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Measuring carbon and water fluxes from Eucalyptus stands in the Congo

Measuring carbon and water fluxes from Eucalyptus stands in the Congo

and litter production by aerial compartment (L A ), will be used to estimate NPP (NPP=G A +G B +L A +L R ), and net carbon gain (NEP=NPP-Rh), that will be compared to the annual net carbon gain estimated by eddy correlation. Other results obtained in this experiment (water and energy fluxes, LAI measurements, etc.) are being used to develop and validate models that simulate the carbon, water and energy budgets of these plantations. References

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Uncertainty in simulating biomass yield and carbon-water fluxes from Euro-Mediterranean grasslands under climate changes

Uncertainty in simulating biomass yield and carbon-water fluxes from Euro-Mediterranean grasslands under climate changes

Uncertainty in simulating biomass yield and carbon-water fluxes from Euro-Mediterranean grasslands under climate changes.. International Livestock Modelling and Research Colloquium, Oct [r]

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A vertically discretised canopy description for ORCHIDEE (SVN r2290) and the modifications to the energy, water and carbon fluxes

A vertically discretised canopy description for ORCHIDEE (SVN r2290) and the modifications to the energy, water and carbon fluxes

1 Introduction Forests play a particularly important role in the global car- bon cycle. Forests store almost 50 % of the terrestrial or- ganic carbon and 90 % of vegetation biomass (Dixon et al., 1994; Pan et al., 2011). Globally, 70 % of the forest is man- aged and the importance of management is still increasing both in relative and absolute terms. In densely populated re- gions, such as Europe, almost all forest is intensively man- aged by humans. Recently, forest management has become a top priority on the agenda of political negotiations to mitigate climate change (Kyoto Protocol, http://unfccc.int/resource/ docs/convkp/kpeng.pdf). Because forest plantations may re- move CO 2 from the atmosphere, if used for energy produc- tion, harvested timber is a substitute for fossil fuel. Forest management thus has great potential for mitigating climate change, which was recognised in the United Nations Frame- work Convention on Climate Change and the Kyoto Protocol. Forests not only influence the global carbon cycle, but they also dramatically affect the water vapour and energy fluxes exchanged with the overlying atmosphere. It has been shown, for example, that the evapotranspiration of young plantations can be so great that the streamflow of neighbouring creeks is reduced by 50 % (Jackson et al., 2005). Modelling studies on the impact of forest plantations in regions that are snow- covered in winter suggest that because of their reflectance (the so-called albedo), forest could increase regional temper- ature by up to four degrees (Betts, 2000; Bala et al., 2007; Davin et al., 2007; Zhao and Jackson, 2014). Management- related changes in the albedo, energy balance and water cycle of forests (Amiro et al., 2006a, b) are of the same magni- tude as the differences between forests, grasslands and crop- lands (Luyssaert et al., 2014). Moreover, changes in the wa- ter vapour and the energy exchange may offset the cooling effect obtained by managing forests as stronger sinks for at- mospheric CO 2 (Pielke et al., 2002). Despite the key implica- tions of forest management on the carbon–energy–water ex- change, there have been no integrated studies on the effects of forest management on the Earth’s climate.
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Uncertainty in simulating biomass yield and carbon-water fluxes from grasslands under climate change

Uncertainty in simulating biomass yield and carbon-water fluxes from grasslands under climate change

References Ainsworth EA and Rogers A 2007. Plant, Cell and Environment 30, 258–270. Asseng S, Ewert F, Rosenzweig C, Jones JW, Hatfield JL, Ruane A, Boote KJ, Thorburn P, Rötter RP, Cammarano D, Brisson N, Basso B, Martre P, Aggarwal PK, Angulo C, Bertuzzi P, Biernath C, Doltra J, Gayler S, Goldberg R, Grant R, Heng L, Hooker JE, Hunt LA, Ingwersen J, Izaurralde RC, Kersebaum KC, Müller C, Naresh Kumar S, Nendel C, O ’Leary G, Olesen JE, Osborne TM, Palosuo T, Priesack E, Ripoche D, Semenov MA, Shcherbak I, Steduto P, Stöckle CO, Stratonovitch P, Streck T, Supit I, Travasso M, Tao F, Waha K, Wallach D, White JW and Wolf J 2013. Uncertainties in simulating wheat yields under climate change. Nature Climate Change 3, 827 –832.
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Uncertainty in simulating biomass yield and carbon-water fluxes from Euro-Mediterranean grasslands under climate changes

Uncertainty in simulating biomass yield and carbon-water fluxes from Euro-Mediterranean grasslands under climate changes

Ma#a Sassari Laqueuille Rothamsted Lelystad Oensingen Monte
Bondone Kempten Grillenburg Management: 


Kemp‐1:
intensive
(4
cuts/year) 


Kemp‐2:
extensive

(2
cuts/year) 


Roth‐1:
NH4
[r]

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The importance of tree demography and root water uptake for modelling the carbon and water cycles of Amazonia

The importance of tree demography and root water uptake for modelling the carbon and water cycles of Amazonia

In this study, we demonstrated that a 2gDGVM (CAN-RS) can reproduce carbon and water fluxes and carbon stocks across 15 Amazonia, and we validated these simulations using local and regional observations. We also compared CAN-RS with earlier versions of the same family of models (ORCHIDEE-TRUNK and ORCHIDEE-CAN). The mechanistic root water uptake module implemented in CAN-RS allows trees to take up water in the deepest soil layer during dry seasons. This feature enables the model to capture the seasonality of GPP and LE, especially over the Guianan and Brazilian Shield (high water retention). The modelled diameter size distribution is improved compared to the TRUNK big-leaf DGVM. However 20
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Dynamical and biogeochemical control on the decadal variability of ocean carbon fluxes

Dynamical and biogeochemical control on the decadal variability of ocean carbon fluxes

the three oceanic regions is set in part by the large-scale cir- culation of water masses and their biogeochemical proper- ties. That is, in regions of dense water mass outcrops and transformations, variations in vertical supply of dissolved in- organic carbon (owing to Ekman-induced upwelling or deep- mixing events) are of larger amplitude than the variations in- herited from thermodynamical properties of surface waters (owing to ocean-atmosphere or ocean-sea ice interactions). This is not the case in regions of dense water mass formation. The fact that low-frequency variations in ocean carbon fluxes are simulated in our model within high latitude oceans is consistent with previous studies conducted on dynamical fields like sea surface temperature, surface air temperature or precipitation (e.g. Boer, 2004, 2000). Of particular interest, a similar study with the same model (i.e., IPSL-CM5A-LR) by Persechino et al. (2013) demonstrates that decadal variations of sea surface temperature amount for 20 % (with a maxi- mum of 50 %) of their interannual variations within the North Atlantic sector. Comparatively, ocean carbon fluxes exhibit low-frequency variations much stronger (∼ 20–40 %) than those of sea surface temperature. Such differences between low-frequency variations of ocean carbon fluxes and other dynamical fields are even stronger in the Southern Ocean, where Boer (2004) shows that multi-model zonal average variations of surface air temperature at decadal time scales only accounts for 10 % of the interannual variability. In our case, decadal variations of ocean carbon fluxes within Sub- polar and Polar Regions of the Antarctic sector amounts to up to 25 %. Such features can be explained by the statistical properties of ocean carbon fluxes, which cannot be approx- imated with a first-order autoregressive process (like other dynamical variables mentioned above) indicating that long- term memory processes likely drive ocean carbon fluxes (and potentially other biogeochemical fluxes like the carbon ex- port, the primary productivity and the remineralisation).
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Anthropogenic perturbation of the carbon fluxes from land to ocean

Anthropogenic perturbation of the carbon fluxes from land to ocean

In summary, although accurate quantification remains challeng- ing, one can firmly conclude that during the industrial era, the later- ally transported C fluxes and the vertically exchanged atmospheric CO 2 fluxes relevant to the land–ocean aquatic continuum have been significantly altered by human activities, the main driver being land- use changes. Our analysis suggests that out of the ~1.1 Pg C yr –1 of extra anthropogenic C delivered to the continuum of land–ocean aquatic systems (0.8 Pg C yr –1 from soils, 0.1 Pg C yr –1 from weath- ering, 0.1 Pg C yr –1 from sewage, 0.1 Pg C yr –1 from enhanced C fixation in inland waters), at present approximately 50% is seques- tered in inland water, estuarine and coastal sediments, <20% is exported to the open ocean and the remaining >30% is emitted to the atmosphere as CO 2 . CO 2 fluxes along the land–ocean contin- uum may not only be altered directly by increased anthropogenic C export from soil and subsequent respiration, but also indirectly by enhanced decomposition of autochthonous organic materials triggered by priming. This indirect process may be a quantitatively relevant contribution to the estimated fluxes and the observed net heterotrophy of many systems, but cannot yet be quantified 45,91 . The uncertainties associated with our breakdown are large and represent
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Present day carbon dioxide fluxes in the coastal ocean and possible feedbacks under global change

Present day carbon dioxide fluxes in the coastal ocean and possible feedbacks under global change

sink of atmospheric CO 2 in open oceans of 1.4 PgC yr -1 . These estimates are prone to large uncertainty mainly due to inadequate representation of the spatial variability and need to be improved based on more data, requiring a concerted global observational effort. The potential feedbacks on increasing atmospheric CO 2 from changes in carbon flows in the coastal ocean could be disproportionately higher than in the open ocean. The changes in carbon flows and related potential feedbacks in the coastal ocean could be driven by 3 main processes: i) changes in coastal physics; ii) changes in land-used, waste water inputs, agricultural fertilizers and changes in hydrological cycle; iii) changes in seawater carbonate chemistry (ocean acidification). These potential feedbacks remain largely unquantified due to a poor understanding of the underlying mechanisms, or lack of modelling to quantify them. Based on reported evaluations and back of the envelop calcula- tions, it is suggested that changes of biological activity due the increased nutrient delivery by rivers would provide by 2100 a negative feedback on increasing atmo- spheric CO 2 of the order of magnitude of the present day sink for atmospheric CO 2 . This negative feedback on increasing atmospheric CO 2 would be one order of magnitude higher than negative feedback due to the decrease of either pelagic or benthic calcification related to ocean acidification, and than the negative feedback related to dissolution of CaCO 3 in sediments. The increase of export production could also provide a significant feedback to increasing atmospheric CO 2 , although based on the conclusions from a single perturbation experiment. Feedbacks on increasing atmospheric CO 2 due to effects of C cycling in continental shelf seas related to changes in circulation or stratification could be important but remain to be quantified.
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Carbon dioxide dynamics and fluxes in coastal waters influenced by river plumes

Carbon dioxide dynamics and fluxes in coastal waters influenced by river plumes

Time and again, the East China Sea (ECS) has been found to be a sink of CO 2 (Chen and Wang 1999 ; Tsunogai et al. 1999 ; Chou et al. 2009 a; Zhai and Dai 2009 ; Tseng et al. 2011 ). This is in part because the Changjiang River not only exports a significant amount of nutrients to the ECS but also a large quantity of freshwater, which also helps to induce an estuarine type flow. That is, the lighter, fresher water flows out of the shelf on the surface, whereas the subsurface, nutrient-rich waters upwell onto the shelf (Chen and Wang 1999 ; Chen et al. 2008 ). The high biological production associated with nutrients brought by the river and this upwelling reduces the pCO 2 in surface waters to below
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Terrestrial and fluvial carbon fluxes in a tropical watershed: Nyong basin, Cameroon

Terrestrial and fluvial carbon fluxes in a tropical watershed: Nyong basin, Cameroon

The Nyong River is the second largest river in Cameroon, with a drainage basin of 27 800 km 2 . The entire basin is within tropical latitudes, between 2°48 ′N to 4°32′N and 9°54′E to 13°30′E. In this study, six sub-basins were sampled every two weeks from April 28, 2005 to April 16, 2007: the small watershed of the Mengong at Nsimi, the Awout watershed (tributary of the So'o) at Messam, the So'o watershed (tributary of the Nyong) at Pont So'o, the Nyong at Mbalmayo, Olama (after the con fluence with the So'o), and down- stream at Edea ( Fig. 1 ). Samples were also collected at the source of the Mengong from a spring, which provides approximately 20% of this tributary's water supply ( Ndam Ngoupayou, 1997 ). The geographic and hydrologic characteristics of these six sub-basins are summarized in Table 1 .
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The impact of lateral carbon fluxes on the European carbon balance

The impact of lateral carbon fluxes on the European carbon balance

as a result of anthropogenic loads increasing the DOC, en- hancing aquatic respiration, and increasing pCO 2 (Neal et al., 1998; Abril et al., 2000). In contrast, northern headwa- ters (e.g. Scottish peatlands) show low pCO 2 values and very high DOC content. This is due to the more recalcitrant nature of DOC leached from old peat soils, and to the rapid evasion of CO 2 to the atmosphere in these fast flowing waters (Hope et al., 2001; Billet et al., 2004). In lakes, DOC is negatively correlated with water residence time, showing the predomi- nant role of microbial and photochemical oxidation (Tranvik, 2005). In some temperate eutrophic rivers, a seasonal and sometimes annual uptake of atmospheric CO 2 is observed (Fig. 6). Atmospheric carbon fixed by aquatic primary pro- duction is then transported downstream as organic carbon. The Loire River, for instance, transports large quantities of algal carbon which are mineralized in the estuarine turbidity maximum, leading to high CO 2 degassing (Meybeck et al., 1988; Abril et al., 2004). In fact, many European macrotidal estuaries behave as “hotspots” for CO 2 degassing, owing to the quantity of organic carbon they receive and to the long residence time of waters and suspended sediments (Frankig- noulle et al., 1998; Abril et al., 2002; Abril and Borges 2004). The relative scarcity of pCO 2 data in continental waters, and the high spatial and temporal variability, renders a bottom-up estimate at the EU-25 scale rather uncertain. In addition, the
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Climate-induced oceanic oxygen fluxes: Implications for the contemporary carbon budget

Climate-induced oceanic oxygen fluxes: Implications for the contemporary carbon budget

mitted to J. Geophys. Res., 2001) and has been used in a previous global warming study [Bopp et al., 2001]. [ 9 ] The model includes five reservoirs: phosphate, phytoplank- ton, zooplankton, dissolved organic matter, and particulate organic matter (POC). It explicitly represents plankton dynamics and the penetration of light into the euphotic zone. Phytoplankton growth depends on the local conditions of light, temperature, and vertical eddy diffusion, which acts to homogenize the concentration of phytoplankton cells throughout the entire mixed layer. Phytoplank- ton growth also depends on the local concentration of phosphate, which is the only limiting nutrient in the model. The model considers one class of zooplankton, feeding on both phytoplankton and POC. POC is assumed to sink at a constant rate of 5 m d 1 in the top 100 m of the water column. Part of the POC reaches 100 m depth and thereby contributes to particulate export production. Subsequently, these particles are exported and remineralized instantaneously at depth according to a power-law function derived from sediment trap fluxes [Suess, 1980].
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Carbon dioxide dynamics in Antarctic pack ice and related air-ice CO2 fluxes

Carbon dioxide dynamics in Antarctic pack ice and related air-ice CO2 fluxes

37 th International Liège Colloquium on Ocean Dynamics, GAS TRANSFER AT WATER SURFACES, May 2 - 6 2005 Carbon dioxide dynamics in Antarctic pack ice and related air-ice CO 2 fluxes D ELILLE B. 1 , A.J. T REVENA 2 , V. S CHOEMANN 3 , C. L ANCELOT 3 , D. L ANNUZEL 4 , M.-L. S AUVÉE 4 , J. DE J ONG 4 , B. T ILBROOK 5,6 , M. F RANKIGNOULLE 1 , A.V. B ORGES 1 , J.-L. T ISON 2

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The effects of teleconnections on carbon fluxes of global terrestrial ecosystems

The effects of teleconnections on carbon fluxes of global terrestrial ecosystems

4. Conclusions Previous studies have suggested that large-scale atmospheric circulation patterns may provide a framework to simplify the study of the link between climate and ecological variability. However, most of these studies have focused on one single teleconnection, generally ENSO (at the global scale), or NAO (in Eurasia). Our study provides a comprehensive analysis of the effects of TCs on variations of global and regional terrestrial ecosystem carbon fluxes. Our results reveal that ENSO, PDO, and to a lesser extent AMO dominate variability in global, hemispherical, and continental carbon fluxes and climatic variables, while the Northern Hemisphere TCs show more regional in fluences. Several communities have found it useful to rely on telecon- nection indices to evaluate ecological and environmental variability from local to global scales [Bastos et al., 2013; Bastos et al., 2016; Cho et al., 2014; Hallett et al., 2004]. The global picture of the spatial distribution of dominant teleconnections described here provides insights on selecting the most suitable teleconnection for local to regional biological studies. For example, our results suggest that AMO is the best teleconnection to analyze seasonal variation of GPP in the Tibetan Plateau and might be a potential driving mechanism of the Sahel regreening [Dardel et al., 2014]. We investigated the mechanisms linking the dominant teleconnec- tion and GPP variations through three key climate conditions, i.e., air temperature, precipitation, and radia- tion (cloud cover as proxy). We find that TCs may be linked to variations in the carbon fluxes through, in general, their control on more than one climate variable. This highlights the potential of these patterns to better represent variability in ecosystem activity since they aggregate the combined variability patterns of temperature, water, and radiation.
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Combining flow-MRI method and modeling approach to assess water fluxes in tomato plant architecture

Combining flow-MRI method and modeling approach to assess water fluxes in tomato plant architecture

Combining flow-MRI method and modeling approach to assess water fluxes in tomato plant architecture Jeanne Simon1,2, Maïda Cardoso 2, Eric Alibert 2, Pierre Valsesia 1, Gilles Vercambre 1, Jean-Luc Verdeil 3, Christophe Coillot 2, Christophe Goze-Bac 2 and Nadia Bertin 1 Water and carbon status throughout growth and development are tightly controlled by the plants and are key components of their response to environmental stresses. Measuring and predicting resource availability and transport within intact plants is a challenge.
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Systematic study of the impact of fresh water fluxes on the glacial carbon cycle

Systematic study of the impact of fresh water fluxes on the glacial carbon cycle

4 Conclusions In conclusion, we have explored the impact of different fresh water fluxes in several climate background states with the CLIMBER-2 model. The duration, amplitude, and shape of the fresh water flux all modulate the evolution of the ocean circulation and the carbon cycle. The longer or greater the flux, the bigger the increase of atmospheric CO 2 is. How- ever, they cannot explain the differences obtained in differ- ent models, i.e. why in some models the ocean takes up carbon while the vegetation releases it and the opposite in other models. In CLIMBER-2 the AMOC takes time before it recovers, which can lead to a greater role of the deeper ocean. The different background states have an important impact on the carbon cycle, especially as the carbon inven- tories in the ocean, terrestrial biosphere and atmosphere are different. Taking into account the sinking of brines in the Southern Ocean in a glacial climate allows CO 2 to start from a value which is closer to proxy data and gives a more simi- lar evolution compared to the ice core records. The location of the fresh water flux has a strong impact on the evolution of the carbon cycle as it results in a very different climatic response. In CLIMBER-2 it leads to a decrease of CO 2 con- trary to the addition of fresh water in the Northern Hemi- sphere. Finally, as shown by previous studies, the response of the carbon cycle strongly depends on a close interplay be- tween the ocean and vegetation responses. The results are very model dependent, both because of the response of the AMOC to the addition of fresh water and because of the cli- matic response to this fresh water flux. A better understand- ing of these differences will require an intercomparison of the impact of the addition of fresh water in carbon-climate models, using a well-defined common experimental setup.
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Barium and carbon fluxes in the Canadian Arctic Archipelago.

Barium and carbon fluxes in the Canadian Arctic Archipelago.

exported from the surface layer is respired in the subsurface layer. We considered two estimates for the respiration of organic matter in the subsurface water column: (a) derived from an inorganic carbon budget (3.8 mol C m −2 yr −1 [Shadwick et al., 2011b]), and (b) using an estimate of the water column inventory of respired DIC according to Shadwick et al. [2011a]. The latter approach was applied to our investigation area, yielding an inventory of 4.1 mol C m −2 . Given an 18‐month residence time for water below the surface layer, as estimated from a set of hydrographic moorings in the Amundsen Gulf in 2003–2004 [Lanos, 2009], this corresponds to an annual production of 2.7 mol C m −2 yr −1 for respiratory DIC. The particulate marine and terrestrial organic carbon flux out of the subsurface layer was estimated according to Forest et al. [2008, Figure 8b]. This flux estimate, although from a slightly different area, covers almost a full year of observations, compared to that of Forest et al. [2011], which cover the period February to July. The extended temporal coverage by Forest et al. [2008] is of particular relevance, since our study, and Forest et al. [2008], reveal maximum C‐export values during summer and autumn (Figure 10), a period not covered by Forest et al. [2011]. The benthic respiration was estimated from the par- ticle and sediment biogeochemical study of Renaud et al. [2007] using their average sediment oxygen demand of 5 mmol O 2 m −2 d −1 . When an O 2 consumption to metabolic
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NET SEDIMENTATION AND SEDIMENT-WATER NUTRIENT FLUXES IN THE EASTERN GULF OF FINLAND (BALTIC SEA)

NET SEDIMENTATION AND SEDIMENT-WATER NUTRIENT FLUXES IN THE EASTERN GULF OF FINLAND (BALTIC SEA)

- Variation in the nutrient concentrations of sédiment between the différent accumulation areas, magnitude of net sédimentation and flux of nutrients from sédiment [r]

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Spatial variability and controls over biomass stocks, carbon fluxes, and resource-use efficiencies across forest ecosystems

Spatial variability and controls over biomass stocks, carbon fluxes, and resource-use efficiencies across forest ecosystems

Table S2: Stand age, mean biomass and its distribution among boreal, temperate, Mediterranean,. 808[r]

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