Invasive plants

Observations of invasive plant species (solid dots) in and around Karlsruhe, crowdsourced from iNaturalist, a global citizen-science database. Invasive plants, also known as neophytes, are species that have been introduced to a new area and spread aggressively, often outcompeting native vegetation and disrupting local ecosystems. The specific species were identified during the workshop ‘On displacement and adaptation’. A noticeable pattern emerges from the data: many of these invasive plants are concentrated along Karlsruhe's rivers, the Alb and Pfinz. This is because waterways often act as natural corridors that facilitate the spread of seeds and plant fragments.

In Karlsruhe, various invasive species pose a threat to both nature and public health. Common ragweed (Ambrosia artemisiifolia) is particularly widespread, with large populations found in Hardtwald Forest and along Linkenheimer Landstraße. The related perennial ragweed (Ambrosia coronopifolia) has also been recorded in the Daxlanden region. In 2015, the city initiated a project under the KLIMOPASS research program to test various control methods with the aim of imiting their spread. Several other invasive species are also common in Karlsruhe, including the tree of heaven, black locust, black cherry, Japanese knotweed, Himalayan balsam and Canadian goldenrod. Many of these populations are concentrated along the Alb and Pfinz rivers, as these waterways act as natural corridors that facilitate dispersal. 

The city’s biodiversity concept also lists other problematic plants, such as Chinese mugwort, cherry laurel and common snowberry, which can have a negative impact on native biodiversity. Since some of these plants are toxic or pose health risks, citizens are advised to consult the Karlsruhe Forestry Office for guidance on how to handle them properly.