How have invasive species contributed to the extinctions recorded in the world?

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) has published its first global report on invasive alien species. The document highlights that 218 of these species have caused the extinction of 1.215 species of plants and animals around the world.

Harmful effects of exotic invasive species

One of the key messages of research carried out in 2023 is that exotic invasive species represent a serious threat to nature, the services it provides to human life and quality of life.

The document mentions that due to human activities, more than 37.000 species of plants and animals have entered different regions of the world, of which 3.500 species are considered invasive due to their negative impact on native species and ecosystems.

These impacts include changes in ecosystem characteristics (27% of reported impacts), resource competition with other species (24%), predation on native animals (18%), and herbivory or plant consumption (12%).

Invasive species: the case of beavers in Patagonia

One of the cases discussed in the publication involved beavers in the Patagonia of Chile and Argentina. “Beavers build dams and change entire ecosystems"." Professor Sven Bacher, co-author of the report and professor at the University of Freiburg in Switzerland, said it is not just one species that is directly affected but the entire community of species.

In fact, beavers are one of the species included in a series of invasive species reports published by Mongabay Latam in 2022-2023. Today, their absolute number is estimated between 100.000 and 150.000 individuals, although greater importance is attributed to the invasion that affected all the water basins of Tierra del Fuego.

"The trees of Patagonia – coihues, lengas, ñires, raulíes and others – belong to the genus Nothofagus, cannot live in wetlands and take several decades to grow. In contrast, pine trees in the United States and Canada take five years to grow.”said Alejandro Valenzuela, a bioecologist specialized in the management of invasive species and associate researcher at the National Scientific and Technical Research Council (Conicet) of Argentina. 

The result was devastating: as soon as the reservoirs created by the beavers, the forest was replaced by grasses, some of which were also exotic, making it the so-called "beaver meadow".

The American continent is among the most vulnerable places to the problems of biological invasions, concentrating 34% of the impacts reported in the IPBES report there. They are followed by Europe and Central Asia with 31%, Asia-Pacific with 25% and Africa with 7%.

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