Soil Microbial Respiration of Sub-Taiga and Forest-Steppe Ecosystemsin European Russia: Field and Laboratory Approaches
Our study focuses on testing laboratory measurements of soil microbial respiration as a proxy that in the field conditions. The soil microbial respiration was measured in field (MR<sub>field</sub>) and laboratory (MR<sub>lab</sub>) conditions monthly (from May to October) in sub-taiga (mixed forest, meadow) and forest-steppe (broad-leaved forest, virgin steppe) ecosystems of the European Russia. The MR<sub>field</sub> was determined through soil respiration partitioning by the conventional substrate-induced respiration method. The MR<sub>lab</sub> was measured as basal respiration of 10 cm topsoil at 22°C and 60% water holding capacity. The contribution of MR<sub>field</sub> to total soil respiration varied during the growing season from 25 to 82% for sub-taiga and from 41 to 88% for forest-steppe. The MR<sub>field</sub> for studied ecosystems varied from 2.2 to 21.7 g СО<sub>2</sub>/(m<sup>2</sup> d), while MR<sub>lab</sub> was from 3.5 to 18.6 g СО<sub>2</sub>/(m<sup>2</sup> d). Similar results obtained by field and laboratory approaches were in 50% of measurements in the sub-taiga ecosystems and in almost 20% of cases on the forest-steppe. The average MR<sub>field</sub> and MR<sub>lab</sub> for growing season did not significantly differ for all studied ecosystems. These findings demonstrate possible prospects of using laboratory measurement of soil microbial respiration during the growing season to approximate and predict average MR<sub>field</sub> for various ecosystems.