Decoupling of Carbon and Nitrogen Under Elevated CO2 in a Typical Alpine Ecosystem

Abstract Aims: Vegetation in high-altitude regions is hypothesized to be more responsive to increasing atmospheric CO2 concentrations due to low CO2 partial pressure. However, this hypothesis and the underlying mechanisms driving this response at an ecosystem scale are poorly understood. We aimed to exploring the biomass allocation and plant carbon-nitrogen relationships in response to elevated CO2 in a Tibet meadow.Methods: Here, a 5-year manipulation experiment was conducted in an alpine meadow (4585 m above sea level) to explore the responses of plant carbon (C), nitrogen (N) and biomass dynamics, as well as their allocation schemes, to elevated CO2 and N fertilization.Results: Elevated CO2 alone significantly enhanced aboveground plant biomass by 98.03 %, exhibiting a stronger CO2 fertilization effect than the global average level (20 %) for grasslands. In contrast to the belowground parts, elevated CO2 caused disproportionally aboveground tissues increment in association with C and N accumulation. These results suggest a potential C limitation for plant growth in alpine ecosystems. N fertilization alleviates the N constraints on CO2 fertilization effects, which strengthened C sequestration capacity for the aboveground plant tissues. Moreover, our results indicate a decoupling between C and N cycles in alpine ecosystems in the face of elevated CO2, especially in the N-enrichment environments.Conclusions: Overall, this study shows a high sensitivity of aboveground plant biomass and decoupled C-N relationships under elevated CO2 for high-elevation alpine ecosystems, highlighting the need to incorporate altitude effects into Earth System Models in predicting C cycle feedback to climate changes.

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Elucidating the Possible Involvement of Maize Aquaporins and Arbuscular Mycorrhizal Symbiosis in the Plant Ammonium and Urea Transport under Drought Stress Conditions

Plants ◽

10.3390/plants9020148 ◽

2020 ◽

Vol 9 (2) ◽

pp. 148 ◽

Cited By ~ 3

Author(s):

Gabriela Quiroga ◽

Gorka Erice ◽

Ricardo Aroca ◽

Antonio Delgado-Huertas ◽

Juan Manuel Ruiz-Lozano

Keyword(s):

Drought Stress ◽

Arbuscular Mycorrhizae ◽

Plant Biomass ◽

Net Photosynthesis ◽

N Fertilization ◽

Stress Conditions ◽

Mycorrhizal Symbiosis ◽

In Planta ◽

N Accumulation ◽

Am Symbiosis

This study investigates the possible involvement of maize aquaporins which are regulated by arbuscular mycorrhizae (AM) in the transport in planta of ammonium and/or urea under well-watered and drought stress conditions. The study also aims to better understand the implication of the AM symbiosis in the uptake of urea and ammonium and its effect on plant physiology and performance under drought stress conditions. AM and non-AM maize plants were cultivated under three levels of urea or ammonium fertilization (0, 3 µM or 10 mM) and subjected or not to drought stress. Plant aquaporins and physiological responses to these treatments were analyzed. AM increased plant biomass in absence of N fertilization or under low urea/ ammonium fertilization, but no effect of the AM symbiosis was observed under high N supply. This effect was associated with reduced oxidative damage to lipids and increased N accumulation in plant tissues. High N fertilization with either ammonium or urea enhanced net photosynthesis (AN) and stomatal conductance (gs) in plants maintained under well-watered conditions, but 14 days after drought stress imposition these parameters declined in AM plants fertilized with high N doses. The aquaporin ZmTIP1;1 was up-regulated by both urea and ammonium and could be transporting these two N forms in planta. The differential regulation of ZmTIP4;1 and ZmPIP2;4 with urea fertilization and of ZmPIP2;4 with NH4+ supply suggests that these two aquaporins may also play a role in N mobilization in planta. At the same time, these aquaporins were also differentially regulated by the AM symbiosis, suggesting a possible role in the AM-mediated plant N homeostasis that deserves future studies.

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Decadal and long-term boreal soil carbon and nitrogen sequestration rates across a variety of ecosystems

Biogeosciences ◽

10.5194/bg-13-4315-2016 ◽

2016 ◽

Vol 13 (15) ◽

pp. 4315-4327 ◽

Cited By ~ 5

Author(s):

Kristen L. Manies ◽

Jennifer W. Harden ◽

Christopher C. Fuller ◽

Merritt R. Turetsky

Keyword(s):

Black Spruce ◽

Spruce Forest ◽

Accumulation Rates ◽

N Accumulation ◽

Soil C ◽

Rich Fen ◽

C Cycle ◽

C And N ◽

The Rich

Abstract. Boreal soils play a critical role in the global carbon (C) cycle; therefore, it is important to understand the mechanisms that control soil C accumulation and loss for this region. Examining C & nitrogen (N) accumulation rates over decades to centuries may provide additional understanding of the dominant mechanisms for their storage, which can be masked by seasonal and interannual variability when investigated over the short term. We examined longer-term accumulation rates, using 210Pb and 14C to date soil layers, for a wide variety of boreal ecosystems: a black spruce forest, a shrub ecosystem, a tussock grass ecosystem, a sedge-dominated ecosystem, and a rich fen. All ecosystems had similar decadal C accumulation rates, averaging 84 ± 42 gC m−2 yr−1. Long-term (century) C accumulation rates were slower than decadal rates, averaging 14 ± 5 gC m−2 yr−1 for all ecosystems except the rich fen, for which the long-term C accumulation rates was more similar to decadal rates (44 ± 5 and 76 ± 9 gC m−2 yr−1, respectively). The rich fen also had the highest long-term N accumulation rates (2.7 gN m−2 yr−1). The lowest N accumulation rate, on both a decadal and long-term basis, was found in the black spruce forest (0.2 and 1.4 gN m−2 yr−1, respectively). Our results suggest that the controls on long-term C and N cycling at the rich fen is fundamentally different from the other ecosystems, likely due to differences in the predominant drivers of nutrient cycling (oxygen availability, for C) and reduced amounts of disturbance by fire (for C and N). This result implies that most shifts in ecosystem vegetation across the boreal region, driven by either climate or succession, will not significantly impact regional C or N dynamics over years to decades. However, ecosystem transitions to or from a rich fen will promote significant shifts in soil C and N storage.

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Phytolith biogeochemistry and silicon regulation of terrestrial biogeochemical carbon cycle

10.5194/egusphere-egu21-2004 ◽

2021 ◽

Author(s):

Zhaoliang Song ◽

Yuntao Wu

Keyword(s):

Organic Carbon ◽

Management Practices ◽

Net Primary Productivity ◽

Plant Biomass ◽

Lignin Content ◽

C Sequestration ◽

Active Management ◽

Abiotic And Biotic Stresses ◽

Biotic Stresses ◽

C Cycle

Phytoliths in most terrestrial plant tissues as a result of silica biomineralization may occlude 0.1&#8211;6% of organic carbon (C). Phytolith-occluded carbon (PhytOC) comes mainly from photosynthesis and can be stable in soil and sediment environments for several hundred to thousand years. Phytolith turnover may influence terrestrial biogeochemical C cycle either directly through phytolith C sequestration or indirectly through regulating plant biomass C composition and accumulation, and soil organic carbon (SOC) stability. Phytolith C sequestration rates in terrestrial ecosystems of China increase in the following order: grasslands < forests < croplands. Active management practices including cultivation of silicon (Si)-rich plants and amendment of Si-rich materials (e.g., basalt powder and biochar) to increase aboveground net primary productivity (ANPP) and Si supply can significantly increase phytolith C sequestration. The dissolved Si from silicate weathering and phytolith dissolution can decrease plant lignin content and increase the accumulation of plant biomass C through mitigating abiotic and biotic stresses and improving stoichiometry of C, nitrogen (N) and phosphorus (P). The recovery of plant biomass C in response to Si accumulation usually exhibits an S-shaped curve under biotic stress and a bell-shaped curve under abiotic stresses. Generally, Si can recover approximately 30 to 40% of plant biomass C under abiotic and biotic stresses. Phytolith and related dissolved Si in soils can increase SOC stability through phytolith adsorption, Si and aluminum interaction, and Si and iron interaction.

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Reference carbon cycle dataset for typical Chinese forests via colocated observations and data assimilation

Scientific Data ◽

10.1038/s41597-021-00826-w ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Honglin He ◽

Rong Ge ◽

Xiaoli Ren ◽

Li Zhang ◽

Qingqing Chang ◽

...

Keyword(s):

Northern Hemisphere ◽

Global Climate ◽

Meteorological Data ◽

C Sequestration ◽

Research Network ◽

Soil Biology ◽

Area Index ◽

Ecosystem Research ◽

Organic C ◽

C Cycle

AbstractChinese forests cover most of the representative forest types in the Northern Hemisphere and function as a large carbon (C) sink in the global C cycle. The availability of long-term C dynamics observations is key to evaluating and understanding C sequestration of these forests. The Chinese Ecosystem Research Network has conducted normalized and systematic monitoring of the soil-biology-atmosphere-water cycle in Chinese forests since 2000. For the first time, a reference dataset of the decadal C cycle dynamics was produced for 10 typical Chinese forests after strict quality control, including biomass, leaf area index, litterfall, soil organic C, and the corresponding meteorological data. Based on these basic but time-discrete C-cycle elements, an assimilated dataset of key C cycle parameters and time-continuous C sequestration functions was generated via model-data fusion, including C allocation, turnover, and soil, vegetation, and ecosystem C storage. These reference data could be used as a benchmark for model development, evaluation and C cycle research under global climate change for typical forests in the Northern Hemisphere.

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Divergent Accumulation of Microbial Residues and Amino Sugars in Loess Soil after Six Years of Different Inorganic Nitrogen Enrichment Scenarios

Applied Sciences ◽

10.3390/app11135788 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5788

Author(s):

Dominic Kwadwo Anning ◽

Zhilong Li ◽

Huizhen Qiu ◽

Delei Deng ◽

Chunhong Zhang ◽

...

Keyword(s):

Plant Biomass ◽

Inorganic Nitrogen ◽

Amino Sugar ◽

N Fertilization ◽

Biochemical Properties ◽

Sugar Accumulation ◽

Amino Sugars ◽

N Enrichment ◽

Over Time ◽

Microbial Residues

Amino sugars are key microbial biomarkers for determining the contribution of microbial residues in soil organic matter (SOM). However, it remains largely unclear as to what extent inorganic nitrogen (N) fertilization can lead to the significant degradation of SOM in alkaline agricultural soils. A six-year field experiment was conducted from 2013 to 2018 to evaluate the effects of chronic N enrichment on microbial residues, amino sugars, and soil biochemical properties under four nitrogen (urea, 46% N) fertilization scenarios: 0 (no-N, control), 75 (low-N), 225 (medium-N), and 375 (high-N) kg N ha−1. The results showed that chronic N enrichment stimulated microbial residues and amino sugar accumulation over time. The medium-N treatment increased the concentration of muramic acid (15.77%), glucosamine (13.55%), galactosamine (18.84%), bacterial residues (16.88%), fungal residues (11.31%), and total microbial residues (12.57%) compared to the control in 2018; however, these concentrations were comparable to the high-N treatment concentrations. The ratio of glucosamine to galactosamine and of glucosamine to muramic acid decreased over time due to a larger increase in bacterial residues as compared to fungal residues. Microbial biomass, soil organic carbon, and aboveground plant biomass positively correlated with microbial residues and amino sugar components. Chronic N enrichment improved the soil biochemical properties and aboveground plant biomass, which stimulated microbial residues and amino sugar accumulation over time.

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Post-thinning soil organic matter evolution and soil CO2 effluxes in temperate radiata pine plantations: impacts of moderate thinning regimes on the forest C cycle

Canadian Journal of Forest Research ◽

10.1139/x2012-137 ◽

2012 ◽

Vol 42 (11) ◽

pp. 1953-1964 ◽

Cited By ~ 4

Author(s):

Irene Fernandez ◽

Juan Gabriel Álvarez-González ◽

Beatríz Carrasco ◽

Ana Daría Ruíz-González ◽

Ana Cabaneiro

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Radiata Pine ◽

Soil Samples ◽

Mitigation Strategies ◽

Change Scenario ◽

Soil C ◽

C Storage ◽

C Cycle ◽

C And N

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.

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Response of Soybean (Glycine max (L.) Merrill) to Mineral Nitrogen Fertilization and Bradyrhizobium japonicum Seed Inoculation

Agronomy ◽

10.3390/agronomy10091300 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1300

Author(s):

Janusz Prusiński ◽

Anna Baturo-Cieśniewska ◽

Magdalena Borowska

Keyword(s):

Nitrogen Fertilization ◽

Bradyrhizobium Japonicum ◽

Plant Density ◽

Higher Plants ◽

High Sensitivity ◽

N Fertilization ◽

Mineral N ◽

Plant Nitrogen ◽

Seed Inoculation ◽

Glycine Max L

A growing interest in soybean cultivation in Poland has been observed in the recent years, however it faces a lot of difficulties resulting from a poorly understood effectiveness of plant nitrogen fertilization and from the introduction of Bradyrhizobium japonicum to the environment. The aim of the study was to evaluate the consistency of response of two soybean cultivars to three different rates of mineral N fertilization and two seed inoculation treatments with B. japonicum in field conditions over four years regardless of previous B. japonicum presence in the soil. A highly-diversified-over-years rainfall and temperature in the growing season do not allow for a definite statement of the differences resulting from seed inoculation and mineral N fertilization applied separately or jointly in soybean. A high sensitivity of the nodulation process to rainfall deficits was noted, which resulted in a decreased amount of B. japonicum DNA measured in qPCR and dry matter of nodules. ‘Annushka’ demonstrated a higher yield of seeds and protein, higher plants and the 1st pod setting. ‘Aldana’, due to a significant decrease in plant density, produced a higher number of pods, seeds per pod and the 1000 seed weight per plant. Both cultivars responded with an increase in the seed yield after seed inoculation with HiStick, also with an application of 30 and 60 kg N, as well as with Nitragina with 60 kg N.

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Manipulation of rhizosphere organisms to enhance glomalin production and C sequestration: Pitfalls and promises

Canadian Journal of Plant Science ◽

10.4141/cjps2013-146 ◽

2014 ◽

Vol 94 (6) ◽

pp. 1025-1032 ◽

Cited By ~ 11

Author(s):

F. L. Walley ◽

A. W. Gillespie ◽

Adekunbi B. Adetona ◽

J. J. Germida ◽

R. E. Farrell

Keyword(s):

Plant Growth ◽

Mycorrhizal Fungi ◽

Plant Growth Promoting Rhizobacteria ◽

C Sequestration ◽

Ionization Mass ◽

Edge Structure ◽

Organic C ◽

Soil C ◽

N Storage ◽

C And N

Walley, F. L., Gillespie, A. W., Adetona, A. B., Germida, J. J. and Farrell, R. E. 2014. Manipulation of rhizosphere organisms to enhance glomalin production and C-sequestration: Pitfalls and promises. Can. J. Plant Sci. 94: 1025–1032. Arbuscular mycorrhizal fungi (AMF) reportedly produce glomalin, a glycoprotein that has the potential to increase soil carbon (C) and nitrogen (N) storage. We hypothesized that interactions between rhizosphere microorganisms, such as plant growth-promoting rhizobacteria (PGPR), and AMF, would influence glomalin production. Our objectives were to determine the effects of AMF/PGPR interactions on plant growth and glomalin production in the rhizosphere of pea (Pisum sativum L.) with the goal of enhancing C and N storage in the rhizosphere. One component of the study focussed on the molecular characterization of glomalin and glomalin-related soil protein (GRSP) using complementary synchrotron-based N and C X-ray absorption near-edge structure (XANES) spectroscopy, pyrolysis field ionization mass spectrometry (Py-FIMS), and proteomics techniques to characterize specific organic C and N fractions associated with glomalin production. Our research ultimately led us to conclude that the proteinaceous material extracted, and characterized in the literature, as GRSP is not exclusively of AMF origin. Our research supports the established concept that GRSP is important to soil quality, and C and N storage, irrespective of origin. However, efforts to manipulate this important soil C pool will remain compromised until we more clearly elucidate the chemical nature and origin of this resource.

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Linking deeply-sourced volatile emissions to plateau growth dynamics in southeastern Tibetan Plateau

Nature Communications ◽

10.1038/s41467-021-24415-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Maoliang Zhang ◽

Zhengfu Guo ◽

Sheng Xu ◽

Peter H. Barry ◽

Yuji Sano ◽

...

Keyword(s):

Tibetan Plateau ◽

Growth Dynamics ◽

High Elevation ◽

Fault System ◽

The Tibetan Plateau ◽

Southeastern Tibetan Plateau ◽

Surface Uplift ◽

Multi Stage ◽

Geodynamic Processes ◽

Underlying Mechanisms

AbstractThe episodic growth of high-elevation orogenic plateaux is controlled by a series of geodynamic processes. However, determining the underlying mechanisms that drive plateau growth dynamics over geological history and constraining the depths at which growth originates, remains challenging. Here we present He-CO2-N2 systematics of hydrothermal fluids that reveal the existence of a lithospheric-scale fault system in the southeastern Tibetan Plateau, whereby multi-stage plateau growth occurred in the geological past and continues to the present. He isotopes provide unambiguous evidence for the involvement of mantle-scale dynamics in lateral expansion and localized surface uplift of the Tibetan Plateau. The excellent correlation between 3He/4He values and strain rates, along the strike of Indian indentation into Asia, suggests non-uniform distribution of stresses between the plateau boundary and interior, which modulate southeastward growth of the Tibetan Plateau within the context of India-Asia convergence. Our results demonstrate that deeply-sourced volatile geochemistry can be used to constrain deep dynamic processes involved in orogenic plateau growth.

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Carbon and nitrogen budgets of a winter rapeseed field in Estonia: a methodology for the quantification of all relevant pools and fluxes

10.5194/egusphere-egu21-15668 ◽

2021 ◽

Author(s):

Jordi Escuer-Gatius ◽

Krista Lõhmus ◽

Merrit Shanskiy ◽

Karin Kauer ◽

Hanna Vahter ◽

...

Keyword(s):

Mass Balance ◽

Environmental Parameters ◽

Balance Method ◽

Nitrogen Budgets ◽

N Cycle ◽

Carbon And Nitrogen ◽

Mass Balance Method ◽

C Cycle ◽

Winter Rapeseed ◽

C And N

Agricultural activities can have several adverse impacts on the environment; such as important greenhouse gas (GHG) emissions. To implement effective mitigation measures and create effective policies, it is necessary to know the full carbon and nitrogen budgets of agro-ecosystems. However, very often, information regarding the pools or fluxes involved in the carbon and nitrogen cycles is limited, and essential complementary data needed for a proper interpretation is lacking.This study aimed to quantify all the relevant pools and fluxes of a winter rapeseed, a widely spread crop in the Europe and Baltic regions. The N2O and CH4 fluxes were measured weekly using the closed static chamber method from August 2016 to August 2017 in a winter rapeseed field in Central Estonia. Additionally, nutrient leaching and soil chemical parameters, as well as environmental parameters like soil moisture, electrical conductivity and temperature were monitored. At the end of the season, the rapeseed and weed biomasses were collected, weighed and analyzed. The remaining relevant fluxes in the N cycle were calculated using various non-empirical methods: NH3 volatilization was estimated from slurry and environmental parameters, N deposition and NOx emissions were obtained from national reports, and N2 emissions were calculated with the mass balance method. Regarding the C cycle, gross primary production (GPP) of the rapeseed field was also calculated by the mass balance method. Simultaneously, for comparison and validation purposes, GPP was estimated from the data provided by MOD17A2H v006 series from NASA, and N2 was estimated from the measured emissions of N2O using the N2:N2O ratio calculated from the DAYCENT model equations.N2 emissions and GPP were the biggest fluxes in the N and C cycles, respectively. N2 emissions were followed by N extracted with plant biomass in the N cycle, while in the carbon cycle soil and plant respiration and NPP were the highest fluxes after GPP. The carbon balance was positive at the soil level, with a net increase in soil carbon during the period, mainly due to GPP carbon capture. Contrarily, the nitrogen balance resulted in a net loss of N due to the losses related to gaseous emissions (N2 and N2O) and leaching.To conclude, it was possible to close the C and N budgets, despite the inherent difficulties of estimating the different C and N environmental pools and fluxes, and the uncertainties deriving from some of the fluxes estimations.

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