Macrofungus communities correlate with moisture and nitrogen abundance in two old-growth conifer forests, Olympic National Park, Washington, USA

Abstract

We characterized the epigeous macrofungus communities in two old-growth conifer forests by collecting sporocarps. Despite the similarity in dominant tree species in the two forests, the macrofungus communities were very different. At the drier, nitrogen-poor Deer Park area, the macrofungi were dominated by ectomycorrhizal species in the genera Cortinarius, Tricholoma, Hydnellum, Suillus, and Sarcodon. At the wetter, higher nitrogen Hoh Valley, the macrofungi were characterized by ectomycorrhizal species in different genera, such as Inocybe, Russula, Amanita, Boletus, and Phaeocollybia, and saprotrophic fungi accounted for a greater proportion of the community. Species richness was similar at the two areas, but sporocarp production was much higher at Deer Park. We propose that (i) these community differences developed over a long time; (ii) they are largely related to differences in ecosystem moisture and nitrogen abundance; and (iii) within the ectomycorrhizal fungi, possible causal mechanisms involve mycelial morphology and carbon allocation within the symbioses. The apparent response to relatively small but presumably long-term differences in nitrogen abundance suggests that sporocarp production by macrofungi could be an effective bioindicator and should be considered in determination of critical loads for atmospheric nitrogen deposition to temperate and boreal forests.Key words: critical nitrogen loads, ectomycorrhizal fungi, macrofungi, macrofungus communities, nitrogen, old-growth conifer forests.

Recent advances in population genetics of ectomycorrhizal mushroomsRussulaspp.

“…The most comprehensive sampling in such a situation requires the location to be continuously monitored over one or more complete fruiting seasons. Because fruit body production depends on many factors and can vary from one year to another, to ascertain the genet persistence over time and identify community temporal changes in a certain habitat, comprehensive sampling over many years may be required (Trudell and Edmonds 2004; Bergemann et al 2006; Durall et al 2006). However, researchers should be cautious in matching sampling strategies to their specific research objectives.…”

Mycorrhizal mushroom diversity and productivity—an indicator of forest health?

“…Increasing nitrate and ammonium inputs in forest ecosystems have been shown to reduce the ectomycorrhizal mycelium growth in the soil (Arnebrant 1994;Nilsson and Wallander 2003) and to decrease the species diversity and fruit-body production of ectomycorrhizal species, whereas saprobic species are much less affected (Ritter and Tölle 1978;Arnolds 1991;Wiklund et al 1995;Wallenda and Kottke 1998;Lilleskov et al 2001;Peter et al 2001;Trudell and Edmonds 2004;Termorshuizen 1993). However, a few ectomycorrhizal species, such as Paxillus involutus and Lactarius rufus, and species of the Thelephoraceae and Corticiaceae are also thought to remain largely unaffected or even to increase their production of fruit bodies in forest soils to which N has been added (Laiho 1970;Ohenoja 1978;Wästerlund 1982;Peter et al 2001).…”

Macrofungal diversity in community-managed sal (Shorea robusta) forests in central Nepal

“…(Trudell and Edmonds 2004; Christensen and Heilmann-Clausen 2009; López-Quintero et al 2012; O’Hanlon and Harrington 2012; Pradhan et al 2013). Climatic conditions as well as phyto-geomorphologic features affect macrofungal fructification (Brunner et al 1992; Yang et al 2006) and thus the chances of their collection during inventory.…”