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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
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
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
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
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
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
Frequency Distribution of Changes
15.1
19.0
11.4
22.2
11.2
15.5
Annual Carbon Loss-Gain-Net Trajectories
America Asia Africa
Indonesia Congo DRC Brazil
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)
Thank you!
