Anna Knoltsch

TL;DR: It is found that microbes retain most immobilized organic N when they are N limited, resulting in low N mineralization, however, when the metabolic control of microbial decomposers switches from N to C limitation, they release an increasing fraction of organic N as ammonium (low NUE).

TL;DR: In this paper, the authors compared gross rates of protein depolymerization, ammonium (N mineralization), and nitrification in seven ecosystems along a latitudinal transect in western Siberia, from tundra to steppe (54°N).

TL;DR: It is found that hydrolytic enzyme activities decreased rapidly with depth, whereas oxidative enzyme activities in mineral horizons were as high as, or higher than in organic topsoil horizons, which suggests that SOM chemistry, spatial separation or physical stabilization of SOM rather than SOM content might determine substrate availability for enzymatic breakdown.

TL;DR: Investigating soils from three regions in the Siberian Arctic, where carbon rich topsoil material has been incorporated into the subsoil (cryoturbation), found that microbial community composition, was similar in cryoturbated material and in surrounding subsoils, although carbon and nitrogen contents were similar in Cryoturbate material and topsoils.

TL;DR: In this paper, the authors provide mechanistic insights into the susceptibility of soil organic matter decomposition in arctic permafrost soils to priming and find that an increased availability of plant-derived organic C particularly stimulated decomposition.