Soil microbial biomass, respiration rate, and temperature dependence on a successional glacier foreland in Ny-Ålesund, Svalbard

We examined soil microbial activities, i.e., biomass, respiration rate, and temperature dependence of the respiration on a glacier foreland in Ny-Ålesund, Svalbard, Norway. We collected soil samples from 4 study sites that were set up along a primary succession (Site 1, the youngest, to Site 4, the oldest). Microbial biomass measured with the SIR method increased with successional age (55 to 724μg C_biomass g^-1 soil d.w. from Site 1 to Site 4). The microbial respiration rate of the soil was measured in a laboratory with an open-flow infrared gas-analyzer system, changing the temperature from 2° to 20°C at 3-4° intervals. The microbial respiration rate increased exponentially with the temperature at all sites. The temperature dependence (Q₁₀) of the microbial respiration rate ranged from 2.2 to 4.1. The microbial respiration rates at a given temperature increased with succession as a step change (0.48, 0.43, 1.26, and 1.29μg C g^-1soil h^-1 at 8°C from Site 1 to Site 4, respectively). However, the substrate-specific respiration rate (respiration rate per gram soil carbon) decreased with successional age (0.034 to 0.006μg C mg^-1C_soil h^-1 from Site 1 to Site 4). A comparison of these respiratory properties with other ecosystems suggested that soil microorganisms in arctic soils have a high potential for decomposition when compared to those of other temperate ecosystems.