Freeze-thaw processes of active layer regulate soil respiration of alpine meadow in the permafrost region of the Qinghai-Tibet Plateau

• Main Authors: Wang, Junfeng, Wu, Qingbai, Yuan, Ziqiang, Kang, Hojeong
• Format: Text
• Language: English
• Published: 2019
• Subjects: permafrost
• Online Access: https://doi.org/10.5194/tc-2019-214; https://tc.copernicus.org/preprints/tc-2019-214/

Freezing and thawing action of the active layer plays a significant role in soil respiration ( R s ) in permafrost regions. However, little is known about how the freeze-thaw process regulates the R s dynamics in different stages for the alpine meadow underlain by permafrost on the Qinghai-Tibet Plateau (QTP). We conducted continuous in-situ measurements of R s and freeze-thaw process of the active layer at an alpine meadow site in the Beiluhe permafrost region of QTP to determine the regulatory mechanisms of the different freeze-thaw stages of the active layer on the R s . We found that the freezing and thawing process of active layer modified the R s dynamics differently in different freeze-thaw stages. The mean R s ranged from 0.56 to 1.75 μmol/m 2 s across the stages, with the lowest value in the SW stage and highest value in the ST stage; and Q 10 among the different freeze-thaw stages changed greatly, with maximum (4.9) in the WC stage and minimum (1.7) in the SW stage. Patterns of R s among the ST, AF, WC, and SW stages differed, and the corresponding contribution percentages of cumulative R s to annual total R s were 61.54, 8.89, 18.35, and 11.2 %, respectively. Soil temperature ( T s ) was the most important driver of R s regardless of soil water status in all stages. Our results suggest that as the climate warming and permafrost degradation continue, great changes in freeze-thaw process patterns may trigger more R s emissions from this ecosystem because of prolonged ST stage.