Threat to biodiversity
Worldwide, invasive alien species constitute one of the leading threats to biodiversity, second only to the destruction and fragmentation of entire habitats.
The spread of alien species decreases biodiversity on average, even if this may locally or regionally increase the number of species present.
Invasive alien species have a multitude of harmful impacts on biodiversity, the functioning of the ecosystem and the ecosystem services thereby maintained. Alien species may threaten indigenous species by competing with them for the same resources, by predation, by spreading diseases or parasites, or by cross-breeding with these species in the wild. Alien species are also known to have changed the structure of food chains and to have affected the functioning of entire ecosystems. The harmful impact of invasive alien species on the natural environment, biodiversity and ecosystem services may, therefore, even have direct and indirect adverse effects on human wellbeing.
Impacts on society
Invasive alien species cause harmful social impacts and substantial financial losses to a variety of actors. Many invasive alien species are major pests for the agriculture and forestry industries. Fishing and fish farming may also suffer from the spread of invasive alien species; Alien species can also pose a health hazard or function as disease carriers.
Invasive alien species also cause problems for recreational activities and tourism. Moreover, they may compromise the functioning of the basic structures of society.
Invasive alien species cause significant financial costs worldwide. In 2001, it was estimated that the annual damage caused by invasive alien species worldwide exceeded USD 1,400 billion (EUR 1,054 billion), equivalent today to around 2 to 3% of combined global GDP. Of the 11,000 or so alien species found in Europe, probably 10-15% to 15% have some kind of harmful ecological or economical impacts. Even a conservative estimate of the value of the damage caused by these invasive alien species totals at least EUR 12.5 billion per year. The majority, 80-90%, of these costs are incurred through the harm and damage caused by invasive alien species and compensation for this, including harm to agriculture, forestry and fisheries, infrastructure damage and harmful impacts on human health.
No overall study has been made of the costs caused by invasive alien species in Finland, but they are known to cause significant losses to the quantity and quality of production (crops and catches). Regular costs are being incurred in Finland, for instance through plant and animal inspections related to alien species, prevention measures against invasive alien species such as giant hogweeds, Himalayan balsam and Japanese rose, and the hunting and trapping of small predators spreading to Finland. Even the costs of disease and pest control, prevention and monitoring cost several million euros per year in Finland.
The impacts of invasive alien species can be detected in several areas of society at once. The potentially most vulnerable areas in Finland are those of substantial importance to the national economy, for instance in forestry. A situation causing devastating economic losses would emerge if one particular invasive alien species disastrous to the forest industry – the pine wood nematode (Bursaphelenchus xylophilus) – were to spread rapidly in Finland’s forests.