Ailanthus (Ailanthus altissima), also known as tree of heaven, is a tree native to China and Southeast Asia, although today it has spread to almost the entire world, especially in temperate and warm areas. Its fast growth, extraordinary regrowth capacity and resistance to contamination have made it one of the most exotic species invasive In many countries, such as Spain, the United States or Australia, where its planting and marketing are prohibited to prevent its uncontrolled expansion.
Description and characteristics of Ailanthus
Deciduous tree and dioecious (there are male and female specimens), the Ailanthus can reach up to 27 meters in height, with an average lifespan of approximately 50 years. The trunk is not very thick compared to its height, reaching 30 centimeters in diameter at maturity. Its crown is umbrella-shaped and its branches expand rapidly, highlighting its leafiness and the length of its compound leaves, which can measure between 40 and 120 cm, composed of 10 to 40 lanceolate leaflets distributed alternately.
An essential characteristic of this species is the unpleasant smell which shed both leaves and bark, especially when crushed. The flowers, grouped in large terminal panicles, are not ornamental and offer a strong aroma, especially the male ones. They bloom in spring or early summer and the fruits are samaras reddish with a central seed, easily dispersed by the wind.
Habitat and invasiveness
Ailanthus altissima It thrives in virtually any soil type: from fertile, moist soils to degraded lots, rocky soils, roadsides, and heavily polluted urban areas. It can withstand both droughts It tolerates light frosts and does not require particularly rich soils; it grows in full sun, semi-shade, or even partial shade if the temperature is suitable. It thrives especially in disturbed environments and open spaces, where it faces little competition.
High invasive capacityThe Ailanthus reproduces both by seed (a single female specimen can produce more than 300.000 per year) and by root sprouts, allowing it to colonize large areas at high speed. Its seeds, with membranous wings, travel long distances on the wind. Furthermore, when cut down or damaged, it generates dozens of sprouts from the root and stump, making its eradication very difficult.
Another of its ecological weapons is the ability to release allelopathic substances These inhibit the germination and growth of other plants beneath their canopy, altering the soil composition and displacing native vegetation. This affects both flora and fauna and reduces the biodiversity of the environment, preventing the arrival of native insects and animals.
Growing and maintaining: how does it behave?
Despite its problems, the Ailanthus has been used as an ornamental tree due to its resilience and rapid growth, especially in avenues, walkways, and for restoring degraded soils or as a windbreak. Its resistance to pollution and drought apparently makes it ideal for urban environments. However, its planting is restricted or prohibited due to its enormous invasive potential.
- Irrigation: It tolerates drought very well; for ornamental planting, weekly watering is usually sufficient.
- Floors: It is not demanding; it grows in fertile, calcareous, sandy, and even degraded soils.
- Pruning: It tolerates formative pruning well, although it encourages the production of root shoots.
- Pests: It is resistant, although it can suffer attacks from mealybugs, aphids or fungal diseases such as verticillium wilt if it receives excessive watering.
- Spread: Mainly by seed or root sprouts; propagation by cuttings is rare and sprouts are produced even at a considerable distance from the parent plant.
Environmental and health impact of Ailanthus
Ailanthus It alters the balance of the ecosystems where it settles. It reduces the diversity of native flora and fauna through competition and allelopathy, consumes large amounts of water and nutrients, and can damage urban infrastructure such as sidewalks, pipes, or foundations due to its aggressive and superficial root system.
From a health perspective, it can cause allergies due to pollen and cause dermatitis in sensitive individuals after contact with the leaves, sap, or bark. In some cases, toxic effects have been reported due to accidental ingestion of parts of the plant or exposure to the metabolites it produces.
Control and eradication
Removing Ailanthus from the environment requires persistence and combined measuresThe most common and effective techniques include:
- Manual start: Effective only on young seedlings and in moist soils to extract the entire root.
- Felling and stump removal: Stumps should be treated with systemic herbicides, such as glyphosate or triclopyr, to prevent regrowth from the roots.
- Herbicide application: They should be used on the basal bark or using "cut and spray" techniques during the peak period of nutrient transfer to the roots (mid- to late summer). The use of herbicides is regulated and must be authorized by the competent authority.
- Biologic control: In some places, the use of phytopathogenic fungi is being investigated.
It is essential to monitor and repeat the treatment for several years to prevent re-infestation, as even small root fragments can cause new outbreaks.
Uses and properties
Despite its problems, the Ailanthus has medicinal properties (astringent, anthelmintic, rubefacient, bactericide, insecticide), and its wood has been used for paper pulp or slope consolidation. However, it should be used with extreme caution due to its toxicity. Some modern studies are investigating its pharmacological potential.
Due to its high invasive potential and ecological risk, it is recommended do not grow it in gardens Nor should you purchase it as an ornamental plant. If you find specimens in the natural environment, notify the environmental authorities to ensure their control and prevent damage to native ecosystems.
El Ailanthus It is a tree that is as capable as it is problematic: its tropical appearance, strength, and regenerative capacity have led it to conquer territories beyond its place of origin, but its irresponsible use continues to compromise the natural wealth of our ecosystems.
