Shift in tree species changes the belowground biota of boreal forests

Abstract

Summary The replacement of native birch with Norway spruce has been initiated in Norway to increase long‐term carbon storage in forests. However, there is limited knowledge on the impacts that aboveground changes will have on the belowground microbiota. We examined which effects a tree species shift from birch to spruce stands has on belowground microbial communities, soil fungal biomass and relationships with vegetation biomass and soil organic carbon (SOC). Replacement of birch with spruce negatively influenced soil bacterial and fungal richness and strongly altered microbial community composition in the forest floor layer, most strikingly for fungi. Tree species‐mediated variation in soil properties was a major factor explaining variation in bacterial communities. For fungi, both soil chemistry and understorey vegetation were important community structuring factors, particularly for ectomycorrhizal fungi. The relative abundance of ectomycorrhizal fungi and the ectomycorrhizal : saprotrophic fungal ratio were higher in spruce compared to birch stands, particularly in the deeper mineral soil layers, and vice versa for saprotrophs. The positive relationship between ergosterol (fungal biomass) and SOC stock in the forest floor layer suggests higher carbon sequestration potential in spruce forest soil, alternatively, that the larger carbon stock leads to an increase in soil fungal biomass.

How does management affect soil C sequestration and greenhouse gas fluxes in boreal and temperate forests? – A review

“…and ascomycete Elaphomyces sp. in native birch stands (Mundra et al, 2022) in line with host tree specificity.…”

“…Tree species mediate plant-microbial interactions (Tedersoo et al, 2016) and therefore dominant tree species change would affect soil microbial composition, understory vegetation, as well as litter and root exudate quality and quantity (Mundra et al, 2022). Replacing birch stands with spruce stands leads to higher fungal biomass in the organic layer correlating with higher SOC and a higher ratio between ectomycorrhizal and saprothropic fungi (Danielsen et al, 2021;Mundra et al, 2022). Considering that most of stable SOC derives from roots and associated fungi (Adamczyk et al, 2019;Clemmensen et al, 2013), a higher amount of fungal biomass under spruce explains the concomitant increase in SOC.…”

Local Community Assembly Mechanisms and the Size of Species Pool Jointly Explain the Beta Diversity of Soil Fungi

“…When considering the drivers of both functional groups together, results have been variable. Some studies have found that both EcM and saprotrophic fungi were influenced by plant communities and soil abiotic factors [ 32 ]. Other studies have shown that EcM fungi were primarily affected by plant communities, soil abiotic factors, and geographical distance, whereas saprotrophic fungi were only influenced by geographical distance [ 33 ].…”

Metatranscriptomics sheds light on the links between the functional traits of fungal guilds and ecological processes in forest soil ecosystems

“…In forest ecosystems, tree species and forest management practices can greatly influence organic matter (OM) chemistry and structure, leading to variations in annual CO 2 uptake and long‐term carbon storage (Kjønaas et al ., 2021; Augusto & Boča, 2022; Jörgensen et al ., 2022). Combined with climatic and soil conditions, tree species composition also has varying impacts on belowground microbial communities, soil microbial activities, fungal biomass, and storage of soil organic carbon (Tedersoo et al ., 2011; Joly et al ., 2016; Ma et al ., 2017; Mundra et al ., 2022). Fungi are major players in the two major life‐supporting processes of trees in forest ecosystems, both directly by supporting tree nutrient uptake and growth and indirectly by driving decomposition (Högberg & Högberg, 2002; Six et al ., 2006; Fontaine et al ., 2011).…”