Short term changes of microbial processes in Icelandic soils to increasing temperatures

[摘要] Temperature change is acknowledged to have a significant effect on soilbiological processes and the corresponding sequestration of carbon andcycling of nutrients. Soils at high latitudes are likely to be particularlyimpacted by increases in temperature. Icelandic soils experience unusuallyfrequent freeze and thaw cycles compare to other Arctic regions, which areincreasing due to a warming climate. As a consequence these soils arefrequently affected by short term temperature fluctuations.

In this study, the short term response of a range of soil microbialparameters (respiration, nutrient availability, microbial biomass carbon,arylphosphatase and dehydrogenase activity) to temperature changes wasmeasured in sub-arctic soils collected from across Iceland. Sample sitesreflected two soil temperature regimes (cryic and frigid) and two land uses(pasture and arable). The soils were sampled from the field frozen,equilibrated at −20 °C and then incubated for two weeks at −10 °C,−2 °C, +2 °C and +10 °. Respiration and enzymatic activity weretemperature dependent. The soil temperature regime affected the soilmicrobial biomass carbon sensitivity to temperatures. When soils wheresampled from the cryic temperature regime a decreasing soil microbialbiomass was detected when temperatures rose above the freezing point. Frigidsoils, sampled from milder climatic conditions, where unaffected bydifference in temperatures. Nitrogen mineralisation did not change withtemperature. At −10 °C, dissolved organic carbon accounted for 88% ofthe fraction of labile carbon which was significantly greater than thatrecorded at +10 °C when dissolved organic carbon accounted for as low as42% of the labile carbon fraction.

[学科分类] 地球化学与岩石