Environmental Pollution 116 (2002) S157–S165
www.elsevier.com/locate/envpol
Carbon storage in northeast China as estimated from vegetation and
soil inventories
Shaoqiang Wanga,b,*, Chenghu Zhoub, Jiyuan Liub, Hanqin Tianb,c, Kerang Lib,
Xiaomei Yangd
a
Laboratory of Remote Sensing Information Science, Institute of Remote Sensing Application, Chinese Academy of Sciences, Beijing 100101,
People’s Republic of China
b
The State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research,
Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
c
The Ecosystem Center, Marine Biological Laboratory, Woods Hole, MA 02543, USA
d
Earth Observation Research Center, National Space Development Agency of Japan, Hamamatsu-cho, Minato-ku, Tokyo 105-8060, Japan
‘‘Capsule’’: Carbon stocks in soil and vegetation in China are 2.81 PgC and 26.43 PgC respectively with the eastern and
northern regions showing the highest carbon storage potential.
Abstract
We have estimated the stocks of carbon in vegetation and soil in northeast China based on data for 122 plots from the fourth
national forest inventory, and for 388 soil profiles from the second national soil survey. The techniques of Geographic Information
System (GIS) have been used to extrapolate site-specific estimates of vegetation and soil organic carbon to the entire area of
northeast China. Our estimate indicates that the amount of carbon in vegetation and soil for the region are 2.81 PgC (1015g C) and
26.43 PgC, respectively, and that the area weighted average density of vegetation and soil organic carbon are 22.7 MgC/ha and
212.7 MgC/ha, respectively. The eastern and northern parts of the region show much higher carbon storage than the rest of the
region. Substantial spatial variations in vegetation and soil organic carbon across northeast China suggest that regional estimates on
carbon stocks and fluxes should take into account these spatial variations. We suggest that the methodology developed can be used
for the entire nation of China as well as other regions of the world. # 2001 Published by Elsevier Science Ltd. All rights reserved.
Keywords: Biomass; China; Soil organic carbon; Vegetation carbon; Terrestrial ecosystem
1. Introduction
Previous studies in the global carbon budget suggest
that terrestrial ecosystems in the mid-latitudes of the
Northern Hemisphere act as a large carbon sink of
atmospheric CO2 (Tans et al., 1990; Ciais et al., 1995).
In particular, recent analyses based on atmospheric CO2
observations and models further indicate that North
America acts as the largest carbon sink (Fan et al.,
1998), 1.7 PgC per year during 1988–1992. Other studies
show that North America C sink for the same period
was small (Field and Fung, 1999; Houghton et al., 1999;
Tian et al., 1999; Schimel et al., 2000). On the other
hand, an analysis by Bousquest et al. (1999) suggests
that a large carbon sink is located in northern Asia. To
reduce uncertainty in the carbon budget over the
regions requires quantifying contemporary carbon storage in terrestrial ecosystems (Brown et al., 1996; Tian
* Corresponding author. Fax: +86-10-6488-9630.
E-mail address: [email protected] (S. Wang).
et al., 1998). Accurately estimating carbon storage and
its dynamics in vegetation and soil is also important for
predicting how terrestrial ecosystem carbon pools may
change as climate and land use change in the future
(Melillo et al., 1996).
Terrestrial ecosystems in northeast China (> 40 N)
play an important role in the global carbon budget
(Bousquest et al., 1999), and are especially susceptible to
future land-use change and projected climate change
(Keeling et al., 1996; Tian et al., 2000). In this region,
the woodland area is about 57.63104 km2 and forest
cover area is about 30.35% of the whole region. Forests
provide about 50% of the wood supply for China.
Major vegetation types include coniferous and broadleaved deciduous forest, cropland, temperate steppe and
grassland. In the past decades, human activities including deforestation have significantly altered the structure
and functioning of ecosystems in this region (Tian et al.,
1995). These ecosystems also provide a good model for
understanding carbon cycling in human-modified ecosystems of other mid-latitude regions.
0269-7491/01/$ - see front matter # 2001 Published by Elsevier Science Ltd. All rights reserved.
PII: S0269-7491(01)00269-X
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S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
Some previous studies indicate that changing climate
and atmospheric composition could significantly influence the evolution of terrestrial ecosystems and biogeochemical cycling in China (Yan et al., 2000). Under a
doubled CO2 climate change scenario using GCMs and
Forest Gap Models (Deng et al., 2000; Yan et al., 2000),
some coniferous forest species would be replaced by
broadleaved forest species and the future warming rate
would determine the succession of broadleaved Pinus
koraiensis forest. However, little is known about the
carbon storage in terrestrial ecosystems of northeast
China, which has limited our capacity of evaluating the
carbon budget and predicting ecosystem response to
climate change. The goals of this study are: (1) to estimate carbon storage in northeast China based on data
from vegetation and soil inventories; (2) to analyze the
spatial variation in vegetation carbon and soil organic
carbon; and (3) to identify the key gaps in quantifying a
regional carbon budget.
2. Materials and method
2.1. Study region and materials
The study area covers about 124104 km2 in Northeast China (115 370 –135 50 E and 38 430 –53 340 N;
Fig. 1). In this area, major vegetation types on hills and
mountains are temperate broadleaved deciduous and
needle-leaved evergreen forest. The dominated vegetation types in the west parts of the region are semi-arid
shrubs, grass and temperate steppe. The area of cropland is about 20% of the whole region. The climate of
most of northeast China is classified as temperate monsoon climate in a majority of region, but the north over
50 N is classified as cold temperate monsoon climate.
Main soil types include the dark-brown earths, brown
coniferous forest soils, gleyed meadow soils, and calcic
chernozems. The long history of agricultural colonization coupled with increasing population density and
economic development has led to significant modification of land-cover types. Northeast China has abundant
natural resources including land resource, which can play
an important role in regional economic development.
To estimate vegetation carbon, we used biomass data
from 122 plots of the fourth national forest inventory,
and other published data in China, official documents
or technical reports (Fang et al., 1996a,b; Li et al., 1996,
1998; Wu et al., 1997; Wang et al., 1998a,b, 1999). To
estimate soil organic carbon, we used data on physical
and chemical variables for every soil stratum from 388
soil profiles of the second national soil survey (National
Soil Survey Office, 1995, 1998). Properties of vegetation
samples include geographical location, vegetation type,
soil type, forest age, land-use pattern, meteorological
index, and biomass. And properties of typical soil
profiles consist of geographical location, soil depth,
organic carbon concentration, altitude, color, consistency, texture, structure, vegetation, terrain position,
parent material, land-use pattern, meteorological index
and bulk density. The collected data were integrated and
analyzed by employing Geographical Information System (GIS) technology to determine the quantity and
spatial distribution of carbon in vegetation biomass
and soil storage of the region. A digital version of the
1:4,000,000 vegetation and soil maps of China was used
as the base map to display the spatial distribution of soil
carbon extent (Figs. 2 and 3). In this region the area of
cropland is about 30.6104 km2, or 24.7% of the total
(Fig. 3; Table 1).
2.2. Estimation of vegetation carbon
We estimated vegetation carbon over the region by
multiplying the area of each vegetation type by vegetation carbon density. We determine the area of vegetation from vegetation maps and statistical records
(Fig. 4). The estimation of vegetation carbon density is
mainly based on the standing biomass data observed in
the field. Standing aboveground biomass data for each
vegetation type was obtained from various published
reports or papers. Carbon content varies among vegetation types, and changes from season-to-season (Li et
al., 1996; Wu et al., 1997). Carbon conversion coefficients are different, considering species, age, formation
and community structure of vegetation types, from 0.45
to 0.55 (Olson et al., 1983; Fang et al., 1996a). In this
study, we used a carbon conversion coefficient of vegetation biomass of 50% (Brown and Lugo, 1984).
2.3. Estimation of soil organic carbon
The quantity of soil organic carbon was calculated by
using carbon density estimated from soil samples and
the total soil area (Post et al., 1982, 1990; Sampson et
al., 1993; Fang et al., 1996b). In this research, we are
able to take advantage of the large number of sampled
soil profiles by considering the physical and chemical
properties of every soil stratum. The laboratory analysis on the 388 soil samples provides reliable estimations
on organic matter concentration, measured soil depth
and bulk density for each soil type. The corresponding
soil organic carbon is subsequently converted from soil
organic content by using the conversion coefficient of
0.58 suggested by Fang et al. (1996b). Based on this
strategy, we firstly calculated the carbon content of
different soil depths in the same soil profile. Then, we
used the depth of each horizon as weighting coefficient
to derive the average physical and chemical properties
of the soil profiles. The average value of profiles was
further aggregated by classifying profiles into different
soil subtypes. Using the area of soil subtypes, and the
S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
Fig. 1. The location of Northeast China (left) and the spatial distribution of soil samples (right).
Fig. 2. The spatial distribution of vegetation types in Northeast China.
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S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
Fig. 3. The spatial distribution of soil types in Northeast China.
aggregated average depth, organic matter concentration and bulk density of different soil subtypes, the
total carbon quantity of a given soil type can be
calculated as:
Cj ¼ 0:58Sj Hj Oj Wj
ð1Þ
where j denotes the given soil type, C is the carbon storage, S is the distribution area, H is the average depth,
O is the average organic matter concentration, W is the
average bulk density.
3. Result and discussion
3.1. Stocks of vegetation and soil organic carbon
Vegetation carbon in northeast China is 2.81 Pg C,
while the average vegetation carbon density is 22.7
MgC/ha. The carbon density in forests is higher than
that of steppes, deserts, meadow and crops (Table 2).
Among forest vegetation types, the carbon density in
needle-leaved evergreen forest on mountains in temperate is the highest, about 110.2 MgC/ha, while the car-
bon density of microphyllous deciduous woodland in
temperate zone is the lowest, about 45.5 MgC/ha. The
carbon density of cold temperate and temperate forests
is relatively high because most of these forests are
mature (Fang et al. 1996a,b). Among non-forest vegetation types, the carbon density of broadleaved deciduous scrub in temperate zone is the highest, about 10.4
MgC/ha and that of temperate needlegrass steppe is the
lowest, about 0.5 MgC/ha.
The carbon storage of needle-leaved deciduous forest
in cold-temperate or on mountains in temperate zone is
the highest, about 0.94 Pg C, but carbon storage of
needle evergreen forest in temperate zone is the lowest,
about 0.04 Pg C because of its smallest area (Table 2).
The vegetation carbon in forests is 2.19 Pg C, or about
77.9% of total vegetation carbon pool in northeast
China. The area of agriculture is about 24.71104 km2,
which is 19.9% of the total land area, however, croplands store only 0.29 Pg C and represents only about
10% of total vegetation carbon. Although the area of
steppe and meadow occupies the largest area
(35.55104 km2), the vegetation carbon is only 0.07 Pg
C, or about 2.5%. This indicates that forests are the
main component of vegetation carbon in northeast
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S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
Table 1
Vegetation biomass in northeast China
Area (104 km2)
Vegetation type
Needle-leaved deciduous forest in cold-temperate or on mountains in
temperate zone
Needle-leaved evergreen forest on mountains in temperate zone
Needle-leaved evergreen forest in temperate zone
Mixed broad-leaved deciduous and needle-leaved evergreen forest in
temperate zone
Broad-leaved deciduous forest in temperate and subtropical zone
Microphyllous deciduous forest in temperate and subtropical zone
Microphyllous deciduous woodland in temperate zone
Carbon density (MgC/ha)
Carbon stock (1015gC)
11.82
79.3
0.94
1.10
0.60
3.36
110.2
60
71.4
0.12
0.04
0.24
11.05
3.43
1.61
51.4
62.5
45.5
0.57
0.21
0.07
Broad-leaved deciduous scrub in temperate or subtropical zone
Tundra with evergreen dwarf-shrub and moss on high mountains in
temperate zone
Temperate forb-grass steppe and xeromesophytic meadow
Temperate needlegrass steppe
Temperate meadow
Alpine and subalpine meadow
Temperate graminoid swamp
24.66
0.16
10.4
2.4
0.26
0.0004
16.90
3.33
10.62
0.06
4.63
3.3
0.5
1
1.8
0.5
0.06
0.002
0.01
0.0001
0.003
One crop annually, cold-resistant economic crops
Two crops annually or three crops in 2 years, and warm temperate
economic forest, deciduous orchard
24.71
5.89
99
82.3
0.24
0.05
22.7
2.81
Total
124
Fig. 4. The spatial distribution of vegetation carbon density in Northeast China (MgC/ha).
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S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
Table 2
Soil organic carbon storage in northeast China
Soil subtype
Paddy soils
Weakly developed brown earths
Aquic brown earths
Yellow-cinnamon soils
Grey fluvo-aquic soils
Salinized fluvo-aquic soils
Wet fluvo-aquic soils
Brown earths
Cinnamon soils
Leached cinnamon soils
Calcic cinnamon soils
Dark-brown earths
Albic dark-brown earths
Meadow dark-brown earths
Gleyed dark-brown earths
Brown coniferous forest soils
Dark gray forest soils
Gray forest soils
Black soils
Albic black soils
Meadow black soils
Bleached beijiang soils
Meadow bleached beijiang soils
Chernozems
Calcic chernozems
Leached chernozems
Meadow chernozems
Alkalized chernozems
Castanozems
Dark castanozems
Meadow castanozems
Brown caliche soils
Meadow soils
Albic meadow soils
Salinized meadow soils
Gleyed meadow soils
Meadow bog soils
Mucky bog soils
Peaty bog soils
Coastal tideland solonchaks
Meadow solonchaks
Alkalinzed solonchaks
Desert aeolian soils
Steppe aeolian soils
Meadow aeolian soils
Total
Area
(104 km2)
0.90
1.45
0.79
1.08
2.30
0.54
0.55
5.83
1.24
1.76
0.26
26.38
2.04
6.10
0.11
10.28
1.62
0.28
0.75
0.75
0.05
1.14
3.15
5.98
8.05
0.08
3.87
0.09
2.32
5.09
0.67
0.08
1.34
4.75
1.40
8.17
1.10
0.53
3.79
0.23
0.06
0.14
0.86
3.51
3.05
124
China. Clearly, change in the area of forests could result
in larger impacts on atmospheric CO2 concentration
than that of steppes, scrubs, crops, swamp and meadow.
For soils in northeast China, the soil organic pool is
26.43 Pg C, with an average soil carbon density of 212.7
MgC/ha. The land area in northeast China is about
12.94% of the nation, but its soil carbon pool is about
28.59% of the national soil carbon pool (Wang et al.,
2000). The carbon stored in soil is almost 10 times the
total in live vegetation in northeast China.
Carbon density
(MgC/ha)
73.6
103.5
100.2
57.6
69.3
62
77.4
119.5
97.3
101
87.9
202.4
127.5
223.3
198
498.8
69.8
153.4
165.9
139.1
203.3
126
171.2
186.7
237.9
219.8
154.9
105.0
93.7
136.1
128.3
52
174.8
21.51
84.1
177.5
203.9
294.3
925.5
80.4
42.1
70.4
24.1
27
36.6
212.7
Carbon stock
(1015gC)
0.07
0.15
0.08
0.06
0.16
0.03
0.04
0.70
0.12
0.18
0.02
5.34
0.26
1.36
0.02
5.13
0.11
0.04
0.12
0.10
0.01
0.14
0.54
1.12
1.92
0.02
0.60
0.01
0.22
0.69
0.09
0.004
0.23
1.02
0.12
1.45
0.22
0.16
3.51
0.02
0.002
0.01
0.02
0.09
0.11
26.43
As expected, the carbon density of peaty bog soils is
the highest, containing about 925.5 MgC/ha, while the
carbon density of desert aeolian soils is the lowest,
about 24.1 MgC/m2 (Table 2). Among soil types, the
carbon pool of dark-brown earths is the highest, containing 5.34 Pg C, while the carbon pool of meadow
solonchaks is the lowest, containing 0.002 Pg C mainly
because of its least area. Seven soil types that carbon
density is above of the average soil carbon density
(Table 2), occupying about 33.58104 km2 (about
S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
S163
Fig. 5. The spatial distribution of soil organic carbon density in Northeast China (MgC/ha).
27.2% of total area), store 13.11 Pg C, or about 49.6%
of total carbon storage in northeast China.
3.2. Spatial distribution of carbon stocks
Vegetation carbon density is highest in the north and
southeast areas of the region, where forests are located,
and lowest in west, east and central regions, where
crops, scrubs, steppe and meadow are located (Fig. 4).
The vegetation carbon density increases as mean annual
temperature decreases from south to north, and increases
as annual precipitation increases from temperate steppe
and swamp in the west to needle-leaved evergreen forest
on mountains in temperate in the east.
Soil carbon density is the highest in the north in the
Daxinganling and Xiaoxinganling mountains (Fig. 5).
Low temperature in the cold temperate conifer forest
zone leads to slow decomposition of soil carbon and low
soil respiration rate, thus soil carbon has accumulated
(Rozhkov et al., 1996). Soil carbon density is low in the
southwest and central area where steppe and crops are
located. Soil carbon density is higher in the east forest
region than in west grassland region.
Carbon density of forest soils and bog soils is very
high. For example, brown coniferous forest soils, darkbrown earths and gray forest soils (northeast), and
peaty bog soils, meadow dark-brown earths have a
higher organic carbon density than that of other soils.
In northeast China, the humid temperate climate and
less-intensive human activities make it favorable for the
growth of temperate forests. Organic matter enters into
soil mainly as deadwood and litterfall, so that the
extensive accumulation is observed in the upper soil
profile. Low temperature and common surface waterlogging slows decomposition in these forests, resulting
in high organic carbon content remaining in the soil
profile.
4. Conclusions
This study shows that the total amount of vegetation
carbon and soil organic carbon is 2.81 and 26.43 Pg C,
respectively, and the average carbon density is 22.7 and
212.7 MgC/m2, respectively. From the spatial distribution of vegetation carbon and soil organic carbon, it is
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S. Wang et al. / Environmental Pollution 116 (2002) S157–S165
revealed that the carbon storage is high in eastern and
northern region in northeast China, where forests are
located. Our GIS-based spatial analysis further suggests
that the regional carbon budget estimate should take
into account spatial heterogeneity in vegetation carbon
and soil organic carbon. Results drawn from this study
provide useful information for policy-making to control
CO2 emission in China. And the methodology developed from this study can be used for the entire nation as
well as the other regions of the world.
Acknowledgements
We thank S. Brown and R.A. Houghton for their
critical comment on an earlier draft. This work was
funded by Japan’s Research Institute of Innovative
Technology for the Earth and the Chinese Academy of
Sciences as a contribution to the project ‘‘Synthesis
analysis of land-use/land-cover changes on terrestrial
carbon cycle using RS and GIS in northeast China’’.
This paper was presented at the USDA Forest Service
Southern Global Change Program sponsored Advances
in Terrestrial Ecosystem: Carbon Inventory, Measurements, and Monitoring Conference held 3–5 October
2000 in Raleigh, North Carolina.
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