Spatial and Temporal Patterns of Carbon Exchanges between the Atmosphere and

Terrestrial Ecosystems of China

Hanqin Tian

Ecosystem and Regional Studies Group

Auburn University, AL 36849, USA &

NASA IDS Project Participants*

*The NASA IDS Project Participants:

• Jerry M. Melillo, David Kicklighter, Ben Felzer, The Ecosystem Center, Marine Biological Laboratory, Woods Hole, USA.

• Steven Running, Maosheng Zhao, Qiaozhen Mu, University of Montana, Missoula, USA.

• Jiyuan Liu, Guoyui Yu, Aifeng Lv, Chaoqun Lv, Wei Ren, Xiaofeng Xu, IGSNRR, Chinese Academy of Sciences, Beijing, 100101, China.

• Ranga Myneni, Yuri Knyazikhin, Nikolay Shabanov, Boston University, Boston, USA.

• Mingliang Liu, Shufen Pan, Hua Chen, Siqing Chen, Guangsheng Chen, Chi Zhang, Auburn University.

Sink and Source of CO2 by Regions as Estimated by Inverse Modeling Approach

Investigators & Sources

North America

Eurasia

Tropics

Fan et al. (1998) (CMC, USA)

1.7 ± 0.5

0.1 ± 0.6

-0.2 ± 0.9

Rayner et al. (1999)

(CRCSHM, Australia)

0.5

0.2

0.0

Bousquet et al. (1999)

(LSCE, France)

0.5 ± 0.6

1.8

-1.1

– The US carbon sink: Forest inventory, bookkeeping model--land use change, and inverse model (Birdsey and Health, 1995, Houghton et al. 1999, Capersen et al. 2000, Pacala et al. 2001) (0.3-0.58 Pg/yr).

– The Eurasian carbon sink has received less attention.

IPCC TAR (Prentice et al. 2001): both North America and Eurasia served as carbon sinks during the 1990s, suggesting a net sink of 1-2.5 Pg C yr-1 that is distributed relatively evenly between North America and Eurasia.

From both scientific and policy perspectives, it is of critical importance to quantify regional carbon budget and mechanisms controlling the carbon cycle.

We haven’t succeeded in answering all problems. The answers we have found only serve to raise a whole set of new questions. In some ways, we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things.

Everything about China, good or bad, is BIG!

China is the world’s third largest country, the most rapidly developing nation and home to 1.3 billion people. Since the early 1980s, the unprecedented combination of economic and population growth has led to a dramatic land transformation across the nation. China is “Natural Laboratory” for studying dynamics of coupled natural and human systems as well as the carbon cycle.

Total Population: 1,306,313,812 (July 2005 est.)

Population distribution of 2000 in China(cell size = 1 km, Unit: persons per km2)

0 – 2

2-5

5-10

10-30

30-50

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100-200

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1200-1300

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1400-1500

1500-1600

1600-1700

1700-1800

1800-1900

1900-2000

2000-2200

> 2200

1950 1970 1978 1990 2000 2002 2020

1317 18

27

3537

60

Ch

ines

e P

op

ula

tio

n u

rba

niz

ed

(%

)

Rapid urbanization in China

Liu, J., H.Q. Tian, M. Liu, D. Zhuang, J.M. Melillo and Z. Zhang (2005). Geophys. Res. Lett., 32, L02405, doi:10.1029/2004GL021649.

Large-scale land transformation estimated with satellite data

OBJECTIVES:

Our study will be organized by two linked questions:

Q1 - HOW HAVE PRIMARY PRODUCTION AND CARBON STORAGE CHANGED IN CHINA OVER THE PAST TWO DECADES?

Q2 - WHAT MECHANISMS HAVE HAD MAJOR EFFECTS ON CHANGES IN THESE FLUXES AND STOCKS? We will consider the relative roles of: (a) climate variability, (b) changes in land cover and use, (c) changes in fire disturbance, (d) changes in the chemistry of precipitation (particularly nitrogen), and (e) changes in the composition of the atmosphere (carbon dioxide, ozone).

APPROACHES:

Here we try to combine remote-sensing data (MODIS, AVHRR, Landsat-TM/ETM) and a set of biogeochemical simulation models (TEM, Biome-BGC and A new model) to quantify the consequences of land transformations and other environmental changes on productivity in forests and other “natural” ecosystems and carbon sequestration.

Satellite Data

Eddy Flux

Ecosystem Experiments

Flask Data

MeasuringModeling

Synthesis

The Integrated Approach Quantifying Regional C Dynamics

BIOME-BGC

The Terrestrial Ecosystem Model (TEM)

A New Model of Coupled Biogeochemical Cycles

Data Development• Climate

• Land use history

• O3

• CO2

• Other data: elevation, soil texture, potential vegetation

1900 2000

18001700

Historical Cropland & Urban area distribution (10 X 10 km)

1961-2000 Annual mean temperature (0.1℃)

1961-2000 Average annual precipitation(0.1mm)

Mean annual N deposition in 1990s in China (mg N/m2)

Mean surface O3 concentration in 1990s in China (Unit: D40)

19881989199019911992199319941995199619971998199920002001

Simulation Experiments

1. Climate Only

2. CO2 only3. Land use only

4. O3 only5. Climate + Land use

6. Climate + CO2 + Land Use

7. Climate + CO2 + O3

8. Climate + CO2 + O3 + Land use

TEM-based estimate on vegetation and soil carbon in 2000 (Climate_CO2_LUCC_O3)

Vegetation CarbonSoil Organic Carbon

gC/m2gC/m2

Change in total carbon storage (gC/m2)

1980-2000

1860-2000

Mean annual Net Carbon Exchange (1981-1990) (gC/m2/yr)

Mean annual Net Carbon Exchange (1991-2000) (gC/m2/yr)

Ozone effect on carbon storage during 1860-2000 (gC/m2)

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.619

80

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

Climate_CO2_LUCC_O3

LUCC only

Climate only

CO2 only

O3 only

Annual Net Carbon Exchange (PgC/yr)

-16.0

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

1860

1865

1870

1875

1880

1885

1890

1895

1900

1905

1910

1915

1920

1925

1930

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1945

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1985

1990

1995

2000

CO2 only

LUCC only

O3 only

Climate only

Climate_CO2_LUCC_O3

Cumulative Net Carbon Exchange (Pg C)

Relative contribution of CO2, climate, land use and O3 to carbon fluxes during 1981-2000 (Pg C/yr)

Annual NPP, HR, NEP and NEE trends during 1961-2000 derived from Biome-BGC.

NPP RH

NEP NEE

Decadal variations in carbon emission induced by forest fires across China

a) Mean AVHRR NPP from 1982-2000 b) NPP trend from 1982-2000 c) Mean MODIS NPP d) Mean NPP as estimated by a new model.

a. b. c.

d.

CH4 emission from cropland derived from a new coupled biogeochemical model

1980 2000

Summary• The combined effect of climate, CO2, land use and O3 on net carbon exchange show that terrestrial China acted as a small carbon sink ( 64 Tg C per year) during 1980-2000, but showing substantial year-to-year variation.

• For the time period from 1980 to 2000, both land use and CO2 resulted in carbon uptake while climate and O3 led to carbon release. During 1860-2000, however, land-use change resulted in a large release of carbon to the atmosphere (about 12 Pg C).

• CH4 emission from agricultural land varied from 6 to 16 Tg C per year. Fire-induced carbon emission is about 11.3 Tg C per year.

• In any year over the period 1980-2000, net carbon exchange can be very large in one location but very small or negative in another location because of the spatial heterogeneity of vegetation, soils and climate.

• Additional factors needed to be considered include N deposition, Forest management and agronomic practices.

• In the future, Model intercomparison needs to be done. Also modeled results need to be evaluated against field data.

ACKNOWLEDGMENT

This study is supported by NASA

Interdisciplinary Science Program

(NNG04GM39C).