Soil Microbial Respiration in Subtaiga and Forest-Steppe Ecosystems of 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 (MRfield) and laboratory (MRlab) conditions monthly (from May to October) in subtaiga (mixed forest, meadow) and forest-steppe (broad-leaved forest, virgin steppe) ecosystems of the European Russia. The MRfield was determined through soil respiration partitioning by the conventional substrate-induced respiration method. The MRlab was measured as basal respiration of 10 cm topsoil at 22°C and 60% water holding capacity. The contribution of MRfield to total soil respiration varied during the growing season from 25 to 82% for subtaiga and from 41 to 88% for forest-steppe. The MRfield for studied ecosystems varied from 2.2 to 21.7 g СО2/(m2 d), while MRlab was from 3.5 to 18.6 g СО2/(m2 d). Similar results obtained by field and laboratory approaches were in 50% of measurements in the subtaiga ecosystems and in almost 20% of cases on the forest-steppe. The average MRfield and MRlab 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 MRfield for various ecosystems.