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Competitive ability of a highly invasive plant: The interplay between resource availability, herbivory and allelopathy

This research project is in competition for funding with one or more projects available across the NERC GW4 Doctoral Training Partnership (DTP). Usually the projects which receive the best applicants will be awarded the funding. Find out more information about the DTP and how to apply.

Application deadline: 7 January 2018

Start date: October 2018

DTP research theme: Living world

Co-supervisor: Dr Regan Early, College of Life and Environmental Sciences, Exeter University and Dr. Bradley A. Welch, Brecon Beacons National Park Authority, Cambrian Way, Brecon


Resource competition plays an important role in determining the dominance of alien species in invaded areas (eg, an invader species’s superior capacity to acquire and retain resources confers an advantage over native species).

How environmental factors (eg, resource availability) affect the outcome of this competitive interaction is unknown. Increasing atmospheric CO2 and N deposition, for example, may enhance resource availability; this can lead to larger herbivore population sizes with resultant changes in food preferences.

This will have, as yet unknown, consequences for interspecific competitive dynamics. Furthermore, the importance of resource competition versus other mechanisms such as allelopathy (ie chemical release by plants that limit growth of neighbouring species) is unknown.

Allelopathy has been proposed as a mechanism facilitating plant invasion; native inhabitants may be susceptible to the novel biochemicals produced. Herbivory has been suggested to influence the release of chemicals with allelopathic potential but rarely has this been empirically corroborated.

Project aims and methods

A highly invasive annual herb, Himalayan balsam, native to the Himalayas and introduced to UK in 1839, is now considered a serious problem, particularly in riparian habitats.

The research will involve sampling field populations of I. glandulifera across the UK, including sampling leaves for molecular analysis, setting up quadrats to measure herbivory damage, measuring density of I. glandulifera and co-occurring native species, and chemical analysis of soil samples.

Glasshouse experiments will also be carried out to examine the outcome of competition between individuals of I. glandulifera from different populations and co-occurring species (eg, Silene dioica) in response to (i) different resource availability (low and high nutrients) and (ii) herbivory.

Laboratory work to carry out analysis of the allelopathic potential of the chemicals released by this plant will be undertaken, including germination assays and complemented with the genetic characterisation of the plants using microsatellites to assess if particular genotypes are associated to stronger or weaker allelopathic phenotypes.


The candidate should be motivated and keen, ideally with research experience in plant sciences. Candidates must have a positive attitude for fieldwork and glasshouse work (growing and looking after plants), but also willing to spend time developing wet-lab skills in genetics and statistical skills.

Case award

The project is supported by CABI and the Brecon Beacons National Park Authority (BBNPA). CABI is a science-based not-for-profit organisation that specialises in agricultural and environmental research. They have experience on working with invasive plant species and have been conducting research into potential natural control agents to combat Himalayan balsam. BBNPA works to protect the natural biodiversity of the Breacon Beacons National Park, to which Himalayan balsam is posing a current threat.


You will be trained in plant ecological and molecular techniques, as well as advanced statistical modelling. Skills development and training will be available through NERC GW4+ DTP, and also through Cardiff University’s Doctoral Academy Programme, which offers an integrated research and professional skills programme including more than 200 topics delivered via workshops, online materials and events (eg, public engagement showcase, Speaking of Science student conference, Three Minute Thesis competition). You will also have the opportunity to attend the research seminar series at OnE, Cardiff.

References and background reading

  • Callaway RM, Ridenour WM (2004) Novel weapons: invasive success and the evolution of increased competitive ability. Frontiers in Ecology and the Environment 2: 436–443.
  • Gioria M, Osborne, BA (2014) Resource competition in plant invasions: emerging patterns and research needs. Frontiers in Plant Science 5: 501.
  • Thelen GC, Vivanco JM, Newingham B, Good W, Bais HP, Landres P, Caesar A, Callaway RM (2005) Insect herbivory stimulates allelopathic exudation by an invasive plant and the suppression of natives. Ecology Letters 8: 209–217.


Dr Julia Sanchez-Vilas

Dr Julia Sanchez Vilas


+44 (0)29 2087 4302
Dr Pablo Orozco ter Wengel

Dr Pablo Orozco-terWengel


+44 (0)29 2087 5206
Dr Hefin Jones

Dr Hefin Jones


Siarad Cymraeg
+44 (0)29 2087 5357


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