Heterotrophic and Autotrophic Components of Soil Respiration in Russian Subtaiga and Forest-steppe Zones Measured by Substrate-induced Respiration Technique

Quantifying response of the soil heterotrophic and autotrophic respiration (RH and RA) to environmental changes is necessary to improve the carbon cycle models of terrestrial ecosystems. Using substrate-induced respiration (SIR) technique, we separated soil respiration (RS) into RH and RA components in subtaiga (mixed forest, meadow) and forest-steppe (broad-leaved forest, steppe) ecosystems of European Russia during the growing season of 2015 (May–October). The RH and RA rates varied 35–200 and 19–534 mg C m–2 h–1 for the subtaiga, 29–216 and 10–227 mg C m–2 h–1 for the forest-steppe. In both vegetation zones, the season average RH was the dominant component of RS in the forests (60–79%), while its contribution in the grasslands was close to 50%. Both RH and RA variations in the forest-steppe ecosystems were better predicted by soil temperature than in the subtaiga ones (R2 = 0.89 vs. R2 = 0.09–0.61). The RA component for the growing season generally exhibited a higher temperature sensitivity than RH. Soil water content significantly affected either RH or RA of the forests, while this relation was not found in the grasslands. The SIR technique showed the RH and RA contributions into RS, the values of which coincide with those of other studies. Using this technique for the dry soil might result in the overestimation of RH and RA. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022.