scholarly journals Supplementary material to "The impact of spatiotemporal variability in atmospheric CO<sub>2</sub> concentration on global terrestrial carbon fluxes"

2018 ◽  
Author(s):  
Eunjee Lee ◽  
Fan-Wei Zeng ◽  
Randal D. Koster ◽  
Brad Weir ◽  
Lesley E. Ott ◽  
...  
Keyword(s):  
Carbon Fluxes ◽  
Spatiotemporal Variability ◽  
Terrestrial Carbon ◽  
Supplementary Material ◽  
The Impact

scholarly journals The impact of spatiotemporal variability in atmospheric CO<sub>2</sub> concentration on global terrestrial carbon fluxes

2018 ◽  
Author(s):  
Eunjee Lee ◽  
Fan-Wei Zeng ◽  
Randal D. Koster ◽  
Brad Weir ◽  
Lesley E. Ott ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Temporal Variability ◽  
Gross Primary Production ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Spatiotemporal Variability ◽  
Terrestrial Carbon ◽  
Diurnal Variability ◽  
Co2 Concentrations ◽  
The Impact

Abstract. Land carbon fluxes, e.g., gross primary production (GPP) and net biome production (NBP), are controlled in part by the responses of terrestrial ecosystems to atmospheric conditions near the Earth's surface. The Coupled Model Intercomparison Project Phase 6 (CMIP6) has recently proposed increased spatial and temporal resolutions for the surface CO2 concentrations used to calculate GPP, and yet a comprehensive evaluation of the consequences of this increased resolution for carbon cycle dynamics is missing. Here, using global offline simulations with a terrestrial biosphere model, the sensitivity of terrestrial carbon cycle fluxes to multiple facets of the spatiotemporal variability of atmospheric CO2 is quantified. Globally, the spatial variability of CO2 is found to increase the mean global GPP by 0.2 PgC year−1, as more vegetated land areas benefit from higher CO2 concentrations induced by the inter-hemisphere gradient. The temporal variability of CO2, however, compensates for this increase, acting to reduce overall global GPP; in particular, consideration of the diurnal variability of atmospheric CO2 reduces multi-year mean global annual GPP by 0.5 PgC year−1 and net land carbon uptake by 0.1 PgC year−1. The relative contribution of the different facets of CO2 variability to GPP are found to vary regionally and seasonally, with the seasonal variation in atmospheric CO2, for example, having a notable impact on GPP in boreal regions during fall. Overall, in terms of estimating global GPP, the magnitudes of the sensitivities found here are minor, indicating that the common practice of applying spatially-uniform and annually increasing CO2 (without higher frequency temporal variability) in offline studies is a reasonable approach – the small errors induced by ignoring CO2 variability are undoubtedly swamped by other uncertainties in the offline calculations. Still, for certain regional- and seasonal-scale GPP estimations, the proper treatment of spatiotemporal CO2 variability appears important.

scholarly journals The impact of spatiotemporal variability in atmospheric CO<sub>2</sub> concentration on global terrestrial carbon fluxes

2018 ◽  
Vol 15 (18) ◽  
pp. 5635-5652 ◽  
Author(s):  
Eunjee Lee ◽  
Fan-Wei Zeng ◽  
Randal D. Koster ◽  
Brad Weir ◽  
Lesley E. Ott ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Temporal Variability ◽  
Gross Primary Production ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Spatiotemporal Variability ◽  
Terrestrial Carbon ◽  
Diurnal Variability ◽  
Co2 Concentrations ◽  
The Impact

Abstract. Land carbon fluxes, e.g., gross primary production (GPP) and net biome production (NBP), are controlled in part by the responses of terrestrial ecosystems to atmospheric conditions near the Earth's surface. The Coupled Model Intercomparison Project Phase 6 (CMIP6) has recently proposed increased spatial and temporal resolutions for the surface CO2 concentrations used to calculate GPP, and yet a comprehensive evaluation of the consequences of this increased resolution for carbon cycle dynamics is missing. Here, using global offline simulations with a terrestrial biosphere model, the sensitivity of terrestrial carbon cycle fluxes to multiple facets of the spatiotemporal variability in atmospheric CO2 is quantified. Globally, the spatial variability in CO2 is found to increase the mean global GPP by a maximum of 0.05 Pg C year−1, as more vegetated land areas benefit from higher CO2 concentrations induced by the inter-hemispheric gradient. The temporal variability in CO2, however, compensates for this increase, acting to reduce overall global GPP; in particular, consideration of the diurnal variability in atmospheric CO2 reduces multi-year mean global annual GPP by 0.5 Pg C year−1 and net land carbon uptake by 0.1 Pg C year−1. The relative contributions of the different facets of CO2 variability to GPP are found to vary regionally and seasonally, with the seasonal variation in atmospheric CO2, for example, having a notable impact on GPP in boreal regions during fall. Overall, in terms of estimating global GPP, the magnitudes of the sensitivities found here are minor, indicating that the common practice of applying spatially uniform and annually increasing CO2 (without higher-frequency temporal variability) in offline studies is a reasonable approach – the small errors induced by ignoring CO2 variability are undoubtedly swamped by other uncertainties in the offline calculations. Still, for certain regional- and seasonal-scale GPP estimations, the proper treatment of spatiotemporal CO2 variability appears important.

European beech is a net annual source of methane (CH4)

2021 ◽  
Author(s):  
Katerina Machacova ◽  
Hannes Warlo ◽  
Kateřina Svobodová ◽  
Thomas Agyei ◽  
Tereza Uchytilová ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Seasonal Dynamics ◽  
Forest Floor ◽  
Greenhouse Gas Emission ◽  
European Beech ◽  
Individual Variability ◽  
Spatiotemporal Variability ◽  
Vegetation Season ◽  
Dormant Season ◽  
The Impact

&lt;p&gt;Trees are known to be sources of methane (CH&lt;sub&gt;4&lt;/sub&gt;), an important greenhouse gas, into the atmosphere. However, still little is known about the seasonality of the tree stem CH&lt;sub&gt;4&lt;/sub&gt; fluxes, particularly for the dormant season, and about the impact of environmental parameters on this gas exchange. This makes the estimation of net annual ecosystem CH&lt;sub&gt;4&lt;/sub&gt; fluxes difficult.&lt;/p&gt;&lt;p&gt;We determined seasonal dynamics of CH&lt;sub&gt;4&lt;/sub&gt; exchange of mature European beech stems (&lt;em&gt;Fagus sylvatica&lt;/em&gt;) and of adjacent forest floor in a temperate montane forest of White Carpathians, Czech Republic, from November 2017 to December 2018. We used static chamber methods and gas chromatographic analyses. We aimed to understand the unknown role in seasonal changes of CH&lt;sub&gt;4&lt;/sub&gt; fluxes of these forests, and the spatiotemporal variability of the tree fluxes.&lt;/p&gt;&lt;p&gt;The beech stems were net annual sources for atmospheric CH&lt;sub&gt;4&lt;/sub&gt;, whereas the forest floor was a predominant sink for CH&lt;sub&gt;4&lt;/sub&gt;. The stem CH&lt;sub&gt;4&lt;/sub&gt; emissions showed high inter-individual variability and clear seasonality following the stem CO&lt;sub&gt;2&lt;/sub&gt; efflux. The fluxes of CH&lt;sub&gt;4&lt;/sub&gt; peaked during the vegetation season, and remained low but significant to the annual totals during winter dormancy. By contrast, the forest floor CH&lt;sub&gt;4&lt;/sub&gt; uptake followed an opposite flux trend with low CH&lt;sub&gt;4&lt;/sub&gt; uptake detected in the winter dormant season and elevated CH&lt;sub&gt;4&lt;/sub&gt; uptake during the vegetation season. Based on our preliminary analyses, the detected high spatial variability in stem CH&lt;sub&gt;4&lt;/sub&gt; emissions can be explained neither by the CH&lt;sub&gt;4&lt;/sub&gt; exchange at the forest floor level, nor by soil CH&lt;sub&gt;4&lt;/sub&gt; concentrations, soil water content and soil temperature, all measured in vertical soil profiles close to the studied trees.&lt;/p&gt;&lt;p&gt;European beech trees, native and widely spread species of Central Europe, seem to markedly contribute to the seasonal dynamics of the ecosystem CH&lt;sub&gt;4&lt;/sub&gt; exchange, and their CH&lt;sub&gt;4&lt;/sub&gt; fluxes should be included into forest greenhouse gas emission inventories.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Acknowledgement&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;This research was supported by the Czech Science Foundation (17-18112Y), National Programme for Sustainability I (LO1415), CzeCOS (LM2015061), and SustES - Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions (CZ.02.1.01/0.0/0.0/16_019/0000797). We thank Libor Bor&amp;#225;k and Leszek Dariusz Laptaszy&amp;#324;ski for their technical and field support.&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Improvement of Soil Respiration Parameterization in a Dynamic Global Vegetation Model and Its Impact on the Simulation of Terrestrial Carbon Fluxes

2018 ◽  
Vol 32 (1) ◽  
pp. 127-143 ◽  
Author(s):  
Dongmin Kim ◽  
Myong-In Lee ◽  
Eunkyo Seo
Keyword(s):  
Spatial Distribution ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Vegetation Type ◽  
Carbon Fluxes ◽  
Decomposition Process ◽  
Spatial And Temporal Variation ◽  
In Situ Observation ◽  
Terrestrial Carbon ◽  
Soil Temperature And Moisture

Abstract The Q10 value represents the soil respiration sensitivity to temperature often used for the parameterization of the soil decomposition process has been assumed to be a constant in conventional numerical models, whereas it exhibits significant spatial and temporal variation in the observations. This study develops a new parameterization method for determining Q10 by considering the soil respiration dependence on soil temperature and moisture obtained by multiple regression for each vegetation type. This study further investigates the impacts of the new parameterization on the global terrestrial carbon flux. Our results show that a nonuniform spatial distribution of Q10 tends to better represent the dependence of the soil respiration process on heterogeneous surface vegetation type compared with the control simulation using a uniform Q10. Moreover, it tends to improve the simulation of the relationship between soil respiration and soil temperature and moisture, particularly over cold and dry regions. The modification has an impact on the soil respiration and carbon decomposition process, which changes gross primary production (GPP) through controlling nutrient assimilation from soil to vegetation. It leads to a realistic spatial distribution of GPP, particularly over high latitudes where the original model has a significant underestimation bias. Improvement in the spatial distribution of GPP leads to a substantial reduction of global mean GPP bias compared with the in situ observation-based reference data. The results highlight that the enhanced sensitivity of soil respiration to the subsurface soil temperature and moisture introduced by the nonuniform spatial distribution of Q10 has contributed to improving the simulation of the terrestrial carbon fluxes and the global carbon cycle.

scholarly journals Unravelling the impact of harvesting pressure on canopy-forming macroalgae

2016 ◽  
Vol 67 (1) ◽  
pp. 153 ◽  
Author(s):  
Doriane Stagnol ◽  
Renaud Michel ◽  
Dominique Davoult
Keyword(s):  
Habitat Characteristics ◽  
Spatiotemporal Variability ◽  
Macrobenthic Assemblages ◽  
Wide Range ◽  
The Matrix ◽  
Commercial Species ◽  
Canopy Removal ◽  
The Impact ◽  
Relevant Finding

Canopy-forming macroalgae create a specific surrounding habitat (the matrix) with their own ecological properties. Previous studies have shown a wide range of responses to canopy removal. Magnitude and strength of the effects of harvesting are thought to be context-dependent, with the macroalgal matrix that can either soften or exacerbate the impact of harvesting. We experimentally examined in situ the effect of harvesting on targeted commercial species, and how these potential impacts might vary in relation to its associated matrix. We found that patterns of recovery following the harvesting disturbance were variable and matrix specific, suggesting that local factors and surrounding habitat characteristics mediated the influence of harvesting. The greatest and longest effects of harvesting were observed for the targeted species that created a dominant and monospecific canopy on their site prior to the disturbance. Another relevant finding was the important natural spatiotemporal variability of macrobenthic assemblages associated with canopy-forming species, which raises concern about the ability to discriminate the natural variability from the disturbance impact. Finally, our results support the need to implement ecosystem-based management, assessing both the habitat conditions and ecological roles of targeted commercial species, in order to insure the sustainability of the resource.

scholarly journals Estimating Asian terrestrial carbon fluxes from CONTRAIL aircraft and surface CO<sub>2</sub> observations for the period 2006–2010

2014 ◽  
Vol 14 (11) ◽  
pp. 5807-5824 ◽  
Author(s):  
H. F. Zhang ◽  
B. Z. Chen ◽  
I. T. van der Laan-Luijk ◽  
T. Machida ◽  
H. Matsueda ◽  
...  
Keyword(s):  
A Priori ◽  
Carbon Fluxes ◽  
Terrestrial Carbon ◽  
Tropical Asia ◽  
Observation Network ◽  
Fossil Fuel Emission ◽  
Annual Total ◽  
Co2 Sink ◽  
Summer Flood ◽  
Ecosystem Flux

Abstract. Current estimates of the terrestrial carbon fluxes in Asia show large uncertainties particularly in the boreal and mid-latitudes and in China. In this paper, we present an updated carbon flux estimate for Asia ("Asia" refers to lands as far west as the Urals and is divided into boreal Eurasia, temperate Eurasia and tropical Asia based on TransCom regions) by introducing aircraft CO2 measurements from the CONTRAIL (Comprehensive Observation Network for Trace gases by Airline) program into an inversion modeling system based on the CarbonTracker framework. We estimated the averaged annual total Asian terrestrial land CO2 sink was about −1.56 Pg C yr−1 over the period 2006–2010, which offsets about one-third of the fossil fuel emission from Asia (+4.15 Pg C yr−1). The uncertainty of the terrestrial uptake estimate was derived from a set of sensitivity tests and ranged from −1.07 to −1.80 Pg C yr−1, comparable to the formal Gaussian error of ±1.18 Pg C yr−1 (1-sigma). The largest sink was found in forests, predominantly in coniferous forests (−0.64 ± 0.70 Pg C yr−1) and mixed forests (−0.14 ± 0.27 Pg C yr−1); and the second and third large carbon sinks were found in grass/shrub lands and croplands, accounting for −0.44 ± 0.48 Pg C yr−1 and −0.20 ± 0.48 Pg C yr−1, respectively. The carbon fluxes per ecosystem type have large a priori Gaussian uncertainties, and the reduction of uncertainty based on assimilation of sparse observations over Asia is modest (8.7–25.5%) for most individual ecosystems. The ecosystem flux adjustments follow the detailed a priori spatial patterns by design, which further increases the reliance on the a priori biosphere exchange model. The peak-to-peak amplitude of inter-annual variability (IAV) was 0.57 Pg C yr−1 ranging from −1.71 Pg C yr−1 to −2.28 Pg C yr−1. The IAV analysis reveals that the Asian CO2 sink was sensitive to climate variations, with the lowest uptake in 2010 concurrent with a summer flood and autumn drought and the largest CO2 sink in 2009 owing to favorable temperature and plentiful precipitation conditions. We also found the inclusion of the CONTRAIL data in the inversion modeling system reduced the uncertainty by 11% over the whole Asian region, with a large reduction in the southeast of boreal Eurasia, southeast of temperate Eurasia and most tropical Asian areas.

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