| Title | Microbial metabolic responses and CO2 emissions differentiated by soil water content variation in subarctic tundra soils |
|---|---|
| Author | Dockyu Kim1*, Namyi Chae2, Mincheol Kim1, Sungjin Nam1, Tai Kyoung Kim1, Ki-Tea Park3, Bang Yong Lee3, Eungbin Kim4, and Hyoungseok Lee1 |
| Address | 1Division of Life Sciences, Korea Polar Research Institute, Incheon 21990, Republic of Korea, 2Institutes of Life Sciences and Natural Resources, Korea University, Seoul 02841, Republic of Korea, 3Division of Atmospheric Sciences, Korea Polar Research Institute, Incheon 21990, Republic of Korea, 4Department of Systems Biology, Yonsei University, Seoul 03722, Republic of Korea |
| Bibliography | Journal of Microbiology, 60(12),1130-1138, 2022, |
| DOI | 10.1007/s12275-022-2378-3 |
| Key Words | Arctic tundra soil, CO2 emission, global warming, microbial decomposition, soil organic matter |
| Abstract | Recent rapid air temperature increases across the northernlatitude tundra have prolonged permafrost thawing and snow melting periods, resulting in increased soil temperature (Ts) and volumetric soil water content (SWC). Under prolonged soil warming at 8°C, Alaskan tundra soils were incubated in a microcosm system and examined for the SWC differential influence on the microbial decomposition activity of large molecular weight (MW) humic substances (HS). When one microcosm soil (AKC1-1) was incubated at a constant SWC of 41% for 90 days (T = 90) and then SWC was gradually decreased from 41% to 29% for another T = 90, the initial HS was partly depolymerized. In contrast, in AKC1-2 incubated at a gradually decreasing SWC from the initial 32% to 10% for T = 90 and then increasing to 27% for another T = 90, HS depolymerization was undetected. Overall, the microbial communities in AKC1-1 could maintain metabolic activity at sufficient and constant SWC during the initial T = 90 incubation. In contrast, AKC1-2 microbes may have been damaged by drought stress during the drying SWC regimen, possibly resulting in the loss of HS decomposition activity, which did not recover even after re-wetting to an optimal SWC range (20–40%). After T = 90, the CO2 production in both treatments was attributed to the increased decomposition of small-MW organic compounds (including aerobic HS-degradative products) within an optimal SWC range. We expect this study to provide new insights into the early effects of warming- and topography-induced SWC variations on the microbial contribution to CO2 emissions via HS decomposition in northern-latitude tundra soil. |