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Ailanthus altissima

Tree of large bipinnate leaves, reddish on the extremities when young, deciduous and with a fetid smell when cut.

Scientific name: Ailanthus altissima (Mill.) Swingle

Common names: tree-of-heaven, Chinese sumac

Family: Simaroubaceae

Status in Portugal:  invasive species (listed in Decreto-Lei nº 92/2019, de 10 julho) and included in the list of species of concern in the European Union, by Regulation (EU) No. 1143/2014 of the European Parliament and of the Council of October 22, 2014).

Risk Assessment score: 20  | Value obtained according to a protocol adapted from the Australian Weed Risk Assessment (Pheloung et al. 1999), by Morais et al. (2017), according to which values above 13 mean that the species has risk of having invasive behavior in the Portuguese territory | Updated on 30/09/2017.

 

Synonymy: Ailanthus glandulosa Desf., Ailanthus peregrina (Buc’hoz) Barkley, Rhus cacodendron Ehrh., Toxicodendron altissimum Miller

Data de atualização: 01/07/2021

Family: 
Simaroubaceae
Appearence: 
Trees and shrubs

How to recognise it

Dioecious tree, forming numerous root sprouts; with a smooth or longitudinally fissured grey rhytidome, small and thick bright brown small branches that are tortuous and medullary.

Leaves: deciduous, alternate, odd-pinnate, with rachis up to 1m, whose first pair of leaflets has 2-4 irregular lobes on the base; young leaves with reddish extremities.

Flowers: small (7-8 mm), greenish and arranged in panicles of 10-20 cm.

Fruits: samaroid monocarps of 3-4 cm, reddish on the beginning.

Flowering: April to July.

 

Similar species

It may be confused with the eastern black walnut (Juglans nigra L.) but it doesn’t present the 2 to 4 irregular lobes on the base of the leaflets and the fruit is similar to a nut.

 

Characteristics that aid invasion

Pioneer species with very rapid growth.

It reproduces by seed producing a high amount of seeds (± 350 000/year) that may disperse up to large distances (by wind) and germinate if they have humidity.

The species is also reproduced vegetatively, spouting vigorously from the root, forming extensive root stolons.

Native distribution area

Temperate Asia (China).

 

Distribution in Portugal

Mainland Portugal (all provinces), Azores archipelago (islands of São Miguel, Santa Maria, Terceira, Graciosa, Pico, Faial and Flores), Madeira archipelago (Madeira island).

 

Geographic areas where there are records of Ailanthus altissima

Other places where the species is invasive

Europe (Spain, France, Greece, Hungary), South Africa, some regions in Australia, North America (Canada, USA), South America, Asia (Japan, Pakistan).

 

Introduction reasons

For ornamental purposes, in urban areas and roadsides.

 

Preferential invasion environments

Disturbed areas, like roadsides, by fences, abandoned agricultural areas and urban spaces.

In natural areas it may establish itself when disturbances occur, starting to appear with some frequency in riparian areas.

It develops in all types of soils, preferring the light and deep ones. It easily adapts to silty soils and others with a low content in nutrients and oxygen.

It develops preferentially in locations with a lot of sun but the seedlings and sprouts may persist on the understory for a large amount of time, waiting for a clearing and then grow rapidly (up to 3 cm/day).

It is one of the most aggressive invasive species in mainland Portugal.

Impacts on ecossystems

It may form dense populations inhibiting the development of native vegetation.

It has allelopathic effects, inhibiting the development of other species.

 

Economic impacts

Expensive control methods.

 

Other impacts

Allergies.

 

Natura 2000 Network habitats more subject to impacts

– Alluvial forests with Alnus glutinosa (Alno-Padion, Alnion incanae, Salicion albae) (91E0);
– Riparian mixed forests of Quercus robur, Ulmus laevis and Ulmus minor, Fraxinus excelsior or Fraxinus angustifolia, along the great rivers (Ulmenion minoris (91F0);
– Salix alba and Populus alba galleries (92A0).

 

Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.

The control methodologies used for Ailanthus altissima include:

 

Physical control

Hand pulling: preferential methodology or seedlings and small plants. In the case of young plants, the use of a fork facilitates root removal. When in more compacted substrates, hand pulling must be made during the rainy season as to facilitate the removal of the root system. It should be guaranteed that no fragments and roots are left in the ground (very important!), because they have large probabilities in originating new sprouts.

 

Physical + chemical control

Cut stump method: apply to adult plants. Chop the trunk as close to the ground as possible and immediately (in the following seconds) apply herbicide (active substance: glyphosate ou triclopyr) to the cut stump. It should be done on the time of greatest plant growth. If shoots should latter on appear, these should be immediately eliminated by pulling or foliar application of herbicide (active substance: glyphosate or triclopyr) or by repeating the initial methodology (cut stump method).

 

Chemical control

Stem injection: preferential methodology for plants with a diameter larger than 5 cm. Apply the herbicide directly on the vascular system by making several cuts (with an axe or saw), at the height most convenient to the operator, in an angle of 45º until the sapwood, and immediately inject (in the following seconds) the herbicide (active substance: glyphosate or triclopyr) in each incision with a squirt bottle. Apply around 1ml (0,5 to 2ml, according to the size of the cut) of herbicide in each incision. The several cuts should be made at the same height on the trunk as to nearly touch, leaving around 2-4 cm of uncut bark between them. For smaller individuals, only 2 or 3 cuts are necessary and they shouldn’t be deep (to prevent the plant breaking.

Foliar application of herbicide: over recent sprouts (25-50 cm tall) or when high germination rates occur. It should be done upon the plant’s greatest growth rate.Spray with herbicide (active substance: glyphosate or triclopyr) limiting as much as possible its application to the target species.

Basal bark method: applied to seedlings up to 15 cm diameter. The herbicide application (active substance: glyphosate or triclopyr) should be made at a height of 30 cm. For larger plants, the herbicide application should be preceded by ring-barking.

 

Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.

CABI (2012) Ailanthus altissima. In: invasive">Invasive species">Species Compendium. CAB International, Wallingford, UK. Available: http://www.cabi.org/isc/ [Retrieved: 06/11/2012].

 

 

Dana ED, Sanz-Elorza M, Vivas S, Sobrino E (2005) Especies vegetales invasoras en Andalucía. Consejería de Medio Ambiente, Junta de Andalucía, Sevilla, 233pp.

 

 

 

 

Dufour-Dror J-M (2012) Alien invasive plants in Israel. The Middle East Nature Conservation Promotion Association, Ahva, Jerusalem, 213pp.

 

 

 

 

Marchante E, Freitas H, Marchante H (2008) Guia prático para a identificação de plantas invasoras de Portugal Continental. Imprensa da Universidade de Coimbra, Coimbra, 183pp.

 

 

 

 

Silva L, Corvelo R, Moura M, Osorio VEM, Carvalho JA (2008) Ailanthus altissima (Mill.) Swingle. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 385-387.

 

 

 

 

Swearingen JM, Pannill P (2009) tree">Tree of heaven – Ailanthus altissima (Mill.) Swingle. In: Plant Conservation Alliance’s Alien Plant Working Group. Weeds gone Wild: Alien Plant Invader of Natural Areas. Available: http://www.nps.gov/plants/alien/fact/pdf/aial1.pdf [Retrieved: 06/11/2012].