Dr Tom Liffen
QM Innovations Scholar

School of Geography
Queen Mary, University of London
Mile End Road
London E1 4NS
t.liffen@qmul.ac.uk 

 

 

 


I am the founder of the London Student Journal of the Environment (LSJE), which is an open-access journal specialising in environmental science and management, the contributions for which are written by students.

Student research is often of a very high quality with interesting results that warrant dissemination to a wider audience. However, at present, there are few avenues through which students can express the findings of their work.

The LSJE provides early researchers with an opportunity to publicise their work, which could be derived from undergraduate/master’s dissertations, or elements of PhD research.

For more information visit www.LSJE.org, email info@lsje.org, and follow @LSJEorg on Twitter


Research Interests

  • The effects of vegetation growth, removal and dynamics on geomorphological and biogeochemical processes in freshwaters.
  • The growth strategies and biomechanical traits of aquatic plants.
  • The functioning of green roofs.


The growth and senescence of Sparganium erectum in the River Blackwater, March - November 2009.

 

Research has demonstrated that under many circumstances and across rivers of all sizes, a range of plant species are associated with fluvial landforms and appear to influence river structure and dynamics, thereby acting as ecosystem engineers. These studies suggest that interactions and feedbacks between fluvial processes and vegetation are a central component of ecosystem function.

My doctoral research explored the capacity of linear emergent macrophytes to act as ecosystem engineers, and the vegetative strategies that enable them to function as such. Focussing on Sparganium erectum, the most abundant linear emergent macrophyte in the UK, I have been able to demonstrate the profound influence this species can have on channel structure, sediment dynamics, and the biomechanical traits that cause these.

Unlike a number of submerged species, S. erectum is able to retain fine sediment throughout winter when its aboveground biomass has decayed. This is central to its capacity to act as an ecosystem engineer, and my research hypothesized that this retention of sediment is linked to the species’ below ground biomass dynamics. To assess this, I developed an ingrowth core method to characterise the below ground zonation of S. erectum biomass.  These results have indicated that the species retains a significant root/rhizome profile in surficial sediment throughout the year, which has a stabilising effect on sediment accumulations.

 

An ingrowth core showing roots and rhizomes of S. erectum.Changing proportions of underground biomass in relation to sediment depth.


Publications:

  • Liffen T, Gurnell AM, O’Hare MT, Pollen-Bankhead N & Simon A. (2011) Biomechanical properties of the emergent macrophyte Sparganium erectum: Implications for fine sediment retention in low energy rivers. Ecological Engineering 37:1925-1931.
  • Pollen-Bankhead N, Thomas RE, Gurnell AM, Liffen T, Simon A & O’Hare MT.  (2011) Quantifying the potential for flow to remove the emergent aquatic macrophyte Sparganium erectum from the margins of low energy rivers. Ecological Engineering 37: 1779-1788.
  • O'Hare JM, O'Hare MT, Gurnell AM, Scarlett PM, Liffen T, McDonald C. (2011) Influence of an ecosystem engineer, the emergent macrophyte Sparganium erectum, on seed trapping in lowland rivers and consequences for landform colonisation. Freshwater Biology 57: 104-115.
  • Liffen, T. (2008) The effect of green roofs on runoff water quality. London, Defra.
  • Liffen, T. (2008) Green Roofs: A policy proposal for the Department for Environment, Food and Rural Affairs. London, Defra.

Conferences

  • Liffen T, Gurnell AM, O’Hare MT, O’Hare J, Bankhead-Pollen N & Simon A. (2011) River ecosystem engineering by the aquatic macrophyte Sparganium erectum: the influence of biomechanical traits on sediment retention and fluvial landform development. European Geophysical Union General Assembly, Vienna.
  • Liffen T. (2010) Working in environmental science.  University of East Anglia careers event, Norwich.
  • Gurnell, A.M., O’Hare, M. T., O’Hare, J., Liffen, T., Bankhead-Pollen, N. & Simon, A (2010). Investigating the potential role of the aquatic plant, Sparganium erectum, in accelerating channel adjustment in channelised and restored river reaches. European Geophysical Union General Assembly, Vienna.