Fungal regulation of carbon and nutrient cycling in boreal forests

Prof. Björn Lindahl

Date: October 17, 2018
Time: 2 pm (s.t.)
Place: F 01 (Büsgenweg 1)

Coniferous forests are found at high latitudes between temperate deciduous forests and tundra, but also in mountains at lower latitudes. Climate change may lead to northward-upward migration of the boreal biome, but forest management also introduces conifers in temperate regions. To predict effects of these changes, the forces that shape the boreal forest have to be better understood – what prevents boreal forest to advance into tundra? What constrain northward expansion of deciduous forests? In this seminar these questions will be approached from a fungal perspective.

Boreal forests are characterized by a more or less extensive, purely organic layer that overlies the mineral soil. Soil fungi play a pivotal role in organic matter production, decomposition, nutrient release and nutrient retention in this “mor layer”. Plant-soil feedbacks are important with ectomycorrhizal – and ericoid mycorrhizal fungi transporting root-derived carbon into the soil system, building organic stocks, but also taking active part in decomposition, releasing bound resources. Oxidative enzymes, primarily produced by basidiomycete fungi, are essential for decomposition of the phenol-rich organic matter of coniferous forests, but ectomycorrhizal and saprotrophic fungal guilds play contrasting roles and the outcome of their competition is decisive in regulation of soil processes.

Boreal forest are intensely exploited for timber production, and clear-cutting has dramatic impact on fungal communities with downstream effects on soil processes. Forestry often has positive short-term effects on nutrient cycling, and young plantations may sequester large amounts of carbon from the atmosphere. However, in a longer time perspective, reductions in fungal diversity and loss of central mycorrhizal processes may put soil fertility at risk.