Realistic rates of nitrogen addition increase carbon flux rates but do not change soil carbon stocks in a temperate grassland

Wilcots, Megan E.; Schroeder, Katie; DeLancey, Lang C.; Kjaer, Savannah J.; Hobbie, Sarah E.; Seabloom, Eric W.; Borer, Elizabeth T.

doi:10.1111/gcb.16272

Cited by 24 publications

(19 citation statements)

References 108 publications

(164 reference statements)

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“…Elevated CO 2 generally stimulates plant growth and vegetation productivity, at least in the absence of strong nutrient limitation (Ainsworth & Long, 2005; de Graaff et al, 2006; Norby et al, 2010), but the increase in plant biomass does not always lead to soil C stock accumulation (van Groenigen et al, 2014), which is contingent on the trade‐off between plant biomass and soil C storage (Terrer et al, 2021). Other global change factors such as N addition and altered precipitation likewise profoundly affect the C pools and fluxes (Liu & Greaver, 2010; Lu et al, 2021; Nielsen & Ball, 2015; Wilcots et al, 2022; Wu et al, 2011; Zheng et al, 2022). These multiple global changes influence the C and nutrient cycling to a greater or lesser extent through soil microorganisms.…”

Section: Introductionmentioning

confidence: 99%

Microbial necromass under global change and implications for soil organic matter

Tie

et al. 2023

Global Change Biology

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Microbial necromass is an important source and component of soil organic matter (SOM), especially within the most stable pools. Global change factors such as anthropogenic nitrogen (N), phosphorus (P), and potassium (K) inputs, climate warming, elevated atmospheric carbon dioxide (eCO 2 ), and periodic precipitation reduction (drought) strongly affect soil microorganisms and consequently, influence microbial necromass formation. The impacts of these global change factors on microbial necromass are poorly understood despite their critical role in the cycling and sequestration of soil carbon (C) and nutrients. Here, we conducted a meta-analysis to reveal general patterns of the effects of nutrient addition, warming, eCO 2 , and drought on amino sugars (biomarkers of microbial necromass) in soils under croplands, forests, and grasslands. Nitrogen addition combined with P and K increased the content of fungal (+21%), bacterial (+22%), and total amino sugars (+9%), consequently leading to increased SOM formation. Nitrogen addition alone increased solely bacterial necromass (+10%) because the decrease of N limitation stimulated bacterial more than fungal growth. Warming increased bacterial necromass, because bacteria have competitive advantages at high temperatures compared to fungi. Other global change factors (P and NP addition, eCO 2 , and drought) had minor effects on microbial necromass because of: (i) compensation of the impacts by opposite processes, and (ii) the short duration of experiments compared to the slow microbial necromass turnover. Future studies should focus on: (i) the stronger response of bacterial necromass to N addition and warming compared to that of fungi, and (ii) the increased microbial necromass contribution to SOM accumulation and stability under NPK fertilization, and thereby for negative feedback to climate warming.

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Section: Introductionmentioning

confidence: 99%

Microbial necromass under global change and implications for soil organic matter

Tie

et al. 2023

Global Change Biology

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“…The effects of low-N addition (5 g m −2 yr −1 ) on most optical and molecular characteristics of soil DOM were inconsistent with those of medium-and high-N addition (10 and 15 g m −2 yr −1 ), indicating that N addition rate was an important moderator. A recent study also reported that realistic rates of N addition differently influence soil C flux rates and C stocks (Wiclots et al 2022). The reason for no significant effects of low-N addition on these characteristics of soil DOM might be associated with no change in soil acidification status and SOC pool under low-N addition.…”

Section: Discussionmentioning

confidence: 93%

“…Alterations in molecular-level information with N addition were probably due to N-induced differences in both soil properties and microbial activities as compared to control plots (Averill and Waring 2018, Li et al 2019, Wiclots et al 2022.…”

Section: Discussionmentioning

confidence: 99%

Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?

Niu

Yin

et al. 2022

Environ. Res. Lett.

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Dissolved organic matter (DOM) plays a key role in forest carbon biogeochemistry by linking soil organic carbon (SOC) sequestration and water fluxes, which is further shaped by elevated atmospheric nitrogen (N) deposition. Although enhanced SOC sequestration was evidenced in tropical forests due to rising N deposition, it remains unclear how long-term N inputs affect soil DOM composition, which regulates SOC sequestration capability due to its mobility and biological instability. Here, the quantity, optical properties, and molecular-level characteristics of soil DOM based on a simulative N deposition experiment with four N addition levels (0, 5, 10, and 15 g m−2 yr−1) were studied in a primary tropical forest in south China. Results showed that 18-year N additions significantly altered soil DOM composition, with an increasing trend in soil dissolved organic carbon content. Medium- (10 g m−2 yr−1) and high-N addition (15 g m−2 yr−1) markedly elevated DOM average molecular weight by 12% and aromaticity, with specific ultraviolet absorbance at 254 nm increasing by 17%, modified aromatic index by 35%, and condensed aromatics by 67%. Medium- and high-N addition also increased recalcitrant DOM components but decreased other DOM components, with increasing percentages of lignin-like, tannin-like, and carboxylic-rich alicyclic molecule-like compounds, and decreasing percentage of more bioavailable contributions with H/C ratio > 1.5. Importantly, significant correlations of the SOC content of the heavy fraction with optical properties and with recalcitrant DOM components were observed. These findings suggest that long-term N additions may alter soil DOM composition in a way to benefit soil OC storage in the primary tropical forests. It merits focusing on the mechanisms to association of soil DOM dynamics with SOC sequestration.

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Section: Seasonal Variation In Nutrient and Consumer Impacts On C Flu...mentioning

confidence: 97%

“…were not changed by nitrogen addition alone (Harpole et al, 2007;Wilcots et al, 2022). Harpole et al (2007) and Wilcots et al (2022) only added nitrogen while we added nitrogen, phosphorus, potassium and micronutrients. The contrasting results between our work and these previous studies for both NEE and above-ground biomass suggest nutrient colimitation not only for plant productivity but also for ecosystem C fluxes (Fay et al, 2015;Harpole et al, 2011).…”

Section: Seasonal Variation In Nutrient and Consumer Impacts On C Flu...mentioning

confidence: 97%

Soil nutrients cause threefold increase in pathogen and herbivore impacts on grassland plant biomass

et al. 2023

Self Cite

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Grasslands play a critical role in the global carbon (C) cycle, covering a quarter of the Earth's land surface and contributing up to 20% to the total terrestrial C sink (Xia et al., 2014). As with most ecosystems, C accumulation in grasslands reflects the balance and seasonal variation of C inputs via photosynthesis (gross primary production, GPP) and C emissions from respiration by microbes, plants and animals (ecosystem respiration, ER). Observational studies and field experiments manipulating food webs have shown that plant consumers

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Realistic rates of nitrogen addition increase carbon flux rates but do not change soil carbon stocks in a temperate grassland

Cited by 24 publications

References 108 publications

Microbial necromass under global change and implications for soil organic matter

Microbial necromass under global change and implications for soil organic matter

Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?

Soil nutrients cause threefold increase in pathogen and herbivore impacts on grassland plant biomass

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