebrates.
Supervisors
Mark EmmersonPrimary Supervisor: | Profile: Mark Emmerson Email: m.emmerson@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Biological Sciences |
Paul HallettSecondary Supervisor: | Profile: Paul Hallett Email: paul.hallett@abdn.ac.uk Institution: University of Aberdeen Department/School: School of Biological Sciences |
Neil ReidAdditional Supervisor: | Profile: Neil Reid Email: neil.reid@qub.ac.uk Institution: Queen's University, Belfast Department/School: School of Biological Sciences |
Additional Supervisor: | Dr. Aurélie Aubry CASE Partner, The Agri-Food and Biosciences Institute E-mail address: Aurelie.aubry@afbini.gov.uk |
References
Donohue et al. (2013) On the dimensionality of ecological stability. Ecology Letters. 16: 421-429.
Jaramillo et al. (2021) Enhancing the sustainability of temperate pasture systems through more diverse swards. Agronomy. 11: 1912. doi: 10.3390/agronomy111011912
Veen et al. (2019) Applying the aboveground-belowground interaction concept in agriculture: Spatio-temporal scales matter. Frontiers in Ecology and Evolution. 7:300. doi: 10.3389/fevo.2019.00300
Expected Training Provision
Skills in soil and invertebrate sampling, experimental design, soil invertebrate extraction and identification, and statistical analysis will be provided. The project will employ experimental field techniques used in soil systems for the assessment of soil food web structure as well as novel application of image based identification of soil invertebrates to morphological groups. Supporting soil chemistry and physical property data will also be collected using hand-held in situ probes and laboratory based nutrient analysis. It is expected that you will present your work to QUADRAT peers as well as at national and international conferences.
Impact
Whilst this project addresses fundamental questions in community and ecosystem ecology regarding the role of biodiversity in providing ecosystem services and ensuring ecological stability, the importance of soil health for maintained food production means that the project results will have wider practical, policy and economic impacts. For example, the AFBI Multispecies Sward Platforms and experiments directly support agri-environmental policy development within the Department of Agriculture, Environment and Rural Affairs (DAERA) in Northern Ireland.
Policy-makers and scientists, as demonstrated by the newly formed Strategic Alliance involving both AFBI and QUB, recognise the importance of understanding the fundamental science for effective restoration and management of healthy soils. In particular, policymakers are now focusing on the social-ecological resilience of systems which together with the detection of ecological sensitivity to pressures, and how it may effect ecological resilience, is critical to minimise climate change forecasts. This project will provide direct support in terms of increasing the ability to detect ecological resilience within surveillance monitoring as well as how to quantify and manage the different aspects of stability. Moreover, it is expected that the modelling component of this work may provide a useful framework or model for effective management of ecological resilience within multi-stressor regimes and extremes that are likely to increase with climate change.
Proposed Supervision
The PhD is a collaboration between partners at the Agri-Food and Biosciences Institute (AFBI), Queen’s University Belfast and the University of Aberdeen through the QUADRAT DTP. The supervisory team bring a combination of skills in agronomy, biodiversity, conservation, food webs and soil biology and physics.
Proposed Timetable
Year 1
Identify field sites and undertake site visits to deploy and establish drought experiments. Sample from sites across a gradient of multispecies sward biodiversity to obtain belowground soil biodiversity data and establish food webs for each of the study sites being used. Undertake botanical surveys of the swards to establish actual diversity measures relative to sown estimates of biodiversity. Construct and deploy drought shelters with appropriate livestock proofing at a subset of multispecies sward sites. Commence Year 1 perturbation experiment and track recovery of perturbed experimental drought plots (leading to manuscript 1). Undertake QUADRAT and QUB specific training as appropriate.
Year 2
Soil mesocosm experiment to quantify the effects of multiple extreme climatic effects (combinatorial effects of drought and flooding). The combination of drought and flooding act as multiple environmental stressors, and aim to vary the magnitude of extremes to quantify potential tipping points on the structure and functioning of belowground soil communities. Simultaneously measure multiple types of stability, i.e. variability, resistance, recovery and persistence of the soil food webs (Manuscript 2). Make ongoing measurements from field based drought experiment. Undertake QUADRAT and QUB specific training as appropriate.
Year 3
Quantify carbon fluxes from multispecies sward soils and relate back to soil food web structure. Quantify microbial (fast) and fungal (slow) energy pathways in soils and understand how energy flow is differentially affected by drought relative to control conditions across the gradient of plant biodiversity reflected in the multispecies swards (Manuscript 3). Undertake QUADRAT and QUB specific training as appropriate.
Year 4 (6 months)
Write up and submission.
QUADRAT Themes
- biodiversity
- environmental-management
Partners
CASE Partnership with AFBI
