Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 1: Effect of sheep grazing

Gong, Yanming; Mohammat, Anwar; Liu, X. J.; Li, K. H.; Christie, Peter; Fang, F.; Song, Wei; Chang, Yaxuan; Han, Wenxuan; Lu, Xiaoming; Liu, Y. Y.; Hu, Yukun

doi:10.5194/bg-11-1743-2014

Cited by 11 publications

(3 citation statements)

References 40 publications

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“…To our knowledge, no previous study examined the different components of ER in response to the N addition gradient. Some studies conducted in alpine grassland demonstrated that N addition had no significant effects on ER (Jiang et al, 2013;Gong et al, 2014), since aboveground biomass did not respond to N addition in their studies. In this study, compared to the control treatment (without N addition), greater plant growth and aboveground biomass under N addition enhanced aboveground plant respiration and thus stimulated ER.…”

Section: Diverse Responses Of C Flux Components To the N Addition Gramentioning

confidence: 90%

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

et al. 2017

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Abstract. Increases in nitrogen (N) deposition can greatly stimulate ecosystem net carbon (C) sequestration through positive N-induced effects on plant productivity. However, how net ecosystem CO 2 exchange (NEE) and its components respond to different N addition rates remains unclear. Using an N addition gradient experiment (six levels: 0, 2, 4, 8, 16, 32 gN m −2 yr −1 ) in an alpine meadow on the Qinghai-Tibetan Plateau, we explored the responses of different ecosystem C fluxes to an N addition gradient and revealed mechanisms underlying the dynamic responses. Results showed that NEE, ecosystem respiration (ER), and gross ecosystem production (GEP) all increased linearly with N addition rates in the first year of treatment but shifted to N saturation responses in the second year with the highest NEE (−7.77 ± 0.48 µmol m −2 s −1 ) occurring under an N addition rate of 8 gN m −2 yr −1 . The saturation responses of NEE and GEP were caused by N-induced accumulation of standing litter, which limited light availability for plant growth under high N addition. The saturation response of ER was mainly due to an N-induced saturation response of aboveground plant respiration and decreasing soil microbial respiration along the N addition gradient, while decreases in soil microbial respiration under high N addition were caused by N-induced reductions in soil pH. We also found that various components of ER, including aboveground plant respiration, soil respiration, root respiration, and microbial respiration, responded differentially to the N addition gradient. These results reveal temporal dynamics of N impacts and the rapid shift in ecosystem C fluxes from N limitation to N saturation. Our findings bring evidence of short-term initial shifts in responses of ecosystem C fluxes to increases in N deposition, which should be considered when predicting long-term changes in ecosystem net C sequestration.

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Section: Diverse Responses Of C Flux Components To the N Addition Gramentioning

confidence: 90%

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

et al. 2017

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“…CC-BY 3.0 License. conducted in alpine grassland demonstrated that N addition had no significant effects on ER (Jiang et al, 2013;Gong et al, 2014), since aboveground biomass did not respond to N addition in their studies. In this study, greater plant growth and aboveground biomass under N addition enhanced aboveground plant respiration and then stimulated ER.…”

Section: Diverse Responses Of C Flux Components To N Addition Gradientmentioning

confidence: 94%

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

Song¹

2016

Preprint

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Abstract. The rising nitrogen (N) deposition could increase ecosystem net carbon (C) sequestration by stimulating plant productivity. However, how net ecosystem CO2 exchange (NEE) and its components respond dynamically to rising N deposition is far from clear. Using an N addition gradient experiment (six levels: 0, 2, 4, 8, 16, 32 gN m&#8722;2 year&#8722;1) in an alpine meadow on the Tibetan Plateau, we explored the responses of different ecosystem C fluxes to an increasing N loading gradient and revealed mechanisms underlying the dynamic responses. Results showed that NEE, ecosystem respiration (ER), and gross ecosystem production (GEP) all increased linearly with N addition rates in the first year of treatment, but shifted to N saturation responses in the second year with the highest NEE (&#8722;7.77 &#177; 0.48 &#181;mol m&#8722;2 s&#8722;1) occurring under N addition rate of 8 gN m&#8722;2 year&#8722;1. The saturation responses of NEE and GEP were caused by N-induced accumulation of standing litter, which limited light availability for plant growth, under high N addition. The saturation response of ER was mainly due to decreases in aboveground plant respiration and soil microbial respiration under high N addition, while the N-induced reduction in soil pH caused declines in soil microbial respiration. We also found that various components of ER, including aboveground plant respiration, soil respiration, root respiration, and microbial respiration, responded differentially to the N addition gradient. The results reveal temporal dynamics of N impacts and the rapid shift of ecosystem C cycle from N limitation to N saturation. These findings are helpful for better understanding and model projection of future terrestrial C sequestration under rising N deposition.

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“…In the third approach, the emissions of CO 2 or other gases are measured at targeted locations or times (Manley et al, 1995;Petersen et al, 1998;Cao et al, 2004;Parkin and Venterea, 2010;Gong et al, 2014). The collection of gas samples has been used to assess the fate of both N and C in a wide range of systems (Omonode et al, 2015;Chang et al, 2016a).…”

Section: A Rapid Methods For Measuring Feces Ammonia-nitrogen and Carbonmentioning

confidence: 99%

A Rapid Method for Measuring Feces Ammonia‐Nitrogen and Carbon Dioxide‐Carbon Emissions and Decomposition Rate Constants

Chang

Clay

et al. 2017

Agronomy Journal

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A rapid approach is needed for determining the eff ectiveness of precision conservation on soil health as evaluated using CO 2 and NH 3 emissions. Th is study demonstrated an approach for calculating CO 2 -C and NH 3 -N emissions and associated rate constants when feces were applied to bare soil or soil + vegetation. In addition, point CO 2 -C emission measurements were compared with near continuous measurements. Th e CO 2 -C emissions were measured at 2 h intervals over 20 d, whereas ammonia volatilization was measured three times daily for 7 d. Total ) showed that temperature and NH 3 -N and CO 2 -C emissions followed diurnal cycles and that they were in-phase with each other. Over 7 d, 20% of feces NH 4 -N was volatilized and that this loss was similar when feces were applied over vegetation or mixed into the soil. Feces additions increased the amplitude of the CO 2 -C diurnal cycle, and the fecal-C fi rst-order rate degradation constants were higher when mixed with soil [0.0109 ± 0.0043 g(g×d) -1 , p = 0.1] than applied over vegetation [0.00454 ± 0.00336 g(g×d) -1 , p = 0.1].

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Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 1: Effect of sheep grazing

Cited by 11 publications

References 40 publications

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

Initial shifts in nitrogen impact on ecosystem carbon fluxes in an alpine meadow: patterns and causes

A Rapid Method for Measuring Feces Ammonia‐Nitrogen and Carbon Dioxide‐Carbon Emissions and Decomposition Rate Constants

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