LAND - Habitat fragmentation and pathways to extinction in dead-wood dependent fungi

Our large material includes >500 species of corticioid and polypore species as fruit bodies on 1,680 spruce logs in 28 dead-wood rich natural-like spruce forests in Norway and Sweden. We detected 9,300 operational taxonomical units (OTUs) as mycelia inside the logs, and 3,500 OTUs in spore material collected from the air. The fruit body data include several species new to Norway and new to science. The rare species are often ecologically specialized in particular kinds of logs that are much fewer in today's forest landscapes than what they used to be before extensive human influence. The common and ecologically generalized species seem to be abundant in all life stages (fruit bodies, mycelia and spores) in both poor and good-quality forest landscapes and in both large and small forest areas. The rare and ecologically specialized species (often red-listed), however, are often absent from the poorest quality forest landscapes, and occur more often in large than in small forest areas. The rare specialists seem to have difficulties persisting in or dispersing to small and isolated forests. Dispersal limitation concerns especially species with thin-walled spores. One key result from our spore viability study is that species with thick-walled spores are able to disperse considerably longer distances than species with thin-walled spores, because thin-walled spores lose their viability sooner when exposed to sunlight. We show that it is possible to help rare fungal species that cannot disperse to distant isolated forests by their own means, by bringing them to the forest as mycelia and inoculating them into dead trees. Six out of seven red-listed polypore species started fruiting within 1 to 7 years after the inoculation. Our spore production data show that the rate of spore production per unit area of hymenophore (spore-producing part of the fungal fruit body) is not lower in isolated forests than in well-connected forests, but for rare species, the total spore production is lower in small forest patches and in forest landscapes that have only a little natural-like forests left. An examination of the whole fungal community at the level of OTUs in the mycelial and airborne spore data reveals an interesting pattern: in northern and western Scandinavia, i.e. in landscapes that have relatively many old forests remaining, OTU richness per unit sample is similar in large forest areas and nearby small patches of old-growth forest. But in southern and eastern Scandinavia, in forest landscapes that have very little old forests remaining, the landscape context becomes critical. Here the small and isolated patches of old-growth forests are clearly more species poor per unit sample than in the nearby large areas of similar forest. Our large species observation data have given new information about the distribution and ecology of hundreds of wood-inhabiting fungal species. This will be useful e.g. for the Red-List work in Norway and Sweden. All species observations from the project are made public through Artskart (Norway), Artportalen (Sweden) and GBIF.

In spite of extensive amount of forest biodiversity research in Fennoscandia, the exact mechanisms behind species declines are still poorly understood. Forests are the most important habitat for red-listed species, and the effects of forestry are the prim ary cause of species becoming threatened. We plan to identify the demographic and genetic processes that disentangle those species of aphyllophorous fungi (polypores and corticioids) that have and have not responded negatively to forest management and fra gmentation. The ecology and distribution of many dead-wood dependent fungal species is deficiently known, and a substantial fraction of the well-known species has declined. In all Fennoscandian countries, around 20% of all aphyllophorous species are class ified as threatened or near-threatened. We will study the variables that affect the occurrence of the species, with a particular focus on how species' life-history traits are linked with their vulnerability to the effects of forestry. This will enable the assessment of conservation needs and the prediction of future population trends. Such information is critical for the design and development of scientifically informed and cost-effective conservation measures. We will study the occurrence of dead-wood de pendent fungi as fruit bodies, mycelia and spores in isolated and well-connected forests. We will also examine the variation in intraspecific genetic diversity and its effects to the viability of populations. Our team has state-of-the-art expertise in fun gal molecular biology. The project takes advantage of the ongoing revolution in molecular biology and sequencing technology, which enables one to combine conventional fruit-body inventories with direct measurements of the mycelial and dispersal stages. We will produce systematic and unbiased information on the distribution and abundance of the entire fungal community, including a large number of threatened and deficiently known species.