Download 2014 State of the Environment Report

State of the Natural
Environment
Unnatural World –
Himalayan Balsam © Shutterstock.com
the impact of invasive non-native
species on Gloucestershire’s native
plants and animals
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Globally, invasive non-native species are the second most significant threat to
biodiversity after habitat loss (1) but this impact often goes unseen as the species
concerned either become accepted as part of the local landscape or are aquatic and
thus hidden from view. Such species can out compete and displace native species but
they also have an impact on the economy which in 2010 was estimated in the UK
alone to be a staggering £1.7 billion annually (2). Gloucestershire has its fair share
of invasive non-native species but what is their impact here and what can be done to
control them?
Invasive non-native species are defined as those species whose introduction and
spread threaten native plants and animals or have other unseen impacts. They are
(1) http://www.nhm.ac.uk/nature-online/biodiversity/what-is-threatening-biodiversity
(2) The economic cost of invasive non-native species on Great Britain. Cabi 2010
Muntjac Deer
Top invasive specieS in the county
Muntjac Deer (Muntiacus reevesi). Descended from escapees from the Woburn Estate around
1925, Muntjac are now found throughout England. With continuing growth in their numbers it
may soon be the most numerous deer species in the UK. They have a significant impact on
woodland coppice re-growth by their browsing and also sensitive ground flora, especially
bluebell bulbs. Status in Gloucestershire: Widespread.
American Mink
Mammals
American Mink (Mustela vison). Escapees and deliberate releases from fur farms in the 1960s
mink are now widespread across the UK. They are voracious predators, especially of the native
water vole which has suffered catastrophic declines due to habitat loss and mink predation.
Status in Gloucestershire: Widespread.
Birds
Ring-necked Parakeet
Canada Goose (Branta canadensis). Introduced into St James’s Park in London in 1665 these
birds are now widespread favouring gravel pits, lakes and parks across the UK. The birds browse
marginal vegetation and contribute to nutrient enrichment of water bodies, reducing species
diversity. Status in Gloucestershire: Widespread.
Ring-necked Parakeet (Psittacula krameri). A native of the Indian sub-continent, these birds
have been kept as pets since Victorian times and are present in the wild as a result of escapes or
deliberate releases, now well established in the London area. First recorded breeding was in Kent
in 1969. The UK’s only naturalised parrot may compete with other native bird species for food and
hole nest sites. Status in Gloucestershire: Occasional reports in the Stroud area.
Top invasive specieS in the county
Giant Hogweed
Himalayan Balsam (Impatiens glandulifera). Introduced in 1839 as a greenhouse plant, this
native of the Himalayas has rapidly spread and can be found across the UK. It out competes
native bankside plants for both space and pollinators and leaves riverbanks bare in the autumn
when it dies back leading to erosion and river siltation.
Status in Gloucestershire: Widespread on most watercourses in the county.
Giant Hogweed (Heracleum mantegazzianum). Native of central Asia, this plant was introduced
as a majestic addition to Victorian gardens and has now spread along watercourses and to waste
places across the country. It is phototoxic and in the presence of sunlight its sap can cause severe
skin irritation. It creates dense stands and out competes native species for space.
Status in Gloucestershire: Abundant along some watercourses, i.e. Painswick Stream.
Japanese Knotweed
Himalayan Balsam
Terrestrial Plants
Japanese Knotweed (Fallopia japonica). Considered to be the world’s worst invasive species,
this native of East Asia was a 19th century introduction to Victorian gardens. Now well established
in the wild this fast growing species spreads by extensive underground stems which can be
three metres deep creating dense stands which shade out native plants. Difficult to control with
traditional herbicides the plant can cause structural damage to concrete foundations, roads and
flood defences. Status in Gloucestershire: Widespread on roadside verges and waste places.
generally species which have been introduced by human action to areas outside
their natural range and have expanded to firmly establish a thriving, self-sustaining
population. These species often cope better in their new environment because of a lack
of controlling factors (i.e. predators). Some introductions happened many centuries
ago (eg. rabbit) but the problem has increased in the past 30 years. An estimated
25% of all introduced species worldwide cause a problem and the number of nonnative species introductions is increasing exponentially as a result of increased travel,
transport, trade and tourism. In Europe, approximately ten new species become
established each year, and there is a rising trend for invertebrates and marine fish
introductions. It is considered that climate change will exacerbate the problem.
Invasive non-native species in Gloucestershire cover a wide range of plant and animal
groups and can be found in most habitats in the county.
Aquatic Plants
Parrot’s Feather
These “Infamous Five” aquatic non-native invasive plant species were banned from
being sold in UK garden centres on 1st April 2014. Once established in garden ponds
they can soon escape into the wild where they can wreak havoc choking watercourses
and displacing native species. BE VIGILANT if buying pond plants – these species may
be on sale but mislabelled, or they could be contaminating other plants. Just a small
fragment could soon be in the countryside and out of control.
Water Fern (Azolla filiculoides). A tiny rampant floating fern like a small pondweed but red in
winter – spreads vegetatively or by spores.
Status in Gloucestershire: Occasional, i.e. Stroudwater Canal.
Parrot’s Feather (Myriophyllum aquaticum). A fast growing native of Central and South America
introduced into Victorian water gardens now on the loose in the British countryside.
Status in Gloucestershire: Locally abundant, i.e. Cotswold rivers, Walmore Common.
Water Primrose (Ludwigia grandiflora). Another South American exotic currently the most
problem invasive species in France where it blocks rivers and drainage systems and contributes
to flooding. Status in Gloucestershire: No records yet.
New Zealand Pygmy Weed (Crassula helmsii). A small succulent plant from Australia and New
Zealand easily spread and very invasive.
Status in Gloucestershire: Widespread in many water bodies across the county.
Aquatic Invertebrates
Water Primrose
Floating Pennywort (Hydrocotyle ranunculoides) A rampant invasive alien around the world but
endangered in parts of its natural range in the USA.
Status in Gloucestershire: Reported from a park pond in Cheltenham.
Top invasive specieS in the county
Signal Crayfish (Pacifastacus leniusculus). Introduced from the USA and farmed for food, it is
a carrier of crayfish plague which is lethal to our native species which is now threatened with
extinction. Native crayfish populations where they remain are being removed to Ark sites as the
only way of conserving them. The plague is easily spread on boots and fishing equipment.
Status in Gloucestershire: Abundant in the Cotswold water Park and most watercourses in
the county.
New Zealand Pygmy Weed
Zebra Mussel (Dreissena polymorpha). A native of the Caspian and Black Seas this species
has spread across the world in the ballast tanks of ships and is a major problem in harbours and
waterways and the water industry where it clogs pipes. The species costs Anglian water £500,000
per annum removing it from water treatment plants.
Status in Gloucestershire: Gloucester & Sharpness Canal.
Zebra Mussel
Killer Shrimps (Dikerogammarus villosus). This native of Eastern Europe now established in
several parts of England is a voracious predator of native invertebrates and small fish and can
dramatically alter aquatic ecosystems. Its spread is being actively monitored by EA.
Status in Gloucestershire: Uncertain but one to look out for.
What can be done?
Considerable effort goes into monitoring and researching the spread of these
unwelcome visitors and identifying control mechanisms. Some are easier to control
than others and many are probably here to stay. Mechanical, physical and biological
methods are being employed in the fight against these species. Trials are currently
underway to see if a rust which is unique to Himalayan balsam in its home range
could be an effective agent to control the spread of this plant in the UK
Giant Hogweed
Non-native invasive species are a problem world-wide. A species which is benign in
its native range can cause havoc when it enters a new ecosystem where the native
species have evolved in its absence and are unable to compete with the new invader.
Plants, birds, animals and invertebrates, especially aquatic plants and animals, can
all become problem visitors.
What the Trust intends to do
What can I do to help?
•Find out more about non-native invasive species and lookout for them in your
local patch
•Report any sightings via the plant tracker app or send your record to GCER
Canada Goose
The Trust recognises the potential threat posed to our native wildlife as a result of
non-native invaders and will give tackling the problem high priority on its reserves
and within its Living Landscape Project areas. Volunteer Groups will be established
in key areas to help with the task. For more information contact…..
•Check out garden and pond plants of concern and avoid buying them
•Report any banned plants that you suspect are being offered for sale
•Don’t transfer anything from your garden pond to a pond in the wild
(i.e. frogspawn)
•Join our volunteer task groups helping to tackle the problem in your area
Links
http://www.nonnativespecies.org
Signal Crayfish
•If you’re a user of waterways follow the “Check Clean Dry” guidelines to avoid
spreading harmful species unwittingly
http://www.nonnativespecies.org/checkcleandry
http://www.plantlife.org.uk/campaigns/invasive_plants
Gloucestershire Wildlife Trust
Conservation Centre, Robinswood Hill Country Park, Reservoir Road, Gloucester, GL4 6SX
Tel: 01452 383333 Fax: 01452 383334
[email protected]
www.gloucestershirewildlifetrust.co.uk
Japanese Knotweed
photographs ©: Shutterstock.com/DJ Taylor/Stephan Morris/Eduardo Rivero/Helen Grose/Martin Fowler/Reece with a C/
Alexander Chelmodeer/Hellen Sergeyeva/Vitalii Hulai/Aigars Reinholds/Dennis Donohue, Wildstock, Amy Lewis, Dave Kilbey
Registered Charity Number: 232580
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