2023-09-01 13:42:36
Table cover for bumblebees. The giant balsam or spring balsam produces much more nectar than any other plant, so all kinds of bees eagerly come to snack on its pink flowers. Not bad for biodiversity, you might say. But it’s not that simple. “As a result, many native wild plants receive fewer visits from bumblebees and therefore less pollination,” explains Naturalis director and Leiden professor Koos Biesmeijer.
Giant balsam originates from the Himalayas and was introduced to Europe from India in the mid-nineteenth century. It is an invasive exotic, a species that conquers its new habitat by pushing out native species or, in the case of animals, by killing them off.
‘Nature is never static, species come and go’
Invasive species are one of the top five causes of global biodiversity loss, following intensive land use, overfishing, climate change and pollution.
The global knowledge platform for biodiversity and ecosystem services IPBES will publish an analysis of the problems posed by invasive species on Monday. Hundreds of scientists and policymakers this week in Bonn, Germany, are putting the dots on the i in the report, which will show solutions and make recommendations.
“Nature is never static, new species come and go,” says Coenraad Krijger, director of the Netherlands of the international union for nature conservation IUCN, who together with Naturalis supports the Dutch participation in IPBES. “But due to human activities, the problems with invasive alien species are increasing rapidly.”
World trade has increased enormously
Humans have been dragging animals and plants around the world for thousands of years. For example, cats and goats have ended up on islands, which are particularly vulnerable to new species. They often form a plague there, Krijger explains. “But now world trade has increased enormously. Species are deliberately towed or they unintentionally come along with ships. In the port of Rotterdam, this happens on a continuous basis.”
The major loss of biodiversity in the Netherlands is mainly due to intensive agriculture, nitrogen and drought, say Biesmeijer and Krijger. The nuisance in the Netherlands is still manageable, although the Japanese knotweed damages pipes, roads and even buildings, and the American crayfish cuts through water plants and changes the entire living environment.
However, as a trading country, the Netherlands plays an important role in the distribution of species around the world. “That is an unintended effect of our economic system,” says Krijger. “People often think it’s just part of it. But things are going too fast, new species are permanently establishing themselves and that is unnatural and harmful. The problem is increasing and it is accelerating. Measures are lagging behind.”
Painful choices
He warns that a structural approach requires painful choices. “Prevention is much better than combat. Once an exotic is somewhere, it is mopping with the tap open. Many organizations, such as nature managers and water boards, are spending an increasing budget on keeping proliferating plants under control.”
A real solution starts with import requirements, stricter controls on cargo and enforcement of violations. “That is now one of the bottlenecks,” says Krijger. “We have an open economy, where all sorts of things come in, Europe has a lot of illegal trade in pets and garden centers also have a great responsibility for what plants they import and what ends up in potting soil. Sometimes you need to set restrictions.
The problem is that the problem is not clear-cut. IPBES is known as the counterpart of the UN climate panel IPCC, and the scientific platforms have sometimes been working together for several years now. But tackling biodiversity loss is even more complicated than stopping climate change. It is often difficult to predict what consequences the establishment of a new species will have on the environment. “More research is needed,” says Krijger. “We need to monitor newly established species. And at least keep an eye on what comes in.”
Invasive exotic species in the Netherlands
Japanese Knotweed (Reynoutria japonica): Grows quickly and crowds out native flora. Its deep roots can cause damage to foundations and pavement.
American crayfish (Procambarus clarkii): Has negative effects on native aquatic animals and ecosystems. Digs holes in banks, which can lead to erosion.
Pennywort (Hydrocotyle ranunculoides): Grows quickly and forms dense mats on the surface of the water, crowding out native aquatic plants.
Asian forest mosquito (Aedes japonicus): Can transmit diseases such as West Nile virus, posing a threat to public health.
Giant Hogweed (Heracleum mantegazzianum): May cause severe burns on skin contact and displaces native vegetation.
The collared parakeet (Psittacula krameri): Disturbs native bird populations and can damage agricultural crops.
Asian longhorn beetle (Anoplophora glabripennis): Threatens trees, especially maples and poplars.
Read also:
From ring-necked parakeets to crayfish: how exotics are turning the world upside down
The ring-necked parakeet, crayfish and the Japanese knotweed are all exotics that should not be in the Netherlands. Biologist and writer Tijs Goldschmidt is fascinated by strange species.
A new puzzle piece in the fight once morest Japanese knotweed: you can drown them
The Japanese knotweed no longer has the status of an elegant garden plant. There now seems to be a working solution to combat the rapidly spreading invasive exotic.
With a little help, you can let nature wipe out invasive species on its own
Biologist Janneke van der Loop wants to use native plants to combat invasive species, such as the rapidly spreading water crassula.
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