Effects of warming, grazing/cutting and nitrogen fertilization on greenhouse gas fluxes during growing seasons in an alpine meadow on the Tibetan Plateau

Zhu, Xiaoxue; Luo, Caiyun; Wang, Shiping; Zhang, Zhenhua; Cui, Shujuan; Bao, Xiaoyu; Jiang, Lili; Li, Yaoming; Li, Xine; Wang, Qi; Zhou, Yang

doi:10.1016/j.agrformet.2015.09.008

Cited by 100 publications

(49 citation statements)

References 85 publications

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“…Our results show that warming resulted in an increase in NEE in the alpine meadow on the Qinghai–Tibetan Plateau in 2012 and 2014. This is consistent with previous results for alpine meadows on the plateau (Hu et al., ; Peng et al., ; Zhu et al., ). However, we found that warming had no significant effect on NEE in 2013.…”

Section: Discussionsupporting

confidence: 94%

“…Moreover, the chamber method used to measure C flux cannot fully represent the natural C flux because of chamber had changed gas exchange. Nevertheless, above‐mentioned methods are acceptable in view of the fact that warming chamber (Klein, Harte, & Zhao, ; Walker et al., ) and chamber method measuring C flux (Chivers, Turetsky, Waddington, Harden, & Mcguire, ; Jiang et al., ; Zhu et al., ) have been widely used in grassland ecosystems. At last, we have relatively small database because of we cannot conduct continuous measurement for C flux in chamber warming method.…”

Section: Discussionmentioning

confidence: 99%

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Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Ganjurjav

Wan

et al. 2017

Ecology and Evolution

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Climate is a driver of terrestrial ecosystem carbon exchange, which is an important product of ecosystem function. The Qinghai–Tibetan Plateau has recently been subjected to a marked increase in temperature as a consequence of global warming. To explore the effects of warming on carbon exchange in grassland ecosystems, we conducted a whole‐year warming experiment between 2012 and 2014 using open‐top chambers placed in an alpine meadow, an alpine steppe, and a cultivated grassland on the central Qinghai–Tibetan Plateau. We measured the gross primary productivity, net ecosystem CO 2 exchange (NEE), ecosystem respiration, and soil respiration using a chamber‐based method during the growing season. The results show that after 3 years of warming, there was significant stimulation of carbon assimilation and emission in the alpine meadow, but both these processes declined in the alpine steppe and the cultivated grassland. Under warming conditions, the soil water content was more important in stimulating ecosystem carbon exchange in the meadow and cultivated grassland than was soil temperature. In the steppe, the soil temperature was negatively correlated with ecosystem carbon exchange. We found that the ambient soil water content was significantly correlated with the magnitude of warming‐induced change in NEE. Under high soil moisture condition, warming has a significant positive effect on NEE, while it has a negative effect under low soil moisture condition. Our results highlight that the NEE in steppe and cultivated grassland have negative responses to warming; after reclamation, the natural meadow would subject to loose more C in warmer condition. Therefore, under future warmer condition, the overextension of cultivated grassland should be avoided and scientific planning of cultivated grassland should be achieved.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Ganjurjav

Wan

et al. 2017

Ecology and Evolution

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“…Repeated ANOVA measurements are in the supporting information; N 2 O flux is shown in Figure S4. However, the N 2 O flux of both control and warming conditions was low, showing a 2 year average of 203 μg m −2 d −1 and 37 μg m −2 d −1 during the thawing period for warming and control, respectively, in agreement with evidence from the Tibetan alpine grassland [ Wei et al ., ; Zhu et al ., ]. However, compared to N accumulation (225 g N m −2 in top 60 cm) under warming, the increase in N 2 O flux under warming was quite small.…”

Section: Discussionmentioning

confidence: 99%

Experimental warming increased soil nitrogen sink in the Tibetan permafrost

Chang

Wang

Yang

et al. 2017

J. Geophys. Res. Biogeosci.

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In permafrost soil, warming regulates the nitrogen (N) cycle either by stimulating N transformation or by enhancing cryoturbation, the mixture of soil layers due to repeated freeze thaw. Here N isotopic values (δ15N) of plants and the soil were investigated in a 7 year warming experiment in a permafrost‐affected alpine meadow on the Qinghai‐Tibetan Plateau. The results revealed that warming significantly decreased the δ15N in the plant (aboveground and belowground parts) and different soil fractions (clay and silt fraction, aggregate, and bulk soil). The decreased soil δ15N was associated with an increase in soil N stock due to greater N fixation. The incremental N retention in plants and soil mineral‐associated fractions from warming resulted in a decrease in soil inorganic N, which constrains the role of nitrification/denitrification in soil δ15N, suggesting a restrained rather than an open N cycle. Furthermore, enhanced cryoturbation under warming, identified by a downward redistribution of 137Cs into deeper layers, promoted N protection from transformation. Overall, the decrease in soil δ15N indicated higher rates of N input through fixation relative to N loss through nitrification and denitrification in permafrost‐affected ecosystems under warming conditions.

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“…With the assembled data sets presently available, we were not able to pinpoint the soil microbial mechanisms underlying positive temperature effects on N 2 O emission at a global scale (Figure 4) (Waghmode et al, 2018). Additionally, enhanced plant growth with increased temperature may increase inorganic nitrogen uptake by the plants, thereby reducing soil nitrogen availability for N 2 O production through nitrification and denitrification (Carter et al, 2012;Dijkstra et al, 2012Dijkstra et al, , 2013Pereira et al, 2013;Zhu et al, 2015). In some cases, plants prioritize aboveground growth in the face of increased temperature while reducing belowground carbon supply (Dieleman et al, 2012), which may limit denitrifier proliferation and thus N 2 O emissions.…”

Section: N 2 O Emission Stimulated By Increased Temperaturementioning

confidence: 99%

Terrestrial N₂O emissions and related functional genes under climate change: A global meta‐analysis

Zheng

Wang

et al. 2019

Global Change Biology

151

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Nitrous oxide (N2O) emissions from soil contribute to global warming and are in turn substantially affected by climate change. However, climate change impacts on N2O production across terrestrial ecosystems remain poorly understood. Here, we synthesized 46 published studies of N2O fluxes and relevant soil functional genes (SFGs, that is, archaeal amoA, bacterial amoA, nosZ, narG, nirK and nirS) to assess their responses to increased temperature, increased or decreased precipitation amounts, and prolonged drought (no change in total precipitation but increase in precipitation intervals) in terrestrial ecosystem (i.e. grasslands, forests, shrublands, tundra and croplands). Across the data set, temperature increased N2O emissions by 33%. However, the effects were highly variable across biomes, with strongest temperature responses in shrublands, variable responses in forests and negative responses in tundra. The warming methods employed also influenced the effects of temperature on N2O emissions (most effectively induced by open‐top chambers). Whole‐day or whole‐year warming treatment significantly enhanced N2O emissions, but daytime, nighttime or short‐season warming did not have significant effects. Regardless of biome, treatment method and season, increased precipitation promoted N2O emission by an average of 55%, while decreased precipitation suppressed N2O emission by 31%, predominantly driven by changes in soil moisture. The effect size of precipitation changes on nirS and nosZ showed a U‐shape relationship with soil moisture; further insight into biotic mechanisms underlying N2O emission response to climate change remain limited by data availability, underlying a need for studies that report SFG. Our findings indicate that climate change substantially affects N2O emission and highlights the urgent need to incorporate this strong feedback into most climate models for convincing projection of future climate change.

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Effects of warming, grazing/cutting and nitrogen fertilization on greenhouse gas fluxes during growing seasons in an alpine meadow on the Tibetan Plateau

Cited by 100 publications

References 85 publications

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Experimental warming increased soil nitrogen sink in the Tibetan permafrost

Terrestrial N₂O emissions and related functional genes under climate change: A global meta‐analysis

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Effects of warming, grazing/cutting and nitrogen fertilization on greenhouse gas fluxes during growing seasons in an alpine meadow on the Tibetan Plateau

Cited by 100 publications

References 85 publications

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Different responses of ecosystem carbon exchange to warming in three types of alpine grassland on the central Qinghai–Tibetan Plateau

Experimental warming increased soil nitrogen sink in the Tibetan permafrost

Terrestrial N2O emissions and related functional genes under climate change: A global meta‐analysis

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Product

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Terrestrial N₂O emissions and related functional genes under climate change: A global meta‐analysis