Study on Soil Respiration Characteristics and Carbon Balance of &lt;i&gt;Kobresia pygmaea&lt;/i&gt; Meadow in Qinghai-Tibet Plateau, China

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.

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

The Cryosphere ◽

10.5194/tc-14-2835-2020 ◽

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.

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Effects of grazing exclusion on soil respiration components in an alpine meadow on the north-eastern Qinghai-Tibet Plateau

CATENA ◽

10.1016/j.catena.2020.104750 ◽

2020 ◽

Vol 194 ◽

pp. 104750

Author(s):

Jinlan Wang ◽

Yuzhen Liu ◽

Wenxia Cao ◽

Wen Li ◽

Xiaojun Wang ◽

...

Keyword(s):

Soil Respiration ◽

Alpine Meadow ◽

Tibet Plateau ◽

Grazing Exclusion ◽

The North ◽

North Eastern ◽

Qinghai Tibet Plateau

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Carbon Balance of Grasslands on the Qinghai-Tibet Plateau under Future Climate Change: A Review

Sustainability ◽

10.3390/su12020533 ◽

2020 ◽

Vol 12 (2) ◽

pp. 533

Author(s):

Rong Leng ◽

Quanzhi Yuan ◽

Yushuang Wang ◽

Qian Kuang ◽

Ping Ren

Keyword(s):

Climate Change ◽

Carbon Balance ◽

Future Climate ◽

Tibet Plateau ◽

Future Climate Change ◽

Balance Study ◽

Model Projection ◽

Climatic Environment ◽

The Future ◽

Qinghai Tibet Plateau

Climate change has brought significant impacts upon the natural ecological environment and human social development. The future carbon balance study has become an important part of research on the impacts of climate change. The Qinghai-Tibet Plateau (QTP) is a key area for studying climate change. Grassland, as a typical ecosystem of the QTP, embodies the sensitivity of the plateau to the climatic environment, so the carbon balance of grassland under future climate change conditions is important for studying global change. This paper reviewed the literature on carbon balance projection of grassland on the QTP under climate change. Two types of research methods were used to analyze and discuss the studies’ results, including experimental scenario projection and model projection. The experiment projected that appropriate temperature and moisture could enhance the carbon sink capacity of a grassland ecosystem, where moisture played a leading role. The model projection results showed that the carbon balance under different spatial and temporal scales were different. Although both can project the carbon balance of the study area, there are still some uncertainties. In addition, this research area should also consider the influence of human activity and plateau pikas to more accurately project the future carbon balance.

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