Preprints
https://doi.org/10.5194/tc-2016-80
https://doi.org/10.5194/tc-2016-80
30 May 2016
 | 30 May 2016
Status: this preprint was under review for the journal TC but the revision was not accepted.

Response of freeze-thaw processes to experimental warming in the permafrost regions of the central Qinghai-Tibet Plateau

Shengyun Chen, Wenjie Liu, Qian Zhao, Lin Zhao, Qingbai Wu, Xingjie Lu, Shichang Kang, Xiang Qin, Shilong Chen, Jiawen Ren, and Dahe Qin

Abstract. Assessing quantitatively effect of climate warming on freeze/thaw index (FI/TI), soil freeze-thaw processes and active layer thickness (ALT) is still lacking in the permafrost regions of the Qinghai-Tibet Plateau (QTP) until now. Experimental warming was manipulated using open top chambers (OTCs) in alpine swamp meadow and alpine steppe ecosystems in the permafrost regions of the central QTP during 2009–2011. Under OTCs treatment, air temperature (Ta) significantly increased in the daytime and decreased in the nighttime, diurnal and annual Ta range significantly enhanced, and mean annual Ta increased by 1.4 °C. Owing to the experimental warming, mean annual soil temperature at the depths from 5 cm to 40 cm was increased by 0.2 ~ 0.7 °C in alpine swamp meadow and 0.3 ~ 1.5 °C in alpine steppe. Mean annual soil moisture content at 10 cm depth decreased by 1.1 % and 0.8 %, and mean annual soil salinity at 10 cm depth significantly increased by 0.3 g L-1 and 0.1 g L-1 in alpine swamp meadow and alpine steppe, respectively. Further, FI was significantly decreased by 410.7 °C d while TI was significantly increased by 460.7 °C d. Likewise, the onset dates of shallow soil thawing at 5–40 cm depths were advanced by 9 days and 8 days while the onset dates of freezing were delayed by 10 days and 4 days in alpine swamp meadow and alpine steppe, respectively. Moreover, soil frozen days were significantly decreased by 28 days and 16 days, but thawed days were increased by 18 days and 6 days, and frozen-thawed days were significantly increased by 10 days and 10 days in alpine swamp meadow and alpine steppe, respectively. Furthermore, ALT would be significantly increased by ~ 6.9 cm and ~ 19.6 cm in alpine swamp meadow and alpine steppe ecosystems, respectively.

Shengyun Chen, Wenjie Liu, Qian Zhao, Lin Zhao, Qingbai Wu, Xingjie Lu, Shichang Kang, Xiang Qin, Shilong Chen, Jiawen Ren, and Dahe Qin
 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Shengyun Chen, Wenjie Liu, Qian Zhao, Lin Zhao, Qingbai Wu, Xingjie Lu, Shichang Kang, Xiang Qin, Shilong Chen, Jiawen Ren, and Dahe Qin
Shengyun Chen, Wenjie Liu, Qian Zhao, Lin Zhao, Qingbai Wu, Xingjie Lu, Shichang Kang, Xiang Qin, Shilong Chen, Jiawen Ren, and Dahe Qin

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Short summary
Experimental warming was manipulated using open top chambers in alpine grassland ecosystem in the permafrost regions of the Qinghai-Tibet Plateau. The results revealed variations of earlier thawing, later freezing and longer freezing-thawing periods in shallow soil. Further, the estimated permafrost table declined under the warming scenarios. The work will be helpful to evaluate the stability of Qinghai-Tibet Railway/Highway and estimate the release of carbon under the future climate warming.