Habitat and Ecology
Suillus americanus mainly occurs in the mountain and subalpine zone, forming an ectomycorrhizal symbiosis with five-needle pines. In Europe, it is associated with Pinus cembra and P. peuce; in North America with P. monticola, P. flexilisand P. strobes; in Siberia with P. pumila and P. sibirica whereas in Asia with P. wallichiana. Even though in most of literature it is allied to five-needle pines exclusively, in Pakistan a mycorrhiza with roots of Abies pindrow, Salix alba and Populus sp. has been described (Sarwar et al. 2011, Sarwarand Khalid 2014), and in India Cedrus deodara and Picea smithiana are mentioned (Verma and Reddy 2016). It grows solitary to scattered and gregarious on both calcareous and siliceous bedrock, registered from acid to neutral and basic soils, with low to moderate nitrogen content (Favre 1960, Fraiture and Otto 2015, Verma and Reddy 2016).
In North Macedonia it is mostly found in old-growth Pinus peuce forests, at an altitude ranging between 1,400-1,800 m a.s.l. from early summer till late autumn (Karadelev and Rusevska 2008, Karadelev et al. 2018) in mountains Pelister and Kajmakcalan. It has only one locality in forest stand of planted Pinus strobus at 900 m a.s.l. in mountain Kitka. Other potential localities are the forests of Macedonian pine in Shar Mountain, in the vicinity of Leshnica and Jelachki Crn Vrv (UNEP 2020). The mycorrhizal partner can be found in other localities too, but those forest stands are recently established (Mandzukovski et al. 2009). Therefore, given the knowledge on availability of appropriate habitat the estimated number of locations is not expected to be higher than 10.