Ailanthus altissima

Ailanthus altissima in Europe: distribution, habitat, usage and threats

C. M. Enescu, T. Houston Durrant, G. Caudullo Ailanthus altissima (Mill.) Swingle, known as tree of heaven, is native to China, but it can be found in several countries across Europe and North America. Tree-of-Heaven is known as an invasive species that can rapidly spread onto disturbed sites or fragmented landscapes.

Description Frequency Tree of heaven (Ailanthus altissima (Mill.) Swingle) is a short- < 25% lived, fast-growing tree, reaching a height of around 20 m and 25% - 50% 50% - 75% 1 70 cm in diameter. The bark is greyish and slightly rough . The > 75% leaves are 0.4-0.7 m long; each leaf comprises 11-25 ovate- lanceolate leaflets which are 5-10 cm long2. The leaflets usually have one or more coarse teeth at the base and each of these teeth has a characteristic gland on the underside1. The flowers appear in late spring, the trees being usually dioecious, but in some cases Greysh smooth bark with longitudinal fessures becoming deeper in old trees. both sexes exist on the same individual1. Male plants have a foul (Copyright Aldo De Bastiani, www.actaplantarum.org: AP) odour while flowering1, 3-5. The winged fruits are twisted at the Threats and Diseases top, membranous, purplish yellow and up to 5 cm long4. Tree-of- Tree of heaven is affected by very few disease and insect Heaven is readily propagated both by seed and vegetatively3. pests, although pathogens such as Verticillium spp. have the potential to become important fungal diseases3. Since it is an invasive species, its presence should be carefully monitored especially around nature reserves or fragile forest stands.

Map 1: Plot distribution and simplified chorology map for Ailanthus altissima. Frequency of Ailanthus altissima occurrences within the field observations as reported by the National Forest Inventories.

abundant across the Mediterranean region4. Its expansion has been facilitated by the worldwide transfer of seeds over the last two centuries and by its ability to grow on poor sites8, 9, urban areas10 and fragmented landscapes11. Habitat and Ecology Tree of heaven tolerates a wide variety of soil types and climatic conditions. It demands a warm climate, but is resistant to drought and air pollution2, 4, although it is sensitive to ozone12. It is a shade intolerant species, preferring open spaces4.

Reddish maturing samaras at the top of a branch Importance and Usage surrounded by the odd-pinnate long leaves. (Copyright NatureServe, www.flickr.com: CC-BY) Tree of heaven has been used for a variety of purposes such Greenish-white flowers in a female tree with 5 petals and short steril stamens. as: ornamental species3, in folk medicine6 or for establishment (Copyright Wendy Cutler, www.flickr.com: CC-BY) Distribution of protective forest shelterbelts8, 13. The species is known for its Tree of heaven is native of central Asia (China) and was first ability to produce allelopathic compounds in its leaflets and introduced to Europe by the French missionary Pierre d’Incaville bark which are toxic to numerous species and which may have 14 more than 260 years ago, who sent seeds from Nanking to potential for development as a natural herbicide . However, its 3, 4, 15 Paris3, 6. Since then, the species has spread over all continents pollen is a known allergen and its invasive nature means except Antarctica4 and is naturalised across large areas of that it is currently in the top 20 environmental weeds identified 5, 7 Europe7. It is limited by low temperatures in the north but is as targets of classical biological control in Europe .

Mature samaras persist in the tree during the winter. (Copyright AnRo0002, commons.wikimedia.org: CC0)

References [1] B. Shah, Arnoldia pp. 21–27 (1997). [9] P. L. Burch, S. M. Zedaker, Journal of [2] F. Clinovschi, Dendrologie (Editura Arboriculture 29, 18 (2003). Universitatii Suceava, 2005). [10] E. Pan, N. Bussak, Journal of [3] P. P. Feret, Journal of Arboriculture 11, Environmental Horticulture 4, 1 (1986). 361 (1985). [11] R. E. Landenberger, N. L. Kota, J. B. [4] I. Kowarik, I. Säumel, Perspectives in Plant McGraw, Plant Ecology 192, 55 (2007). Ecology, Evolution and Systematics 8, [12] E. Gravano, M. Ferretti, F. Bussotti, P. 207 (2007). Grossoni, Forest Growth Responses [5] A. W. Sheppard, R. H. Shaw, R. Sforza, to the Pollution Climate of the 21st Weed Research 46, 93 (2006). Century, L. Sheppard, Cape, eds. (Springer Netherlands, 1999), pp. 267–272. [6] S. Y. Hu, Arnoldia 39, 29 (1979). [13] L. Udvardy, Acta Botanica Hungarica 41, [7] P. Pyšek, et al., Handbook of Alien Species 299 (1998). in Europe (Springer Netherlands, 2009), vol. 3 of Invading Nature - Springer Series [14] R. M. Heisey, American Journal of Botany in Invasion Ecology, pp. 43–61. 83, 192 (1996). [8] C. M. Enescu, Journal of Horticulture, [15] M. Ballero, A. Ariu, P. Falagiani, Allergy 58, Forestry and Biotechnology 18, 66 (2014). 532 (2003).

This is an extended summary of the chapter. The full version of this chapter (revised and peer-reviewed) will be published online at https://w3id.org/mtv/FISE-Comm/v01/e01ca33. The purpose of this summary is to provide an accessible dissemination of the related main topics. This QR code points to the full online version, where the most updated content may be freely accessed. Please, cite as: Enescu, C. M., Houston Durrant, T., Caudullo, G., 2016. Ailanthus Female shade-tree with fruits along an urban road (male trees are rarely used as they have a foul odour during flowering). altissima in Europe: distribution, habitat, usage and threats. (Copyright Marina Torres, commons.wikimedia.org: PD) In: San-Miguel-Ayanz, J., de Rigo, D., Caudullo, G., Houston Durrant, T., Mauri, A. (Eds.), European Atlas of Forest Tree Species. Publ. Off. EU, Luxembourg, pp. e01ca33+ Tree species | European Atlas of Forest Tree Species 61