Ecological continuity and assumed indicator fungi in boreal forest: The importance of the landscape matrix

In a boreal forest in southeast Norway, we evaluated the relative importance of stand-level structures versus historical data on forest age and absence of logging (at two spatial scales; stand and surrounding landscape), on the presence and abundance of the wood-rotting fungi Phellinus nigrolimitatus and Cystostereum murraii. Both species are often considered to be indicators of long-time continuous presence of downed logs in Scandinavian forest stands. Of the stand-level variables, number of logs in late stages of decay was positively related to P. nigrolimitatus presence, while diversity of coarse woody debris was positively related to the abundance of the species. Both the presence and abundance of P. nigrolimitatus was strongly and positively correlated with the area of forest uninterrupted by major disturbance the past 240 years (equalling 140 years of "old growth continuity") in the surrounding landscape (80 ha). For C. murraii, consistent results was not found. We conclude that the causal relationships between ecological continuity and possible indicator species must be investigated on a larger scale than the stand-level as the condition of the forest surrounding a stand can have a large influence on these relationships.