EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
EU NON-NATIVE ORGANISM RISK ASSESSMENT SCHEME
Name of organism: Acer negundo
Author: Jan Pergl
Reviewer: Laurent J. Lamarque
Risk Assessment Area: Europe, Czech Rep.
Draft: January 2016
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
EU CHAPPEAU
QUESTION
RESPONSE
1. In how many EU member states has this species been recorded?
List them.
Countries and regions listed: Austria, Azores, Belgium, Bulgaria, Corse (Corsica),
Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Great Britain,
Greece, Hungary, Italy, Latvia, Lithuania, Moldova, Netherlands, Poland, Portugal,
Romania, Sardegna, Spain, Sweden, Switzerland, Turkey (in Europe), Ukraine
(DAISIE; Nobanis).
Countries and regions listed: Austria, Azores, Belgium, Corse (Corsica), Czech
Republic, Estonia, France, Germany, Great Britain, Greece, Hungary, Italy, Latvia,
Lithuania, Netherlands, Poland, Romania, Spain, Sweden, Turkey (in Europe)
(DAISIE; Nobanis).
In all of the regions where it is naturalized (DAISIE; Nobanis).
2. In how many EU member states has this species currently
established populations? List them.
3. In how many EU member states has this species shown signs of
invasiveness? List them.
4. In which EU Biogeographic areas could this species establish?
5. In how many EU Member States could this species establish in the
future [given current climate] (including those where it is already
established)? List them.
6. In how many EU member states could this species become invasive
in the future [given current climate] (where it is not already
established)?
All Europe. Based on the current distribution ranging from Baltic countries and
Norway in the North to Mediterranean regions in the South, and similar to the
native range the species has a high potential to establish in the whole RA region
and elsewhere in Eurasia (DAISIE; Medrzycki 2007).
The species is already widely distributed in Europe. Based on the current
distribution ranging from Baltic countries and Norway in the North to
Mediterranean regions in the South, the species has a high potential to establish in
the whole RA region and elsewhere in Eurasia (DAISIE; Medrzycki 2007).
Same as the establishing potential with exception of Northern parts of Norway and
Sweden due to limits of its tolerance to cold conditions.
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
SECTION A – Organism Information and Screening
Stage 1. Organism Information
RESPONSE
COMMENT
1. Identify the organism. Is it clearly a single
taxonomic entity and can it be adequately
distinguished from other entities of the same
rank?
Acer negundo
Clearly defined species with several varieties
(Maeglin & Ohmann 1973; Cullen et al. 2011).
Being an important ornamental tree, many
cultivars exist but the variegated forms are the
most commonly planted (Gelderen et al. 1994).
The environmental risk from the varieties appears
recently; propagule pressure from var.
Aureomarginatum in riparian zones in e.g. France
is much more intense leading to higher presence
of the trees in seminatural environment. The
same can appear from other popular varieties like
var. Flamingo (Lamarque, pers. comm).
2. If not a single taxonomic entity, can it be
redefined? (if necessary use the response box to
re-define the organism and carry on)
no
3. Does a relevant earlier risk assessment exist?
(give details of any previous risk assessment)
No
Not known
North America
Acer negundo has a wide distribution extending
from southern Alberta and central Manitoba to
north-eastern Texas and New Jersey (Everson &
Boucher 1998; Medrzycki 2007). A. negundo has
been probably naturalized in Maine, southern
Quebec, New Brunswick, Nova Scotia, Prince
4. If there is an earlier risk assessment is it still
entirely valid, or only partly valid?
5. Where is the organism native?
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
6. What is the global distribution of the organism
(excluding Europe)?
7. What is the distribution of the organism in
Europe?
8. Is the organism known to be invasive (i.e. to
threaten organisms, habitats or ecosystems)
anywhere in the world?
9. Describe any known socio-economic benefits of
the organism in the risk assessment area.
Edward Island, and in southeastern Washington
and eastern Oregon. Some geographical varieties
of the species occur also in mountains of Mexico
(states Nuevo Leon, San Luis Potosi, and south to
Chihuahua) and in Guatemala (Rosario 1988;
http://esp.cr.usgs.gov/data/little/acernegu.pdf).
New Zealand, Africa, Australia, Asia, N and S A. negundo has been introduced also to Australia,
America, Europe
South Africa, New Zealand, Asia and S. America
(Brazil) (Weber 2003; http://www.invasives.org.za
/legislation/item/881-ash-leaved-maple-acernegundo-ash). The distribution range is
temperate-meridional (Rothmaler 2005).
as above, widespread
All Europe from Baltic countries and Norway in
the North to Mediterranean regions in the South
with exception of Northern parts of Europe
(DAISIE; Medrzycki 2007). The species is also
occurring in the European part of Russia.
Yes.
Yes, it is considered problematic in many
European countries (DAISIE; Nobanis). A. negundo
is currently considered invasive throughout
southern, central and eastern Europe where it
mostly occurs in riparian habitats (Erfmeier et al.
2011; Lamarque et al. 2012)
horticulture, landscaping, forest nurseries
It has been introduced intentionally into many
regions throughout Europe for horticultural and
landscaping purposes (planted in hedges, and
horticultural ambitions) (Kowarik 2003; Medrzycki
2007). Little economic use is made of this species
in timber of fuel production (CABI). Acer negundo
is now used by forestry nurseries as a rootstock
for Japanese maples (especially in France)
(Lamarque, pers. comm.)
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
SECTION B – Detailed assessment
PROBABILITY OF ENTRY
Important instructions:
 Entry is the introduction of an organism into Europe. Not to be confused with spread, the movement of an organism within Europe.
 For organisms which are already present in Europe, only complete the entry section for current active pathways of entry or if relevant potential
future pathways. The entry section need not be completed for organisms which have entered in the past and have no current pathways of entry.
QUESTION
RESPONSE
[chose one entry,
delete all others]
1.1. How many active pathways are relevant to the
potential entry of this organism?
moderate number
(If there are no active pathways or potential future
pathways respond N/A and move to the Establishment
section)
CONFIDENCE
[chose one
entry, delete all
others]
medium
COMMENT
A. negundo is already widely present in Europe and is
reproducing especially by seeds. Resprouting is
common but not used for spread (Maeglin & Ohman
1973). So any transport can be due to unintentional
seed transport (contaminants, stowaway) or as a result
of intentional planting (import of seeds (but this can be
minimized) (Höfle et al. 2014). A. negundo can be
intentionally spread as it is used in forestry nurseries as
a rootstock. There is a higher probability of secondary
introductions from the alien range. Many varieties (for
ornamental purposes) are introduced and are planted.
1.2. List relevant pathways through which the organism
could enter. Where possible give detail about the specific
origins and end points of the pathways.
For each pathway answer questions 1.3 to 1.10 (copy and
paste additional rows at the end of this section as
necessary).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
Pathway name:
1.3. Is entry along this pathway intentional (e.g. the
organism is imported for trade) or accidental (the
organism is a contaminant of imported goods)?
(If intentional, only answer questions 1.4, 1.9, 1.10, 1.11)
1.4. How likely is it that large numbers of the organism
will travel along this pathway from the point(s) of origin
over the course of one year?
Subnote: In your comment discuss how likely the
organism is to get onto the pathway in the first place.
1.5. How likely is the organism to survive during passage
along the pathway (excluding management practices that
would kill the organism)?
Subnote: In your comment consider whether the
organism could multiply along the pathway.
1.6. How likely is the organism to survive existing
management practices during passage along the
pathway?
1.7. How likely is the organism to enter Europe
undetected?
1.8. How likely is the organism to arrive during the
months of the year most appropriate for establishment?
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
1.9. How likely is the organism to be able to transfer from
the pathway to a suitable habitat or host?
1.10. Estimate the overall likelihood of entry into Europe
based on this pathway?
End of pathway assessment, repeat as necessary.
1.11. Estimate the overall likelihood of entry into Europe
based on all pathways (comment on the key issues that
lead to this conclusion).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
PROBABILITY OF ESTABLISHMENT
Important instructions:
 For organisms which are already well established in Europe, only complete questions 1.15 and 1.21 then move onto the spread section. If uncertain,
check with the Non-native Species Secretariat.
QUESTION
1.12. How likely is it that the organism will be able to
establish in Europe based on the similarity between
climatic conditions in Europe and the organism’s current
distribution?
RESPONSE
CONFIDENCE
COMMENT
widespread
high
Acer negundo L. (boxelder or Manitoba maple) is a
deciduous early to mid-successionnal tree species.
It mainly occurs in flood-plains and riparian
systems (alluvial forests) but can also be found in
dry coniferous forests, oak savannas and
1.13. How likely is it that the organism will be able to
establish in Europe based on the similarity between other
abiotic conditions in Europe and the organism’s current
distribution?
1.14. How likely is it that the organism will become
established in protected conditions (in which the
environment is artificially maintained, such as wildlife
parks, glasshouses, aquaculture facilities, terraria,
zoological gardens) in Europe?
Subnote: gardens are not considered protected
conditions
1.15. How widespread are habitats or species necessary
for the survival, development and multiplication of the
organism in Europe?
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
grasslands (Ward et al. 2002). Invaded habitats
are characterized by high rate of flood
disturbance and high soil nutrient level (Porté et
al. 2011; Lamarque et al. 2012). Beside these
(semi-)natural stands, it is also frequent along
roadsides, in industrial wastelands or dry ruderal
sites (Dawson & Ehleringer 1993; Erfmeier et al.
2011).
1.16. If the organism requires another species for critical
stages in its life cycle then how likely is the organism to
become associated with such species in Europe?
1.17. How likely is it that establishment will occur despite
competition from existing species in Europe?
1.18. How likely is it that establishment will occur despite
predators, parasites or pathogens already present in
Europe?
1.19. How likely is the organism to establish despite
existing management practices in Europe?
1.20. How likely are management practices in Europe to
facilitate establishment?
1.21. How likely is it that biological properties of the
organism would allow it to survive eradication campaigns
in Europe?
likely
high
Used methods for management of Acer negundo
include mechanical and chemical approaches
(Pergl et al., in press). As A. negundo has a good
ability of resprouting, all treatments require
subsequent monitoring and control of shoots
emerging from remaining seeds, roots or stumps
(mainly by herbicide). A. negundo is a species
reproducing mainly by seeds. Seed sources in
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
urban areas are continuously providing seeds to
natural areas. No other specific traits are known
to affect the output of the eradication (CABI; Pergl
et al., in press).
1.22. How likely are the biological characteristics of the
organism to facilitate its establishment?
1.23. How likely is the capacity to spread of the organism
to facilitate its establishment?
1.24. How likely is the adaptability of the organism to
facilitate its establishment?
1.25. How likely is it that the organism could establish
despite low genetic diversity in the founder population?
1.26. Based on the history of invasion by this organism
elsewhere in the world, how likely is to establish in
Europe? (If possible, specify the instances in the
comments box.)
1.27. If the organism does not establish, then how likely
is it that transient populations will continue to occur?
Subnote: Red-eared Terrapin, a species which cannot reproduce in GB but is established because of continual
release, is an example of a transient species.
1.28. Estimate the overall likelihood of establishment
(mention any key issues in the comment box).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
PROBABILITY OF SPREAD
Important notes:
 Spread is defined as the expansion of the geographical distribution of a pest within an area.
QUESTION
RESPONSE
CONFIDENCE
COMMENT
2.1. How important is the expected spread of this
organism in Europe by natural means? (Please list and
comment on the mechanisms for natural spread.)
major
high
2.2. How important is the expected spread of this
organism in Europe by human assistance? (Please list and
comment on the mechanisms for human-assisted
spread.)
moderate
high
2.3. Within Europe, how difficult would it be to contain
the organism?
with some difficulty
low
2.4. Based on the answers to questions on the potential
for establishment and spread in Europe, define the area
all Europe except
the northern part
very high
The natural spread of Acer negundo is based on the
spread of seeds as the long-distance spread via
vegetative means is not probable. Seeds are winged
to be easily transported by wind and water (Höfle et
al. 2014). Therefore the species’ long distance
dispersal occurs along water coursesas well as along
transport corridors (roads, railways) from the urban
sites where are they planted originally. The species
can nonetheless be eliminated from late successional
forests by natural processes (succession) (Saccone et
al. 2010)
The core distribution of the species is in urban areas
where it is planted for ornamental reasons (Kowarik
2003) and in (semi-)natural stands in alluvial forests
(Medrzycki 2007). Therefore soil transport can be of
significant importance, but not as high as its natural
spread by wind. Crucial is human intentional planting
allowing further spread and creating new foci ready
for invasion.
There are not known large scale eradications focused
on this species only. Therefore, if management will
start, then initial costs can be relatively high.
see 7 of Section A and 1.15
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
endangered by the organism.
2.5. What proportion (%) of the area/habitat suitable for
establishment (i.e. those parts of Europe were the
species could establish), if any, has already been
colonised by the organism?
2.6. What proportion (%) of the area/habitat suitable for
establishment, if any, do you expect to have been
invaded by the organism five years from now (including
any current presence)?
2.7. What other timeframe (in years) would be
appropriate to estimate any significant further spread of
the organism in Europe? (Please comment on why this
timeframe is chosen.)
impossible to quantify
impossible to quantify
20
high
A. negundo reaches flowering maturity normally
after 8 years (Maeglin & Ohman 1973). The species is
fast growing but generally not exceeding 60 years of
age (Maeglin & Ohmann 1973). Therefore a short
timeframe can be suitable to assess any significant
further spread in Europe.
Impossible to quantify properly as it depends on land
use change and management actions against Acer
negundo.
rapidly
medium
The species is already spreading Northward in
France, as managers now consider it a problem in
riparian areas in Dordogne and Loire (Lamarque,
pers. comm.). In Germany it is reported that A.
negundo is able to adapt and invade new ecosystems
and environments (Erfmeier et al. 2011). The spread
of the species depends on several issues: i) land use;
the level of urbanization, proportion of abandoned
areas, ii) propagule pressure; planting frequency
mainly in urban and (semi-)natural areas
(plantations), and (iii) possible climate change that
2.8. In this timeframe what proportion (%) of the
endangered area/habitat (including any currently
occupied areas/habitats) is likely to have been invaded by
this organism?
2.9. Estimate the overall potential for future spread for
this organism in Europe (using the comment box to
indicate any key issues).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
will enable this species to invade northern parts of
Europe. The species can tolerate a wide range of
environmental conditions that enable it to establish
on many habitat types (Ward et al. 2002; Erfmeier et
al. 2011; Porté et al. 2011; Lamarque et al. 2012;
Saccone et al. 2013).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
PROBABILITY OF IMPACT
Important instructions:
 When assessing potential future impacts, climate change should not be taken into account. This is done in later questions at the end of the
assessment.
 Where one type of impact may affect another (e.g. disease may also cause economic impact) the assessor should try to separate the effects (e.g. in
this case note the economic impact of disease in the response and comments of the disease question, but do not include them in the economic
section).
 Note questions 2.10–2.14 relate to economic impact and 2.15–2.21 to environmental impact. Each set of questions starts with the impact
elsewhere in the world, then considers impacts in Europe separating known impacts to date (i.e. past and current impacts) from potential future
impacts. Key words are in bold for emphasis.
QUESTION
RESPONSE
CONFIDENCE
COMMENTS
2.10. How great is the economic loss caused by the
organism within its existing geographic range, including
the cost of any current management?
minimal
medium
Not economic impact known, except of being producer
of alergenic pollen (Sousa et al. 2012). Direct
eradication costs were not estimated.
2.11. How great is the economic cost of the organism
currently in Europe excluding management costs (include
any past costs in your response)?
minimal
medium
as above
2.12. How great is the economic cost of the organism
likely to be in the future in Europe excluding
management costs?
minimal
medium
as above; depends on the species distribution
2.13. How great are the economic costs associated with
managing this organism currently in Europe (include any
past costs in your response)?
minor
medium
Eradication in PA, and vulnerable areas
2.14. How great are the economic costs associated with
moderate
medium
If management practices are applied in the future, their
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
managing this organism likely to be in the future in
Europe?
2.15. How important is environmental harm caused by
the organism within its existing geographic range
excluding Europe?
moderate
medium
2.16. How important is the impact of the organism on
biodiversity (e.g. decline in native species, changes in
native species communities, hybridisation) currently in
Europe (include any past impact in your response)?
moderate
medium
2.17. How important is the impact of the organism on
biodiversity likely to be in the future in Europe?
moderate
medium
2.18. How important is alteration of ecosystem function
(e.g. habitat change, nutrient cycling, trophic
interactions), including losses to ecosystem services,
minor
medium
cost will be higher and higher due to the species’
current wide distribution and ongoing spread in
Europe.
The species is native to N. America, therefore there are
limited information on its impact as invasive species
outside Europe. Some studies in the USA looked at
species interactions including A. negundo (e.g. Everson
& Boucher 1998; DeWine & Cooper 2010). In Australia
it is in some states thought to have the potential to
become a very serious environmental weed. This
concern has resulted in a Weed Management Plan
being developed for this species. It was recently also
declared a pest plant and its sale is now prohibited in
the
ACT
(http://keyserver.lucidcentral.org
/weeds/data/03030800-0b07-490a-8d04-605030c0f01
/media/Html/Acer_negundo.htm). If occurring in
nature valued ecosystems the impact to the vegetation
can be high. The species is able to outcompete native
vegetation due to forming dense populations and by
allelopathic effects (references from Europe: Medrzycki
2007; Krevš et al. 2013; Lamarque et al. 2013).
Highly significant. If occurring in nature valued
ecosystems the impact to the vegetation can be high.
The species is able to outcompete native vegetation
due to forming dense populations and via allelopathic
effects (Medrzycki 2007; Krevš et al. 2013; Lamarque et
al. 2013).
as above
The species has allelopathic effects to the soil (Csiszár
et al. 2013; Krevš et al. 2013).
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
caused by the organism currently in Europe (include any
past impact in your response)?
2.19. How important is alteration of ecosystem function
(e.g. habitat change, nutrient cycling, trophic
interactions), including losses to ecosystem services,
caused by the organism likely to be in Europe in the
future?
moderate
medium
as above
2.20. How important is decline in conservation status
(e.g. sites of nature conservation value, WFD
classification) caused by the organism currently in
Europe?
moderate
medium
Invades nature protected areas especially in Southern
and Eastern Europe (Saccone et al. 2013; Höfle et al.
2014; Batanjski et al. 2015). Affects biodiversity and
ecosystem functions as described in 2.16 and 2.18.
2.21. How important is decline in conservation status
(e.g. sites of nature conservation value, WFD
classification) caused by the organism likely to be in the
future in Europe?
moderate
medium
as above
2.22. How important is it that genetic traits of the
organism could be carried to other species, modifying
their genetic nature and making their economic,
environmental or social effects more serious?
minimal
high
not known
2.23. How important is social, human health or other
harm (not directly included in economic and
environmental categories) caused by the organism within
its existing geographic range?
minimal
high
There are not else known negative socio-economic
impacts of A. negundo.
2.24. How important is the impact of the organism as
food, a host, a symbiont or a vector for other damaging
organisms (e.g. diseases)?
minimal
high
not known
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
2.25. How important might other impacts not already
covered by previous questions be resulting from
introduction of the organism? (specify in the comment
box)
minimal
medium
All known impacts were described above.
2.26. How important are the expected impacts of the
organism despite any natural control by other organisms,
such as predators, parasites or pathogens that may
already be present in Europe?
minimal
medium
There is no efficient biocontrol of A. negundo now in
Europe. Therefore the impacts refer mainly to 2.11,
2.15, 2.16 and 2.18.
2.27. Indicate any parts of Europe where economic,
environmental and social impacts are particularly likely
to occur (provide as much detail as possible).
in all occupied
area
high
as above
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
RISK SUMMARIES
Summarise Entry
Summarise Establishment
Summarise Spread
RESPONSE
very likely
very likely
rapidly
CONFIDENCE
very high
very high
high
Summarise Impact
moderate
high
Conclusion of the risk assessment
high
very high
COMMENT
already present in Europe
already present in Europe
depends on the management and awareness, but its
potential is to spread rapidly
impact on diversity
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
ADDITIONAL QUESTIONS – CLIMATE CHANGE
3.1. What aspects of climate change, if any, are most
likely to affect the risk assessment for this organism?
species is now
particularly
limited by cold
climate, global
change will
enable its
spread and
establish in
other regions
(but also
reduce its
spread in
Mediterranean
regions)
high
3.2. What is the likely timeframe for such changes?
3.3. What aspects of the risk assessment are most likely
to change as a result of climate change?
The species is already present in many countries and
cities in Europe, the potential for establishment in
climatically suitable regions is significant. The species is
already present in majority of available regions with
exception of north of Nordic countries (DAISIE; Hrázský
2005; Medrzycki 2007). Effects on elevated CO2 on
Acer negundo was analysed but for RA the results are
not valuable (Silva et al. 2015).
Depends on the rate of climate change.
distribution,
local
abundance
high
ADDITIONAL QUESTIONS – RESEARCH
4.1. If there is any research that would significantly
strengthen confidence in the risk assessment please
summarise this here.
effect of
climate
change,
impact in
other
invaded
regions than
Europe,
impacts of climate change, ability to invade other
habitats than wetlands as a consequence of plasticity
or adaptation, invasive potential of the planted
varieties
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
habitat
suitability for
invasion
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
REFERENCES:
Batanjski V, Kabaš E, Kuzmanović N, Vukojičić S, Lakušić D, Jovanović S (2015) New invasive forest communities in the riparian fragile habitats – the case
study from Ramsar site Carska bara (Vojvodina, Serbia). Šumarski list 139: 155–169
CABI http://www.cabi.org/isc/datasheet/2862; accessed November 2015
Csiszár Á, Korda M, Schmidt D, Šporčić D, Teleki B, Tiborcz V, Zagyvai G, Bartha D (2013) Allelopathic potential of some invasive woody plant species
occuring in Hungary. Allelopathy J 31: p309
Culeen J, Knees SG, Cubey HS (2011) The European garden flora. Cambridge University Press
DAISIE http://www.europe-aliens.org; accessed November 2015
Dawson TE, Ehleringer JR (1993) Gender-specific physiology, carbon isotope discrimination, and habitat distribution in boxelder, Acer negundo. Ecology 74:
798–815
DeWine JM, Cooper DJ (2010) Habitat overlap and facilitation in tamarisk and box elder stands: implications for tamarisk control using native plants. Rest.
Ecol. 18: 349–358
Erfmeier A, Bohnke M, Bruelheide H (2011) Secondary invasion of Acer negundo: the role of phenotypic responses versus local adaptation. Biol Invas 13:
1599–1614
Everson DA, Boucher DH (1998) Tree species-richness and topographic complexity along the riparian edge of the Potomac River. Forest Ecol Manage 109:
305–314
Höfle R, Dullinger S, Essl F (2014) Different factors affect the local distribution, persistence and spread of alien tree species in floodplain forests. Basic Appl
Ecol 15: 426–434
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
Species name – common
boxelder
Acer negundo
Acer negundo
Link to Risk Assessment and supplementary document
4.3 (a) found, based on available scientific evidence, to be alien to the territory
of the Union excluding the outermost regions;
Native to North America
4.3 (b) found, based on available scientific evidence, to be capable of
establishing a viable population and spreading in the environment under current
conditions and in foreseeable climate change conditions in one biogeographical
region shared by more than two Member States or one marine subregion
excluding their outermost regions;
Refer to question 1–6, section "probability of spread"
The plant is already present in: Austria, Azores, Belgium, Bulgaria, Corse (Corsica),
Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Great Britain,
Greece, Hungary, Italy, Latvia, Lithuania, Moldova, Netherlands, Poland, Portugal,
Romania, Sardegna, Spain, Sweden, Switzerland, Turkey (in Europe), Ukraine (DAISIE;
Nobanis).
4.3 (c) based on available scientific evidence, likely to have a significant adverse
impact on biodiversity or the related ecosystem services, and may also have an
adverse impact on human health or the economy;
Refer to the risk assessment (responses to questions 2.10 to 2.27).
4.3 (d) demonstrated by a risk assessment carried out pursuant to Article 5(1)
that concerted action at Union level is required to prevent their introduction,
establishment or spread;
Concerted action at Union level is required:
- in order to prevent invasion into the MS where this species is not currently
established and prevent further spread in the MS where this species is already
present.
- Biodiversity or related ecosystem services: the plant has negative impacts on
native plant communities, habitats and ecosystems, including areas of high
conservation value, given its ability to create dense stands, allelopathy, and its
ability to modify the structure of the invaded communities.
- Human health: can cause allergic reactions
- Economy: not known significant effects on economy
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
4.3 (e) likely that the inclusion on the Union list will effectively prevent, minimise
or mitigate their adverse impact.
4.6 due consideration to the implementation cost for Member States, the cost of
inaction, the cost-effectiveness and the socio-economic aspects
- action now will help prevent this species from becoming a wider problem across
the EU.
- Prevention (Article 7): Restrictions on keeping, sale, transport, exchange, breeding
and release of this species will prevent its wider establishment across the EU. The
plant is mainly spread by trade and intentional support in urban region. From
gardens and cities its seeds are easily dispersed by wind, which facilitates the
establishment in uninvaded habitats.
- Early detection and rapid eradication (Articles 14–18): prevent further spread and
to act at the very early stage of invasion.
- Management (Articles 19–20): as mentioned, control of the species can be
difficult once established, reinforcing the need to prevent the further spread and
further introductions of this species in the unaffected MS.
Implementation cost:
- Prevention: the plant is relatively popular, but banning the trade would not cause
problems for the sectors concerned. Species substitution would be an option.
Given the ease of spread of this plant and the costs linked to its management once
established, prevention would be the cheapest course of action
- Early detection and rapid eradication: given the costs of management, a prompt
response to newly establishing populations will be important to avoid later
management costs.
- Management: containment and control likely to be costly at beginning of the
management, which reinforces the need for preventive action.
- In urban areas where is low dispersal risk plant can be tolerated
Cost of inaction:
Wide scale spread of this species with environmental impacts, as well as human
health impacts.
Cost-effectiveness
Eradication will be important to prevent additional spread to avoid costs linked to
managing the species when widely established.
4.6 The Union list shall include as a priority those invasive alien species that:
Socio-economic aspects:
The plant is traded mostly as an ornamental species.
The plant is present in almost all MS, but coordinate action is needed to minimize its
adverse impact.
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EU NON-NATIVE SPECIES RISK ANALYSIS – RISK ASSESSMENT TEMPLATE V1.0 (27-04-15) Acer negundo
(a) are not yet present in the Union or are at an early stage of invasion and are
most likely to have a significant adverse impact;
4.6 The Union list shall include as a priority those invasive alien species that:
(b) are already established in the Union and have the most significant adverse
impact.
The plant is present in almost all MS, and therefore coordinate action is needed to
minimize its adverse impact on biodiversity. There is a high risk for further spread in
protected areas in countries where it is already established.
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