QUADRAT DTP CASE: How multispecies grassland swards affect soil food web functioning and resilience in response to climate change

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 by 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. In particular, the regeneration of soil structure by diverse roots may help counter-act negative impacts from compaction and other management stresses that make soils less able to store and transport water in the face of droughts and flooding. 

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, you will impose experimental droughts across a gradient of multispecies sward diversity, and 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. 

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 successful candidate will avail of a range of experimental 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 research environments in both organisations. 

Skills and Training: skills in soil and invertebrate sampling, experimental design, soil invertebrate extraction and identification, soil testing and statistical analysis will be provided. 

Candidate Background: The successful candidate should have experience of experimental design, use of R, an undergraduate degree in a relevant discipline e.g. ecology, zoology, conservation. The candidate will also require a full clean driving license. The following are desirable, but not essential; experience of soil systems, agricultural ecology, food webs and/or biodiversity functioning experiments. Experience working with the identification of terrestrial invertebrates.