Status, Changes and Impacts of Permafrost on Qinghai-Tibet Plateau

2020 ◽  
Author(s):  
Lin Zhao ◽  
Guojie Hu ◽  
Defu Zou ◽  
Ren Li ◽  
Yu Sheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Active Layer ◽  
Climate Warming ◽  
Global Climate ◽  
Tibet Plateau ◽  
Active Layer Thickness ◽  
Permafrost Region ◽  
Permafrost Degradation ◽  
Qinghai Tibet Plateau

<p>Due to the climate warming, permafrost on the Qinghai-Tibet Plateau (QTP) was degradating in the past decades. Since its impacts on East Asian monsoon, and even on the global climate system, it is fundamental to reveal permafrost status, changes and its physical processes. Based on previous research results and new observation data, this paper reviews the characteristics of the status of permafrost on the QTP, including the active layer thickness (ALT), the spatial distribution of permafrost, permafrost temperature and thickness, as well as the ground ice and soil carbon storage in permafrost region.</p><p>The results showed that the permafrost and seasonally frozen ground area (excluding glaciers and lakes) is 1.06 million square kilometters and 1.45 million square kilometters on the QTP. The permafrost thickness varies greatly among topography, with the maximum value in mountainous areas, which could be deeper than 200 m, while the minimum value in the flat areas and mountain valleys, which could be less than 60 m. The mean value of active layer thickness is about 2.3 m. Soil temperature at 0~10 cm, 10~40 cm, 40~100 cm, 100~200 cm increased at a rate of 0.439, 0.449, 0.396, and 0.259°C/10a, respectively, from 1980 to 2015. The increasing rate of the soil temperature at the bottom of active layer was 0.486 oC/10a from 2004 to 2018.</p><p>The volume of ground ice contained in permafrost on QTP is estimated up to 1.27×10<sup>4</sup> km<sup>3</sup> (liquid water equivalent). The soil organic carbon staored in the upper 2 m of soils within the permafrost region is about 17 Pg. Most of the research results showed that the permafrost ecosystem is still a carbon sink at the present, but it might be shifted to a carbon source due to the loss of soil organic carbon along with permafrost degradation.</p><p>Overall, the plateau permafrost has undergone remarkable degradation during past decades, which are clearly proven by the increasing ALTs and ground temperature. Most of the permafrost on the QTP belongs to the unstable permafrost, meaning that permafrost over TPQ is very sensitive to climate warming. The permafrost interacts closely with water, soil, greenhouse gases emission and biosphere. Therefore, the permafrost degradation greatly affects the regional hydrology, ecology and even the global climate system.</p>

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

2019 ◽  
Author(s):  
Junfeng Wang ◽  
Qingbai Wu ◽  
Ziqiang Yuan ◽  
Hojeong Kang
Keyword(s):  
Soil Respiration ◽  
Active Layer ◽  
Alpine Meadow ◽  
Water Status ◽  
Tibet Plateau ◽  
Permafrost Region ◽  
Permafrost Degradation ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Qinghai Tibet Plateau

Abstract. Freezing and thawing action of the active layer plays a significant role in soil respiration (Rs) in permafrost regions. However, little is known about how the freeze-thaw process regulates the Rs dynamics in different stages for the alpine meadow underlain by permafrost on the Qinghai-Tibet Plateau (QTP). We conducted continuous in-situ measurements of Rs 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 Rs. We found that the freezing and thawing process of active layer modified the Rs dynamics differently in different freeze-thaw stages. The mean Rs ranged from 0.56 to 1.75 μmol/m2s across the stages, with the lowest value in the SW stage and highest value in the ST stage; and Q10 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 Rs among the ST, AF, WC, and SW stages differed, and the corresponding contribution percentages of cumulative Rs to annual total Rs were 61.54, 8.89, 18.35, and 11.2 %, respectively. Soil temperature (Ts) was the most important driver of Rs 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 Rs emissions from this ecosystem because of prolonged ST stage.

scholarly journals Soil respiration of alpine meadow is controlled by freeze–thaw processes of active layer in the permafrost region of the Qinghai–Tibet Plateau

2020 ◽  
Vol 14 (9) ◽  
pp. 2835-2848
Author(s):  
Junfeng Wang ◽  
Qingbai Wu ◽  
Ziqiang Yuan ◽  
Hojeong Kang
Keyword(s):  
Soil Respiration ◽  
Active Layer ◽  
Alpine Meadow ◽  
Tibet Plateau ◽  
Permafrost Region ◽  
Permafrost Degradation ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Qinghai Tibet Plateau

Abstract. Freezing and thawing action of the active layer plays a significant role in soil respiration (Rs) in permafrost regions. However, little is known about how the freeze–thaw processes affect the Rs dynamics in different stages of the alpine meadow underlain by permafrost in the Qinghai–Tibet Plateau (QTP). We conducted continuous in situ measurements of Rs and freeze–thaw processes of the active layer at an alpine meadow site in the Beiluhe permafrost region of the QTP and divided the freeze–thaw processes into four different stages in a complete freeze–thaw cycle, comprising the summer thawing (ST) stage, autumn freezing (AF) stage, winter cooling (WC) stage, and spring warming (SW) stage. We found that the freeze–thaw processes have various effects on the Rs dynamics in different freeze–thaw stages. The mean Rs ranged from 0.12 to 3.18 µmol m−2 s−1 across the stages, with the lowest value in WC and highest value in ST. Q10 among the different freeze–thaw stages changed greatly, with the maximum (4.91±0.35) in WC and minimum (0.33±0.21) in AF. Patterns of Rs among the ST, AF, WC, and SW stages differed, and the corresponding contribution percentages of cumulative Rs to total Rs of a complete freeze–thaw cycle (1692.98±51.43 g CO2 m−2) were 61.32±0.32 %, 8.89±0.18 %, 18.43±0.11 %, and 11.29±0.11 %, respectively. Soil temperature (Ts) was the most important driver of Rs regardless of soil water status in all stages. Our results suggest that as climate change and permafrost degradation continue, great changes in freeze–thaw process patterns may trigger more Rs emissions from this ecosystem because of a prolonged ST stage.

Profile distributions of soil organic carbon fractions in a permafrost region of the Qinghai–Tibet Plateau

2020 ◽  
Vol 31 (4) ◽  
pp. 538-547 ◽  
Author(s):  
Zi‐Qiang Yuan ◽  
Hui‐Jun Jin ◽  
Qing‐Feng Wang ◽  
Qing‐Bai Wu ◽  
Guo‐Yu Li ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Tibet Plateau ◽  
Permafrost Region ◽  
Carbon Fractions ◽  
Organic Carbon Fractions ◽  
Soil Organic Carbon Fractions ◽  
Qinghai Tibet Plateau

scholarly journals Importance of active layer freeze-thaw cycles on the riverine dissolved carbon export on the Qinghai-Tibet Plateau permafrost region

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7146 ◽  
Author(s):  
Chunlin Song ◽  
Genxu Wang ◽  
Tianxu Mao ◽  
Xiaopeng Chen ◽  
Kewei Huang ◽  
...  
Keyword(s):  
Active Layer ◽  
Carbonic Acid ◽  
Tibet Plateau ◽  
Vegetation Coverage ◽  
Permafrost Region ◽  
Permafrost Degradation ◽  
Carbon Export ◽  
Dissolved Carbon ◽  
Total Runoff ◽  
Qinghai Tibet Plateau

The Qinghai-Tibet Plateau (QTP) is experiencing severe permafrost degradation, which can affect the hydrological and biogeochemical processes. Yet how the permafrost change affects riverine carbon export remains uncertain. Here, we investigated the seasonal variations of dissolved inorganic and organic carbon (DIC and DOC) during flow seasons in a watershed located in the central QTP permafrost region. The results showed that riverine DIC concentrations (27.81 ± 9.75 mg L−1) were much higher than DOC concentrations (6.57 ± 2.24 mg L−1). DIC and DOC fluxes were 3.95 and 0.94 g C m−2 year−1, respectively. DIC concentrations increased from initial thaw (May) to freeze period (October), while DOC concentrations remained relatively steady. Daily dissolved carbon concentrations were more closely correlated with baseflow than that with total runoff. Spatially, average DIC and DOC concentrations were positively correlated with vegetation coverage but negatively correlated with bare land coverage. DIC concentrations increased with the thawed and frozen depths due to increased soil interflow, more thaw-released carbon, more groundwater contribution, and possibly more carbonate weathering by soil CO2 formed carbonic acid. The DIC and DOC fluxes increased with thawed depth and decreased with frozen layer thickness. The seasonality of riverine dissolved carbon export was highly dependent on active layer thawing and freezing processes, which highlights the importance of changing permafrost for riverine carbon export. Future warming in the QTP permafrost region may alter the quantity and mechanisms of riverine carbon export.

scholarly journals ACTIVE LAYER THICKNESS RETRIEVAL OVER THE QINGHAI-TIBET PLATEAU FROM 2000 TO 2020 BASED ON INSAR-MEASURED SUBSIDENCE AND MULTI-LAYER SOIL MOISTURE

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 437-442
Author(s):  
T. Chang ◽  
J. Han ◽  
Z. Li ◽  
Y. Wen ◽  
T. Hao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Layer Thickness ◽  
Active Layer ◽  
Surface Deformation ◽  
Tibet Plateau ◽  
Active Layer Thickness ◽  
Permafrost Region ◽  
Radar Images ◽  
Soil Moisture Data ◽  
Qinghai Tibet Plateau

Abstract. Active layer thickness (ALT) is an important index to reflect the stability of permafrost. The retrieval of ALT based on Interferometric Synthetic Aperture Radar (InSAR) technology has been investigated recently in permafrost research. However, most of such studies are carried out in a limited extend and relatively short temporal coverage. The combination of temporal-spatial multi-layer soil moisture data and multi-temporal InSAR is a promising approach for the large-scale characterization of ALT. In this study, we employed Small Baseline Subset Interferometry (SBAS-InSAR) technology to obtain the seasonal surface deformation from radar images of Envisat and Sentinel-1 in a permafrost region of Qinghai-Tibet Plateau (QTP). We attempt to verify and calibrate the temporal-spatial multi-layer soil moisture product in combination with the in-situ data. Based on the land subsidence data and the temporal-spatial multi-layer soil moisture data, we further improve method to retrieve the ALT information. This paper describes the progress so far and point out the future work.

scholarly journals Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation

2021 ◽  
Vol 118 (25) ◽  
pp. e2025321118
Author(s):  
Ming-Hui Wu ◽  
Sheng-Yun Chen ◽  
Jian-Wei Chen ◽  
Kai Xue ◽  
Shi-Long Chen ◽  
...  
Keyword(s):  
Active Layer ◽  
Tibet Plateau ◽  
Permafrost Degradation ◽  
Soil C ◽  
C Cycling ◽  
Microbial Stability ◽  
The Stability ◽  
Qinghai Tibet Plateau ◽  
Permafrost Regions

Permafrost degradation may induce soil carbon (C) loss, critical for global C cycling, and be mediated by microbes. Despite larger C stored within the active layer of permafrost regions, which are more affected by warming, and the critical roles of Qinghai-Tibet Plateau in C cycling, most previous studies focused on the permafrost layer and in high-latitude areas. We demonstrate in situ that permafrost degradation alters the diversity and potentially decreases the stability of active layer microbial communities. These changes are associated with soil C loss and potentially a positive C feedback. This study provides insights into microbial-mediated mechanisms responsible for C loss within the active layer in degraded permafrost, aiding in the modeling of C emission under future scenarios.

scholarly journals Estimation of Soil Organic Carbon Storage in Palustrine Wetlands, China

2020 ◽  
Vol 17 (13) ◽  
pp. 4646
Author(s):  
Lu Han ◽  
Zhongmei Wan ◽  
Yuedong Guo ◽  
Changchun Song ◽  
Shaofei Jin ◽  
...  
Keyword(s):  
Data Collection ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Measurement Data ◽  
Carbon Stocks ◽  
Tibet Plateau ◽  
Accurate Estimation ◽  
Organic Carbon Content ◽  
Actual Measurement ◽  
Qinghai Tibet Plateau

Wetlands regulate the balance of global organic carbon. Small changes in the carbon stocks of wetland ecosystem play a crucial role in the regional soil carbon cycle. However, an accurate estimation of carbon stocks is still be debated for China’s wetlands ecosystem due to the limitation of data collection and methodology. Here, we investigate the soil organic carbon (SOC) storage in a 1-m depth in China’s palustrine wetlands. A total of 1383 sample data were collected from palustrine wetlands in China. The data sources are divided into three parts, respectively, data collection from published literature, data from books, and actual measurement data of sample points. The results demonstrate that there is considerable SOC storage in China’s palustrine wetlands (9.945 Pg C), primarily abundant in the northeast, northwest arid and semi-arid as well as Qinghai-Tibet Plateau regions. The SOC density in per unit area soil was higher in the wetland area of northeast, southwest and Qinghai-Tibet plateau. Within China terrestrial scale, the temperature and precipitation differences caused by latitude were the main environmental factors affecting the organic carbon content. Furthermore, except for the southeast and south wetland region, SOC content decreased with depth.

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