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

CATENA ◽  
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

scholarly journals Nitrogen fertilizer regulates soil respiration by altering the organic carbon storage in root and topsoil in alpine meadow of the north-eastern Qinghai-Tibet Plateau

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Wen Li ◽  
Jinlan Wang ◽  
Xiaolong Li ◽  
Shilin Wang ◽  
Wenhui Liu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Tibetan Plateau ◽  
Soil Respiration ◽  
Alpine Meadow ◽  
Growing Season ◽  
N Storage ◽  
The North ◽  
C Storage ◽  
North Eastern ◽  
C And N

Abstract Soil respiration (Rs) plays a critical role in the global carbon (C) balance, especially in the context of globally increasing nitrogen (N) deposition. However, how N-addition influences C cycle remains unclear. Here, we applied seven levels of N application (0 (N0), 54 (N1), 90 (N2), 126 (N3), 144 (N4), 180 (N5) and 216 kg N ha−1 yr−1 (N6)) to quantify their impacts on Rs and its components (autotrophic respiration (Ra) and heterotrophic respiration (Rh)) and C and N storage in vegetation and soil in alpine meadow on the northeast margin of the Qinghai-Tibetan Plateau. We used a structural equation model (SEM) to explore the relative contributions of C and N storage, soil temperature and soil moisture and their direct and indirect pathways in regulating soil respiration. Our results revealed that the Rs, Ra and Rh, C and N storage in plant, root and soil (0–10 cm and 10–20 cm) all showed initial increases and then tended to decrease at the threshold level of 180 kg N ha−1 yr−1. The SEM results indicated that soil temperature had a greater impact on Rs than did volumetric soil moisture. Moreover, SEM also showed that C storage (in root, 0–10 and 10–20 cm soil layers) was the most important factor driving Rs. Furthermore, multiple linear regression model showed that the combined root C storage, 0–10 cm and 10–20 cm soil layer C storage explained 97.4–97.6% variations in Rs; explained 94.5–96% variations in Ra; and explained 96.3–98.1% in Rh. Therefore, the growing season soil respiration and its components can be well predicted by the organic C storage in root and topsoil in alpine meadow of the north-eastern Qinghai-Tibetan Plateau. Our study reveals the importance of topsoil and root C storage in driving growing season Rs in alpine meadow on the northeast margin of Qinghai-Tibetan Plateau.

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.

Long-term grazing exclusion greatly improve carbon and nitrogen store in an alpine meadow on the northern Qinghai-Tibet Plateau

CATENA ◽  
2021 ◽  
Vol 197 ◽  
pp. 104955
Author(s):  
Licong Dai ◽  
Ruiyu Fu ◽  
Xiaowei Guo ◽  
Yangong Du ◽  
Li Lin ◽  
...  
Keyword(s):  
Alpine Meadow ◽  
Tibet Plateau ◽  
Carbon And Nitrogen ◽  
Grazing Exclusion ◽  
Qinghai Tibet Plateau

scholarly journals Effects of rodent-induced land degradation on ecosytem carbon fluxes in alpine meadow in the Qinghai–Tibet Plateau, China

2014 ◽  
Vol 6 (2) ◽  
pp. 3003-3023 ◽  
Author(s):  
F. Peng ◽  
Y. Quangang ◽  
X. Xue ◽  
J. Guo ◽  
T. Wang
Keyword(s):  
Soil Respiration ◽  
Land Degradation ◽  
Alpine Meadow ◽  
Net Ecosystem Exchange ◽  
Growing Season ◽  
Tibet Plateau ◽  
Organic C ◽  
Soil C ◽  
Significant Difference ◽  
Qinghai Tibet Plateau

Abstract. Land degradation induced by rodent activities is extensively occurred in alpine meadow ecosystem in the Qinghai–Tibet Plateau that would affect the ecosystem carbon (C) balance. We conducted a field experiment with six levels of land degradation (D1–D6, degradation aggravates from D1 to D6) to investigate the effects of land degradation on ecosystem C fluxes. Soil respiration (Rs), net ecosystem exchange (NEE), ecosystem respiration (ER) and gross ecosystem production (GEP) were measured from June to September 2012. Soil respiration, ER, GEP and above-ground biomass (AGB) was significantly higher in slightly degraded (D3 and D6) than in severely degraded land (D1, D2, D4 and D5). Positive averages of NEE in the growing season indicate that alpine meadow ecosystem is a weak C sink during the growing season. Net ecosystem exchange had no significant difference among different degraded levels, but the average NEE in slightly degraded group was 33.6% higher than in severely degraded group. Soil respiration, ER and NEE were positively correlated with AGB whereas soil organic C, labile soil C, total nitrogen (N) and inorganic nitrogen were associated with root biomass (RB). Our results highlight the decline of vegetation C storage of alpine meadow ecosystem with increasing number of rodent holes and suggest the control of AGB on ecosystem C fluxes, and the control of RB on soil C and N with development of land degradation.

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