In the 2015 Red List 4, 273 out of the 21 600 assessed species have become red-listed (NT, VU, EN, CR, RE or DD), and 2,029 of them have been assigned to one of the categories VU, EN or CR. These numbers have increased since 2010 by 3.6 and 4.4 %, respectively – mainly due to the increased number of assessed species. The percentage of red-listed vs. assessed species in the 2015 Red List equals 19.8 % – a figure which has remained fairly constant since the 2 000 Red List. The factors posing a threat to the greatest number of Swedish species are logging and overgrowth of their habitats. There are, however, also a few positive trends. The situation of amphibians and large mammals has improved since 2000, largely due to successful conservation actions and/or new legislation.
We would like to emphasize the following five conclusions:
Overgrowth constitutes one of the greatest threats to the Swedish red-listed species. This applies to several habitat types including meadows, pastures forests and wetlands. There are several reasons behind overgrowth, for instance cessation of cutting and grazing, lack of natural disturbances such as fire or flooding, tree planting, fertilisation, nitrogen deposition, ditching and a warmer/drier climate.
The marine environment is subjected to major habitat changes, and our knowledge of marine habitats is very incomplete. No less that 53% of all red-listed marine species have been placed in the category Data Deficient (DD). Most of them have become red-listed because their distribution area has dwindled due to habitat destruction or deteriorating habitat quality. Trawling has an adverse effect on extensive bottom areas, and has been identified as the single factor threatening the largest number of red-listed species. Eutrophication and toxic substances are other main factors behind the fact that many species which used to be common near the coast occur exclusively around remote off-shore shoals today.
Many red-listed species require a so called mosaic landscape, i.e. a habitat comprising a mixture of at least two elements, e.g. forest edges with their mixture forests and open areas. Sustainable use and preservation of this kind of landscape necessitates cooperation between social sectors (mainly agriculture and forestry).
Every time when the distribution area of a species decreases, and it vanishes from localities where it used to occur, a local or regional extinction has taken place. “Extinction” is, in other words, not a term applicable only to the species classified as Regionally Extinct (RE) on the Red List, but to all species with a decreasing distribution area and/or extent of occurrence.
The status assessments made by the Swedish Species Information Centre are based on both expert knowledge and data from various sources, mainly observations recorded in the Swedish Species Observation System, where individual amateurs are major contributors. The commitment of private persons thus constitutes an invaluable source of information about the distribution and status of individual Swedish species.