Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration

Ciais, Philippe; Yao, Yitong; Gasser, Thomas; Baccini, Alessandro; Wang, Yilong; Lauerwald, Ronny; Peng, Shushi; Bastos, Ana; Li, Wei; Raymond, Peter A.; Canadell, Josep G.; Peters, Glen P.; Andres, R.J.; Chang, Jinfeng; Ye, Chao; Dolman, A. J.; Haverd, Vanessa; Hartmann, Jens; Laruelle, Goulven Gildas; Konings, Alexandra G.; King, A. W.; Liu, Yi; Luyssaert, Sebastiaan; Maignan, Fabienne; Patra, Prabir K.; Peregon, Anna; Regnier, Pierre; Pongratz, Julia; Poulter, Benjamin; Shvidenko, А.; Valentini, Riccardo; Wang, Rong; Broquet, Grégoire; Yin, Yi; Zscheischler, Jakob; Guenet, Bertrand; Goll, Daniel S.; Ballantyne, A. P.; Yang, Hui; Qiu, Chunjing; Zhu, Dan

doi:10.1093/nsr/nwaa145

Cited by 94 publications

(101 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This value is assumed to represent the water level over the riverbanks at which the maximum horizontal extent of floodplain inundation is reached. We then ran the model for a final time and validated the outputs against discharge data at Brazzaville (Cochonneau et al, 2006;Fig. 1).…”

Section: Calibration Of Hydrologymentioning

confidence: 99%

See 1 more Smart Citation

Historical and future contributions of inland waters to the Congo Basin carbon balance

et al. 2021

Self Cite

View full text Add to dashboard Cite

Abstract. As the second largest area of contiguous tropical rainforest and second largest river basin in the world, the Congo Basin has a significant role to play in the global carbon (C) cycle. For the present day, it has been shown that a significant proportion of global terrestrial net primary productivity (NPP) is transferred laterally to the land–ocean aquatic continuum (LOAC) as dissolved CO2, dissolved organic carbon (DOC), and particulate organic carbon (POC). Whilst the importance of LOAC fluxes in the Congo Basin has been demonstrated for the present day, it is not known to what extent these fluxes have been perturbed historically, how they are likely to change under future climate change and land use scenarios, and in turn what impact these changes might have on the overall C cycle of the basin. Here we apply the ORCHILEAK model to the Congo Basin and estimate that 4 % of terrestrial NPP (NPP = 5800±166 Tg C yr−1) is currently exported from soils and vegetation to inland waters. Further, our results suggest that aquatic C fluxes may have undergone considerable perturbation since 1861 to the present day, with aquatic CO2 evasion and C export to the coast increasing by 26 % (186±41 to 235±54 Tg C yr−1) and 25 % (12±3 to 15±4 Tg C yr−1), respectively, largely because of rising atmospheric CO2 concentrations. Moreover, under climate scenario RCP6.0 we predict that this perturbation could continue; over the full simulation period (1861–2099), we estimate that aquatic CO2 evasion and C export to the coast could increase by 79 % and 67 %, respectively. Finally, we show that the proportion of terrestrial NPP lost to the LOAC could increase from approximately 3 % to 5 % from 1861–2099 as a result of increasing atmospheric CO2 concentrations and climate change. However, our future projections of the Congo Basin C fluxes in particular need to be interpreted with some caution due to model limitations. We discuss these limitations, including the wider challenges associated with applying the current generation of land surface models which ignore nutrient dynamics to make future projections of the tropical C cycle, along with potential next steps.

show abstract

Section: Calibration Of Hydrologymentioning

confidence: 99%

“…Seasonality of simulated versus observed discharge at (a) Brazzaville on the Congo (for the 1990-2005 monthly mean;Cochonneau et al, 2006), (b) Bangui on the Oubangui (2010-2012;Bouillon et al, 2014), and (c) flooded area in the central (approx. 200 000 km 2 ) part of the Cuvette Centrale wetlands versus GIEMS…”

mentioning

confidence: 99%

Historical and future contributions of inland waters to the Congo Basin carbon balance

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Nevertheless, some key mechanisms are still missing in most of those models, including lateral fluxes of C from the land to ocean. It has been hypothesized that the exclusion of lateral C transfers in land surface components of ESMs implies a significant overestimation of soil heterotrophic respiration and/or C accumulation in global C budget accounting (Ciais et al, 2020; Jackson et al, 2002; Janssens et al, 2003). With state‐of‐the‐art ESMs such as those used for the 5th assessment report of the IPCC (Ciais et al, 2013), the non‐representation of lateral C transfers may thus induce a biased quantification of the land C sink and its response to changing CO 2 and climate (Janssens et al, 2003; Walsh et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance

Nakhavali

Lauerwald

Regnier

et al. 2020

Global Change Biology

Self Cite

View full text Add to dashboard Cite

The leaching of dissolved organic carbon (DOC) from soils to the river network is an overlooked component of the terrestrial soil C budget. Measurements of DOC concentrations in soil, runoff and drainage are scarce and their spatial distribution highly skewed towards industrialized countries. The contribution of terrestrial DOC leaching to the global‐scale C balance of terrestrial ecosystems thus remains poorly constrained. Here, using a process based, integrative, modelling approach to upscale from existing observations, we estimate a global terrestrial DOC leaching flux of 0.28 ± 0.07 Gt C year−1 which is conservative, as it only includes the contribution of mineral soils. Our results suggest that globally about 15% of the terrestrial Net Ecosystem Productivity (NEP, calculated as the difference between Net Primary Production and soil respiration) is exported to aquatic systems as leached DOC. In the tropical rainforest, the leached fraction of terrestrial NEP even reaches 22%. Furthermore, we simulated spatial‐temporal trends in DOC leaching from soil to the river networks from 1860 to 2010. We estimated a global increase in terrestrial DOC inputs to river network of 35 Tg C year−1 (14%) from 1860 to 2010. Despite their low global contribution to the DOC leaching flux, boreal regions have the highest relative increase (28%) while tropics have the lowest relative increase (9%) over the historical period (1860s compared to 2000s). The results from our observationally constrained model approach demonstrate that DOC leaching is a significant flux in the terrestrial C budget at regional and global scales.

show abstract

“…Besides, the definition of the presented τ veg in our study did not account for the turnover of disturbance processes, such as fire, grazing (fGrazing) and wood products (fWood). The global estimates of fGrazing and fWood were obtained from Ciais et al (2020); they were 0.7 and 1.0 Pg C year −1 , respectively. When accounting for carbon loss via all the disturbances and excluding pixels with extensive land use changes (see Section 2), global τ veg was estimated to be 9.7 years (based on the mean cVeg from Carvalhais et al, 2014 and Liu et al, 2015) and 8.4 years (based on the cVeg from Carvalhais et al, 2014 only).…”

Section: Discussionmentioning

confidence: 99%

Data‐driven estimates of global litter production imply slower vegetation carbon turnover

Wang

et al. 2021

Global Change Biology

Self Cite

View full text Add to dashboard Cite

Accurate quantification of vegetation carbon turnover time (τveg) is critical for reducing uncertainties in terrestrial vegetation response to future climate change. However, in the absence of global information of litter production, τveg could only be estimated based on net primary productivity under the steady‐state assumption. Here, we applied a machine‐learning approach to derive a global dataset of litter production by linking 2401 field observations and global environmental drivers. Results suggested that the observation‐based estimate of global natural ecosystem litter production was 44.3 ± 0.4 Pg C year−1. By contrast, land‐surface models (LSMs) overestimated the global litter production by about 27%. With this new global litter production dataset, we estimated global τveg (mean value 10.3 ± 1.4 years) and its spatial distribution. Compared to our observation‐based τveg, modelled τveg tended to underestimate τveg at high latitudes. Our empirically derived gridded datasets of litter production and τveg will help constrain global vegetation models and improve the prediction of global carbon cycle.

show abstract

Empirical estimates of regional carbon budgets imply reduced global soil heterotrophic respiration

Cited by 94 publications

References 84 publications

Historical and future contributions of inland waters to the Congo Basin carbon balance

Historical and future contributions of inland waters to the Congo Basin carbon balance

Leaching of dissolved organic carbon from mineral soils plays a significant role in the terrestrial carbon balance

Data‐driven estimates of global litter production imply slower vegetation carbon turnover

Contact Info

Product

Resources

About