Epigeic lichen communities of taiga and tundra regions

Abstract

The major physiognomic and ecological categories of the lichen-rich, epigeic communities in the boreal (taiga) and arctic (tundra) zones are defined and their syntaxonomy and ecology in Europe, Asia and North America is reviewed. In the boreal and hemiarctic areas open, dry, acidophytic lichen woodlands are widespread, especially on sandy habitats. Their epigeic lichen synusiae are usually dominated by four fruticose Cladina species, being extremely homogeneous in species composition and structure throughout the boreal zone, while the dominant trees and the other vascular plant flora of the woodlands are geographically more variable. No phytosociological classification system exists that would cover most of these communities over the circumpolar regions. Very similar communities, though much more poorly known, are found on thin soils over Precambrian rock outcrops. Other sites to produce epigeic lichen communities include open sand dunes, treeless heathlands, drier bogs and many seral stages, like those on road banks. Boreal lichen-rich communities on eutrophic soils may be developed in semiarid regions, in particular. In the Arctic, lichens are common in most communities, and the driest ones are regularly lichen-dominated, whether acidophytic or eutrophytic, chionophytic or achionophytic. Detailed syntaxonomic systems for their classification have been developed, especially in Greenland and Scandinavian mountains (in oroarctic zones in the latter regions). The richest fruticose lichen areas are in continental, hemiarctic timberline regions in northern Siberia and Canada. The southern and middle arctic subzones are also characterized by many macrolichens, such as Cetraria cucullata, C. nivalis, Alectoria ochroleuca, and Thamnolia vermicularis, but everywhere also small, crustose lichens are common on soil, such as Rinodina turfacea and Lopadium pezizoideum, which are often overlooked in vegetation analyses. The presence of microlichens and the formation of mosaic micropatterns of soil lichen communities is particularly typical of the northern arctic subzone. The conservation problems of the boreal and arctic lichen communities include overgrazing by reindeer or caribou, which has caused delichenization in some regions, extensive forest and tundra fires, use of heavy transport vehicles in forestry and tundra operations, and, locally, heavy industrial air pollution. 40

Finnish botanists and mycologists in the Arctic

“…Ahti has collected also bryophytes and vascular plants during these expeditions. Specimens are deposited at H. Epigeic lichen communities of taiga and tundra regions were reviewed circumpolarly by Ahti and Oksanen (1990). It is based on extensive literature reviews and on field work performed by Ahti.…”

Influence of ground substrate on establishment of reindeer lichen after artificial dispersal

“…is one of the first fruticose lichens to appear, then C. arbuscula (Wallr. ), C. rangiferina (L.), and C. stellaris (Opiz) is usually the last (Kershaw 1977, Ahti andOksanen 1990). Lichens can reproduce either sexually or asexually.…”

“…Reindeer lichens grow mainly in oligotrophic habitats (Ahti and Oksanen 1990), such as dry sites dominated by Scots pine (Pinus sylvestris L.), where they compete successfully with other ground vegetation species because they can rely on water supplied through precipitation and atmospheric humidity. Thus, unlike vascular plants they are not limited to taking up water, or nitrogen and phosphorous, from the soil (Crittenden et al 1994, Ellis et al 2004).…”

Influence of Time since Fire and Micro-Habitat Availability on Terricolous Lichen Communities in Black Spruce (Picea mariana) Boreal Forests

“…Terricolous lichens are known to exhibit different community structures on different types of surficial deposits [64], and thus the relationships with forest continuity could be different on soil types with coarser or finer textures, something that should be investigated by future studies.…”