Investigating functional traits is an important tool for understanding fungal communities, yet ecological functions of fungal pigmentation remain poorly investigated. Recent studies support the thermal-melanism hypothesis for fungal color lightness in relation to macroclimate, but it remains unclear if microclimate also affects fungal pigmentation. In this study I use fruit bodies of wood-living polypores to further investigate this subject. While previous studies have used database-derived color lightness from photos often taken under unknown and non-standardized conditions, here I extract all color values from standardized photos taken in situ. In contrast to previous studies that have only examined fungal color lightness, I also studied the other components of the CIE L*a*b* color space, which may be related to e.g. protection, thermoregulation or signaling. I investigated community-level fungal pigmentation of pore surfaces and caps of polypores in fragmented forest patches in northern Sweden, in relation to microclimate proxies, deadwood availability and surrounding landscape structure. Two types of multiple linear regression models were used, one for community weighted means (CWM) and one for the coefficient of variance (CV) of patch level pigmentation. While no support was found for the thermal-melanism hypothesis in this study, saturation in the yellow spectrum was positively related to canopy cover and forest patch size. Variance in lightness of pore surfaces and in saturation in the red spectrum of caps was also positively related to diversity of decay stages and forest patch size respectively. These results indicate previously unknown relationships between fungal pigmentation and environment which warrant further research.

Conservation of wood-decaying fungi requires improved knowledge about the long-term effects of forest management; regarding habitat loss, fragmentation and fire suppression. To better understand such effects, I examined the influence of area, isolation, fire history and forest stand characteristics on communities of wood-decaying fungi. Species richness and composition were studied along a gradient of 22 forested islands varying in size (0.16 to 17.58 ha) and fire history (spanning 5000 years) in a boreal forest archipelago in northern Sweden. A total of 490 records of 41 polypore species were found in 33 circular plots, each 0.1 ha in size. Species richness and the number of red-listed species were analyzed using generalized linear models (GLMs), while species composition was examined using non-metric multidimensional scaling (NMDS) ordination. The species composition was clearly different between recent-fire (< 300 years since last fire) and old-fire (≥ 300 years since last fire) islands, mirroring the shift in tree species composition as pine-associated fungal species were replaced by spruce-associated fungal species. The volume of logs was the only variable influencing the species richness, although the diversity of logs showed a clear trend of also influencing species richness positively. The results demonstrate the importance of having both recent-fire and old-fire forests as landscape-level habitats and species pools, where fire naturally would constitute a key role for maintaining forest biodiversity in the boreal forest landscape. The results also stress the importance of dead wood for species richness at the individual forest stands.