Warming and drought increase but wetness reduces the net sink of CH4 in alpine meadow on the Tibetan Plateau

Zhang, Zhenhua; Wang, Guangshuai; Wang, Hao; Qi, Qi; Yang, Yunfeng; He, Jin‐Sheng

doi:10.1016/j.apsoil.2021.104061

Cited by 16 publications

(23 citation statements)

References 34 publications

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“…We found much higher warming‐induced CH 4 uptake in the cold season when the control plots were experiencing F–T cycle, which resulted in significant increases in the net CH 4 uptake during the cold season for both warming treatments and at the annual scale for the high‐level warming. This finding agreed with Lin et al (2015) and Zhang et al (2021), who also reported a stronger warming effect on CH 4 uptake during the cold season. However, warming‐induced increases in CH 4 uptake during the cold season in our study were much greater (72%–270% vs. 49%–62%) than the previous studies (Lin et al, 2015; Zhang et al, 2021), especially for the high‐level warming.…”

Section: Discussionsupporting

confidence: 93%

“…During the cold season when soils of the control were experiencing freeze-thaw cycles, increased CH 4 uptake under warming was mainly driven by soil temperature and soil water content. This suggest that the neglection of soil F-T stages might be the reason for the conflicting results of factors controlling the warming impacts on CH 4 uptake in studies of Chen et al (2017a) and Zhang et al (2021) in the alpine meadow. Another study also illustrated that the dominant roles of soil temperature and soil water content on CH 4 fluxes varied with soil freezing and thawing dynamics in an alpine steppe (Yun et al, 2018).…”

Section: Soil Chemical and Microbial Controls On Annual Ch 4 Uptakementioning

confidence: 99%

“…However, previous studies have reported conflicting findings on the factors controlling warming impacts on CH 4 uptake in different seasons (Chen et al, 2017a;Lin et al, 2015;Zhang et al, 2021). For instance, Chen et al (2017a) measured CH 4 uptake from spring thaw to autumn freeze and reported that soil temperature dominated CH 4 uptake during the entire study period, while Zhang et al (2021) reported that warming-induced increase in CH 4 uptake was strongly correlated with soil temperature during the nongrowing season but controlled by soil moisture in the growing season. But even here, the controlling factors of warming effects on CH 4 uptake during different stages of the F-T cycle were rarely studied to date, and the mechanisms underlying the impacts of warming on CH 4 uptake in the entire F-T cycle are still highly uncertain.…”

Section: Introductionmentioning

confidence: 99%

“…Soil moisture and temperature have been widely reported as the main factors that determine warming effects on CH 4 uptake in alpine grasslands (Li et al, 2020; Lin et al, 2015; Zhang et al, 2021). Specifically, methanotrophs are highly temperature sensitive (Conrad, 2007), such that the rate at which they consume CH 4 increases with temperature rise.…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, methanotrophs are highly temperature sensitive (Conrad, 2007), such that the rate at which they consume CH 4 increases with temperature rise. Moreover, warming enhances evapotranspiration, which leads to a drier and more aerated soil system with greater diffusivity and more substrates (O 2 and CH 4 ) that may promote the methanotroph abundance and change the structure of methanotrophs (Dijkstra et al, 2011; Li et al, 2020; Zhang et al, 2021; Zheng et al, 2012). However, previous studies have reported conflicting findings on the factors controlling warming impacts on CH 4 uptake in different seasons (Chen et al, 2017a; Lin et al, 2015; Zhang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Increased annual methane uptake driven by warmer winters in an alpine meadow

Wang

Elberling

et al. 2022

Global Change Biology

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Pronounced nongrowing season warming and changes in soil freeze-thaw (F-T) cycles can dramatically alter net methane (CH 4 ) exchange rates between soils and the atmosphere. However, the magnitudes and drivers of warming impacts on CH 4 uptake in different stages of the F-T cycle are poorly understood in cold alpine ecosystems, which have been found to be a net sink of atmospheric CH 4 . Here, we reported a year-round ecosystem daily CH 4 uptake in an alpine meadow on the Qinghai-Tibetan Plateau after a 5-year warming experiment that included a control, a low-level warming treatment (+2.4℃ at 5 cm soil depth), and a high-level warming treatment (+4.5℃ at 5 cm soil depth). We found that warming shortened the F-T cycle under the lowlevel warming and soils did not freeze under the high-level warming. Although both warming treatments increased the mean CH 4 uptake rate, only the high-level warming significantly increased annual CH 4 uptake compared to the control. The warminginduced stimulation of CH 4 uptake mainly occurred in the cold season, which was mostly during spring thaw under low-level warming and during the frozen winter under high-level warming due to a longer period with thawed soil. We also found that warming significantly stimulated daily CH 4 uptake mainly by reducing near-surface soil water content in the warm season, whereas both soil water content and temperature controlled daily CH 4 uptake in different ways during the autumn freeze, frozen winter, and spring thaw periods of the control. Our study revealed a strong warming effect on CH 4 uptake during the entire F-T cycle in the alpine meadow, especially the unfrozen winter. Our results also suggested the important roles of soil pH, available phosphorus, and methanotroph abundance in regulating annual CH 4 uptake in response to warming, which should be incorporated into biogeochemical models for accurately forecasting CH 4 fluxes under future climate scenarios.

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