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Baccini a 20150708_1730_upmc_jussieu_-_amphi_24

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Baccini a 20150708_1730_upmc_jussieu_-_amphi_24

  1. 1. Net Carbon Gain and Loss in the World's Tropical Vegetation: New Estimates for the 2003 – 2014 Period A. Baccini1,W. Walker1, L. Carvahlo2, D. Sulla-Menashe2, R. A. Houghton1 1The Woods Hole Research Center 2Boston University
  2. 2. Carbon density trajectories over time and space 2003 2014 • Time series approach based on “change point” analysis • For each 500 m x 500 m pixel we identify the trajectory of carbon density
  3. 3. Continuous spatially explicit carbon density change Gain Stable Loss Mg/ha Mg/ha Mg/ha Gain = 59.2 StdEr = 24.2 P-V = 0.041 Loss = -201.2 StdEr =8.4 P-V = 0.003 StdEr = 46.1 P-V = 0.99 190 km x 215 km
  4. 4. Consistent with deforestation and sensitive to “degradation” ? Deforestation Landsat baased (30 m resolution) Hansen et al. 2014 Gain Stable Loss Mg/ha Mg/ha Mg/ha 190 km x 215 km Gain = 59.2 StdEr = 24.2 P-V = 0.041 Loss = -201.2 StdEr =8.4 P-V = 0.003 StdEr = 46.1 P-V = 0.99
  5. 5. Annual Losses and Gains Net Loss (TgC y−1) Net Gain (TgC y−1) Net (TgC y−1) America 515.0±69.5 -191.2±18.2 324.8±73.5 Africa 205.0±24.7 -132.9±19.3 72.1±32.9 Asia 140.7±17.9 -112.4±10.3 28.2±21.5 Totals 860.7±80.2 -436.5±31.0 424.2±92.0
  6. 6. Carbon Density Gain • Carbon Density Gain have rarely been estimated with exception of Philips et al. 1998, Baker et al. 2004 • Estimates across 59 samples in old-growth forest report net uptake of 0.61 and 0.91 (only gain samples) MgC ha-1 • This study reports 0.78 (old-growth), 0.95 (all forests) MgC ha-1
  7. 7. Frequency Distribution of Changes 15.1 19.0 11.4 22.2 11.2 15.5
  8. 8. Annual Carbon Loss-Gain-Net Trajectories America AsiaAfrica IndonesiaCongo DRCBrazil
  9. 9. Summary • Losses exceed gains on every continent. Tropical forests are a net source of 424.2 ± 92.0 Tg C yr-1 of which 59.8 % is attributable to America, 23.8 % to Africa, and 16.3 % to Asia. • Annual analysis indicates a general upward trend of net sources coming from tropical forests • Sensitive to losses (deforestation, degradation, natural disturbance) and gain (growth, reforestation, and afforestation)
  10. 10. Thank you!

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