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Fraxinus pennsylvanica

Identity

Common name: Green ash
Synonyms: Fraxinus pubescens
Origin: North America
Plant type: Tree
Life cycle: Perennial
Code of conduct: Annex II
Invasive status (ISEIA protocol): Watch list
Main ornemental function: Ornamental tree

Description

Tree up to 30 to 40 m tall with composed leaves (7 to 9 leaflets), deciduous. Leaflets are lanceolate to ovate with entire margins. Green coloured flower. Fruits are winged samaras.

Spread

F. pennsylvanica mainly reproduces by seeds. This tree can produce a high number of seeds, dispersed by wind at distances up to 150 m long. Longer distance dispersal by rivers are also possible. Dispersion potential is high. Planted as ornamental.

Habitat

The green ash is a pioneer species of riparian forests, adapted to survive in flooded soils both in its native and introduced range. In Central Europe, it is mainly observed in riparian mixed forests of Quercus robur, Ulmus spp. and Fraxinus excelsior, along the great rivers (Ulmenion minoris, Natura 2000 habitat). Although this habitat is no more represented in Belgium, green ash has been recently discovered as isolated individuals along rivers and canals in Western Belgium.

Impact

Species classified B1 in Belgium. Thanks to its resistance to flooding, the green ash can overcomes other tree species in the alluvial conditions of Central Europe. It is able to outcompete native species and to modify the vegetation structure in this environment. Plant extracts contain allelopathic compounds. As riparian forests submitted to regular flooding events are poorly represented in Belgium, green ash is not likely to cause important environmental damages. The species is present in isolated populations. For more information about this species, click here

Recommendation

Avoid planting this species near rivers and wet habitats, especially in the vicinity of protected areas (natural reserves, Natura 2000 sites, etc.).

Possible native alternative

Main ornemental function

Ornamental tree

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