Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland

Zhu, Cheng; Ma, Yuling; Wu, Honghui; Sun, Tao; Pierre, Kimberly J. La; Sun, Zewei; Yu, Qiang

doi:10.1038/srep33541

Cited by 46 publications

(43 citation statements)

References 43 publications

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“…Similarly, net ecosystem CO 2 exchange (NEE) and its components of gross ecosystem production (GEP) and ecosystem respiration (ER) may also respond nonlinearly to increasing N loading rates (Fleischer et al, 2013;Gomez-Casanovas et al, 2016;Tian et al, 2016). In the N-limited stage, low rates of N addition could stimulate ecosystem productivity (Aber et al, 1989), GEP (Fleischer et al, 2013;Gomez-Casanovas et al, 2016), and ER (Hasselquist et al, 2012;Zhu et al, 2016), while in the N saturation stage, high doses of N addition could have negative effects on GEP and ER (Treseder, 2008;Janssens et al, 2010;Maaroufi et al, 2015). The unbalanced responses of GEP and ER may lead to changes in NEE.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…Other studies have shown that the effects of N fertilizer application on CO 2 , CH 4 , and N 2 O emission are dependent on the form of N (Cai et al 2007;Peng et al 2011). Differences in soil structure and climate conditions between study sites may also have an effect, with the range of responses varying from no effect at all to positive or negative effects depending on ecosystem type, age, dominant plant species and soil chemical characteristics (Pregitzer et al 2008;Rodriguez et al 2014;Xiao 2017;Zhu et al 2016a), N loads in the soil in combination with climatic conditions (Alster et al 2013), and experiment duration (Zhou et al 2014). Grazing exclusion significantly decreased annual average CO 2 emission (Table 2) in our study.…”

Section: Ghg Fluxesmentioning

confidence: 98%

CO2, CH4 and N2O fluxes in an alpine meadow on the Tibetan Plateau as affected by N-addition and grazing exclusion

Luo

Wang

Zhang

et al. 2020

Nutr Cycl Agroecosyst

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Limited understanding of the effects of enhanced nitrogen (N) addition and grazing exclusion (E) on greenhouse gases fluxes (GHGs: CO 2 , CH 4 , and N 2 O) in grasslands constrains our ability to respond to the challenges of future climate change. In this study, we conducted a field experiment using a static closed opaque chamber to investigate the response of GHG fluxes to N addition (69 kg N ha-1 year-1 applied in 3 splits) and grazing exclusion in an alpine meadow on the Tibetan Plateau during the growing seasons from 2011 to 2013. Our results showed that winter grazing significantly raised soil temperature (ST), while grazing exclusion (E) had no effect on soil moisture (SM), and N fertilizer (F) had no effect on ST or SM. Aboveground biomass (AB) and root biomass (RB) were not significantly affected by E in 2011-2013 (p [ 0.05), but F significantly affected AB and RB (p \ 0.05). Compared with winter grazing, only E substantially reduced seasonal mean CO 2 emissions (by about 20.1%) during the experimental period. E did not significantly directly affect CH 4 uptake, whereas N addition reduced seasonal mean CH 4 uptake by about 6.5%, and N addition changed seasonal average absorption of N 2 O into an emission source. CO 2 flux is the major contributor to CO 2 equivalent emissions in this area. Our results indicate that exclosure from livestock grazing might be a promising measure to reduce CO 2 emissions, while enhanced N addition might reduce CH 4 uptake and increase N 2 O emission in the alpine meadow under future climate change.

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“…Soil moisture is an important determinant for altering soil respiration, especially under climate warming [146] . N addition either increased or decreased soil respiration, and such effects strongly depend on N level [147] .…”

Section: Responses Of Nutrient Cyclingmentioning

confidence: 98%

Grassland ecology in China: perspectives and challenges

Wang

Liu

et al. 2018

Front. Agr. Sci. Eng.

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During the last few decades, there have been an increasing number of studies on grassland ecology in China, involving the classic ecology concepts or theories and the applicable ecological principles of grassland conservation or management. This paper reviews the main progress in the following aspects. (1) Research on grassland species adaptation and resistance, population dynamics and foraging behavior, and biodiversity and community stability. (2) Research on managed grassland ecosystems (grassland grazing ecology) including grazing effects on grassland ecosystem function and foraging behavior by large herbivores. (3) Global climate change and grassland processes and functioning. (4) Applied research on grassland restoration and ecosystem health assessments such as vegetation restoration, restoration of ecosystem functioning, and assessment methods. There have been significant advances in grassland ecology, including the functions of ecosystem biodiversity, the ecological stoichiometry mechanisms affecting grassland community stability, grazing regulation of plant diversity and nutrient cycling. Grassland ecologists have succeeded in making these advances through observational, experimental and theoretical studies. Nevertheless, there are still significant challenges for the grassland ecology research, including understanding of grassland spatial processes, grassland grazing and multi-functionality, integrated effects of global climate change across grassland areas, as well as the ecological methodology and experimental techniques in grassland ecology.

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Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland

Cited by 46 publications

References 43 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

CO2, CH4 and N2O fluxes in an alpine meadow on the Tibetan Plateau as affected by N-addition and grazing exclusion

Grassland ecology in China: perspectives and challenges

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