StoiCa · Resilience of Soil Stoichiometry in subartic soils under Temperature-Induced Soil Carbon Losses: Where does the N go?

Resilience of Soil Stoichiometry in subartic soils under Temperature-Induced Soil Carbon Losses: Where does the N go?

Global warming can trigger enormous releases of carbon (C) from soils, with positive feedbacks to climate change. Northern high latitude soils can constitute a major contributor to this positive feedback loop. Climate change predictions are however still largely uncertain, partly due the lack of accurate representation of vegetation and soil microbial feedbacks and C and nitrogen (N) interactions. Warming enhances microbial mineralization of soil organic matter (SOM) (i.e. soil C outputs) to a higher degree than vegetation productivity (i.e. soil C inputs), resulting in large C losses from northern soils. Pioneer results point to proportional N losses in response to warming, which may be the key to this phenomenon. StoiCa combined the expertise of a multidisciplinary group of leading researchers on ecosystem stoichiometry and stable N isotopic methods with the existence of unique and established research sites in geothermal systems in Iceland to reveal the fate of N lost in response to warming, and uncover the mechanisms behind observed soil C losses. This project directly addresses two cross-cutting priorities of sustainable development and climate action from the H2020 Work Programme and it also represented an exceptional opportunity for the candidate to acquire essential skills that positioned her as a highly competitive European researcher in climate change biogeochemistry. StoiCa`s findings suggest a strong control of microbial physiology and C:N stoichiometric needs on the retention of soil N and on the resilience of soil C stocks from high-latitudes to warming, particularly during periods of vegetation dormancy and low C inputs. In mineral soils, soil microbes are predominantly C limited (Soong et al. 2019), microbial N mineralization predominates to N immobilization and microbes rather use DON as a C source, releasing mineral N as a byproduct. This has crucial implications for the responses of mineral soils of high latitudes to warming, where most of the N release is in asynchrony with plant N uptake. Warming may therefore cause an opening of the N cycle in these ecosystems, diminishing their capacity to sustain levels of vegetation biomass and productivity with consequent cascade effects on plant C inputs to the soil (Marañón-Jimenez et al. in prep). These results may imply that high latitude mineral soils are much more vulnerable to warming induces C losses than has been predicted by ecosystem models and that their contribution to positive climate change feedbacks may have been underestimated.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз