They are among us

Eliminating damage from invasive species already costs eu countries more than 10 billion euros a year – but the worst is yet to come, researchers warn

The fact that a plant or animal species no longer lives in the place where it originated does not necessarily pose a problem. Germany’s fauna and flora also consists of many "foreign", which we have long since ceased to regard as such. Corn poppies and cornflowers are as much a part of the landscape as most crops, pears and plums, many grains, tomatoes and potatoes. Since the discovery of america, 12,000 plant species have been brought to central europe – after the romans had already brought countless species to our latitudes.

However, it sometimes happens that a newcomer copes better with the local environmental conditions than its long-established neighbors. In such a case it can happen that native species are displaced – this is called an invasive species. Although only a small percentage of new arrivals are able to take advantage of conditions (out of 1,000 new species, about 100 gain some prominence, ten are bred in, and only one becomes a problem), the phenomenon has become the second most important cause of biodiversity loss, right after habitat destruction.

They are among us

The washbar, formerly found only in fur farms, has become established especially in northern central germany. Its impact on biodiversity is controversial. (photo: quartl. License: cc-by-sa)

This does not even take into account the difficulties that homo sapiens sapiens, the large ape that has migrated from africa, causes to the environment with its often smelly tools and leftovers. There are sufferers in every coarseness: the native marienkafer is beset by the asian marienkafer (which has far more points and was originally intended to "only" to help in the biological control of pests). Streams are now often exclusively overgrown by the indian knapweed. The american mink, freed from fur farms in coarse numbers thanks to various animal welfare campaigns, competes all too successfully with the smaller european mink. The giant barbary steal, which comes from the caucasus and was initially recommended in this country as a bee pasture and game cover, is spreading thanks to its up to 80.000 individual hemorrhages and up to 30.000 seeds per plant rapidly – its poison, however, can cause serious damage to health.

The problems seem dramatic, but well known. In fact, it may be that the worst is yet to come for the indigenous nature. This is the opinion of an international team of researchers who have studied the distribution of ten taxonomic groups in 28 european countries and placed them in relation to socio-economic development. As the scientists explain in their article published in the us academy of sciences (pnas), today we are struggling with the consequences of the animal and plant invasions that occurred at the turn of the 20th century. Century were set in motion.

They are among us

The pollen of the beifub ambrosia belongs to the strongest allergy triggers – for the same allergic effect only one fifth of the pollen is necessary in comparison with grass pollen. It originates from north america, but since the 1990s it has been spreading increasingly in germany as well. (photo: brunga. License: cc-by-sa)

Researchers speak of invasion debt: a delay between the economic growth leading to the spread of alien species and the time when the consequences of the invasion are economically traceable. This delay does not apply to all species to the same extent – it is smaller for species with high mobility such as birds or insects. Factors include the length of a generation or the time needed to adapt to the new conditions. Overall, however, the invasion debt in europe is likely to be around 100 years. The costs for the economy and nature conservation will therefore continue to rise in the coming decades – even if the invasion of new species can be stopped immediately and completely (which is completely unrealistic) the scientists therefore call for the establishment of a kind of early warning system that would alert people in good time to potentially dangerous newcomers to flora and fauna.

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