Transcript Presentation - Global Carbon Project

The carbon balance of
terrestrial ecosystems in China
during the 1980s and 1990s
Shilong Piao, Jingyun Fang, Philippe Ciais,
Philippe Peylin, Yao Huang, Stephen Sitch, Tao Wang
April 2009
1
Regional C budget (hi)story
 in 1998, a very controversial study by Fan et al. finds a huge NA sink
‘seen from the atmosphere’ (1.7 Pg C / yr)
 in 2001, Pacala et al. estimate C budget in USA (0.3-0.58 Pg C / yr)
 in 2003, Janssen et al. estimate C budget in Europe (0.14-0.21 PgC/yr)
in 2007, Stephens et al. Estimate a NH sink of 1.5 ± 1.5 Pg C / yr
much smaller than in prevous inversions studies -> this call for an
assessment using bottom up data
 China?
2
Spatial distribution climae
Mean annual temperature
Annual Precipitaion
3
Distribution of vegetation types in China
4
Distribution of NPP in China
70
80
90
100
110
120
130
140
45
40
35
30
25
NPP (gC / m2 / yr)
20
15
0-10
10-20
20-50
50-100
100-200
200-300
300-500
500-700
700-1000
5
Afforestation/reforestation projects
-China contributed about one quarter of the
global plantation area.
-Forest plantation benefit net carbon
uptake
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Kauppi et al., (2006)
Significant climate change
Temperature change
Precipitation change
- During the past two decades, mean annual temperature over China increased by more than 0.5 ºC/decade.
- Warmer-dryer in the North and warmer-wetter in the South where most productive ecosystems are
distributed.
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Based on CRU climate data (Mitchell et al., 2003)
Grassland
Shrub
HOW DID CARBON STORAGE RESPOND TO
CLIMATE AND HUMAN DISTURBANCE
OVER THE PAST 20-YEARS?
Forest
Crop
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Methods used in this study
1000 km
Upscaling
Prediction
Atmospheric inverse Model
10 km
ha
dm
Downscaling
Verification
+ Integration by modeling (Moses-Triffid;
LPJ; Sheffield-DGVM; Hyland; ORCHIDEE) 9
Datasets
1. Forest inventories and field biomass data
~200,000 permanent and temporary sample plots, 5 periods: 1977-81,
1984-88, 1989-93, 1994-98, 1999-2004
2. Grassland biomass inventory data
3. Cropland SOC survey data, statistics for crop yield,
area, and others
4. NDVI datasets
The NDVI data were from the GIMMS (Global Inventory Monitoring and
Modeling Study) group derived from NOAA/AVHRR land dataset, with 8 km
resolution for each 15 days from 1981 to 1999.
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Inventory and satellite based estimation
Forest
75±35 Tg
C/yr
Grassland
Crop
7±3 Tg C/yr
13±1 Tg C/yr
22±10 Tg
C/yr
26±11 Tg
C/yr
39±9 Tg C/yr
vegetation
4±4 Tg C/yr
6±1 Tg C/yr
Soil
Fire
Total net C balance
(?)
- 3 Tg C/yr
Shrub
Bamboo
1±1 Tg C/yr
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Inventory and satellite based estimation
Forest
75±35 Tg
C/yr
Grassland
Crop
7±3 Tg C/yr
13±1 Tg C/yr
22±10 Tg
C/yr
26±11 Tg
C/yr
39±9 Tg C/yr
vegetation
4±4 Tg C/yr
6±1 Tg C/yr
Soil
Fire
177±73 Tg =
C/yr
- 3 Tg C/yr
Shrub
Bamboo
1±1 Tg C/yr
Limitations: Not included wetland; trees out forests (four-side trees and individual
tress)
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Atmospheric inversion estimation
Prior flux information
LMDZ transport model
observations
Optimized fluxes
Limitations: scarce
atmospheric netwrork
(only 9 sites in North
Asia) and uncertainty
from transport model
The mean result of the
inversion ensemble over
the period 1996 – 2004 is a
net CO2 uptake of 0.35 Pg
C/yr.
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The link between inventory and atmospheric inversion estimation
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Carbon balance of Chinese terrestrial ecosystems
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Spatial distribution of the C balance in China
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Comparison of C balance in different regions
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NEP vs. fossile fule CO2 emission
Raupach et al., (2007)
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Why large C sinks?
●
●
large-scale reforestation
changes of energy consumption
structure and vegetation recovery
●
intensive agriculture practices
●
regional climate changes
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(i) Reforestation and afforestation
China is the largest country with planted forests, about 1/4 of total
global plantations (FAO, 2001)
Countries with the largest proportion of the
world’s forest plantations, 2000
% of total global plantation area
FAO (2001)
▲
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(ii) Change of energy consumption strucure and
recovery of vegetation
In the last 30 yrs, firewood, charcoals, and crop straws that had been
used as major energy sources in the most rural areas have been steadily
replaced with fossil fuels. This on the one hand has increased the
consumption of fossil fuels, but it accelerated the recovery of vegetation,
especially of scrubs.
Movement of rural residents to cities reduced pressure to nature.
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(iii) Intensive agriculture practices
expansion of straw incorporation, shallow plowing, irrigation, and
no-till farming have increased C sequestration in agricultural soils.
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(iv) Regional climate changes
Inter-annual changes in
seasonal precipitation
Despite no significant change
in annual rainfall, summer
precipitation in China has
significantly increased by 2.5
mm each year over the last 2
decades.
Summer
Spring
Autumn
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Conclusions
• Comprehensive estimate of Chinese ecosystems carbon budget
• A carbon sink of 0.19 to 0.26 Pg C / yr
Offsets ≈ 28-37% of emissions over 1980-2000
Offsets ≈ 16-22% of emissions over 2001-2005
• 50% forest; up to 30% in shrublands
• More than 65% of the sinks are distributed in southern China
owing to regional climate change, reforestation and afforestatioin
programmes acive, and shrubland recovery.
• Recent trends in agricultural practice also cause an increase in
carbon sequestration.
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References
•
Janssens IA. et al. (2003), Europe's terrestrial biosphere absorbs 7 to 12% of
European anthropogenic CO2 emissions. Science, 300, 1538-1542.
•
Kauppi PE, Ausuble JH, Fang JY, Mather A, Sedjo RA, Waggoner PE (2006),
Returning forest analyzed with the forest identity. PNAS, 103, 17574-17579
•
Mitchell TD, Jones PD (2005), An improved method of constructing a
database of monthly climate observations and associated high-resolution
grids. Int. J. Climatol, 25, 693-712
•
Pacala SW et al. (2001), Consistent land- and atmosphere-based US carbon
sink estimates. Science, 292, 2316-2320.
•
Piao SL, Fang JY, Ciais P, Peylin P, Huang Y, Sitch S, Wang T (2009), The
Carbon balance of terrestrial ecosystems in China. Nature,
doil:10.1038/nature07944 [in press]
•
Raupach MR, Marland G, Ciais P, LeQuere C, Canadell JG, Klepper G, Field
CB (2007), Global and regional drivers of accelarating CO2 emissions. PNAS,
104, 10288-10293
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Thank you!
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