the GiGLer

The newsletter of Greenspace Information of Greater London CIC

London Invasive Species Initiative

Jo Heisse, of the Environment Agency, Conservation Officer.

Creeping water primrose - an invasive species

The London Invasive Species Initiative (LISI) is a newly formed group under the London Biodiversity Partnership, which aims to co-ordinate action to prevent, control and eradicate invasive non-native species in London.

LISI was formed in response to national policy initiatives seeking a co-ordinated national approach to invasive non-native species as well as a recognised need for this to happen in London.

Invasive species are a hot and, at times, emotive topic. There are undoubtedly some non-native species which are highly invasive and a cause for concern for our environment and wildlife. Local action groups exist across the country but no one organisation or body is responsible for dealing with invasive species and problems are often dealt with in a piecemeal manner. Raising awareness and taking co-ordinated action on invasive non-native species in a pragmatic, risk aware approach can only benefit the environment and debates surrounding how we interact with it.

This is particularly important given London’s rich natural history – its great diversity of species and wide range of habitats, create a unique wildlife resource. However, this richness is threatened by the presence of invasive non-native species, that have according to DEFRA, ‘the ability to spread causing damage to the environment, the economy, our health or the way we live’. Such species are usually from different continents. In the UK they are unaffected by the natural pests and diseases which control their spread in their native range. They have high or effective rates of reproduction, making them highly mobile. The risk of these causing harm or becoming invasive is increased in London by the effects of the urban heat island and climate change. New and emerging invasive non-native species are also highly likely to appear in London due to the presence of a port and several airports and high rates of importation.

The River Wandle choked with floating pennywort and azolla.

Many non-native invasive species are aquatic. In the city, several waterways are currently infested with large rafts of floating pennywort (Hydrocotyle ranunculoides). When left unmanaged, these cover sections of the Wandle and Thamesmead Canals, forming rafts 1-2m deep across areas of usually open water.

Such invasions increase the risk of flooding, impact on the recreational use of these watercourses and reduce species diversity. The regular appearance of American mink (Mustela vison) presents a very serious threat to London’s water vole populations while another notorious invasive species, New Zealand Pigmyweed (Crassula helmsii), is smothering large areas of Wimbledon Common.

On land, tree-of-heaven (Ailanthus altissima) seedlings are appearing alongside roads, pavements and railway embankments all over the city. All of these species dominate or have the potential to dominate ecosystems, reducing ecological diversity and causing costly and time consuming environmental damage.

In order to help tackle some of these issues, the London Invasive Species Initiative has six main objectives; to:

1.     Collate and monitor data on the distribution and spread of invasive non-native species in London.

2.     Develop an action plan to address the species of most urgent concern.

3.     Facilitate control and eradication projects for high priority species.

4.     Provide a link between research and practitioners to support the evidence base on invasive non-native species.

5.     Act as an early warning system for new and emerging invasive non-native species.

6.     Promote awareness of the risks and impacts associated with invasive non-native species.

Many of these objectives are entirely reliant on accurate and up to date biodiversity data. GiGL is a key partner, providing a local service tailored to the project. Without accurate mapping and monitoring of species present in London and reporting of new records, it would be impossible to take targeted action to manage these.

One of the first steps of the initiative has been to short list non-native species of concern for London. As part of this exercise, GiGL undertook a data audit to identify the number of records of each species of concern and cross-reference this with records for SSSIs, rivers, SINCs and boroughs across London. This has given the group a good idea of the non-native species data that are available and an idea of where the worst impacts may be occurring and consequently where to focus resources and priority actions. GiGL will continue to undertake analysis of available invasive species data to support LISI in meeting the objectives outlined.

Effective action on invasive non-native species relies on effective monitoring and prevention, closely followed by control and eradication of new and small-scale infestations. Without an effective local data recording scheme, this would be more difficult to put into practice. This is particularly important for new or emerging species such as creeping water primrose (Ludwigia grandiflora ) where rapid action is important to prevent its rapid spread and where eradication would become increasingly unlikely the longer the species is present on a site.

Recognsing the importance of effective monitoring, GiGL is going to make it even easier for people to submit invasive species records by creating a dedicated survey form on behalf of LISI, which will soon be accessible via the GiGL website. Also, to help people take action to eradicate invasive species, a new section will be added to the data search reports, which GiGL provide mainly regularly to consultants working on behalf of developers.

Since the inception of LISI, it has become apparent that a great deal of knowledge exists on invasive non-native species present in London but this is not necessarily being recorded or validated. We would encourage all GiGL partners to record and send in non-native species data in order to enable LISI to focus its resources on the most problematic species.  LISI have already made a call for data on a small number of species and we anticipate following this with regular further calls for invasive non-native species data to be sent to GiGL.

Should any partner be interested in joining LISI or require further information on the group, please contact Joanna Heisse at the Environment Agency.

LISI is chaired by the Environment Agency and is a partnership between a large number of organisations. The Natural History Museum, Natural England, London Boroughs Biodiversity Forum, London Wildlife Trust and GiGL have been core partners in helping to set the group up, along with support from the GB Non-Native Species Secretariat. Many additional organisations have signed up as active members. These include the Wildfowl and Wetlands Trust, London Natural History Society, Kew Gardens, Network Rail, Thames21, BAA, Thames Landscape Strategy, Lee Valley Park, Wandle Trust, British Waterways, Kings College London, University College London, Imperial College and Queen Mary University.


  1. Stephen Skelton on November 2014 at 10:24 am

    My garden backs onto an underground railway embankment which for many years has had japanese knotweed growing on it. Occasionally they come and spray it, but often leaving small areas which grow up again. There is also an area of land which appears to belong to the railway, but which is landlocked and cannot be easily accessed but which is also growing JK. I have been in contact with Transport for London and they have responded, but just say they know about it and are dealing with it. However, they have made no attempt to spray in the landlocked area and I suspect they are just fobbing me off and hope I will go away. Is there anything that can be done to wake them up? Serve some sort of notice on them perhaps?

  2. Julie Cox on December 2014 at 12:52 pm

    Hi Stephen, thank you for your comment. We passed your question onto Karen from LISI who says the following:

    I am sorry to hear that you need to deal with Japanese knotweed, but I am glad to let you know that Transport for London (TFL) do have a management programme for Japanese knotweed (and indeed other invasive non-native species) on their network, and are aware of the requirements under the relevant legislation and communicate with LISI regularly regarding invasive species.

    Unfortunately to effectively kill Japanese Knotweed it does takes several years of treatment which is probably why you are seeing regrowth. We normally advise people to let TFL know about sites, as new patches can appear along the network. As you have already done this it should receive treatment next year. I am more than happy to email TFL again with the sites for you, especially the one you say hasn’t received treatment yet, to ensure they are on the maintenance programme.

    If you would like to discuss it further please do feel free to email me at and we would be happy to help where possible.

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