Microbial respiration activities of soils from different climatic regions of European Russia

The aim of this study was to survey and evaluate the microbial respiration of main soil types (gleyic Cryosols, umbric Albeluvisols, albic Luvisols, luvic Chemozems, Kastanozems) across European Russia, from semiarid to polar climatic zones. Soil was sampled from 0-5 and 5-10 cm layers at natural (forest, grassland, fallow) and corresponding sites under agricultural land use. Soil microbial biomass carbon (C-mic) determined by the substrate-induced respiration method and basal respiration (BR) were measured under standardized laboratory conditions (22 degrees C, 60% WHC). The ratios of BR/C-mic and C-mic/C-org were also calculated. C-mic and BR were highest in polar (gleyic Cryosols) and temperate (albic Luvisols, luvic Chemozems) climatic zones, the lowest were in boreal (umbric Luvisols) and semiarid (Kastanozems). Cmic, BR and C-mic/C-org ratios were higher in 0-5 cm layers compared to the corresponding 5-10 cm and in natural sites versus in arable. Principal component analysis yielded a clear separation of the vegetation zones with respect to the several principal components (PC). PC1 was composed of C-mic BR, soil chemical (C-org, N-tot) and texture parameters. PC2 was composed of climatic (MAT, MAP) and soil pH variables. Three-way ANOVA indicated that soil type, ecosystem and layer factors, and their interactions accounted for almost 98 and 99% of the total variance in C-mic and BR, respectively. (c) 2007 Published by Elsevier Masson SAS.