European regional assessment: Near Threatened (NT)
EU 27 regional assessment: Near Threatened (NT)

Calypso bulbosa has European occurrences in Finland, Sweden, and European Russia. It can be found in more than 1,500 sites but the populations are decreasing throughout its range. This species can be affected by climate change as it needs snow cover in winter to keep its buds from freezing. The loss of forest dynamics, forest management or clearance for settlements and for agriculture, construction of power lines, quarrying, and the collection of this species for trade, pose major threats. Voles are also seen as a potential threat in Finland which hosts the bigger part of the population of this species. Overall, the populations are declining and even without exact data about the rate of decline and timeframe at European scale, it can be assumed that it will be close to the threshold for Vulnerable A3c. The species is therefore assessed as Near Threatened.

Calypso bulbosa is native to the subarctic and temperate northern Hemisphere. In Europe, it occurs in Finland, Sweden, and Russia where it can be found in central, east, north and northwest European Russia. In Russia, it is distributed rather widely but scattered into central Ural and western Siberia. The area of occupancy in Sweden is 1,787 km² (ArtDatabanken 2010). In Finland, the main distribution area is in Central Lapland in the north, but there are single populations outside of this range from north to east-central Finland (A. Jäkäläniemi pers. comm. 2011).

The total population in Sweden counts between 5,000 and 20,000 mature individuals with a slightly decreasing trend. It is known from 500-800 localities (ArtDatabanken 2010).
 
In Finland, Calypso bulbosa has 145 000- 150 000 individuals, spread over 1,143 sites. The sites can be in quite close proximity (100-200 meters), so they can count as patches of bigger populations. The best estimate of the number of populations is 900-1,000. In addition to extant populations there are 69 extinct populations and 87 populations of which the status is unknown (A. Jäkäläniemi pers. comm. 2011).

In Russia, the populations are decreasing in the St. Petersburg region, and some populations of European Russia have gone extinct. The number of known populations is small; they are usually found solitary or in small groups (Tzvelev 2000).

Calypso bulbosa has been found in Picea spp. taiga boreal woodland (Commission of the European Communities 2009). It grows in base-rich, semi-open forests, mainly coniferous or rarely in mixed forests on calcareous soils. The colonisation of this plant is poorly known. Its flowers are pollinated by bumblebees.

The species flowers very early in summer and is dependent on queen bumblebees, that wake from winter hibernation. The fruit production varies considerably between the years, being very high in some years and reaching up to 80%. The peak fruit production years occur, when the main nectar sources of bumblebees, Salix species, have a short flowering period due to warm weather. In that case Calypso bulbosa is the only flowering plant around and the bumblebees visit its nectarless flowers quite often. In other years, it suffers from pollen limitation, but the Finnish populations still have a remarkably higher fruit production than Swedish or US populations. The species needs a long time to produce a flower, about 10-15 years. Dormancy is quite often present in its early years and typically lasts 1-3 years, rarely longer (A. Jäkäläniemi pers. comm. 2011).

Calypso bulbosa can colonize nearby sites if a larger source population is nearby. In those situations it can recolonize the habitats which have been under forest management such as clearcuttings (A. Jäkäläniemi pers. comm. 2011)

This plant is dependent on snow cover in the winter as the buds are on the surface. If there is no snow, the buds will freeze and therefore climate change could pose a threat to the species (S. Ericsson pers. comm. 2010). Climate change may threaten the southern Finnish populations (A. Jäkäläniemi pers. comm. 2011).

In Sweden, loss of forest dynamics could pose a bigger threat than forest management or clearance (S. Ericsson pers. comm. 2010). In Russia, the deforestation for settlements (e.g. holiday homes) and for agriculture, construction of power lines, quarrying, and the collection of this species for trade, pose the biggest threats (I. Illarionova pers. comm. 2010).

In Finland, voles are perceived as the main threat. In peak vole years, they can eat over 90% of plants. In 2011, the damage caused by voles was very high and many populations have been badly eaten during winter and spring. However, since the decade that the populations have been monitored, this is the first bad year, and it remains to be seen how the populations recover from the herbivore attack (A. Jäkäläniemi pers. comm. 2011). Although other experts agree that voles affect C. bulbosa, they do not agree that they are posing a threat to the species. Voles eat the leaves but seldom eat the underground part of the orchid and most species survive vole attacks and show an increased production of flowers in the following year (R. Alexandersson pers. comm. 2011).

In Russia, it is collected from the wild for horticultural trade but it is impossible to cultivate in gardens.

All orchids are included under Annex B of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Calypso bulbosa is listed on Annex II of the Habitats Directive.

It is categorized as Critically Endangered in Russia (I. Illarionova pers. comm. 2010) and protected in nearly all the regions of the European part of Russia. In Sweden, it is classed as Vulnerable B2ab(iii,iv,v) and is protected by national law (Gärdenfors 2010). In Finland, it is classed as Vulnerable A3c (Rassi et al. 2010).

More information on reproductive mechanisms of the plant is needed.