Tricholoma joachimii is a rare European fungus forming mycorrhiza with Pinus. The species is confined to more or less base-rich, semi-open, xerothermic forests on sandy soils.

Few known localities, small population, heavily fragmented and confined to a rare habitat threatened by forestry.

The status and trend of the population is inferred from field observations combined with the known habitat decline. Past, ongoing and future habitat declines are estimated to impact negatively on all populations of T. joachimii iand the future looks bleak for this species. Estimated decline of area and quality of appropriate forest habitat has been and will continue to be be just under 30 % over 50 years. The length of evaluation period used for these estimates (50 years = three generations) follows recommendations of Dahlberg and Mueller (2011).  It is listed as Near Threatened because it almost qualifies for listing as Vulnerable under criteria A2c+3c+4c .

Reports of Tricholoma joachimii in USA (Oregon) needs to be revised whether it belongs to same taxon as European material. It is not considered as the same taxon as in Europe here. Also findings recorded as T. joachimii in parts of Europe with different ecology, i.e. associated with Pinus pinaster in acid soils, need to be revisited to check for conspecificity. These observations are neither considered to belong to the same taxon.

This species is rare and scattered in South-Central Europe with a few isolated populations in northern Europe (Sweden, Norway).

Currently know from less than 50 localities in 11 countries. The real number may be 10x higher and are cautially estimated to 500-1.000 inferring maximum 10.000-20.000 individuals. The habitat requirement, i.e. oldgrowth semiopen Pinus forests, is under threat from forestry and densification with spruce. Small subpopulations and heavily fragmented. The species are probably decreasing with more than 15% (maybe even as high as 30%) in 3 generations (50y).

Tricholoma joachimii is a mycorrhizal fungus association with Pinus spp. The species seems confined to more or less base-rich, semi-open or xerothermic forests on sandy soils. Probably confined and adapted to semi-opened mixed forests that once where common and used for extensive grazing.

The main threat to the species is forestry, especially clearcutting. Also replacement of semi-open mixed forest types with more dense and uniform Picea-dominated forests is negative. In part of its range the species is probably also loosing habitats due to suppression in fire frequency which results in more homogenic forest eco-systems.

The actions suggested is mainly focused on area protection and restoration of habitats incl. shrub removal and reintroduction of cattle to graze the forests. In Sweden there is an Action plan for the species (Johansson & Bohus-Jensen 2010). So far its resulted in an increase in knowledge but very few new localities found. All in all only known from 10 localities and about 100 carpophores seen.

Bohus-Jensen, E. Artfaktablad Tricholoma joachimii. Link: http://www.artfakta.se/artfaktablad/Tricholoma_Joachimii_2072.pdf
Christensen M, Heilmann-Clausen J, 2013. The genus Tricholoma. Fungi of Northern Europe - vol 4: 1-228.
Johansson, P. & Bohus-Jensen, E. 2011. Åtgärdsprogram för sienamusseron, Tricholoma joachimii 2011-2015 . Link: http://www.lansstyrelsen.se/gotland/SiteCollectionDocuments/Sv/Publikationer/Natur-och-miljö/Hotade-arter/sienamusseron-2011-2015.pdf
Redlist of Slovak fungi. Link: http://www.wsl.ch/eccf/Slovakia.pdf