Nitrogen availability and precipitation variability regulated CO2 fertilization effects on carbon fluxes in an alpine grassland

2021 ◽  
Vol 307 ◽  
pp. 108524
Author(s):  
Yao Chen ◽  
Yangjian Zhang ◽  
Ning Chen ◽  
Nan Cong ◽  
Juntao Zhu ◽  
...  
Keyword(s):  
Nitrogen Availability ◽  
Carbon Fluxes ◽  
Precipitation Variability ◽  
Alpine Grassland ◽  
Co2 Fertilization ◽  
Fertilization Effects

Carbon fluxes and environmental controls across different alpine grassland types on the Tibetan Plateau

2021 ◽  
Vol 311 ◽  
pp. 108694
Author(s):  
Yuyang Wang ◽  
Jingfeng Xiao ◽  
Yaoming Ma ◽  
Yiqi Luo ◽  
Zeyong Hu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Carbon Fluxes ◽  
Alpine Grassland ◽  
The Tibetan Plateau ◽  
Environmental Controls ◽  
Grassland Types

scholarly journals Projected changes of alpine grassland carbon dynamics in response to climate change and elevated CO2concentrations under Representative Concentration Pathways (RCP) scenarios

2019 ◽  
Author(s):  
Pengfei Han ◽  
Xiaohui Lin ◽  
Wen Zhang ◽  
Guocheng Wang
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
Carbon Cycle ◽  
Carbon Budget ◽  
Carbon Fluxes ◽  
Carbon Dynamics ◽  
Alpine Grassland ◽  
The Tibetan Plateau ◽  
Rcp Scenarios ◽  
Representative Concentration Pathways

AbstractThe Tibetan Plateau is an important component of the global carbon cycle due to the large permafrost carbon pool and its vulnerability to climate warming. The Tibetan Plateau has experienced a noticeable warming over the past few decades and is projected to continue warming in the future. However, the direction and magnitude of carbon fluxes responses to climate change and elevated CO2concentration under Representative Concentration Pathways (RCP) scenarios in the Tibetan Plateau grassland are poorly known. Here, we used a calibrated and validated biogeochemistry model, CENTURY, to quantify the contributions of climate change and elevated CO2on the future carbon budget in the alpine grassland under three RCP scenarios. Though the Tibetan Plateau grassland was projected a net carbon sink of 16 ~ 25 Tg C yr-1in the 21st century, the capacity of carbon sequestration was predicted to decrease gradually because climate-driven increases in heterotrophic respiration (Rh) (with linear slopes 0.49 ~ 1.62 g C m-2yr-1) was greater than the net primary production (NPP) (0.35 ~ 1.52 g C m-2yr-1). However, the elevated CO2contributed more to plant growth (1.9% ~ 7.3%) than decomposition (1.7% ~ 6.1%), which could offset the warming-induced carbon loss. The interannual and decadal-scale dynamics of the carbon fluxes in the alpine grassland were primarily controlled by temperature, while the role of precipitation became increasingly important in modulating carbon cycle. The strengthened correlation between precipitation and carbon budget suggested that further research should consider the performance of precipitation in evaluating carbon dynamics in a warmer climate scenario.

scholarly journals Can we reconcile differences in estimates of carbon fluxes from land-use change and forestry for the 1990s?

2008 ◽  
Vol 8 (1) ◽  
pp. 3843-3893 ◽  
Author(s):  
A. Ito ◽  
J. E. Penner ◽  
M. J. Prather ◽  
C. P. de Campos ◽  
R. A. Houghton ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Carbon Fluxes ◽  
Terrestrial Carbon ◽  
Co2 Fertilization ◽  
Uncertainty Range ◽  
Inverse Models ◽  
The Usa

Abstract. The effect of Land Use Change and Forestry (LUCF) on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantly smaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation of carbon uptake or emissions due to LUC.

scholarly journals Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past three decades

2015 ◽  
Vol 15 (15) ◽  
pp. 21449-21494 ◽  
Author(s):  
X. Yue ◽  
N. Unger ◽  
Y. Zheng
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Carbon Fluxes ◽  
Global Scale ◽  
Carbon Uptake ◽  
Terrestrial Biosphere ◽  
Co2 Fertilization ◽  
Tropical Regions ◽  
Plant Volatile ◽  
Main Driver

Abstract. The terrestrial biosphere has experienced dramatic changes in recent decades. Estimates of historical trends in land carbon fluxes remain uncertain because long-term observations are limited on the global scale. Here, we use the Yale Interactive terrestrial Biosphere (YIBs) model to estimate decadal trends in land carbon fluxes and emissions of biogenic volatile organic compounds (BVOCs) and to identify the key drivers for these changes during 1982–2011. Driven with hourly meteorology from WFDEI (WATCH Forcing Data methodology applied to ERA-Interim data), the model simulates an increasing trend of 297 Tg C a−2 in gross primary productivity (GPP) and 185 Tg C a−2 in the net primary productivity (NPP). CO2 fertilization is the main driver for the flux changes in forest ecosystems, while meteorology dominates the changes in grasslands and shrublands. Warming boosts summer GPP and NPP at high latitudes, while drought dampens carbon uptake in tropical regions. North of 30° N, increasing temperatures induce a substantial extension of 0.22 day a−1 for the growing season; however, this phenological change alone does not promote regional carbon uptake and BVOC emissions. Nevertheless, increases of LAI at peak season accounts for ~ 25 % of the trends in GPP and isoprene emissions at the northern lands. The net land sink shows statistically insignificant increases of only 3 Tg C a−2 globally because of simultaneous increases in soil respiration. In contrast, driven with alternative meteorology from MERRA (Modern Era-Retrospective Analysis), the model predicts significant increases of 59 Tg C a−2 in the land sink due to strengthened uptake in the Amazon. Global BVOC emissions are calculated using two schemes. With the photosynthesis-dependent scheme, the model predicts increases of 0.4 Tg C a−2 in isoprene emissions, which are mainly attributed to warming trends because CO2 fertilization and inhibition effects offset each other. Using the MEGAN (Model of Emissions of Gases and Aerosols from Nature) scheme, the YIBs model simulates global reductions of 1.1 Tg C a−2 in isoprene and 0.04 Tg C a−2 in monoterpene emissions in response to the CO2 inhibition effects. Land use change shows limited impacts on global carbon fluxes and BVOC emissions, but there are regional contrasting impacts over Europe (afforestation) and China (deforestation).

scholarly journals Effects of nitrogen fertilization on the understorey carbon balance over the growing season in a boreal Pine forest

2013 ◽  
Vol 10 (8) ◽  
pp. 14093-14113
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Nitrogen Availability ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Carbon Uptake ◽  
Sink Strength ◽  
Understorey Vegetation ◽  
Ecosystem Carbon ◽  
Photosynthetic Carbon

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate. We quantified the effects of nitrogen availability on carbon fluxes from a relatively understudied component of these forests – understorey vegetation – at three intervals over the summer growing period in a northern Swedish Scots Pine stand. Nitrogen addition altered both photosynthetic carbon uptake and respiratory release, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net ecosystem carbon uptake only in the late growing season. We find evidence for species-specific control of understorey carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of photosynthetic carbon uptake with data on plant carbon dioxide release from the study site, indicate that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in understorey and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

scholarly journals Can we reconcile differences in estimates of carbon fluxes from land-use change and forestry for the 1990s?

2008 ◽  
Vol 8 (12) ◽  
pp. 3291-3310 ◽  
Author(s):  
A. Ito ◽  
J. E. Penner ◽  
M. J. Prather ◽  
C. P. de Campos ◽  
R. A. Houghton ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Land Cover ◽  
Land Cover Change ◽  
Carbon Fluxes ◽  
Terrestrial Carbon ◽  
Co2 Fertilization ◽  
Uncertainty Range ◽  
Inverse Models ◽  
The Usa

Abstract. The effect of Land Use Change and Forestry (LUCF) on terrestrial carbon fluxes can be regarded as a carbon credit or debit under the UNFCCC, but scientific uncertainty in the estimates for LUCF remains large. Here, we assess the LUCF estimates by examining a variety of models of different types with different land cover change maps in the 1990s. Annual carbon pools and their changes are separated into different components for separate geographical regions, while annual land cover change areas and carbon fluxes are disaggregated into different LUCF activities and the biospheric response due to CO2 fertilization and climate change. We developed a consolidated estimate of the terrestrial carbon fluxes that combines book-keeping models with process-based biogeochemical models and inventory estimates and yields an estimate of the global terrestrial carbon flux that is within the uncertainty range developed in the IPCC 4th Assessment Report. We examined the USA and Brazil as case studies in order to assess the cause of differences from the UNFCCC reported carbon fluxes. Major differences in the litter and soil organic matter components are found for the USA. Differences in Brazil result from assumptions about the LUC for agricultural purposes. The effects of CO2 fertilization and climate change also vary significantly in Brazil. Our consolidated estimate shows that the small sink in Latin America is within the uncertainty range from inverse models, but that the sink in the USA is significantly smaller than the inverse models estimates. Because there are different sources of errors at the country level, there is no easy reconciliation of different estimates of carbon fluxes at the global level. Clearly, further work is required to develop data sets for historical land cover change areas and models of biogeochemical changes for an accurate representation of carbon uptake or emissions due to LUC.

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