ForBioFunCtioN: Forest soil carbon and the effects of climate change and forest management

Boreal forests are among the most carbon (C) rich forest types in the world and store up to 80% of its total C in the soil. Forest soil C development under climate change has received increased scientific attention yet large uncertainties remain, not least in terms of magnitude and direction of soil C responses. As with climate change, large uncertainties remain in terms of the effects of forest management on soil C sequestration and storage. Nonetheless, it is clear that forest management measures can have far reaching effects on ecosystem functioning and soil conditions. For example, clear cutting is a widely undertaken felling method in Scandinavia which profoundly affects the forest ecosystem and its functioning, including the soil. Nitrogen (N) fertilization is another common practice in Scandinavia which, despite uncertainties regarding effects on soil C dynamics, is being promoted as a climate change mitigation tool. A more novel practice of biochar addition to soils has been shown to have positive effects on soil conditions, including soil C storage, but studies on biochar in the context of forests are few.

In the face of climate change, the ForBioFunCtioN project is dedicated to investigating the response of boreal forest soil CO₂ and CH₄ fluxes to experimentally increased temperatures and increased precipitation – climatic changes in line with projections over Norway – within a forest management context. The experiment is set in a Norwegian spruce-dominated bilberry chronosequence, including a clear-cut site, a middle-aged thinned stand, a mature stand and an old unmanaged stand. Warming, simulated increased precipitation, N fertilizer and biochar additions will be applied on experimental plots in an additive manner that allows for disentangling the effects of individual parameters from interaction effects. Flux measurements will be undertaken at high temporal resolution using the state-of-the-art LI-7810 Trace Gas Analyzer (©LI-COR Biosciences). The presentation will show the experimental setup and first measurements from the large-scale experiment.