Dominance of temperature over organic matter composition and mineral protection in priming effect regulation

Le résumé fourni par la source

Consensus is emerging that the turnover of native soil organic matter (SOM) through the priming effect (PE) can be controlled by plant, soil and climate variables. Here, we apply a systematic approach to the quantitative assessment of the relative importance of plant C input quality, SOM persistence and temperature in regulating PE. We conducted a unique laboratory microcosm experiment comparing OM fractions originating from the topsoil and subsoil of a Central European temperate mixed forest incubated at two different temperatures, simulating the effects of climate warming. We repeatedly added 13 C-labelled deciduous or coniferous leaf leachates or root exudates and determined PE. Our study emphasizes the critical role of temperature in regulating PE, with warming generally leading to reduced SOM turnover via PE and thus enhancing C storage in soils. Further, our results indicate the importance of OM composition together with mineral protection for PE regulation. Moreover, our findings challenge contemporary concepts that see mineral-associated OM as a stable SOM pool, and provide proof that at least a part of this pool is available with increased temperature. Our results thus provide new perspectives for future modelling and management efforts, and these may help promote enhanced SOM accumulation under future climate scenarios.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.