Invasive alien species

various herbs
Invasive alien species, here Himalayan Balsam (Impatiens glandulifera) and Canada goldenrod (Solidago canadensis) <br>© BLE

An invasive alien species is a species that has been introduced to areas outside its natural area of occurrence, then has heavily spread with considerable adversely effects to the native biodiversity. Invasive species can be animals, plants or fungi, in general they are named neobiota.

With the increasing flows of international transport and goods, the risk of organisms being unintentionally transported across the borders of their natural areas of occurrence has increased significantly. Distribution means are for example freshly lumbered or processed wood, ballast water of shipping (for bacteria, algae and crustacean), air traffic with their hosts (exempli gratia malaria mosquito), ornamental plants (snails, worms) or imported foodstuff (bacteria, virus).

But not only the unintentional, also the intentional introduction of plants and animals increases. It is estimated, that almost half of the alien plant species in Germany have been introduced intentionally, most of them as ornamental plants, the others are agricultural or forest plants. However, only some of them become invasive. This also applies for animals with only a few species, that have become invasive like the raccoon, the bullfrog or the Chinese mitten crab.

Potential impacts from invasive alien species

The spread of invasive alien species can pose risks to the native biodiversity, the agricultural production, the cultural landscape and to human, animal and plant health (exempli gratia allergenic plants, pathogens).

The occurrence of alien pathogens can damage species to such an extent, that their existence becomes threatened. The loss of elm trees to elm disease across Europe is a prime example. The fungus, that causes the disease was introduced with imported timber and has decimated native elms to such an extent that the before widespread common elm has been listed as highly endangered on Germany's Red List of threatened species.

Another example and current problem is the spread of the Pacific oyster which is displacing native blue mussels in their habitats. This poses a threat to mussel cultivation and thus to one of the key sources of income in coastal fisheries.

Measures to prevent introduction and spread of invasive alien species

Politic and science are strongly engaged in the issue of invasive alien species and neobiota respectively. With the ratification of the Convention on Biodiversity (CBD) Germany committed itself to counteract the described problems. Given the international character of the issue, close international collaboration is substantial. The 6th conference of the Parties (COP 6) of the CBD adopted the Guiding Principles for the prevention, introduction and mitigation of impacts of alien species. The International Plant Protection Convention (IPCC) aims at the prevention of the introduction and spread of pests of plants.

The European and Mediterranean Plant Protection Organization (EPPO) lists invasive plant species on its "Alert list" to achieve early warning of member states. Close collaboration exists with the Berne Convention on the Conservation of European Wildlife and Natural Habitats. The European Council Directive on the Conservation of natural habitats and of wild fauna and flora (Habitats Directive) obliges its Member States to regulate the intended settlement of non-native species in such a manner that the native biodiversity is not affected.

On the national level the Federal Nature Conservation Act regulates the practice with invasive alien species to prevent the native biodiversity. The internet platform "Neoflora" provides extensive information on alien plant species in Germany. "Neoflora" is operated by the German Federal Agency for Nature Conservation (BfN) in close cooperation with the Institute of Ecology of the Technical University Berlin and the European Group on Biological Invasions (NEOBIOTA).

The Institute for National and International Plant Health of the Julius-Kuehn-Institute contributes actively to the work of IPPC, EPPO and the EU.