Spore deposition of wood‐decaying fungi: importance of landscape composition

The abundance of many species of wood‐decaying fungi has decreased dramatically in Swedish boreal forests over the last century. Therefore, we have investigated the relationship between the spore dispersal of wood‐decaying fungi and two key features of landscape composition, namely the amount and age of old forest stands at different spatial scales. Spore deposition was monitored in two regions, using sampling methods based on recording the dikaryotisation of monokaryotic mycelia on nutrient agar and wood discs. The studied species, all mainly confined to Norway spruce in the boreal forest zone, were Fomitopsis pinicola, Fomitopsis rosea , Gloeoporus taxicola , Phlebia centrifuga and Trichaptum laricinum . The study of forestry intensity showed for both regions, that the spore deposition for F. pinicola , F. rosea and G. taxicola was higher in circular plots (radius 2‐km) with a high proportion of old Norway spruce forest (>80 yr) than in plots with a lower proportion of old forest. Analysis of the variation in spore deposition of F. rosea and P. centrifuga in relation to the proportion of old spruce forest within 1, 2 and 3 km of the spore sampling point showed that the proportion of old forest within a 3‐km radius explained more of the variation than the proportions within 1‐ and 2‐km radii. In addition, the proportion of forest older than 140 yr explained more of the variation than the proportion of younger forests. Thus, the results show that the spore deposition of the studied species strongly depends on the landscape composition at both regional and local scales. Further, the spore deposition at the local scale was best explained by the proportion of >140 yr old spruce forest, which exceeds the common harvest rotation period.