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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 2019

Start date: October 2019

DTP research theme: Living World


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

This project aims to investigate the role of resource competition and allelopathy, under different environmental conditions, particularly (but not limited to) in the context of varying resource availability and herbivory, in facilitating the invasion of Himalayan balsam (Impatiens glandulifera).

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.


You should be motivated and keen, ideally with research experience in plant sciences. You 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. Ideally, some experience of invertebrate biology / ecology would be helpful.

Case or Collaborative Partner

The project is supported by the Brecon Beacons National Park Authority (BBNPA). The authority works to protect the natural biodiversity of the Brecon Beacons National Park, to which Himalayan balsam is posing a current threat. Authority ecologists have in-situ experience on the spread and impact of Himalayan balsam in the native range, and in applying measures to control its spread.


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 Divisional Research Seminar Series of Organisms and Environment at Cardiff University.

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.
  • Golivets M, Wallin KF (2018) Neighbour tolerance, not suppression, provides competitive advantage to non‚Äźnative plants. Ecology Letters 21: 745-759.
  • 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-terWengel

Dr Pablo Orozco-terWengel

Senior Lecturer

+44 (0)29 2087 5206
Dr Hefin Jones

Dr Hefin Jones

Senior Lecturer

Welsh speaking
+44 (0)29 2087 5357


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