Fraxinus pennsylvanica

Red Ash

Fraxinus pennsylvanica, also known as red ash or green ash, is a medium-sized to large deciduous tree that originated in North America. The tree usually reaches a height of 12-25 metres, but can also grow up to 35 metres under ideal conditions. It has a grey to brown bark that forms deep cracks and furrows with age. The leaves of the tree are imparipinnate with 5-9 lanceolate to oval leaflets. They have a dark green upper side and a lighter underside. The tree produces small, purple to green flowers that appear before the leaves shoot in spring. These develop into wing-like fruits, so-called samaras, which can reach a length of 2.5 to 5 cm. The red ash is considered a very robust and adaptable species that can thrive in a wide range of soil conditions and grows both in wet riparian forests and on dry sites.

Types of damage

Ecological damage

The species has a high reproductive potential and can form monocultures, especially along riverbanks and lakeshores, which affects biodiversity. It can displace native plants and thus change the structure and function of ecosystems. In Germany, this is particularly true for riparian forests, in whose flood depressions the red ash can quickly form dominant stands.

Region of origin

North America

Introduction vectors

Horticulture

Fraxinus pennsylvanica has often been used as an ornamental shrub or for landscaping. The movement of plant material, for example in nurseries or garden centres, can contribute to the spread of the species.

Forestry

Fraxinus pennsylvanica has been planted in some regions for forestry purposes. Its wood is well suited for the production of furniture or sports equipment; moreover, the species has an extensive root system that can help prevent soil erosion. Therefore, it was preferably planted in areas with slopes or along watercourses.

Current distribution

Based on the FlorKart Database of the Federal Agency for Nature Conservation, as of 2013

Miscellaneous

Family

The olive family (Oleaceae) comprises about 25 genera with around 600 species. They are distributed worldwide, mainly in temperate to tropical regions. The family includes shrubs and trees, occasionally also lianas. A distinctive feature is the milky sap that is often present. The flowers are usually four-celled and often fragrant. Many species have economic importance, especially the olive tree (Olea europaea) as a source of olives and olive oil. Other well-known representatives are the genera Forsythia and Jasmin (Jasminum) as ornamental plants, the Ash (Fraxinus) as timber and the Common Lilac (Syringa vulgaris) as an ornamental and fragrant plant.

Climate change

Fraxinus pennsylvanica has not yet filled its potentially suitable habitat under current climate conditions. It benefits from climate change because in the future its potentially suitable habitat will increase. The environmental factors that most influence its spread are soil type, summer precipitation, summer temperature, autumn temperature and altitude.

Positive effects

Whereas at the end of the 19th century the red ash was still considered in forestry because of its flood tolerance, today it is mainly relevant because of its drought resistance. In the course of climate change, periods of drought may become more frequent and intense, and compared to the native ash, the red ash shows a higher resistance under these conditions.

Dispersion forecast

Indicates the proportion of land suitable for habitat under current and future climate conditions (2060-2080) under three emission scenarios (RCP26, RCP45 & RCP85).

Habitat suitability maps

Instructions for use: Click here

Habitat suitability under current climate conditions

These habitat suitability maps show for Fraxinus pennsylvanica where suitable habitat conditions exist.

The map on the left shows this for current climate conditions. Below this are maps for the time classes 2040-2060 and 2061-2080, in which three different emission scenarios can be selected.

The slider at the top left allows you to adjust the opacity of the map to make orientation easier.

By clicking on the respective quadrant, information on the environmental conditions present in it can be called up.

The methodology is explained here .

Habitat suitability 2040 - 2060

2040-2060: In the RCP2.6 scenario, GHG emissions are expected to peak by 2040 through comprehensive mitigation measures and to decline rapidly thereafter. By 2060, global warming would stabilise at about 1.5°C above pre-industrial levels. Subtle changes in precipitation patterns could vary regionally, with some areas facing increased drought and others increased precipitation.

2040-2060: Under RCP4.5, GHG emissions would continue to increase until 2040, but stabilise at a high level thereafter. By 2060, there could be a global temperature increase of about 2°C above pre-industrial levels. This scenario would likely cause moderate changes in precipitation patterns, with potential regional differences.

2040-2060: Under RCP8.5, which assumes continued intensive use of fossil fuels, greenhouse gas emissions would rise sharply by 2060. The global temperature increase could be around 2.5-3°C. In this scenario, significant changes in precipitation patterns could occur, with an increased likelihood of extreme weather events.

Habitat suitability 2061 - 2080

2060-2080: By 2080, global warming could be limited to below 2°C in the RCP2.6 scenario, provided emission reductions are consistently pursued. Impacts on precipitation patterns would likely stabilise, although regional variance would remain significant.

2060-2080: In the RCP4.5 scenario, global temperatures would continue to increase and could be around 2.5°C above pre-industrial levels by 2080. Changes in precipitation patterns would likely increase and regional differences could become more pronounced.

2060-2080: Under RCP8.5, global temperatures could rise by more than 4°C above pre-industrial levels by 2080. Precipitation patterns would be expected to change significantly, with further increases in the frequency and intensity of extreme weather events. This would have far-reaching impacts on ecological and socio-economic systems.