A4 Invasive alien species adversely affect the full 
range of nature's contributions to people, imposing 
an economic burden (well established) {4.4.1}. 
Some alien species have been intentionally introduced for 
their benefits to people, often without consideration or 
knowledge of their negative impacts (well established)
{3.3.1}. However, nearly 80 per cent of the documented 
impacts of invasive alien species on nature's contributions to 
people are negative (well established) {4.4.1}. Reduction in 
food supply is by far the most frequently reported impact 
across all taxa and regions (well established) {4.4.1, 4.6.2}. 
In terrestrial systems, invasive alien plants are the taxonomic 
group most frequently reported as having a negative impact, 
particularly in cultivated areas and temperate and boreal 
forests (well established) {4.4.2.1}. For example, in northwestern Europe, Picea sitchensis (Sitka spruce) severely 
alters habitats such as coastal heathlands and mires, which 
are important habitats for threatened and endangered 
plants, birds and other species, and for local cultural 
heritage (well established) {4.3.2.1}. In coastal areas, 
invasive alien invertebrates are the most frequently reported 
taxonomic group with an impact on nature's contributions to 
people, particularly provision of food (well established)
SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
Figure SPM 2 Examples of invasive alien species with a negative impact on nature (green), 
and, in some cases, nature's contributions to people (yellow) and/or good 
quality of life (teal). 