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Invasive Species in the UK Overseas Territories

Alien invasive species are recognised as one of the key drivers of biodiversity loss and their impacts are particularly significant on islands. For effective conservation management, UKOTs require a good understanding of the nature and distribution of non-native species and a risk assessment of their potential invasiveness. This ongoing project provides valuable baseline data on non-native species in UKOTs and is making them available via the UKOTs online herbarium.
Invasive plants smother areas of eroded soil on St Helena, excluding native species
(Image: Colin Clubbe)

Current fieldwork by the UKOTs team and their in-Territory partners is documenting the occurrence and distribution of non-native species across UKOTs. Mostly as an integral part of species inventory programmes where all plant species are being documented, there have been a few targeted invasive species activities. In particular Kew collaborated in the South Atlantic Invasive Species Project, a major three-yearEuropean Union funded project co-ordinated by RSPB. Major botanical components completed comprise:

  • Checklist of non-native species and assessment of key invasive species and their potential threats for St Helena
  • Checklist of non-native species and assessment of key invasive species and their potential threats for Ascension Island
  • Checklist of non-native species and assessment of key invasive species and their potential threats for the Falkland Islands
  • Checklist of non-native plants on South Georgia, to provide baseline information on their presence, distribution and invasive potential, enabling the Government of South Georgia to make informed decisions for conservation management – see  project page: Survey of Introduced Vascular Plants in South Georgia
  • Checklist of non-native species and assessment of key invasive species and their potential threats for Tristan da Cunha
  • Regional workshop held on Ascension which resulted in the development of a South Atlantic Invasive Species Strategy and Action Plan which has been approved by the relevant Government Officials of each of the South Atlantic Overseas Territories

Other major invasive surveys completed during this period comprise:

  • Updated checklist of non-native species of the British Indian Ocean Territory (BIOT) as part of the 2010 Scientific Expedition, the outcomes of which contributed valuable biodiversity information as part of the justification for the establishment of the Chagos Marine Protected Area (MPA) in 2010, the world’s largest MPA
  • Review of the non-native species and assessment of invasiveness for the Montserrat Centre Hills – see project page: Enabling the People of Montserrat to Conserve the Centre Hills
  • Documentation of the distribution and impacts of the invasive pine tortoise scale (Toumeyella parvicornis), currently devastating the native pineyard habitats of the Turks and Caicos Islands - see project page: Turks and Caicos Islands Pine Recovery Programme

Specimens have been incorporated into the Kew herbarium, digitized and scanned and made available via the UKOTs Online Herbarium. Data have been repatriated to the relevant UKOT Government and NGO where appropriate and are being used to help inform conservation management decisions and in many cases developing improved biosecurity procedures. Some risk assessment work is being undertaken for specific species including invasive thistles (Cirsium arvense and Carduus tenuiflorus) in the Falkland Islands and whiteweed (Austroeupatorium inulifolium) on St Helena.  

Project partners and collaborators


Conservation Department, Ascension Island Government

British Indian Ocean Territory

Chagos Conservation Trust

BIOT Government

Falkland Islands

Department of Environment, Falkland Islands Government

Falklands Conservation


Department of Environment, Government of Montserrat

Montserrat National Trust

St Helena

Agriculture and Natural Resources Department, Government of St Helena

St Helena National Trust

South Georgia

South Georgia Government

South Georgia Heritage Trust

Tristan da Cunha

Department of Conservation, Government of Tristan da Cunha


British Antarctic Survey

Royal Society for the Protection of Birds

Project funders


European Commission - European Commission - Project No 9 PTO REG5/L; PTR 003/05/EDFIX


Overseas Territories Environment Programme (OTEP)

The Darwin Initiative

Annex material


Clubbe, C. & Hamilton, M., & Corcoran, M. (2010). Using the Global Strategy for Plant Conservation to Guide Conservation Implementation in the UK Overseas Territories. Kew Bulletin 65: 509-717.

Conference papers and reports

UKOTs Online Herbarium

Gremmen, N. & Halbertsma, R. L. (2009). Alien plants and their impact on Tristan da Cunha Part 1: General account

Cheesman, O.D. & Clubbe, C. (2007). Dealing with Alien Invasive Species – Introduction, Overview and Conclusions. pp 193-200 in Biodiversity That Matters: a conference on conservation in UK Overseas Territories and other small island communities Jersey 6th to 12th October 2006 (ed. M. Pienkowski).

Clubbe, C., Hamilton, M. & Corcoran, M. (2010). The role of native species nurseries in mitigating threats from invasive species: case studies from UK Overseas Territories. Proceedings of the 4th Global Botanic Gardens Congress, June 2010.

Darlow, A. 2010. The South Atlantic Invasive Species (SAIS) Project. pp 270-273 in Making the Right Connections: a conference on conservation in UK Overseas Territories,Crown Dependencies and other small island communities, Grand Cayman 30th May to 5th June 2009 (ed. by M. Pienkowski, O. Cheesman, C. Quick & A. Pienkowski). UK Overseas Territories Conservation Forum

South Atlantic Invasive Species Strategy and Action Plan (2010)

MSc Theses

Stow, S. (2008) Non-native plant distribution in Montserrat: Conservation and Ecological aspects

Hardman, C. (2009) Invasive plants in the Turks and Caicos Islands

Davey, A. (2011) Mapping the distribution and prioritising the control of Casuarina equisetifolia in the Turks and Caicos Islands