Evidence item

Here we test the prevalence of functional limitations and how introducing active layer microorganisms can mitigate these across four widespread permafrost soil types. We measure the production of CO2, CH4, N2O, nitrate and ammonium content, bacterial community composition and genes controlling nitrogen cycling. By restoring functions with a diverse microbial community from a temperate grassland, we demonstrate widespread functional limitations in permafrost soils, as CO2 and N2O emissions increased across permafrost types over 389 days. However, realistic active layer inocula increased CO2 or N2O production less than observed with the diverse microbial community, and not systematically, due to unsuccessful coalescence or limitations in the inoculating soil communities themselves.