Invasive species
Exotic (or non-native) species are species which do not naturally occur in a country or region, they often only occur there because of the effects of humans. Exotic invasive species are species which are not only non-native, but also spread out from locations to which they are introduced. In the UK such species may include rhododendron, grey squirrel and the New Zealand flatworm (although in fact there are hundreds more).
Carpobrotus edulis
Invasive species are recognised as one of the five major reasons for biodiversity loss (along with habitat loss/degradation, over-harvesting, pollution and synergistic effects). This biodiversity loss can occur because of effects like:
- competition with native species
- impacts on ecosystem functioning
- predation / herbivory on native species
- transmission of diseases
Not only do these impacts damage the environment, but they may cause tremendous economic loss in areas such as agriculture, fisheries, forestry, food security and public health. Indeed the total economic impact of invasive species in the United States was estimated at $137 billion per year (Pimental et al. 2000).
Work in SENR concentrates on the ecology and economics of invasive species in the UK and the Mediterranean basin and on invasive woody plants in the tropics. We are particularly interested in understanding:
Sand dunes in Mallorca.
- predicting the invasiveness of plant species
- predicting the vulnerability of ecosystems to invasion
- field assessment of the demography and impacts on biodiversity of invasive woody plants
- ecological means by which vertebrates out compete native species
- perception of exotic species by local people
- financial impact of invasive exotics, both costs and benefits
- impacts of invasive species on ecosystem functioning
- assessing the importance of invasives in nature conservation
- policies for managing the risk of invasives
- development and testing of management and control methods for invasive woody plants
For further details on socio-economics and risk, contact Professor Gareth Edwards-Jones; email g.ejones@bangor.ac.uk
For further details on tropical issues, plant ecology and trees, contact Dr John Healey; email j.healey@bangor.ac.uk
Abersoch in North Wales!
References
Pimental, D., Lach, L., Zuniga, R. & Morrison, D. 2000. Environmental and Economic Costs of Nonindigenous Species in the United States. BioScience 50 (1): 53-65.
Healey, J.R., Knorpel, D. and Ayres, S. (2002) Is invasive beech displacing native tree species from a semi-natural woodland in North Wales? Abstracts of the Annual Meeting of the British Ecological Society, University of York, 18-20 December 2002.
Binggeli, P., Hall, J.B. & Healey, J.R. (2002) Invasive woody plants in the tropics: a growing concern. Abstracts of the Annual Meeting of the British Ecological Society, University of York, 18-20 December 2002.
Case study
A beautiful killer
The crowns of P. undulatum trees
Carpobrotus edulis is valued for its beauty ....but it's a killer.
Here it has escaped from a garden and is smothering native plants on sand dunes in Mallorca
Not restricted to the Mediterranean – this killer has also got to Abersoch in North Wales!
Invasive tropical trees
Pittosporum undulatum is an Australian tree that has become a severe invader in five tropical or warm temperate countries and naturalized in at least seven others. It is native to New South Wales (Australia). Whilst its invasion is accelerated by natural or human disturbance, it is even able to invade undisturbed forests.
Secondary forest heavily invaded
by P. undulatum
The crowns of P. undulatum trees that have invaded montane forest in Jamaica can be seen as a bright scarlet colour using infra-red film photography.
Secondary forest heavily invaded by P. undulatum which is shading out the regeneration of virtually all the indigenous plant species.