We used species-specific spore traps to measure airborne dispersal of the wood decay fungus Phlebia centrifuga (spore size 6.5-9  2.5-3 mm) up to 1000 m distance from a point source. We fitted two simple dispersal models, an empirical power law model and a semi-mechanistic diffusion model to the data using the Bayesian approach. The diffusion model provided a better fit than the power law model which underestimated deposition at 3-55 m and overestimated deposition at longer and shorter distances. Model fit improved by allowing overdispersion, suggesting that spores are not dispersed independently but wind can transport spores in groups inside discrete air packages up to considerable distances. Using the fitted diffusion model and available information on the establishment rates of wood-decay fungi, we examine the distance up to which colonisation from a single fruit body is likely to occur. We conclude that the diluting effect of distance and low establishment success make the occurrence of P. centrifuga dispersal limited possibly already at the distance of tens of metres and very probably at a few hundred metres from the nearest fruit body, despite the fact that under favourable conditions a high proportion of the spores can disperse considerably further. This conclusion is likely to hold generally for those fungal species that inhabit fragmented landscapes, have specialised resource and habitat requirements, and have similar spore size and other dispersal traits as P. centrifuga.

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1. Retention forestry and prescribed burning aim to alleviate the negative effects of forestry on biodiversity by maintaining the structural elements of natural forests in managed forests. We present the long-term effects of these methods on polypore fungi, a taxonomic group that has been severely affected by forestry. 2. Using a 10-year, large-scale field experiment, we studied how prescribed burning and two different tree retention levels (10 and 50 m 3 ha À1 ) affect polypore fungi. We monitored polypore sporocarps on 2767 individually marked trees four times over the study period: in the first autumn after the treatments, and again 2, 4 and 10 years after the treatments.3. The number of polypore species and records initially increased rather slowly but showed a marked increasing trend towards the end of the 10-year monitoring period. After 2 years, the higher retention sites had an average 8Á5 species and the low retention sites 4Á5 species per site. After 4 years, the difference was 14 vs. 9 species and after 10 years 26 vs. 19 species. Red-listed species were not found often on the trunks earlier than 10 years after the treatments. 4. Prescribed burning increased the number of polypore species and records along with time. Furthermore, 13 species favoured burned sites, while only six species favoured unburned sites, and the differences in the composition of species assemblages between burned and unburned sites were evident 10 years after the treatments. 5. Synthesis and applications. We show, for the first time, that retention trees can host rich polypore assemblages, and even some red-listed species, and, thus, be useful in conservation of forest biodiversity outside protected areas. Higher retention levels maintain more diverse polypore assemblages. Prescribed burning increases the positive effects of retention forestry by creating substrates that are typical in the early-successional natural forests.

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