Epiphyte Flora and Diversity on Basal Trunks of Six Old-Growth Forest Tree Species in Southern and Middle Boreal Finland

Abstract

Epiphytic lichen and bryophyte species composition, richness and diversity were surveyed on basal trunks of six common old-growth forest tree species, Picea abies, Pinus sylvestris, Betula pendula, Alnus incana, Salix caprea and Populus tremula, in two old-growth forest areas, one in southern and one in middle boreal Finland. The average species numbers per tree ranged from 18 (Picea) to 27 (Salix) in the southern and from 20 (Populus) to 31 (Salix) in the middle boreal area. A few widespread habitat-generalist species, such as the foliose lichens Hypogymnia physodes and Platismatia glauca, were most abundant on all the tree species, except Populus. Most other epiphyte species showed at least a slight preference for one or two tree species. Populus proved to have the most distinct flora characterized by the abundance of certain, rather specialized crustose lichens and bryophytes. The number of species that occurred on only one tree species was highest on Populus (9) in the southern and on Alnus (18) in the middle boreal area. Differences in bark acidity and structure were the most likely explanations for the differences between tree species in the epiphytic flora and diversity. Salix and Populus were the most important of the tree species studied for the conservation of epiphyte diversity in the boreal forests of Finland.

The importance of host tree age, size and growth rate as determinants of epiphytic lichen diversity in boreal spruce forests

“…On finer spatial scales, forest stand variables such as stand age and tree species composition become more important (Holien 1998;Hyvärinen et al 1992;Will-Wolf et al 2006;Neitlich and McCune 1997). On the scale of the single tree, variables like tree species, branch quality, bark texture, tree size and tree age have been shown to significantly explain variation in epiphytic species composition and diversity (Holien 1997;Kuusinen 1996;Gauslaa et al 1998;Löbel et al 2006;Fritz et al 2009). …”

“…Epiphyte diversity is also influenced by temporal processes like tree ageing. Several studies have examined the importance of tree age in relation to epiphytic lichen diversity (Hilmo and Såstad 2001;Hyvärinen et al 1992;Kuusinen 1996;Johansson et al 2007). Tree age may affect diversity in various ways.…”

Tree and stand level variables influencing diversity of lichens on temperate broad-leaved trees in boreo-nemoral floodplain forests

“…The most highlighted physical characteristics of the substrate influencing the composition of epiphytic lichens are the roughness, thickness, hardness and water-holding capacity of bark (Culberson 1955;Mistry and Berardi 2005). From the chemical properties of the bark, bark acidity is considered to have the highest influence on the composition of lichen species (Bates and Brown 1981;Kuusinen 1996;Löbel et al 2006). The identity of the tree species has been suggested as less important, mostly considering the fact that bark pH varies largely within tree species along the environmental gradients (Farmer et al 1991;Gustafsson and Eriksson 1995).…”

“…Epiphytic lichens represent an important component of the forest ecosystem and have proved to be sensible indicators of its functions (Will-Wolf et al 2002), therefore, the lichen communities on deciduous and coniferous trees are intensively studied in regions of temperate and boreal forests (Culberson 1955;Barkman 1958;Yarraton 1972;Kuusinen 1996;Jüriado et al 2003).…”

Bryophyte species richness and composition in young forests regenerated after clear-cut logging versus after wildfire and spruce budworm outbreak

“…Mezaka and Znotina 2006). Kuusinen (1996) found bryophyte assemblages on aspen treebases to be distinct when compared with the composition found on five other common tree species in eastern Fennoscandia, presumably as a consequence of its unique bark structure with high water-holding capacity and pH. In addition, the high light availability early in the season prior to canopy development might also be beneficial for more light-demanding species in this and all other guilds as well.…”