1 Invasive species threats |
1. Invasive non-native (or alien) species
exhibit greater abundance, density, or competitive dominance than
species that are native to an area, and so adversely affect an
existing ecology or habitat. They can also have detrimental effects
on human health and well-being and on economically important activities.
The rate of introduction of such species has accelerated with
the expansion of international trade and travel. A study in 2012
counted 1,875 non-native species established in Great Britaina
figure increasing by 10 species a yearof which 282 had
become invasive. At
the global level, invasive species were ranked as one of most
important drivers of biodiversity loss by the Millennium Ecosystem
Assessment in 2005.
2. The UK has existing international
obligations to address the effects of invasive species. The UN
Convention on Biological Diversity requires member states: "as
far as possible and as appropriate, [to] prevent the introduction
of, control or eradicate those alien species which threaten ecosystems,
habitats or species".
One of the Convention's Strategic Plan targets, adopted in 2010
at Nagoya, is that "by 2020, invasive alien species and pathways
are identified and prioritised, priority species are controlled
or eradicated, and measures are in place to manage pathways to
prevent their introduction and establishment". In addition,
the Convention on the Conservation of European Wildlife and Natural
Habitats commits contracting parties to control invasive species.
3. The Nagoya target is also reflected
in the EU biodiversity strategy: "By 2020, invasive alien
species and their pathways are identified and prioritised, priority
species are controlled or eradicated, and pathways are managed
to prevent the introduction and establishment of new [invasive
species]". To help
achieve this target, the EU is in the process of negotiating and
agreeing aRegulation on the Prevention and Management of the
Introduction and Spread of Invasive Alien Species.
This would apply to all invasive species other than where they
alter their natural range without human intervention or where
controls on them already exist in other European regulatory regimes.The
Government told us that the proposed regulation "addresses
all of our objectives", and that the "consistent approach
across the EU" it will produce "represents a considerable
improvement on the current disjointed situation across Europe".
4. In Great Britain, policy is coordinated
by the Non-native Species Secretariat which brings together the
environment departments and agencies of England, Scotland and
Wales. The Secretariat is responsible for overseeing the 2008
Great Britain Invasive Non-native Species Framework Strategy.
Work to revise and update the Strategy has been underway
since September 2013. The Secretariat would also have to coordinate
any further requirements from the implementation of the proposed
5. We made a commitment to examine the
issue of invasive species in our 2013 report on Wildlife Crime.
We did so at this time because negotiations were underway in the
European Commission on the proposed invasive species regulation
and because the Great Britain Invasive Non-native Species Framework
Strategy was being revised. We took oral evidence from 19
witnesses over four sessions, including academics, research bodies,
NGOs, industry groups, regulatory bodies and Lord de Mauley, the
Defra Parliamentary Under-Secretary of State for natural environment
Defining invasive non-native species
6. A species is defined as native in
Great Britain if it re-colonised after the end of the last period
of glaciation. Professor
Chris Thomas of the University of York pointed out that not all
of the animals and plants now seen in Britain were here 11,000
years ago, and since then species "have flowed back and forth
supposedly non-native species, such as rabbits, were in fact present
here in previous interglacial warm periods.
The proposed EU regulation defines a non-native species in terms
of being "introduced outside their natural range".It
deals with species introduced by human intervention and excludes
"species changing their natural range without human intervention,
in response to changing ecological conditions and climate change".It
requires that species which, based on available scientific evidence,
are likely to have significant adverse impacts on biodiversity
or related ecosystem services, should be placed on anEU'List of
Species of Concern' (paragraph 24).
Effects on biodiversity
7. Dr Richard Shaw of the research group
CABI suggested to us that invasive non-native species have
biodiversity impacts distinct from invasive native species.
Dr Mark Spencer from the Natural History Museum noted that native
invasive species are constrained by pathogens and predators, whereas
non-native species are not. The Tree of Heaven from south-east
Asian, for example, faces native British biodiversity with no
"taste for that plant", allowing it "to spread
like wildfire once the environmental conditions [here] are the
Chris Thomas believed that some non-native species can cause widespread
change to native species, citing the example of the replacement
of the Red Squirrel bythe Grey over most of Britain, which was
assisted by the spread of a shared disease (squirrel pox) to which
Grey Squirrel is more resistant.He noted, nevertheless, that despite
the influx of 1,875 non-native species, "we have not had
any species-level extinctions from Britain" and that the
empirical evidence suggested that if 1,000 more non-native species
were added it would be only likely to result in the extinction
of "a few" native species.
8. Dr Helen Roy from the Centre of Ecology
and Hydrology, on the other hand, told us that the 15% of invasive
non-native species that do cause problems cause "extreme
Dr Niall Moore from the Non-Native Species Secretariat also raised
concerns from NGO Plantlife that Starfruit
was "probably going to become extinct" in Britain because
of the invasive New Zealand Pygmyweed plant. The Tansy Beetle,
which feeds on the Tansy plant that is being excluded from river
banks by invasive Himalayan Balsam, could also become extinct
9. Biosecuritythe exclusion,
eradication, and effective management of pests and unwanted organismsis
at risk from the importation of commodities and live plants and
animals, and from international travel. Invasive species are often
vectors for plant and animal disease.
Professor Chris Thomas noted that although some are significantAsh
Dieback and Bluetongue in sheepthere is a large number
of other less severe non-native diseases which arrive but go unnoticed.
Defra is currently reviewing its approach to biosecurity,
for which the Food and Environment Research Agency has been commissioned
to examine biosecurity policies in New Zealand and Australia for
comparison. New Zealand's
Biosecurity Act 1993 and Biosecurity Law Reform Act 2012 emphasise
the management of biosecurity threats offshore, in their country
of origin. Dr Richard
Shaw from CABI told us that the New Zealand and Australian biosecurity
model was significantly in advance of the rest of the world, but
biosecurity in Great Britain was in advance of that in the rest
10. A difficulty for policy-making in
this field is that any regulations to reduce biosecurity risks
would need to comply with World Trade Organisation agreements
and EU legislation. It also needs to integrate policies on invasive
species and biosecurity. However, in the European Commission the
Directorate General for Health and Consumers is responsible for
the animal, plant and human health regulatory framework, while
invasive species policy falls under the Directorate General for
the Environment. The proposed EU regulation on invasive species
is intended to be aligned with, but not overlap, existing EU legislation:It
will not apply to the organisms targeted by over 40existing pieces
of European legislation on animal health and plant diseases.
11. Coherence between the proposed
EU regulations on invasive species and on Animal and Plant Health
regimes would help improve understanding of the risks and increase
compliance with the regulatory frameworks. The risks posed to
biosecurity in Britain, as exemplified the Ash Dieback epidemic,
make it imperative that an integrated approach is taken to managing
the routes of biological invasion into the EU. The Government
must engage with the EU's workin revising the Plant and Animal
Health regulatory frameworks to ensure the result is a unified
approach to biosecurity threats betweentheseregulatory frameworks
and the invasive species framework.
PROTECTING BIODIVERSITY IN THE OVERSEAS
12. The proposed EU Regulation would
require member states with 'outermost regions' (which are fully
part of the EU) to draw up lists of species of concern for those
regions. It would not apply to UK Overseas Territories despite,
as we noted in our recent report on the Overseas Territories,the
Territories containing 90% of the biodiversity found within the
UK and Territories combined,and
more globally threatened species than in the UK.
Invasive species are one of the primary drivers of biodiversity
loss in the Overseas Territories. In many cases, we noted, there
was a lack of surveillance and monitoring in the Territories,
as well as weaknesses in environmental legislation, implementation
and technical expertise. However, Lord de Mauley told us that
the Overseas Territories' biosecurity issues had to be considered
in the context of theirdistinct constitutional relationship with
the UKand that Territory Governments were responsible for the
protection and conservation of their natural environments.
That mirrored the thrust of the Government Response we subsequently
received to our Overseas Territoriesreport.
13. Given the vulnerability of biodiversity
in the UK Overseas Territories to invasive species and its unique
value, it is imperative that the Government assist the Territories
to assess and address the pathways for newly arriving species.
It should provide them with further support to address the most
pressing gaps in their biosecurity frameworks and to draw up 'lists
of concern' for the Territories in line with those that will be
required for the EU 'Outermost Regions' by the proposed EU directive.
Adverse effects on ecosystem services
14. The lack of a framework for quantifyingthe
effects of invasive species on ecosystem services (the beneficial
goods and services we derive from habitats and biodiversity)
limits the Government's ability to predict when and where those
effects will arise. Professor Chris Thomas argued that adding
new species to ecosystems in Britain could increase their resilience
to environmental change.
Others, however, identified risks to ecosystems. The Angling Trust
told us how Himalayan Balsam affects fish in rivers: it excludes
all the other flora from river banks, and when it dies back in
the autumn there is heavy erosion and silting of the river.
Anglian Water found that the silting affected water quality and
so increased the cost of water treatment.
Richard Shaw believed"the true costs to the country [of invasive
species] are very high indeed".Dr
Helen Roy highlighted that some had an adverse "ecosystem
engineer" effect, which was difficult to quantify.
The lack of a database on ecosystem effects means that habitats
need to be monitored, as we discuss below.
Effects on human health and economic
15. Richard Shaw argued that every sector
of society was affected by invasive species, at a large and increasing
cost. The European
Environment Agency has estimated that the cost to the EU of a
range of invasive species was at least 12 billion a year.
The Country Land and Business Association (CLA) highlighted three
high-cost examples: £10million a year in damage to trees
by grey squirrels, £1.5billion to eradicate Japanese Knotweed
and £11million to eradicate Rhododendron from one national
park in Wales alone.
The City of London Law Society calculated that the annual cost
of dealing with Japanese Knotweed in Britain was £165 million,
and that the cost of removing it from the Olympic site was £70
million. The Angling
Trust cited the North American Signal Crayfishand 'Killer Shrimp'
which predates fish stocks, and plants such as Floating Pennywort
which deprives fish of oxygen. The cost of water treatment increases
when Zebra Mussels clog intake pipes.
16. Some invasive species have direct
human health effects. Anglers coming into contact with Giant Hogweed
received skin inflammations.
The pollen of Common Ragweed causes asthma.
The Asian Hornet, which might soon arrive here, has killed six
people in France.
TheOak Processionary Moth can cause respiratory and skin problems.Dr
Niall Moore told us that although human health was included in
invasive species risk assessments, there was a case for including
Public Health England on the Board of the Non-native Species Secretariat.
With a different perspective, Mark Spencer suggested to us that
there was an over-emphasis on the impact of invasive species on
wildlife habitats, when in fact new invasive species often have
significant consequencesfor human well-being.
17. There are potential human health
effects from invasive species, not just biodiversity impacts.Public
Health England should be integrated into the work of the Non-native
Species Secretariat, to help it address human health and well-being
A changing environmental baseline
18. The approach taken to invasive species
needs to be considered in the context of wider environmental change.
Dr Mark Spencer highlighted that habitats which were "heavily
impacted by humans in adverse ways are often much more vulnerable
to biological invasions".With
environmental changes increasingly being caused by human activities,
it would be ever more difficult to identify a change in a species'
range that was caused by only natural factors. He suggested, therefore,
that reponses to non-native species might need to become more
nuanced in the future.
Professor Chris Thomas argued that with three-quarters of species
having already shifted their distributions because of climate
change, conservation had to be increasingly about managing major
changes which were already happening.
Many insects were arriving and plants were already being grown
in our gardens, he said, which were "likely to be a major
source of new species effectively becoming wild in Britain".
He told us:
we are going to have new biological
communities from separate species we have not had before. I would
encourage people not to take an "any change is bad"
attitude, but to say, "let us try to identify the fights
that we wish to engage in", defined by whether they cause
major changes that we are not happy about, and whether the fight
is winnable. 
Chris Thomas believed that any strategy
or legislative framework should not result in controls which impaired
conservation for species threatened by climate change.
He told us:
we are risking, by our actions
on repelling foreign species, inadvertently increasing the global
extinction rate over what we could achieve. If there is a certain
number of species, let us say restricted to local areas in Southern
or Central Europe that are truly endangered by climate change,
if we bring them here and potentially save some of them, it would
not work for all of them, and it will have some impacts on native
Lord de Mauley told us, however, that
the Government was not yet at the point at which it was:
wholeheartedly welcoming new species
because our existing species are dying out because of climate
change. We are focused at the moment still on preventing new invasions
and on tackling, to the extent that we can, and controlling those
that we have here.
19. Environmental changes caused
by humans, including through climate change, are affecting the
global distribution of species. One aspect of climate change adaptation
will be a need to increasingly focus on conservation, where changes
in species distributions have to be managed rather than simply
resisted. That will determine over the years ahead the need for,
and realism of, the measures put forward by the proposed EU directive,
which we discuss below in Part 2.
20. The Government should use the
opportunity of the ongoing revision of its Non-native Species
Strategy to begin a public debate on the implications of changes
in our biodiversity and ecosystems driven by still increasing
climate change and international trade, including our approach
to nature conservation.
1 Helen Roy et al, Non-native Species in Great Britain: Establishment, detection and reporting to inform effective decision making
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