The significance of retention trees for survival of ectomycorrhizal fungi in clear‐cut Scots pine forests

Abstract

1. Forestry with short stand generations and simplified forest structures has markedly affected forest biodiversity. One group of organisms adversely affected by clear-cutting is ectomycorrhizal (ECM) fungi, as they are associated with the roots of living trees. Retention forestry is a way of reducing logging impacts and enhancing biodiversity conservation. Increasing the proportion of trees retained at harvest may improve ECM fungal diversity.2. We investigated the potential for lifeboating of ECM fungi through the harvesting phase in an experimental field study in a 190-year-old Scots pine forest in northern Sweden. The experiment comprised four levels of tree retention-unlogged forest, plots with 60% or 30% of evenly distributed trees retained and clear-cuts without retained trees. We sampled soils and determined identities, frequencies and relative abundances of ECM fungal species during 3 years following logging through the use of high-throughput sequencing of amplified ITS2 markers.3. We identified 149 ECM fungal species, with the five most abundant species accounting for 50% of the total ECM fungal amplicons. Three years after harvesting, the proportion of ECM sequences in the total amplicon pool had decreased proportionally to the extent of tree removal. In clear-cuts, ECM fungal relative abundance had decreased by 95%, while ECM fungal species richness had declined by 75%, compared to unlogged plots. 4. Tree retention enabled the maintenance of the most frequent ECM species, while more lowly abundant species were progressively lost at random with increasing level of tree removal. Five of the most frequent ECM fungal species remained present after clear-cutting, probably associated with pine seedlings. Synthesis and applications.Tree retention can moderate short-term and potentially also long-term logging impacts on ECM fungi. Local ECM fungal diversity is preserved in proportion to the amount of retained trees. Abundant species may be largely maintained, even by low levels of tree retention and on naturally established seedlings. However, conservation of more infrequent species requires higher levels of tree retention, and our results suggest that around 75% of the ECM species are lost with the forest certification standard of 5% retention trees left at logging. tension limit of the boreal biome, as we wanted to study a diverse ECM fungal community unaffected by modern forestry. Scots pine forest is the most abundant type of forest ecosystem in northern Fennoscandia and commonly monodominant with respect to tree species (Stokland et al., 2003). K E Y W O R D S biodiversity, conservation, ectomycorrhizal fungal community, forest management, highthroughput sequencing, logging, soil, tree retention

Regional-Scale In-Depth Analysis of Soil Fungal Diversity Reveals Strong pH and Plant Species Effects in Northern Europe

“…In selectively harvested plots, the decline in overall fungal richness was related to decrease in EcM fungi and yeasts. Our results are thus partly consistent with a study in Northern Sweden that found 30-40% decline in EcM fungal diversity in a few years after partial harvesting (Sterkenburg et al, 2019) but in a disagreement with studies in Spanish Mediterranean forests revealing no effect (Castano et al, 2018a;Parlade et al, 2019). However, our study corroborates the long-term selective harvesting effect on composition of fungi and specifically EcM fungi in Mediterranean forests, which was not evident in Sweden.…”

“…It has been argued that the diversity of soil organisms is of particular importance for ecosystem services and resilience to disturbances, with a potential to ameliorate stress caused by global change ( Langenheder et al, 2010 ; Bardgett and van der Putten, 2014 ). Many of these soil organisms are vulnerable to shifts in land use, changing climate and ecosystem management ( Van der Putten, 2013 ; George et al, 2019 ; Makiola et al, 2019 ; Sterkenburg et al, 2019 ); therefore, some of the most conspicuous rare species are protected ( Dahlberg et al, 2010 ). However, fungal species that have large fruitbodies represent only a tip of the iceberg in the enormous diversity of soil mycobiome, much of which is cryptic and previously undocumented.…”

“…The regional geographic scale is important to consider, because this is typically little affected by historical dispersal limitation and climate (except montane systems), especially the covariation of climate with vegetation and soil properties – all inherent to larger geographic scales ( Lomolino et al, 2006 ). Multiple highly focused studies have demonstrated the effects of land use, dominant plant species, soil properties, pollution and management by humans on soil microorganisms ( Rousk et al, 2010a ; Hartmann et al, 2012 ; Urbanova et al, 2015 ; Creamer et al, 2016 ; Sterkenburg et al, 2019 ). However, these studies do not enable us to understand the relative importance of these factors because of their limited ecological scope.…”

Detection of Retention Trees on Clearcuts, a 50-Year Perspective

“…These results cannot by themselves be used to determine whether this is sufficient to maintain biodiversity in accordance with the objectives in the Forestry Act, although it demonstrates that today's clearcuts are more structurally diverse than those 50 years ago. This structural diversity has at least the potential to support comparatively more biodiversity and other studies, with focus on how retention forestry affect species taxa and functional groups, show positive effects on abundance and richness both in short and long term perspective (Franklin, Macdonald, & Nielsen, 2019;Pastur et al, 2019;Savrak, Remm, & Lohmus, 2019;Sterkenburg, Clemmensen, Lindahl, & Dahlberg, 2019). However, assessing the extent to which current practices actually supports critical species is outside the scope of this work.…”

Sheep nemabiome diversity and its response to anthelmintic treatment in Swedish sheep herds

“…The aims were to nd out how nematode community structure (species composition and diversity) were in uenced; i) by host age (in ewes and lambs), ii) in the shortterm following recent anthelmintic treatment with ABZ, IVM or LEV, and iii) long-term in samples collected several years apart. For this we used DNA extracted from composite larval cultures which then were analyzed using a PacBio NGS pipeline generating sequence data (amplicons) that were clustered into OTUs with a speci cally designed analysis framework developed for eukaryotes (SCATA) [33][34][35]. We identi ed ve common OTUs representing 97% of the reads, among which H. contortus and T. circumcincta were the two dominant species.…”