Browsing by Subject "SEQUESTRATION"

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    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: An expert assessment
    (Environmental Research Letters, 2016-03-07) Abbott, BW; Jones, JB; Schuur, EAG; Chapin, FS; Bowden, WB; Bret-Harte, MS; Epstein, HE; Flannigan, MD; Harms, TK; Hollingsworth, TN; Mack, MC; McGuire, AD; Natali, SM; Rocha, AV; Tank, SE; Turetsky, MR; Vonk, JE; Wickland, KP; Aiken, GR; Alexander, HD; Amon, RMW; Benscoter, BW; Bergeron, Y; Bishop, K; Blarquez, O; Bond-Lamberty, B; Breen, AL; Buffam, I; Cai, Y; Carcaillet, C; Carey, SK; Chen, JM; Chen, HYH; Christensen, TR; Cooper, LW; Cornelissen, JHC; De Groot, WJ; Deluca, TH; Dorrepaal, E; Fetcher, N; Finlay, JC; Forbes, BC; French, NHF; Gauthier, S; Girardin, MP; Goetz, SJ; Goldammer, JG; Gough, L; Grogan, P; Guo, L; Higuera, PE; Hinzman, L; Hu, FS; Hugelius, G; Jafarov, EE; Jandt, R; Johnstone, JF; Karlsson, J; Kasischke, ES; Kattner, G; Kelly, R; Keuper, F; Kling, GW; Kortelainen, P; Kouki, J; Kuhry, P; Laudon, H; Laurion, I; MacDonald, RW; Mann, PJ; Martikainen, PJ; McClelland, JW; Molau, U; Oberbauer, SF; Olefeldt, D; Paré, D; Parisien, MA; Payette, S; Peng, C; Pokrovsky, OS; Rastetter, EB; Raymond, PA; Raynolds, MK; Rein, G; Reynolds, JF; Robards, M; Rogers, BM; Schdel, C; Schaefer, K; Schmidt, IK; Shvidenko, A; Sky, J; Spencer, RGM; Starr, G; Striegl, RG; Teisserenc, R; Tranvik, LJ; Virtanen, T; Welker, JM; Zimov, S
    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.
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    ItemOpen Access
    Estimates and determinants of stocks of deep soil carbon in Gabon, Central Africa
    (Geoderma, 2019-05-01) Wade, AM; Richter, DD; Medjibe, VP; Bacon, AR; Heine, PR; White, LJT; Poulsen, JR
    © 2019 Despite the importance of tropical forest carbon to the global carbon cycle, research on carbon stocks is incomplete in major areas of the tropical world. Nowhere in the tropics is this more the case than in Africa, and especially Central Africa, where carbon stocks are known to be high but a scarcity of data limits understanding of carbon stocks and drivers. In this study, we present the first nation-wide measurements and determinants of soil carbon in Gabon, a nation in Central Africa. We estimated soil carbon to a 2-m depth using a systematic, random design of 59 plots located across Gabon. Soil carbon to a 2-m depth averaged 163 Mg ha −1 with a CV of 61%. These soil carbon stocks accounted for approximately half of the total carbon accumulated in aboveground biomass and soil pools. Nearly a third of soil carbon was stored in the second meter of soil, averaging 58 Mg ha −1 with a CV of 94%. Lithology, soil type, and terrain attributes were found to be significant predictors of cumulative SOC stocks to a 2-m depth. Current protocols of the IPCC are to sample soil carbon from the surface 30 cm, which in this study would underestimate soil carbon by 60% and underestimate ecosystem carbon by 30%. A nonlinear model using a power function predicted cumulative soil carbon stocks in the second meter with an average error of prediction of 3.2 Mg ha −1 (CV = 915%) of measured values. The magnitude and turnover of deep soil carbon in tropical forests needs to be estimated as more countries prioritize carbon accounting and monitoring in response to accelerating land-use change.