["Foster, A","Jones, D. L","Cooper, E. J","Roberts, P"]2016-12-01期刊论文
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Warmer winters in Arctic regions may melt insulating snow cover and subject soils to more freeze-thaw cycles. The effect of freeze-thaw cycles on the microbial use of low molecular weight, dissolved organic carbon (LMW-DOC) is poorly understood. In this study, soils from the Arctic heath tundra, Arctic meadow tundra and a temperate grassland were frozen to -7.5 A degrees C and thawed once and three times. Subsequently, the mineralisation of 3 LMW-DOC substrates types (sugars, amino acids and peptides) was measured over an 8-day period and compared to controls which had not been frozen. This allowed the comparison of freeze-thaw effects between Arctic and temperate soil and between different substrates. The results showed that freeze-thaw cycles had no significant effect on C mineralisation in the Arctic tundra soils. In contrast, for the same intensity freeze-thaw cycles, a significant effect on C mineralisation was observed for all substrate types in the temperate soil although the response was substrate specific. Peptide and amino acid mineralisation were similarly affected by FT, whilst glucose had a different response. Further work is required to fully understand microbial use of LMW-DOC after freeze-thaw, yet these results suggest that relatively short freeze-thaw cycles have little effect on microbial use of LMW-DOC in Arctic tundra soils after thaw.
