Richness of epiphytic lichens in differently agedPicea abiesplantations situated in the oceanic region of Central Norway

Abstract

AbstractThis study aims to investigate patterns of species richness and abundance in relation to stand age in 71Picea abiesplantations, aged between 9 and 85 years, situated in the oceanic region of Central Norway. The study has shown that plantations within the oceanic spruce forests can support a relatively high number of epiphytic lichen species. Some of the oldest plantations hosted several old-forest associated species, e.g.Hypogymnia vittata, Lobaria pulmonaria, Pseudocyphellaria crocataandRamalina thrausta. The number of species was influenced significantly by stand age and increased rapidly in stands <20 years old. Stands >30 years old showed no clear increase in species number, except for a high number of species in the two oldest stands. The colonization pattern could be characterized as an additional entrance of species, rather than by a replacement sequence. The probability of occurrence increased steeply at young stand ages (<20 years) forBryoriaspp.,Cavernularia hultenii, Platismatia glauca, Parmelia sulcataandUsneaspp. A lower rate of colonization was characteristic forAlectoria sarmentosa, Parmelia saxatilisandPlatismatia norvegica. The cover of foliose lichens on the branches showed an almost unimodal response to stand age. The cover of lichens was highest on branches in middle-aged plantations. The reason for the lower lichen cover in late successional stages, compared to middle-aged stands, could be due to reduced light in the lower canopy of mature plantations. Increased rotation cycle, creation of gaps and short distance to sources of propagules are factors suggested to promote species richness and abundance in forest plantations.