Taxonomy

Ailanthus altissima | Tree-of-heaven | Crann na nDéithe

Pre 2017

2017 - 2020

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).

Impacts

Biodiversity - Due to its highly competitive nature and rapid growth rates, this species can out-compete and therefore displace native flora in an area (CABI, 2021). Additionally, it produces a toxin that enters the soil and inhibits the growth of other plant species in order to better colonise an area (CABI, 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 2021

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.

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.

DAISIE Factsheet

Global Invasive Species Database

CABI Datasheet

Images