Status
Conservation status
Not Assessed
Legal status
Regulated Invasive Alien Species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].
Native status
Non-native
First reported in the wild
September 2019
Invasiveness
Invasive species - risk of Medium Impact
Irish status
Not Established
Introduction pathways - 1
Release in Nature
Introduction pathways subclass - 1
Landscape/flora/fauna improvement
Invasive score
17
NAPRA Ireland risk assessed
No
Number of hectads recorded in
2
Species Biology
Identification
This broadleaved perennial species typically stands at 6-10 m in height but can grow up to 30 m in some environments (CABI, 2021). The leaves are long (up to 90 cm); pinnately compound (the leaf is divided into smaller leaflets) and range from pubescent (hairy) to nearly glabrous (hairless) (CABI, 2021). Each leaf consists of up to 25 leaflets that are ovate (round, wider at base) with acute tips and contain 1-3 pairs of glandular teeth near the base (CABI, 2021).
The flowers are small
and yellow and occur in large panicles (dense clusters) (CABI, 2021). This species produces
a large volume of reddish-brown seeds (CABI, 2021).
Ecology
Invasive species in North
America, where it has naturalised, due to allopathic effects (releasing
chemicals into the soil that supress other vegetation) and its ability to
outcompete native species (Small et al., 2010). No effects are recorded for
Ireland to date due to the limited distribution of this species here.
Although
this species thrives in moist climates, areas of heavy, monsoon level rainfall
are not suitable as the high levels of water will result in the death of the
seeds (CABI, 2021). It can reproduce both
sexually (through seeds) and asexually (through vegetative reproduction) and a
single tree can produce up to 350,000 seeds per year (Global Invasive Species Database, 2021). This species is
dioecious which means it will have male and female flowers on different trees
rather than both on a single tree (monecious) (Global Invasive Species Database, 2021). It grows rapidly with
stump sprouts growing at up to 3 cm per day (Global Invasive Species Database, 2021). A rapid growth rate
such as this may increase its effectiveness as an invasive alien species.
In its native area of China, this species is often used for lumber and fuelwood as well as other products such as traditional herbal medicine (Global Invasive Species Database, 2021).
Habitat
Associated
with freshwater habitats in subtropical/warm temperate climates but is capable
of establishing itself in cool-temperate to tropical climates also (CABI, 2021; Encyclopedia of Life, 2021).
In
terms of suitable habitats to establish as an invasive, this species can get a
foothold alongside roads, ditches, fields, scrubland and riparian habitats (CABI, 2021). Adequate moisture
levels are one of these species main requirements.
Pathway and vector description
Not currently recorded in the wild in Ireland. It is widely available for sale.
Mechanism of impact
Competition, Poisoning/Toxicity
Management approach
As the
Tree of heaven is listed as an Invasive Alien Species of Union concern under
the EU Regulations of Invasive Alien Species, it cannot be imported, traded, or
released to the wild. Measures must also be taken to prevent spread of existing
populations of it (European Commission, 2017).
Mechanical control
Young
plants can be pulled, dug up or cut using a mower to prevent them from growing
large and colonising an area. This method is not known to be highly effective
on its own however as it can take many years to deplete the root system and
missing a mowing cycle can allow the plant to rapidly grow to the point where
it can not be mowed (Gover, Kuhns and Johnson, 2004). The most effective
steps to take after mowing would be to immediately follow up with some form of
chemical control method (Gover, Kuhns and Johnson, 2004).
Chemical control
Herbicides
can be an effective management tool for the control of this species. They can
be applied in multiple ways such as spayed directly on to the leaves (foliar
application), sprayed or painted on to the stem (basal bark application) or
applied to an open cut on the stem (cut surface application) (Gover, Kuhns and Johnson, 2004).
Foliar
application is typically done with a sprayer which simply sprays the target
area with a herbicide and is typically more broad in application than other
methods, although ‘spot applications’ can be used which are more precise in
spraying (Gover, Kuhns and Johnson, 2004). Foliar spraying is
most effective between full canopy development and autumn when leaves begin to
die off (Gover, Kuhns and Johnson, 2004).
Basal
bark application is simply spraying the base of each stem with a herbicide (Gover, Kuhns and Johnson, 2004). This method is highly
selective to the chances of spray drift and subsequent elimination of
non-target species is significantly reduced with this method. This method is
labour intensive however as each stem must be individually treated by hand (Gover, Kuhns and Johnson, 2004).
‘Cut
surface’ treatments such as stump treatment, hack-and-squirt and injection
treatments are all similar to basal bark application except they all involve
applying the herbicide to some form of open wound in the stem or injecting the
herbicide in to the stem using a needle (Gover, Kuhns and Johnson, 2004). These methods are
highly selective with a low chance of impacting non-target flora but are highly
labour intensive also (Gover, Kuhns and Johnson, 2004).
Cultural control
If
this species is faced with a habitat that already has established floral
species and a good ground cover, it will provide strong competition for the
invader and reduce its ability to colonise an area (Gover, Kuhns and Johnson, 2004). Cultural control
involves supporting ground cover of alternate species to take up the area so
that the invasive plant cannot dominate an area as the intact ground cover
makes it harder for the invader to establish itself (Gover, Kuhns and Johnson, 2004). The plants used in
this control method would change depending on the country and habitat used but
it may act as a long-term control method that does not require herbicide
treatment.
Broad environment
Terrestrial
Habitat description
In other regions it has invaded woodland and waste ground, in Ireland it is found in gardens and parks.
Species group
Plant
Native region
North America, Temperate Asia, Australasia
Similar species
Some
similar species include Carya illinoinensis, Rhus typhina and Juglans nigra (Global Invasive Species Database,
2021). Rhus typhina and Juglans nigra have
been recorded in Ireland but their level of invasiveness and status is unknown.
Distribution
World distribution(GBIF)
Irish distribution
Occasionally present, vagrant - Localised. Two records of 'Heritage trees', one in St Partick's College, Kildare and one in the National Botanic Gardens believed to be 50-100 years old.
Native distribution
In its
native region of China, this species can be found from Liaoning and Hebei in
the north to Guangxi and Fujian in the south. It can also be found to the east
in Zhejiang and Shandong and the west in Gansu (CABI, 2021).
Temporal change
Date of first record category
Unknown
Fifty year date category
Unknown
Records submitted to Data Centre in 2024
The following map is interactive. If you would prefer to view it full screen then click here.
How can you help
Report
any sightings of this species to the National Biodiversity Data Centre,
including a photograph, if possible.
Dispose
of unwanted specimens in a responsible manner that does not allow them in to
the natural environment.
Avoid
purchasing this species for ornamental purposes.
Further information
CABI
Invasive Species Compendium: https://www.cabi.org/isc/datasheet/3889
Global
Invasive Species Database: http://www.iucngisd.org/gisd/species.php?sc=319
Encyclopaedia
Of Life: https://eol.org/pages/5614169
GBIF:
https://www.gbif.org/species/3190653
Invasive
Species Ireland: http://invasivespeciesireland.com/species-accounts/potential/terrestrial/tree-of-heaven
References
Publications
CABI, 2021. Ailanthus altissima (tree-of-heaven). [online]
Available at: <https://www.cabi.org/isc/datasheet/3889> [Accessed 25 Jun.
2021].
Constán-Nava, S., Bonet, A., Pastor, E. and Lledó, M.J.,
2010. Long-term control of the invasive tree Ailanthus altissima: Insights from
Mediterranean protected forests. Forest Ecology and Management, [online]
260(6), pp.1058–1064. Available at:
<https://www.sciencedirect.com/science/article/abs/pii/S0378112710003622>
[Accessed 25 Jun. 2021].
Encyclopedia of Life, 2021. Tree Of Heaven. [online]
Available at: <https://eol.org/pages/5614169> [Accessed 25 Jun. 2021].
European Commission, 2017. Invasive Alien Species of Union
concern. [online] Luxembourg. Available at:
<https://ec.europa.eu/environment/nature/pdf/IAS_brochure_species.pdf>
[Accessed 25 Jun. 2021].
Global Invasive Species Database, 2021. Ailanthus
altissima. [online] Available at:
<http://www.iucngisd.org/gisd/species.php?sc=319> [Accessed 28 Jun.
2021].
Gover, A., Kuhns, L. and Johnson, J., 2004. Managing
Tree-of-Heaven (Ailanthus altissima) on Roadsides. [online] Available at:
<https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjF1ImT9LnxAhVDRBUIHXyMCksQFjACegQIBxAD&url=https%3A%2F%2Fplantscience.psu.edu%2Fresearch%2Fprojects%2Fvegetative-management%2Fpublications%2Froadside-vegetative-mangement-factsheets>
[Accessed 28 Jun. 2021].
Invasive Species Ireland, 2021. Tree-of-heaven.
[online] Available at: <http://invasivespeciesireland.com/species-accounts/potential/terrestrial/tree-of-heaven>
[Accessed 28 Jun. 2021].
Weber, E. (2003). Invasive plant species of the world: a reference guide to environmental weeds. CABI publishing.
Small, C. J., White, D. C., & Hargbol, B. (2010). Allelopathic influences of the invasive Ailanthus altissima on a native and a non-native herb. The Journal of the Torrey Botanical Society, 137(4):366-372.
Stace, C. (1997). New Flora of the British Isles 2nd Edition. Cambridge University Press, Cambridge.