Burning harvested sites enhances polypore diversity

Abstract

Prescribed burning after clear-cut has been used as a silvicultural method, but it has also been found to support biodiversity. We asked what is the impact of fire on polypores that grow on stumps and slash left on clear-cut sites.

Eighteen one-hectare study stands were cut with different levels of retention trees and nine of the sites were burned the following summer. The study sites are located in eastern Finland in forests that are dominated by Pinus sylvestris. We sampled stumps and slash for polypores ten years after cuttings and burnings.

We sampled 14 235 stumps and 13 345 pieces of slash and counted 7 179 polypore records of 74 species on these. More polypores were found from burned stumps compared to the unburned stumps, but burning had no effect on polypores on slash. We found also some red-listed polypore species both from stumps and slash - more from those sites where the resource had been burned. All red-listed species that were found on unburned sites were found also on burned sites, except for one species.

Our results show that stumps and slash can be valuable substrates for wood-decaying fungi, including rare and red-listed species, on clear-cut forest stands. We recommend avoiding full-scale stump and slash harvest. e.g. for the purposes of bioenergy production, on clear-cut areas. Instead, we encourage to retain stumps and to apply prescribed burnings on harvested sites, to enhance polypore diversity in managed forests.