Abstract
Summary Fungi are known to exert a significant influence over soil organic matter (SOM) turnover, however understanding of the effects of fungal community structure on SOM dynamics and its consequences for ecosystem fertility is fragmentary.Here we studied soil fungal guilds and SOM decomposition processes along a fertility gradient in a temperate mountain beech forest. High-throughput sequencing was used to investigate fungal communities. Carbon and nitrogen stocks, enzymatic activity and microbial respiration were measured.While ectomycorrhizal fungal abundance was not related to fertility, saprotrophic ascomycetes showed higher relative abundances under more fertile conditions. The activity of oxidising enzymes and respiration rates in mineral soil were related positively to fertility and saprotrophic fungi. In addition, organic layer carbon and nitrogen stocks were lower on the more fertile plots, although tree biomass and litter input were higher. Together, the results indicated a faster SOM turnover at the fertile end of the gradient.We suggest that there is a positive feedback mechanism between SOM turnover and fertility that is mediated by soil fungi to a significant extent. By underlining the importance of fungi for soil fertility and plant growth, these findings furthermore emphasise the dependency of carbon cycling on fungal communities below ground.
Highlights
The fertility of forest soils is a fundamental factor governing plant growth and ecosystem carbon (C) balances (Vicca et al, 2012; Binkley & Fisher, 2013)
Fertility is an ecosystem characteristic describing the relative availability of below-ground resources required for plant growth (Chapin III et al, 2002), and depends on soil properties such as water availability and the supply of mineral nutrients mobilised from both weathering of the geological substrate and turnover of soil organic matter (SOM) (Hansson et al, 2020)
The investigated fertility gradient was characterised by plant species such as Carex alba, Helleborus niger, and Daphne laureola at less fertile plots, and Mercurialis perennis and Allium ursinum at more fertile plots (Table S1)
Summary
The fertility of forest soils is a fundamental factor governing plant growth and ecosystem carbon (C) balances (Vicca et al, 2012; Binkley & Fisher, 2013). Fertility is an ecosystem characteristic describing the relative availability of below-ground resources required for plant growth (Chapin III et al, 2002), and depends on soil properties such as water availability and the supply of mineral nutrients mobilised from both weathering of the geological substrate and turnover of soil organic matter (SOM) (Hansson et al, 2020). Fungal-mediated decomposition and interactions among fungal guilds were identified to link soil fertility and SOM turnover in a boreal forest (Kyaschenko et al, 2017b). Whether this holds true for other forest ecosystems is, unknown
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