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Last update:2nd June 2008 Quick links:
What are non-native & invasive speces Invasive non native species framework strategy Top 10 most wanted alien species Japanese Knotweed in the South West Giant Hogweed in the South West Floating pennwort in the South West Top mouthed gudgeon in the South West Audit of non-native species in England What you can do - postcode native plant database Useful websites:Environment Agency - invasive / non-native species Defra horticultural code of practice
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Non-Native and Invasive SpeciesWhat's new on this page...
One of the greatest threats to Britain’s native plants and habitats is from invasions of non-native plants, many of which were introduced into gardens and parks over the last couple of centuries and have subsequently escaped into towns and the countryside. What are non-native / invasive species?When non-native species become invasive they can transform ecosystems, and threaten native and endangered species. Invasive non-native species also damage economic interests, such as agriculture, forestry and infrastructure, and can threaten public health. The scale of this problem is so serious that they have been identified as one of the main causes of biodiversity loss worldwide as well as resulting in the loss of locally distinctive biodiversity. Not all non-native plants are invasive however, in fact many of us have them in our gardens which may never escape into the surrounding area. Defra have produced guidance on helping to prevent the spread of invasive non-native species - horticultural code of practice (March 2005). This report provides advice and guidance on the safe use, control and disposal of invasive non-native plants for everyone engaged in horticulture and related activities that involve the use of plants. Guidance for the control of invasive weeds in or near fresh water is also available from the Environment Agency. Invasive Non Natives Species Framework Strategy for Great BritainEngland, Scotland and Wales launched the first coordinated plan to reduce the threat to Britain’s native biodiversity from invasive non-native species on the 28th May 2008. The GB Invasive Non-native Species Framework Strategy is intended to provide a strategic framework within which the actions of government departments, their related bodies and key stakeholders can be better co-ordinated. Its overall aim is to minimise the risks posed, and reduce the negative impacts caused, by invasive non-native species in Great Britain. Invasive non-native species such as Floating Pennywort and the North American Signal Crayfish can have a serious impact on our native wildlife and economic interests. Controlling their spread is key to conserving our native wildlife. Key measures in the strategy include:
Top 10 most wanted foreign speciesThe Environment Agency is today releasing a top-ten most wanted list of foreign species that have overstayed their environmental visa. The American signal crayfish and the American mink may originally be from across the pond, but they are now taking over British waterways, out-muscling native competition and spreading disease. For the native white-clawed crayfish and water vole, these invasive species are over sized, over sexed and over here. But these are just two of the recent arrivals that have taken advantage of Britain’s complimentary living conditions, with the Environment Agency compiling the top ten invasive species marked for containment and removal.
All above plants are covered by pest-control legislation: The Wildlife and Countryside Act 1981 provides the primary controls on the release of non-native species into the wild in Great Britain. It is an offence under section 14(2) of the Act to ‘plant or otherwise cause to grow in the wild’ any plant listed in Schedule 9, Part II. Examples of non-native and invasive species in the South WestJapanese KnotweedJapanese Knotweed was introduced to the UK as an ornamental plant during the 1800s. It is commonly found today along railway lines, riverbanks, roads and footpaths, in graveyards, on derelict sites or anywhere that it has been dumped, dropped or deposited. It has now been recorded in over 50% of the 10 km squares used to map plant distribution. The only place it is not found is the Orkney Islands Although Japanese Knotweed is not toxic to humans, animals or other plants, it offers a poor habitat for native insects, birds and mammals. Japanese knotweed is an invasive species that can:
Under the Wildlife and Countryside Act 1981 / Wildlife (Northern Ireland) Order 1985 it is an offence "to plant or otherwise encourage" the growth of Japanese Knotweed. This could include cutting the plant or roots and disturbing surrounding soil if not correctly managed. Specific problems, caused by Japanese knotweed (Japanese Knotweed Alliance):
Find out more:Japanese Knotweed AllianceThe Japanese Knotweed Alliance was established in November 1999 to highlight the problems posed by this invasive weed and to promote its natural control with biological predators. The core of the alliance consists of CABI Bioscience (formerly the International Institute of Biological Control) the Welsh Development Agency, the Environment Agency, National Botanic Garden of Wales and Cornell University. This website contains information on:
The Environment AgencyThe Environment Agency has detailed information available on Japanese Knotweed, including:
Cornwall Knotweed ForumThe Cornwall Knotweed Forum is a co-operative venture between the following bodies (inter alia): The Environment Agency, University of Exeter in Cornwall, The National Trust, Cornwall County Council, English Nature. This website has information on:
Devon Japanese Knotweed ForumDevon Japanese Knotweed Forum aims to control this species within the County. Information includes:
Giant HogweedGiant hogweed was introduced to Britain in 1893 as an ornamental plant, however, it escaped from gardens and now colonises many areas of wasteland and riverbanks. Forming dense colonies of plants up to 16 foot high, these plants suppress the growth of native plants and grasses, this plant leaves river banks bare of vegetation in winter so increasing the risk of erosion and recolonisation from seeds washed downstream. The Wildlife and Countryside Act 1981 provides the primary controls on the release of non-native species into the wild in Great Britain. It is an offence under section 14(2) of the Act to ‘plant or otherwise cause to grow in the wild’ any plant listed in Schedule 9, Part II. This includes Giant hogweed. Giant Hogweed is a health hazard. Small hairs containing poisonous sap can be found on the stems, edges and undersides of leaves, which cause painful blistering and severe skin irritation. A factsheet on Giant Hogweed is available from the Environment Agency Tackling giant hogweed as a major hazard in the Tamar ValleyAn Environment Agency awareness day was held on the 27th June 2006 at Morwellham Quay, near Tavistock, aimed at those who feel they are fighting a losing battle against invasive plants in the Tamar Valley. The ecology of Giant Hogweed, Japanese Knotweed and Himalayan Balsam, how they can be controlled and the legal issues surrounding these invasive species were all discussed. Organised by the Tamar Valley Invasive Group, the day aims to provide an understanding of why control work needs to be done and what people can do to help alleviate the problem. The Tamar Valley Invasive Group, a partnership between the Environment Agency, English Nature, Tamar Valley AONB Service and The Silvanus Trust, has been undertaking surveying and control of Giant Hogweed along the Tamar and Tavy. More information about the event is available from Jez Ralph on (01579) 372100 or email jez.ralph@silvanus.cornwall.ac.uk Floating pennywortFloating pennywort, native plant of North America, was first brought
into Britain in the 1980’s by the aquatic nursery This weed has been found to be growing throughout the South West but a recent report from the Environment Agency (September 2005) highlights the problems in the River Tone (Somerset) for the second year running. This latest outbreak is between Ham and Newbridge Sluice between Taunton and Bridgwater. There are around a dozen clumps of the weed, each around eight square metres in size. The Environment Agency has now managed to remove this weed, however, another smaller outbreak has been now been reported downstream. This has now been removed by hand and we hope that the impact of this weed will continue to reduce. Last year there was an outbreak of the weed further upstream, and patches were also discovered on the River Tamar on the Devon/Cornwall border. The weed needs to be removed and destroyed either by hand or machinery to prevent it spreading downstream. Floating pennwort can also cause a potential flood risk problem. A mat of this weed can weigh several tonnes and as the weed mat moves downstream it can become lodged against bridges and other structures. On the River Tone the moors are flooded regularly and it is this annual flooding that gives the area it's ecological interest and it's designations. The water is pumped out via pumping stations during periods of flood and the water level in the ditches maintained by the same pumps at all other times. Damage can occur to these pumps as the pennywort is sucked in, causing mechanical as well as financial problems. Find out moreAnyone requiring more information on recognising and controlling floating pennywort and other invasive aquatic weeds should access the information sheets provided at http://www.capm.org.uk The Wildlife and Countryside Act 1981 provides the primary control on the release of non-native species into the wild. It is an offence under section 14(2) of the Act to ‘plant or otherwise cause to grow in the wild’ any plant listed in Schedule 9 Part 11 of the Act. A factsheet on floating pennywort is available from the Environment Agency. Top Mouth Gudgeon
An alien fish that threatened to wipe out the local fish population in two East Devon lakes and the River Otter has been successfully removed by the Environment Agency. The Top Mouth Gudgeon was discovered in lakes at Bicton College and Bicton Park Botanical Gardens near East Budleigh in 2004. Measuring only 3-4 cm in length, the tiny invader outcompetes native species and also carries a damaging parasite that can interfere with the breeding cycle of salmon and trout. The Environment Agency took action in 2006 after thousands of the gudgeon were waShed into the Bicton stream during a thunderstorm. A gravel filter was installed to prevent the invader from spreading, but the gudgeon were swept past the filter after the lake overflowed. Environment Agency fisheries officers removed around 6,000 of the fish from the stream and, by acting swiftly, prevented it from moving downstream and colonising the Colaton Raleigh Stream which in turn flows into the River Otter. But the battle was far from over. With an estimated 100,000 alien fish still in the smaller lake the local fish population was still under threat and there was a risk that, once again, the gudgeon would escape and spread into nearby rivers and streams. It was decided that the only solution was eradication. In March 2007, the Environment Agency's fisheries officers carried out a rescue operation and removed native species including carp from the two lakes. With the native fish safely relocated to temporary holding ponds, a pesticide (poison) was then used to eradicate the Top Mouth Gudgeon. Rotenone is an environmentally safe pesticide that only targets fish and quickly breaks down in the environment. It doesn't harm other aquatic life such as insects, mammals or birds. Last autumn, Environment Agency fisheries officers electro-fished the lakes and Bicton Stream and could find no sign of the gudgeon. In late April 2008 officers carried out a second survey of the area to confirm their findings. MontbretiaMany invasive alien plants that are now threatening our native flora in Cornwall have been introduced into the wild from garden throw-outs. The list is long and includes winter heliotrope, Japanese knotweed, Hottentot fig, three-cornered leek, Spanish bluebell, and one that is much in evidence along our roadsides at the moment – montbretia, also known by its Latin name, Crocosmia. Montbretia is a vigorous, hybrid perennial plant from South Africa. It has bright green, spear-shaped leaves which appear in spring, and are followed by long spikes of small, orange, tubular flowers in late summer and autumn. Each plant has a string of flattened corms under the ground, up to 14 or more in number, each capable of producing another plant. Originally spread to the wild from garden rubbish, montbretia now competes fiercely with native plant species. It is a hybrid, but produces viable seed in western coastal areas of the British Isles, and it moves rapidly along roadsides, across wasteland and down water courses by this means and by corm production, the corms being dispersed by the movement of soil containing them, e.g. in roadworks or garden waste. As each corm breaks off it forms a new plant with corms of its own – in this way the clump thickens and spreads. Long rhizomes are also produced, each of which initiates new corms which grow into more plants. Some new variants of montbretia are particularly vigorous and can spread at a rate of 1m to 2m per annum. Like many species that become regarded as weeds, montbretia can tolerate a range of environmental conditions. It will grow in any soil – wet or dry, rich or poor, in sun or in shade, and is not eaten by slugs. Although bright and generally regarded as attractive, montbretia is an aggressive bully and will dominate the ground layer, crowding out other plants and preventing the germination of any native seeds in the soil. In Australia the plant has been classed as a noxious weed and it is illegal to sell it or allow it to spread to adjacent land. Spraying is not generally a very successful method of removal. Montbretia can be controlled by digging deeply and removing the corms, but patience and persistence are required to get them all, and the procedure may have to be repeated over successive years. Once removed, montbretia corms should not be put in the compost. The leaves can be cut from the corms and composted, or put in the green waste system but corms should be crushed on a hard surface, allowed to dry out and then incinerated, or alternatively can be put in a black plastic bag for disposal with non-recyclable material. The problems of removal would not arise if such plants were not introduced into the wild in the first place. Please dispose of your garden rubbish responsibly - don’t throw it on the road verge or over your garden hedge. Help protect Cornwall’s diverse and colourful displays of native wild flowers by preventing the “escape” of alien species. For more information, please contact the Wildlife Information Service at Cornwall Wildlife Trust on 01872 273939. Source: Cornwall Wildlife Trust (2006) Audit of non-native species in England
2,721 non-native species and hybrids have been found in the wild in England, including 1,798 flowering plants (making up 73% of the total) most of which have escaped from gardens.
Detailed analysis was done on 1,413 species considered to be most significant and showed that 1,177 are considered to be established in England. The vast majority of non-native species don’t cause any environmental or economic problems but some species can cause considerable damage. Japanese knotweed, for example, can grow through concrete, damage property and destroy habitats by swamping the other plants. Invasive non-native species impact on biodiversity and the natural environment by displacing or preying upon native species, by changing habitats, or by introducing new diseases or parasites. The invasions can have serious economic and ecological consequences. The ecological cost may be the irretrievable loss of native species and ecosystems, including loss of characteristic local distinctiveness. The report identifies 19 species which have strongly negative environmental impacts. These include:
Some non-native animals and plants have beneficial effects. The report identified four animals (common pheasant, greylag goose, red-legged partridge and Rhizophagus grandis a predatory beetle used for pest biocontrol in forestry) and 51 plants – mainly tree crops and field crops - that had strongly positive economic impacts. Others have mixed effects, for example, Buddleja (butterfly bush) is considered to have strongly positive environmental impacts as a useful nectar source for some insects, notably butterflies, but can also colonise bare ground habitats important for other invertebrates, such as the Bombadeer beetle. It also has a major negative economic effect, because of the cost of herbicide applications to railway lines. In the last 20 years some invasive non-native species have increased considerably, at least doubling their numbers, including the freshwater fish topmouth gudgeon, Canada goose, Chinese muntjac, New Zealand pygmyweed and butterfly bush. New species continue to arrive and spread rapidly, for example the horse chestnut leaf miner, which probably first appeared in 2002. Introduced animals occupy a wide variety of habitats, but plants are more selective, being strongly concentrated on cultivated, built and derelict land. This has potential important economic and environmental considerations for our towns and cities, where many of these new species are establishing and can be very expensive to remove. Invasive species also affect sustainable development and land or resource management, and can result in impacts on human interest, for example by causing financial losses or public health issues. English Nature will now use these results to decide which nuisance non-native species pose a threat to English wildlife and how they can be tackled. Postcode native plant databaseYou can help by reporting non-native or invasive species to your local authority. You can also opt to plant native species in your garden.
The Natural History Museum has a database of native plants and wildlife that is searchable by postcode. The aim of the Postcode Plants Database is to encourage gardeners and other horticulturalists to plant the native trees, shrubs and flowers that are local to their areas. By typing in a postcode householders, schools, garden centres and councils can obtain tailor-made lists of local plants, many of which are both hospitable to wildlife and suitable for gardens within their postal districts. It is hoped that this database will foster greater understanding and awareness of the local environment, helping people to appreciate local plants and their importance for wildlife
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The
Audit of non-native species in England