Global maps of current and future nitrogen mineralization

2020 ◽  
Author(s):  
Julia Maschler ◽  
Daniel S. Maynard ◽  
Devin Routh ◽  
Johan van den Hoogen ◽  
Zhaolei Li ◽  
...  
Keyword(s):  
Nitrogen Mineralization ◽  
Climate Models ◽  
Net Primary Productivity ◽  
Plant Biomass ◽  
Global Scale ◽  
N Availability ◽  
Soil N ◽  
Climate Conditions ◽  
Tropical Regions ◽  
Terrestrial Carbon Sequestration

<p>Soil nitrogen is a prominent determinant of plant growth, with nitrogen (N) availability being a key driver of terrestrial carbon sequestration. The local availability of soil N is thus crucial to our understanding of broad-scale trends in soil fertility, productivity, and carbon dynamics. Here, we provide global, high-resolution maps of current and future (2050) potential net nitrogen mineralization (N-min), revealing global patterns in soil N availability. Highest mineralization rates are found in warm and moist tropical regions, leading to a strong latitudinal gradient in N-min. We observed a positive correlation of N-min rates with human population density and net primary productivity. Projected climate conditions for 2050 suggest that N availability will further decrease in areas of low N availability and increase in areas of high N availability, thereby intensifying current global trends. These results shed light on the core processes governing productivity at a global scale, providing an opportunity to improve the accuracy of plant biomass and climate models.</p>

scholarly journals Assessing the Robustness of Future Extreme Precipitation Intensification in the CMIP5 Ensemble

2018 ◽  
Vol 31 (16) ◽  
pp. 6505-6525 ◽  
Author(s):  
Margot Bador ◽  
Markus G. Donat ◽  
Olivier Geoffroy ◽  
Lisa V. Alexander
Keyword(s):  
Extreme Precipitation ◽  
Climate Models ◽  
Internal Variability ◽  
Global Scale ◽  
Grid Cells ◽  
Wet Season ◽  
Tropical Regions ◽  
Projected Changes ◽  
Background Climate ◽  
Climate Noise

Abstract A warming climate is expected to intensify extreme precipitation, and climate models project a general intensification of annual extreme precipitation in most regions of the globe throughout the twenty-first century. We investigate the robustness of this future intensification over land across different models, regions, and seasons and evaluate the role of model interdependencies in the CMIP5 ensemble. Strong similarities in extreme precipitation changes are found between models that share atmospheric physics, turning an ensemble of 27 models into around 14 projections. We find that future annual extreme precipitation intensity increases in the majority of models and in the majority of land grid cells, from the driest to the wettest regions, as defined by each model’s precipitation climatology. The intermodel spread is generally larger over wet than over dry regions, smaller in the dry season compared to the wet season and at the annual scale, and largely reduced in extratropical compared to tropical regions and at the global scale. For each model, the future increase in annual and seasonal maximum daily precipitation amounts exceeds the range of simulated internal variability in the majority of land grid cells. At both annual and seasonal scales, however, there are a few regions where the change is still within the background climate noise, but their size and location differ between models. In extratropical regions, the signal-to-noise ratio of projected changes in extreme precipitation is particularly robust across models because of a similar change and background climate noise, whereas projected changes are less robust in the tropics.

scholarly journals Nitrogen availability controls plant carbon storage with warming

2021 ◽  
Author(s):  
Guiyao Zhou ◽  
César Terrer ◽  
Bruce Hungate ◽  
Natasja van Gestel ◽  
Xuhui Zhou ◽  
...  
Keyword(s):  
Nitrogen Availability ◽  
Plant Biomass ◽  
Meta Analysis ◽  
C:N Ratio ◽  
Belowground Biomass ◽  
Climate Projections ◽  
N Availability ◽  
Soil N ◽  
C Storage ◽  
Induced Changes

Abstract Plants may slow global warming through enhanced growth, because increased levels of photosynthesis stimulate the land carbon (C) sink. However, the key drivers determining responses of plants to warming remain unclear, causing uncertainty in climate projections. Using meta- analysis, we show that the effect of experimental warming on plant biomass is best explained by soil nitrogen (N) availability. Warming-induced changes in total, aboveground and belowground biomass all positively correlated with soil C:N ratio, an indicator of soil N availability. In factorial N × warming experiments, warming increased plant biomass more strongly under low N than under high N availability. Together, these results suggest that warming stimulates plant C storage most strongly in ecosystems where N limits plant growth. Thus, incorporating the soil N status of ecosystems into Earth system models may improve predictions of future carbon-climate feedbacks.

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 Nitrogen isotopic composition of plants and soil in an arid mountainous terrain: sunny slope versus shady slope

2017 ◽  
Author(s):  
Chongjuan Chen ◽  
Yufu Jia ◽  
Yuzhen Chen ◽  
Imran Mehmood ◽  
Yunting Fang ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Regional Scale ◽  
Local Environment ◽  
Global Scale ◽  
Influential Factors ◽  
N Cycling ◽  
N Availability ◽  
Soil N ◽  
The Difference ◽  
Soil Δ15n

Abstract. Nitrogen cycling is tightly associated with environment. Sunny slope of a given mountain could significantly differ from shady slope in environment. Thus, N cycling should also be different between the two slopes. Since leaf δ15N, soil δ15N and △δ15Nleaf-soil (△δ15Nleaf-soil = leaf δ15N − soil δ15N) could reflect the N cycling characteristics, we put forward a hypothesis that leaf δ15N, soil δ15N and △δ15Nleaf-soil should differ across the two slopes. However, such a comparative study between two slopes has never been conducted yet. In addition, environmental effects on leaf and soil δ15N derived from studies at global scale were often found to be different from that at regional scale. This led to our argument that environmental effects on leaf and soil δ15N could depend on local environment. To confirm our hypothesis and argument, we measured leaf and soil δ15N on the sunny and shady slopes of Mount Tianshan. Remarkable environment differences between the two slopes provided an ideal opportunity for our test. The study showed that leaf δ15N, soil δ15N and △δ15Nleaf-soil on the sunny slope were greater than that on the shady slope although the difference in soil δ15N was not significant. The result confirmed our hypothesis and suggested that the sunny slope has higher soil N transformation rates and soil N availability than the shady slope. Besides, this study observed that the significant influential factors of leaf δ15N were temperature, precipitation, leaf N, leaf C / N and silt / clay ratio on the shady slope, whereas on the sunny slope only leaf C / N was related to leaf δ15N. The significant influential factors of soil δ15N were temperature, precipitation and silt / clay ratio on the shady slope, whereas on the sunny slope MAP and soil moisture exerted significant effects. Precipitation exerted contrary effects on soil δ15N between the two slopes. Thus, this study supported our argument that the relationships between leaf and soil δ15N and environmental factors are local-dependent.

scholarly journals Comparing different generations of idealized solar geoengineering simulations in the Geoengineering Model Intercomparison Project (GeoMIP)

2021 ◽  
Vol 21 (6) ◽  
pp. 4231-4247
Author(s):  
Ben Kravitz ◽  
Douglas G. MacMartin ◽  
Daniele Visioni ◽  
Olivier Boucher ◽  
Jason N. S. Cole ◽  
...  
Keyword(s):  
Climate Models ◽  
Net Primary Productivity ◽  
Hydrological Cycle ◽  
Co2 Concentration ◽  
Global Scale ◽  
Model Intercomparison ◽  
Two Generations ◽  
Temporary Solution ◽  
Solar Geoengineering ◽  
Intercomparison Project

Abstract. Solar geoengineering has been receiving increased attention in recent years as a potential temporary solution to offset global warming. One method of approximating global-scale solar geoengineering in climate models is via solar reduction experiments. Two generations of models in the Geoengineering Model Intercomparison Project (GeoMIP) have now simulated offsetting a quadrupling of the CO2 concentration with solar reduction. This simulation is idealized and designed to elicit large responses in the models. Here, we show that energetics, temperature, and hydrological cycle changes in this experiment are statistically indistinguishable between the two ensembles. Of the variables analyzed here, the only major differences involve highly parameterized and uncertain processes, such as cloud forcing or terrestrial net primary productivity. We conclude that despite numerous structural differences and uncertainties in models over the past two generations of models, including an increase in climate sensitivity in the latest generation of models, the models are consistent in their aggregate climate response to global solar dimming.

Soil N2O emissions from temperate cropland agroforestry and monoculture systems

2021 ◽  
Author(s):  
Guodong Shao ◽  
Guntars Martinson ◽  
Jie Luo ◽  
Xenia Bischel ◽  
Dan Niu ◽  
...  
Keyword(s):  
Western Europe ◽  
Temporal Dynamics ◽  
Pore Space ◽  
Tree Age ◽  
Soil Types ◽  
N2o Emissions ◽  
N Availability ◽  
Soil N ◽  
Mineral N ◽  
Climate Conditions

<p>Monoculture cropland is a major contributor to agriculture-related sources of N<sub>2</sub>O emission, a potent greenhouse gas and an agent of ozone depletion. Cropland agroforestry has the potential to minimize deleterious environmental impacts. Presently, there is no systematic comparison of soil N<sub>2</sub>O emission between cropland agroforestry (CAF) and monoculture systems (MC) in Western Europe. Our study aimed to (1) quantify the spatial-temporal dynamics of soil N<sub>2</sub>O fluxes, and (2) determine their soil controlling factors in CAF and MC. We selected three sites with different soil types (Phaeozem, Cambisol, and Arenosol) in Germany. Each site has paired CAF and MC (agroforestry sites consisted of 12-m wide tree row and 48-m wide crop row and were established in 2007, 2008 and 2019 in these soil types, respectively). In each management system at each site, we had four replicate plots. In the CAF, we conducted measurements in the tree row and within the crop row at 1 m, 7 m, and 24 m from the tree row. We measured soil N<sub>2</sub>O fluxes monthly over 2 years (March 2018‒February 2020) using static vented chambers method. Following gas sampling, we also measured soil temperature, water-filled pore space (WFPS), and mineral N (NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>-</sup>) within the same day. Across all sites, soil moisture and N availability were major drivers of soil N<sub>2</sub>O fluxes. Both CAF and MC were net sources of soil N<sub>2</sub>O at all sites. At the site with Phaeozem soil, annual soil N<sub>2</sub>O emissions from CAF in both years (1.84 ± 0.35 and 1.17 ± 0.30 kg N ha<sup>−</sup><sup>1</sup> yr<sup>−</sup><sup>1</sup>) were greater than MC (0.89 ± 0.09 and 0.34 ± 0.05 kg N ha<sup>−</sup><sup>1</sup> yr<sup>−</sup><sup>1</sup>) (<em>P</em> = 0.03). At the site with Cambisol soil, annual soil N<sub>2</sub>O emission did not differ between MC (0.49 ± 0.07 kg N ha<sup>−</sup><sup>1</sup> yr<sup>−</sup><sup>1</sup>) and CAF (0.73 ± 0.13 kg N ha<sup>−</sup><sup>1</sup> yr<sup>−</sup><sup>1</sup>) in 2018/2019 (<em>P</em> = 0.20) whereas in 2019/2020 MC was 134% greater than CAF (2.92 ± 0.45 and 1.25 ± 0.08 kg N ha<sup>−</sup><sup>1</sup> yr<sup>−</sup><sup>1</sup>, respectively; <em>P</em> = 0.03). The inter-annual differences were largely related to crop types and to climate conditions. At the site with Arenosol soil, there was no difference between CAF and MC. Our results indicated that CAF may decrease, maintain and/or increase soil N<sub>2</sub>O emissions compared to MC depending on tree age, soil characteristics, management and precipitation.</p>

Understanding the Complex Interaction Between Soil N Availability and Soil C Dynamics Under Changing Climate Conditions 1

2018 ◽  
pp. 337-348 ◽  
Author(s):  
Pratap Srivastava ◽  
Rishikesh Singh ◽  
Sachchidanand Tripathi ◽  
Hema Singh ◽  
Akhilesh Singh Raghubanshi
Keyword(s):  
Complex Interaction ◽  
N Availability ◽  
Soil N ◽  
Soil C ◽  
Climate Conditions ◽  
Soil N Availability ◽  
Changing Climate ◽  
C Dynamics

scholarly journals Comparing different generations of idealized solar geoengineering simulations in the Geoengineering Model Intercomparison Project (GeoMIP)

2020 ◽  
Author(s):  
Ben Kravitz ◽  
Douglas G. MacMartin ◽  
Daniele Visioni ◽  
Olivier Boucher ◽  
Jason N. S. Cole ◽  
...  
Keyword(s):  
Climate Models ◽  
Net Primary Productivity ◽  
Hydrological Cycle ◽  
Co2 Concentration ◽  
Global Scale ◽  
Model Intercomparison ◽  
Cloud Forcing ◽  
Temporary Solution ◽  
Solar Geoengineering ◽  
Intercomparison Project

Abstract. Solar geoengineering has been receiving increased attention in recent years as a potential temporary solution to offset global warming. One method of approximating global-scale solar geoengineering in climate models is via solar reduction experiments. Two generations of models in the Geoengineering Model Intercomparison Project (GeoMIP) have now simulated offsetting a quadrupling of the CO2 concentration with solar reduction. This simulation is artificial and designed to elicit large responses in the models. Here we show that energetics, temperature, and hydrological cycle changes in this experiment are statistically indistinguishable between the two ensembles. Of the variables analyzed here, the only major differences involve highly parameterized and uncertain processes, such as cloud forcing or terrestrial net primary productivity. We conclude that despite numerous structural differences and uncertainties in models over the past 20 years, including an increase in climate sensitivity in the latest generation of models, broad conclusions about the climate response to global solar dimming remain robust.

scholarly journals Frameworks on Patterns of Grasslands’ Sensitivity to Forecast Extreme Drought

2020 ◽  
Vol 12 (19) ◽  
pp. 7837
Author(s):  
Taofeek O. Muraina
Keyword(s):  
Climate Models ◽  
Net Primary Productivity ◽  
Global Scale ◽  
Ambient Condition ◽  
Extreme Drought ◽  
Ecosystem Functions ◽  
Negative Slope ◽  
Precipitation Gradient ◽  
Global Precipitation ◽  
The Relationship

Climate models have predicted the future occurrence of extreme drought (ED). The management, conservation, or restoration of grasslands following ED requires a robust prior knowledge of the patterns and mechanisms of sensitivity—declining rate of ecosystem functions due to ED. Yet, the global-scale pattern of grasslands’ sensitivity to any ED event remains unresolved. Here, frameworks were built to predict the sensitivity patterns of above-ground net primary productivity (ANPP) spanning the global precipitation gradient under ED. The frameworks particularly present three sensitivity patterns that could manipulate (weaken, strengthen, or erode) the orthodox positive precipitation–productivity relationship which exists under non-drought (ambient) condition. First, the slope of the relationship could become steeper via higher sensitivity at xeric sites than mesic and hydric ones. Second, if the sensitivity emerges highest in hydric, followed by mesic, then xeric, a weakened slope, flat line, or negative slope would emerge. Lastly, if the sensitivity emerges unexpectedly similar across the precipitation gradient, the slope of the relationship would remain similar to that of the ambient condition. Overall, the frameworks provide background knowledge on possible differences or similarities in responses of grasslands to forecast ED, and could stimulate increase in conduct of experiments to unravel the impacts of ED on grasslands. More importantly, the frameworks indicate the need for reconciliation of conflicting hypotheses of grasslands’ sensitivity to ED through global-scale experiments.

scholarly journals Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past 3 decades

2015 ◽  
Vol 15 (20) ◽  
pp. 11931-11948 ◽  
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 ◽  
Area Index ◽  
Tropical Regions ◽  
Plant Volatile

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 by 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 leaf area index 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. 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).

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