Climate warming alters subsoil but not topsoil carbon dynamics in alpine grassland

Jia, Juan; Cao, Zhenjiao; Liu, Chengzhu; Zhang, Zhenhua; Li, Lin; Wang, Yiyun; Haghipour, Negar; Wacker, Lukas; Bao, Hongyan; Dittmar, Thorsten; Simpson, Myrna J.; Yang, Huan; Crowther, Thomas W.; Eglinton, Timothy I.; He, Jin‐Sheng; Feng, Xiaojuan

doi:10.1111/gcb.14823

Cited by 121 publications

(79 citation statements)

References 51 publications

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“…Manipulation experiments simulating climate change commonly apply uniform warming treatments (Jia et al, 2019; Ma et al, 2018), but this does not allow the potential ecological impacts of the differential seasonal warming observed in high‐latitude areas to be determined. To disentangle the processes caused by the observed temperature increases at different times of year on the Tibetan Plateau, a specific winter warming treatment was imposed in addition to a year‐round warming treatment that would allow the identification and isolation of physical (soil aggregate size), chemical (labile and stable organic carbon pools), and biological (community structure and carbon degradation genes) processes specifically related to winter warming in this study.…”

Section: Introductionmentioning

confidence: 99%

Microbial metabolic response to winter warming stabilizes soil carbon

Tian

Zong

Hartley

et al. 2021

Global Change Biology

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Current consensus on global climate change predicts warming trends with more pronounced temperature changes in winter than summer in the Northern Hemisphere at high latitudes. Moderate increases in soil temperature are generally related to faster rates of soil organic carbon (SOC) decomposition in Northern ecosystems, but there is evidence that SOC stocks have remained remarkably stable or even increased on the Tibetan Plateau under these conditions. This intriguing observation points to altered soil microbial mediation of carbon‐cycling feedbacks in this region that might be related to seasonal warming. This study investigated the unexplained SOC stabilization observed on the Tibetan Plateau by quantifying microbial responses to experimental seasonal warming in a typical alpine meadow. Ecosystem respiration was reduced by 17%–38% under winter warming compared with year‐round warming or no warming and coincided with decreased abundances of fungi and functional genes that control labile and stable organic carbon decomposition. Compared with year‐round warming, winter warming slowed macroaggregate turnover rates by 1.6 times, increased fine intra‐aggregate particulate organic matter content by 75%, and increased carbon stabilized in microaggregates within stable macroaggregates by 56%. Larger bacterial “necromass” (amino sugars) concentrations in soil under winter warming coincided with a 12% increase in carboxyl‐C. These results indicate the enhanced physical preservation of SOC under winter warming and emphasize the role of soil microorganisms in aggregate life cycles. In summary, the divergent responses of SOC persistence in soils exposed to winter warming compared to year‐round warming are explained by the slowing of microbial decomposition but increasing physical protection of microbially derived organic compounds. Consequently, the soil microbial response to winter warming on the Tibetan Plateau may cause negative feedbacks to global climate change and should be considered in Earth system models.

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Section: Introductionmentioning

confidence: 99%

Microbial metabolic response to winter warming stabilizes soil carbon

Tian

Zong

Hartley

et al. 2021

Global Change Biology

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“…The impact of grazing on soil C may differ with depth because the amount of below‐ground biomass may also vary with depth (Schuman et al, 1999) and also because different layers of the soil profile are affected to varying extent by environmental conditions (Jia et al., 2019). As mentioned earlier, the effect of grazing on soil C has been examined extensively for the surface horizon, with most studies reporting a decrease in soil C, especially under high grazing intensity (Sun et al., 2011; Zhang et al., 2018; Zhou et al., 2017).…”

Section: Introductionmentioning

confidence: 99%

Light grazing facilitates carbon accumulation in subsoil in Chinese grasslands: A meta‐analysis

Jiang

Lai

et al. 2020

Global Change Biology

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Grazing by livestock greatly affects the soil carbon (C) cycle in grassland ecosystems. However, the effects of grazing at different intensities and durations on the dynamics of soil C in its subsoil layers are not clearly understood. Here, we compiled data from 78 sites (in total 122 published studies) to examine the effects of varying grazing intensities and durations on soil C content at different depths for grasslands in China.

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“…Up to now, some studies have examined the responses of SOC stocks to experimental warming on the Tibetan Plateau, however, previous studies mainly concentrated on the absolute SOC content and labile SOC fractions, such as microbial biomass and dissolved organic C (Luo et al, 2009;Yu, Shen, Zhang, Sun, & Fu, 2014;Zhou et al, 2013). As a consequence, experimental evidence about warming effects on SOM molecular composition is still limited (Guan et al, 2018;Jia et al, 2019). Particularly, no study has yet addressed warming-induced changes in SOM molecular composition and the associated mechanisms across Tibetan permafrost ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Warming alters surface soil organic matter composition despite unchanged carbon stocks in a Tibetan permafrost ecosystem

Peng

Chen

et al. 2019

Functional Ecology

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Climate warming can alter ecosystem carbon (C) balance and also the composition of soil organic matter (SOM), with important local and global implications. However, the extent to which rising temperature affects SOM composition in permafrost ecosystems remains poorly understood. Here, we experimentally warmed a permafrost ecosystem by open‐top chambers (OTCs) on the Tibetan Plateau for 4 years to quantify the responses of C inputs via vegetation production, C losses via soil respiration and soil organic carbon (SOC) stocks in the top 30 cm. We also characterized the molecular composition of SOM using 13C nuclear magnetic resonance (NMR) and biomarker analyses. The results indicated that warming treatment significantly increased root biomass, soil respiration, heterotrophic respiration and its contribution to soil respiration by 16.7%, 49.0%, 63.2% and 9.5% respectively. While we observed no change in SOC stocks, warming altered SOM composition in the 0–10 cm layer during the fourth experimental year. Warming increased the abundance of the alkyl C component (3.9%) and decreased aromatic C (5.1%), primarily lignin. The decrease in lignin‐derived compounds was attributable to the increased soil phenol oxidase activity. Overall, the substantial increase in heterotrophic respiration and rapid degradation of relatively recalcitrant C components such as lignin demonstrate that Tibetan SOC stocks are vulnerable to climate warming, which could trigger positive C–climate feedback in a warmer world. A free Plain Language Summary can be found within the Supporting Information of this article.

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Climate warming alters subsoil but not topsoil carbon dynamics in alpine grassland

Cited by 121 publications

References 51 publications

Microbial metabolic response to winter warming stabilizes soil carbon

Microbial metabolic response to winter warming stabilizes soil carbon

Light grazing facilitates carbon accumulation in subsoil in Chinese grasslands: A meta‐analysis

Warming alters surface soil organic matter composition despite unchanged carbon stocks in a Tibetan permafrost ecosystem

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