Abstract
In temperate forests, climate seasonality restricts the photosynthetic activity of primary producers to the warm season from spring to autumn, while the cold season with temperatures below the freezing point represents a period of strongly reduced plant activity. Although soil microorganisms are active all-year-round, their expressions show seasonal patterns. This is especially visible on the ectomycorrhizal fungi, the most abundant guild of fungi in coniferous forests. We quantified the production of fungal mycelia using ingrowth sandbags in the organic layer of soil in temperate coniferous forest and analysed the composition of fungal communities in four consecutive seasons. We show that fungal biomass production is as low as 0.029 µg g−1 of sand in December–March, while it reaches 0.122 µg g−1 in June–September. The majority of fungi show distinct patterns of seasonal mycelial production, with most ectomycorrhizal fungi colonising ingrowth bags in the spring or summer, while the autumn and winter colonisation was mostly due to moulds. Our results indicate that fungal taxa differ in their seasonal patterns of mycelial production. Although fungal biomass turnover appears all-year-round, its rates are much faster in the period of plant activity than in the cold season.
Highlights
Fungi play important ecological roles in forests: besides the free-living saprotrophs, diverse fungal groups interact with plants as mycorrhizal symbionts or important pathogens
We addressed the question of seasonal production of extrametrical ECM fungal mycelia in a mature spruce forest using the incubation of ingrowth bags filled with sand across four consecutive three-month periods representing different seasons and analysed the composition of the fungal community within the bags to track the seasonality of mycelial production of different fungal species across the year
Given that ectomycorrhizal fungi account for a large proportion of the total soil microbial biomass in some systems, e.g., boreal and temperate forests [10], the death and turnover of mycorrhizal fungal tissues undoubtedly substantially contribute to the pool of dead microbial biomass that serves both as a primary resource for decomposers [6,53] and as a source of soil organic matter formation and C
Summary
Fungi play important ecological roles in forests: besides the free-living saprotrophs, diverse fungal groups interact with plants as mycorrhizal symbionts or important pathogens. In the temperate and boreal regions, the research on fungi in forest ecosystems substantially increased our understanding of their ecology [1] and biogeography [2]. Due to their interactions with forest trees, fungi greatly contribute to the soil C balance by affecting both the net primary production (NPP) of forests and carbon (C) mineralisation and sequestration [3]. The contribution of saprotrophic and mycorrhizal fungi to the decomposition of soil organic matter contribute to ecosystem-level C mineralisation [8,9].
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