forest biomass carbon sinks in east asia, with special reference to the relative contributions of...

Forest biomass carbon sinks in East Asia, with specialreference to the relative contributions of forest expansionand forest growthJ INGYUN FANG1 , 2 , ZHAOD I GUO1 , 3 , HU I FENG HU2 , TOMOMICH I KATO4 ,

H IROYUK I MURAOKA5 and YOWHAN SON6

1Department of Ecology, College of Urban and Environmental Science, and Key Laboratory for Earth Surface Processes of the

Ministry of Education, Peking University, Beijing, 100871, China, 2State Key Laboratory of Vegetation and Environmental

Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, 3National Satellite Meteorological Center,

China Meteorological Administration, Beijing, 100081, China, 4Laboratoire des Sciences du Climat et de l’ Environnement, IPSL,

CEA-CNRS-UVSQ, Orme des Merisiers, Gif sur Yvette, 91191, France, 5Institute for Basin Ecosystem Studies, Gifu University,

1-1 Yanagido, Gifu, 501-1193, Japan, 6Division of Environmental Science and Ecological Engineering, Korea University,

Anam-dong, Sungbuk-ku, 136-701, Seoul Korea

Abstract

Forests play an important role in regional and global carbon (C) cycles. With extensive afforestation and reforestation

efforts over the last several decades, forests in East Asia have largely expanded, but the dynamics of their C stocks

have not been fully assessed. We estimated biomass C stocks of the forests in all five East Asian countries (China,

Japan, North Korea, South Korea, and Mongolia) between the 1970s and the 2000s, using the biomass expansion fac-

tor method and forest inventory data. Forest area and biomass C density in the whole region increased from

179.78 9 106 ha and 38.6 Mg C ha�1 in the 1970s to 196.65 9 106 ha and 45.5 Mg C ha�1 in the 2000s, respectively.

The C stock increased from 6.9 Pg C to 8.9 Pg C, with an averaged sequestration rate of 66.9 Tg C yr�1. Among the

five countries, China and Japan were two major contributors to the total region’s forest C sink, with respective contri-

butions of 71.1% and 32.9%. In China, the areal expansion of forest land was a larger contributor to C sinks than

increased biomass density for all forests (60.0% vs. 40.0%) and for planted forests (58.1% vs. 41.9%), while the latter

contributed more than the former for natural forests (87.0% vs. 13.0%). In Japan, increased biomass density domi-

nated the C sink for all (101.5%), planted (91.1%), and natural (123.8%) forests. Forests in South Korea also acted as a

C sink, contributing 9.4% of the total region’s sink because of increased forest growth (98.6%). Compared to these

countries, the reduction in forest land in both North Korea and Mongolia caused a C loss at an average rate of 9.0 Tg

C yr�1, equal to 13.4% of the total region’s C sink. Over the last four decades, the biomass C sequestration by East

Asia’s forests offset 5.8% of its contemporary fossil-fuel CO2 emissions.

Keywords: biomass density, biomass expansion factor, carbon sink, China, East Asia, forest area, forest inventory, Japan,

Mongolia, North Korea, South Korea

Received 14 June 2013 and accepted 15 November 2013

Introduction

As the largest part of terrestrial ecosystems, forests

occupy around 30% of the global land surface with

about 4.2 9 109 ha (Kramer, 1981; Bonan, 2008). It is

estimated that over 80% of terrestrial vegetation carbon

(C) is stored in forests (Pan et al., 2011), and the annual

C flux between forests and the atmosphere through pho-

tosynthesis and respiration accounts for 50–90% of the

total annual flux of terrestrial ecosystems (Winjum et al.,

1993; Malhi et al., 2002). Because of their capacity for C

storage and high productivity, forest ecosystems play a

dominant role in the global C cycle (IPCC, 2007; Pan

et al., 2011). The Kyoto Protocol, which was approved in

the 1997 United Nations (UN) meeting on climate

change, clearly suggested increasing C sequestration

through afforestation and reforestation to meet green-

house gas emission targets (Brown et al., 1999). There-

fore, estimation of forest biomass C sinks or sources and

their spatial and temporal distributions is both of scien-

tific and of political importance (Watson et al., 2000;

Fang et al., 2001; Janssens et al., 2003; Nabuurs et al.,

2003; Birdsey et al., 2006; McKinley et al., 2011).

Since the early 1970s, regional and national forest

inventories have been carried out across the world and

provide data for estimating forest biomass on a regional

Correspondence: Jingyun Fang, tel. + 86 10 6276 5578, fax +86 10

6275 6560, e-mails: [email protected];

[email protected]

© 2014 John Wiley & Sons Ltd 2019

Global Change Biology (2014) 20, 2019–2030, doi: 10.1111/gcb.12512

Global Change Biology

or national scale (e.g., Brown & Lugo, 1984; Kauppi

et al., 1992; Turner et al., 1995; Schroeder et al., 1997;

Fang et al., 1998, 2001, 2005, 2007; Brown & Schroeder,

1999; Choi et al., 2002; Goodale et al., 2002; Liski et al.,

2003; Li et al., 2010; Pan et al., 2011). Using forest inven-

tory data and long-term ecosystem C studies, Pan et al.

(2011) recently estimated that the current C stock in the

world’s forest ecosystems was 861 � 66 Pg C (1

Pg = 1015 g), with 363 � 28 Pg C (42%) in above- and

belowground live biomass. Global forests have func-

tioned as a significant C sink over the last two decades,

but there exists a large regional and temporal difference

in the magnitude of that sink (Pan et al., 2011). There-

fore, detailed assessment of regional forest C sinks/

sources and their spatial and temporal distributions is

necessary for understanding the dynamics, processes,

and mechanisms of the terrestrial C cycle (Goodale

et al., 2002; Birdsey et al., 2006; Fang et al., 2010;

McKinley et al., 2011). During the past decade, several

key regional programs such as the North American

Carbon Program, Carbon Europe Integrated Project,

and African Carbon Project have been established to

clarify regional C budgets and have greatly contributed

to knowledge of the C cycle in their respective regions

(Fang et al., 2010; http://www.globalcarbonproject.

org/carbontrends).

East Asia, which includes the five countries of China,

Japan, Democratic People’s Republic of Korea (hence-

forth referred to North Korea), Republic of Korea

(South Korea), and Mongolia, is located at the eastern

margin of the Eurasian Continent and the western coast

of the Pacific Ocean (Fig. 1). This area has a population

of more than 1.5 billion and covers about 1.2 9 109 ha

land area, of which 22% (254.6 9 106 ha) is occupied

by forests (FAO, 2010a; Table S1). As one of the most

active regions in the global economy, it is of great

importance both in scientific understanding of the

region’s forest C cycle and in the use of appropriate for-

est management strategies. Characterized by a warm-

humid climate that is under the influence of the Asian

monsoon, East Asia has abundant forest types that

range from tropical rainforests and evergreen broadleaf

forests in the south to boreal forests in the north, pro-

viding a model for exploring heterogeneity of ecologi-

cal attributes of C cycle.

East Asia has experienced extensive afforestation and

reforestation activities over the past several decades,

with about 34.2% of the global plantations located

in this region (90.2 9 106 ha in East Asia and

264.1 9 106 ha in the globe in 2010) (FAO, 2010a). This

abundance of plantations could provide insight into the

effect of forest management on the dynamics of forest

C stocks and C sinks or sources (Fang et al., 2010).

Using a process-based model of the terrestrial C cycle,

Ito (2008) conducted the first regional estimation of the

C budget of terrestrial ecosystems in East Asia and esti-

mated that 73.1 Pg C was stored in vegetation and soil

with an average C sequestration rate of 98.8 Tg C yr�1

(1 Tg = 1012 g) in East Asian forests during 2000–2005.Since the mid-1990s, using national forest inventory

data, several studies have estimated forest biomass C

stocks in China (e.g., Fang et al., 1998, 2001, 2007; Guo

et al., 2010), Japan (Fang et al., 2005) and South Korea

(Choi et al., 2002; Li et al., 2010), and these studies

Fig. 1 Locations of the five East Asian countries in this study.

© 2014 John Wiley & Sons Ltd, Global Change Biology, 20, 2019–2030

2020 J . FANG et al.

conclude that forests in all these countries have

functioned as C sinks since the late 1970s. However, a

long-term study that uses consistent methods and well-

qualified data sets to evaluate changes in biomass C

stocks and the size of C sinks or sources for East Asian

forests is lacking. This study uses statistically sound

inventory data from the 1970s to the 2000s to estimate

forest biomass C stocks and C sinks or sources for the

entire East Asia region using the biomass expansion

factor (BEF) method and forest inventory data (for

China, Japan, and South Korea) and FAO (Food and

Agriculture Organization of the United Nations) data

(for North Korea and Mongolia). Furthermore, we dis-

cuss the relative contributions of forest areal expansion

and increased biomass C density to explore the possible

mechanisms for forest C dynamics in this region over

the last four decades.

Materials and methods

Forest inventory data

In recent decades, China, Japan, and South Korea have period-

ically conducted national-level forest resource inventories.

These inventories provide information on forest area and tim-

ber volume for each forest type for each administrative unit

(e.g., Fang et al., 2005, 2007; Li et al., 2010).

China’s forest inventory data used in this study included

seven periods: 1973–1976, 1977–1981, 1984–1988, 1989–1993,

1994–1998, 1999–2003, and 2004–2008 (Chinese Ministry of

Forestry, 1977, 1983, 1989, 1994, 2000, 2005, 2010). In the inven-

tories, China’s forests were classified into three categories:

stands (including natural and planted forests), economic for-

ests (woods with the primary objective of production of fruits,

edible oils, drinks, flavorings, industrial raw materials, and

medicinal materials), and bamboo forests. In this study, ‘for-

est’ only refers to ‘forest stands’ with canopy coverage ≥ 20%

and therefore excludes economic and bamboo forests (Fang

et al., 2007). For each forest stand, the inventories documented

detailed information on forest type, age class, area, and

volume at the provincial level.

Japan’s forest inventory data included seven periods: 1966–

1975, 1976–1980, 1981–1985, 1986–1990, 1991–1995, 1996–2000,

and 2001–2005, and were compiled from Japan’s Forest

Resources Statistics for 1975, 1980, 1985, 1990, 1995, 2000, and

2005 (Japan Agency of Forestry, 1978, 1982, 1987, 1992, 2000,

2003, 2008). In the inventories, forest is defined as land with

≥20% canopy coverage for government-owned lands and

>30% canopy coverage for community- and privately owned

lands (Fang et al., 2005; Wang et al., 2011).

South Korea’s forest inventory data included five periods:

1972–1974, 1975–1982, 1983–1992, 1993–2000, and 2001–2007,

and were compiled from the Agriculture and Forestry Statisti-

cal Yearbooks for 1974, 1982, 1992, 2000, and 2007 (Korean

Ministry of Agriculture & Forestry, 1975, 1983, 1993, 2001,

2008). In the inventories, forest was defined as land with ≥30%canopy coverage for government-, community-, and privately

owned lands (Li et al., 2010).

Due to the lack of forest inventory data in North Korea and

Mongolia, FAO statistics were used to estimate total forest

area and timber volume for these two countries in 1990, 2000,

2005, and 2010 (FAO, 2006, 2010a). According to the FAO

report on Global Forest Resource Assessment 2010, forest was

defined as land spanning more than 0.5 hectares with trees tal-

ler than 5 meters and a canopy cover >10%, or trees able to

reach these thresholds in situ. The thresholds for tree height

and the areal extent for a forest are similar in the FAO criteria

to that of inventories in China, Japan, and South Korea, but

that for canopy cover is smaller than the other inventories and

may result in relatively higher estimates of forest area for

North Korea and Mongolia. We obtained the information on

the forest area and timber volume for North Korea in 1970

from Lee (2006), and for Mongolia in 1974 from Persson (1974)

and the Mongolian Ministry of Environment, Nature & Tour-

ism (2009). Forest area and timber volume in 1980 for these

two countries were estimated by assuming linear relationships

of each variable between the 1970s and 1990.

Table 1 summarizes the periods of inventory data or FAO

reports that were used to estimate the forest biomass C stocks

for the five countries from the 1970s to the 2000s.

Estimation of forest biomass C stocks

Because forest inventories only report forest area and timber

volume, but do not provide detailed information on forest bio-

mass, it is necessary to develop allometric relationships

between forest biomass and forest timber volume for each

forest type (Fang et al., 1998, 2001; Brown & Schroeder, 1999).

The BEF, which is defined as the ratio of stand biomass to

timber volume (Mg m�3) (1 Mg = 106 g), is used to convert

timber volume from forest inventory to biomass (e.g., Fang

et al., 2001, 2005; Guo et al., 2010; Li et al., 2010). Previous

studies have suggested that BEF is not constant, but var-

ies with forest age, site class, stand density, and site quality

(e.g., Brown & Lugo, 1992; Schroeder et al., 1997; Fang et al.,

1998, 2001, 2005; Brown & Schroeder, 1999; Brown et al., 1999).

Fang et al. (1996, 1998, 2001, 2005), Fang and Wang (2001)

derived a simple reciprocal equation from direct field

Table 1 Periods of inventory data or FAO reports used for estimating biomass C stocks for the five countries

Decade China Japan North Korea South Korea Mongolia

1970s 1973–1976; 1977–1981 1966–1975; 1976–1980 1970; 1980 1972–1974; 1975–1982 1974; 1980

1980s 1984–1988 1981–1985; 1986–1990 1980; 1990 1983–1992 1980; 1990

1990s 1989–1993; 1994–1998 1991–1995; 1996–2000 1990; 2000 1993–2000 1990; 2000

2000s 1999–2003; 2004–2008 2001–2005 2000; 2005; 2010 2001–2007 2000; 2005; 2010


FOREST BIOMASS C SINKS IN EAST ASIA 2021

measurements to express the BEF-timber volume relationship

by forest type in China and Japan:

BEF ¼ aþ b=x ð1Þ

where x is the timber volume per unit area (m3 ha�1), and a

and b are constants for each specific forest type. In Eqn (1),

when timber volume is very large (such as mature forest), BEF

will approach to a constant parameter, a, while it will be extre-

mely large when timber volume is quite small (such as young

forest). This simple mathematic relationship fits for almost all

forest types. With this simple BEF approach, one can easily

calculate regional or national forest biomass based on direct

field measurements and forest inventory data. For detailed

information about the BEF method, see Fang et al. (1998, 2001,

2007) and Guo et al. (2010) for China, Fang et al. (2005) for

Japan, and Li et al. (2010) for South Korea. Parameters of the

BEF equations for major forest types in China, Japan, and

South Korea are listed in Table S2.

In this study, we used the BEF method with parameters for

each forest type from Guo et al. (2010) and Fang et al. (2005) to

calculate forest biomass in China and Japan, respectively, from

the 1970s to the 2000s. It should be mentioned that the forest

inventory data from 1973 to 1976 for China included only total

forest area and timber volume at the provincial level. Fang &

Chen (2001) established an empirical, linear relationship

between mean biomass and mean volume at the provincial

level using China’s forest inventory data between 1977 and

1998. We used recent forest inventory data and an updated

robust linear relationship to calculate provincial forest bio-

mass in China from 1973 to 1976:

BD ¼ 0:704VDþ 19:953ðR2 ¼ 0:968; n ¼ 211Þ ð2Þ

where BD and VD are biomass density (Mg ha�1) and volume

density (m3 ha�1), respectively.

Before 1994, forest was defined as land with >30% canopy

coverage in China (Fang et al., 2001). The 1994–1998 inventory

data provided both criteria (20% and 30% canopy coverage),

and Fang et al. (2007) found that there existed robust linear

relationships for the forest area and biomass C stock between

the two criteria at the provincial level. In this study, we modi-

fied their equations with power function relationships to

obtain more accurate conversions:

AREA0:2 ¼ 1:290AREA0:9950:3 ðR2 ¼ 0:996; n ¼ 30Þ ð3Þ

CARBON0:2 ¼ 1:147CARBON0:9960:3 ðR2 ¼ 0:998; n ¼ 30Þ ð4Þ

where AREA and CARBON are forest area (104 ha) and

biomass C stock (Tg C) in a province, respectively; subscripts

0.3 and 0.2 stand for the criterion of >30% and ≥20% canopy

coverage, respectively.

As a result, the provincial forest areas and biomass C stocks

with the new criterion in China in 1973–1976, 1977–1981,

1984–1988, and 1989–1993 were calculated based on Eqns (3)

and (4), and corresponding forest C densities were hence

obtained.

For South Korea, we adopted the results of forest biomass

from the 1970s to the 2000s estimated by Li et al. (2010), who

used the same BEF method as Fang et al. (1998, 2001) for three

major forest types (coniferous, deciduous, and mixed forests)

in South Korea.

According to the recent report on Global Forest Resources

Assessment 2010 from FAO, major forest types in North Korea

were oak (Quercus), pine (Pinus), and larch (Larix) (FAO,

2010b), and major forest types in Mongolia were Siberian larch

(Larix sibirica), Siberian pine (Pinus sibirica), Scots pine (Pinus

sylvestris), and Betula (Betula platyphylla) (FAO, 2010c). There

were no direct field measurement data for these two countries

and therefore we could not establish BEF functions, but the

forest types in these two countries are very similar to those in

the northeast and north China. Therefore, similar to Eqn (2),

we used the data in the northeast and north China and estab-

lished empirical relationships between provincial mean bio-

mass and mean volume for North Korea [Eqn (5)] and

Mongolia [Eqn (6)], to estimate forest biomass for these two

countries from the 1970s to the 2000s:

BD ¼ 0:969VDþ 12:800ðR2 ¼ 0:953; n ¼ 178Þ ð5Þ

BD ¼ 0:898VDþ 19:311ðR2 ¼ 0:965; n ¼ 122Þ ð6Þwhere BD and VD are the same as Eqn (2).

We used a factor of 0.5 to convert biomass to C stock in this

study (Fang et al., 2001, 2005).

Data of NDVI and forested area

Remotely sensed normalized difference vegetation index

(NDVI) data are not only an indicator of land cover and vege-

tation growth (e.g., leaf area index and net primary produc-

tion) but also used as a surrogate of growing conditions for

vegetation (i.e., the physical environment for plant growth,

such as soil conditions, moisture, temperature, and light avail-

ability) (Potter et al., 1993; Field et al., 1995; Fang et al., 2003).

Because we do not have direct measures of growing condi-

tions at a national scale, we use NDVI and its trend over time

to compare the growing conditions of forested areas among

East Asian countries. In general, a large NDVI value and a

positive NDVI trend imply good site quality and favorable

growing conditions for vegetation.

The NDVI data used in this study come from the third ver-

sion of the AVHRR NDVI archive, provided by the Global

Inventory Monitoring and Modeling Studies group at a spatial

resolution of 8 9 8 km2 over 15 day intervals for the period of

1982 to 2011 (Beck et al., 2011). This data set is one of the most

accurate products with which to assess the change in vegeta-

tion growth over time and is used widely to depict long-term

change in global and regional vegetation cover (Fensholt &

Proud, 2012). To eliminate spurious NDVI trends caused by

winter snow, our analysis focused on the interannual changes

in the forested areas during the growing season (May to

September) for East Asia.

In addition, we used the global land cover data set with a

resolution of 8 9 8 km2, generated by University of Maryland

(http://glcf.umiacs.umd.edu/data/landcover/; Hansen et al.,

1998, 2000), to document forest area for each East Asian coun-

try, except Mongolia because of data unavailability.



Calculation of change rates of forest area, C density, andC stock

We used the concept of Forest Identity, proposed by Kauppi

et al. (2006) and Waggoner (2008), to explore the relative con-

tribution of changes in forest area and biomass C density

(biomass C stock per area) to the C sink for China, Japan, and

South Korea. According to the Forest Identity concept, forest

area (A, ha), biomass C density (D, Mg C ha�1), and total bio-

mass C stock (M, Tg C) can be linked using Eqn (7), and their

change rates (a, d, and m) over time (t) can be linked with

Eqns (8) and (9). By calculating these attributes, we can assess

the relative contribution of changes in forest area and bio-

mass C density to the change in total biomass C stock (i.e., C

sink):

M ¼ A�D ð7Þ

Because ln (M) = ln (A) + ln (D),

the change rates (m, a, and d) of M, A and D should be:

1

M

dM

dt¼ 1

A

dA

dtþ 1

D

dD

dt; or

d lnðMÞdt

¼ d lnðAÞdt

þ d lnðDÞdt

ð8Þ

Let

m � d lnðMÞdt

; a � d lnðAÞdt

; d � d lnðDÞdt

Then, m ¼ aþ d (9)

where M, A, and D represent total biomass C stock (Tg C, or

Pg C), forest area (ha), and biomass C density (Mg C ha�1) at

the national level, respectively; and m, a, and d depict the

corresponding derivatives (or change rate) of these attributes

over time. This identity combines the values of forest area

with the biomass density into the changing biomass C stock

(i.e., C sink).

Results

Changes in forest area

In East Asia, forest area increased by 9.4% from

179.78 9 106 ha in the 1970s to 196.65 9 106 ha in the

2000s, with most of this increase in China (Table 2).

The forest area in China increased by 21.88 9 106 ha,

from an initial area of 127.31 9 106 ha to 149.19 9

106 ha by the 2000s, which accounted for 129.7% of the

total area increment in the East Asian region. Forest

area in North Korea and Mongolia decreased by

3.08 9 106 and 1.86 9 106 ha over the study period,

respectively, representing 32.8 and 14.1% of the respec-

tive country’s forest area in the 1970s. There was a

slight decrease of 0.18 9 106 ha in Japan and a slight

increase of 0.11 9 106 ha in South Korea (Table 2).

Changes in forest biomass C density, total C stock, and Csink

The biomass C density in the region had dramatically

increased from 38.6 Mg C ha�1 in the 1970s to 45.5 Mg

Table 2 Forest area, C stocks, and C sinks for each country in East Asia from the 1970s to the 2000s

Period East Asia China Japan North Korea South Korea Mongolia

Area (106 ha)

1970s 179.78 127.31 23.82 9.38 6.10 13.17

1980s 183.14 131.69 23.79 8.59 6.29 12.78

1990s 185.62 136.06 23.60 7.57 6.26 12.13

2000s 196.65 149.19 23.64 6.30 6.21 11.31

Net change 16.87 21.88 �0.18 �3.08 0.11 �1.86

C stock (Tg C)

1970s 6937 4719 954 339 51 874

1980s 7301 4885 1173 311 106 826

1990s 7989 5395 1395 274 157 768

2000s 8944 6145 1615 232 240 712

Net change 2007 1426 661 �107 189 �162

C density (Mg C ha�1)

1970s 38.6 37.1 40.1 36.1 8.4 66.4

1980s 39.9 37.1 49.3 36.2 16.9 64.6

1990s 43.0 39.7 59.1 36.2 25.1 63.3

2000s 45.5 41.2 68.3 36.8 38.6 63.0

Net change 6.9 4.1 28.3 0.7 30.3 �3.4

C sink (Tg C yr�1)

1970s–1980s 36.4 16.6 21.9 �2.8 5.5 �4.8

1980s–1990s 68.8 51.0 22.2 �3.7 5.1 �5.8

1990s–2000s 95.5 75.0 22.0 �4.2 8.3 �5.6

1970s–2000s 66.9 47.5 22.0 �3.6 6.3 �5.4



C ha�1 in the 2000s (Table 2). Among the five countries,

the largest increase in biomass C density (30.3 Mg

C ha�1) was in South Korea, with an initial biomass C

density of 8.4 Mg C ha�1 and a biomass C density of

38.6 Mg C ha�1 by the 2000s. Biomass C density

increased in Japan and China from 40.1 and 37.1 Mg

C ha�1 in the 1970s to 68.3 and 41.2 Mg C ha�1 in the

2000s, with a net increase of 28.3 and 4.1 Mg C ha�1,

respectively. It did not change much (ranging from 36.1

to 36.8 Mg C ha�1 over the four decades) in North

Korea and had a slight decrease of 3.4 Mg C ha�1 in

Mongolia (66.4 Mg C ha�1 in the beginning to 63.0 Mg

C ha�1 in the 2000s).

Total forest biomass C stocks in the region increased

by 28.9%, from 6937 Tg C in the 1970s to 8944 Tg C in

the 2000s, resulting in a net accumulation of 2007 Tg C.

The increase was attributed to increases in China,

Japan, and South Korea: over the four decades, the C

stocks increased by 1426, 661, and 189 Tg C in China,

Japan, and South Korea, respectively, from initial stocks

of 4719, 954, and 51 Tg C to the stocks of 6145, 1615,

and 240 Tg C by the 2000s, which accounted for 71.1,

32.9, and 9.4% of the total accumulation. On the other

hand, the C stocks in North Korea and Mongolia

decreased from initial stocks of 339 and 874 Tg C to 232

and 712 Tg C by the 2000s, with an accumulated C loss

of 107 and 162 Tg, respectively.

Across the entire East Asian region, biomass C sinks

increased from 36.4 Tg C yr�1 during the 1970s–1980sto 95.5 Tg C yr�1 during the 1990s–2000s, at an average

rate of 66.9 Tg C yr�1 over the four decades. Not sur-

prisingly, among the five countries, the largest C sink

occurred in China. Over the study period, China’s for-

ests contributed 47.5 Tg C yr�1 (71.1%) to the total

region’s C sink and increased from an initial value of

16.6 Tg C yr�1 to 75.0 Tg C yr�1 during the 1990s–2000s. Forests in Japan and South Korea also functioned

as C sinks, with an average C gain of 22.0 Tg yr�1 in

Japan and 6.3 Tg yr�1 in South Korea, accounting for

32.9% and 9.4% of the total region’s C sink, respec-

tively. North Korea and Mongolia showed C losses of

3.6 and 5.4 Tg yr�1 averaged over the last 40 years,

respectively.

Relative contributions of forest area and biomass densityto C sinks

To quantitate the relative contribution of areal expan-

sion and increased regrowth (biomass density) to the

total C sink of forests in the three countries (China,

Japan, and South Korea) with C sinks, we calculated

the relative change rates of forest area (a) and biomass

C density (d) for all, planted, and natural forests in

China and Japan, and for all forests in South Korea in

each period and over the four decades, using the con-

cept of Forest Identity (Kauppi et al., 2006; Waggoner,

2008) (Fig. 2; Table S3).

For all forests, the mean change rates of forest

area and biomass density were 0.264% yr�1 and

0.175% yr�1 in China, respectively, with a larger contri-

bution of the former than that of the latter (60.0% vs.

40.0%) to the C sink over the last 40 years (Fig. 2a).

These rates and relative contributions were very much

different from those in Japan and South Korea. In those

two countries, forest area either decreased slightly (for

Japan, with a = �0.013% yr�1) or did not change much

(for South Korea, with a = 0.030% yr�1), and thus their

contribution of areal expansion to the C sink was very

small or negative. However, the biomass density of

(a)

(b)

Fig. 2 Mean change rates of forest area and biomass density

and their relative contributions to changes in total biomass C

stock (i.e., C sink) for China, Japan, and South Korea over the

40 years. (a) For all forests in the three countries; and (b) for

planted and natural forests in China and Japan. Numbers above

bars are relative contributions (%) of forest area and biomass

density to the total C sink over the four decades. The minus

value for the change rate of forest area in Japan shows that for-

est area has shrunk and made its negative contribution to the C

sink. The change rates were only calculated for all forests in

South Korea because data were not available for planted and

natural forests or a small area of natural forests in the country.

For details, see text and Table S3.



these countries increased remarkably, with respective

average rates of 0.869 and 2.148% yr�1 that contributed

almost all of their C sinks (101.5% for Japan and 98.6%

for South Korea) (Fig. 2a). The minus value for the

change rate of forest area in Japan reveals that the area

of forests has shrunk by a rate of �0.013% yr�1 and

thus exerted a negative influence (�1.5%) on C gain,

acting as a C source over the four decades.

For planted forests (Fig. 2b), areal expansion made a

larger contribution to the C sink than did the change in

biomass density (58.1% vs. 41.9%) in China, with a

change rate of 1.249 and 0.902% yr�1, respectively.

Compared with those in China, Japan’s forests showed

much different patterns: increased biomass density

dominated the C sink with a contribution of 91.1%

(d = 1.235% yr�1) and the areal expansion only contrib-

uted 8.9% (a = 0.120% yr�1) of the C sink.

In contrast to planted forests, increased biomass den-

sity of natural forests (Fig. 2b) in China was a greater

contributor to the C sink than was areal expansion

(87.0% vs. 13.0%), with d and a of 0.217 and

0.032% yr�1, respectively. In Japan, increased biomass

density was responsible for all the C sink (123.9%),

while the area of natural forests has shrunk by 6.4%

over the last 40 years (a = �0.110% yr�1) (also, see

Table 3).

We calculated the change rates of forest area and bio-

mass density and their relative contributions to the C

sink for each period for the three countries (Table S3).

In general, the change rate (m, or C sink) of the total C

stock tended to increase in China, but decrease in Japan

and South Korea, suggesting that the C sink strength

increased in China’s forests, but declined in the other

two countries. For example, for all forests in China, the

m value increased from 0.173% yr�1 during the 1970s–1980s to 0.650% yr�1 during the 1990s–2000s, whereas

it decreased from 1.030% yr�1 to 0.731% yr�1 in Japan

and from 3.521% yr�1 to 2.089% yr�1 in South Korea,

respectively (Table S3). However, this trend was not

very evident in the different periods for planted and

natural forests because of their contrasting patterns of

changes in forest area and biomass density.

Discussion

Forest C sinks in East Asia and the relative contributionsof forest area and biomass density

Over the last four decades, East Asia’s forests have

functioned as a persistent C sink, with a peak of 95.5 Tg

C yr�1 in the 2000s (Table 2). This sink was attributed

to increased C stocks in China, Japan, and South Korea;

however, the mechanisms underlying the C sinks in

these three countries were quite different.

In China, areal expansion and forest regrowth (i.e.,

increase in biomass density) were the major contribu-

tors to this C sequestration and have made a respective

contribution of 60.0% and 40.0% to the C sink for all for-

ests (Fig. 2a; Table S3). Among a total of 1426 Tg C

sequestration within China’s forests, planted and natu-

ral forests have almost equal contributions (703 and 723

Tg C, respectively) (Tables 2 and 3), but were driven by

different mechanisms (Fig. 2b). For planted forests,

areal expansion and biomass density made a respective

contribution of 58.1% and 41.9% to the C sink (Fig. 2b).

During the study period, 90% of the forest area incre-

ment was from planted forests, mainly because of the

implementation of national afforestation and reforesta-

tion projects since the 1970s (Fang et al., 2001; Lei,

2005). As a result, the area of planted forests dramati-

cally increased from 16.44 9 106 ha to 36.15 9 106 ha

in the 2000s, and its proportion to the total forest area

Table 3 Forest area, C stocks, and C densities for planted and natural forests in China and Japan from the 1970s to the 2000s

Period

Planted forests Natural forests

Area

(106 ha)

C stock

(Tg C)

C density

(Mg C ha�1)

Area

(106 ha)

C stock

(Tg C)

C density

(Mg C ha�1)

China

1970s 16.44 249 15.1 110.87 4470 40.3

1980s 23.47 418 17.8 108.22 4467 41.3

1990s 27.95 584 20.9 108.11 4811 44.5

2000s 36.15 952 26.3 113.04 5193 45.9

Net change 19.71 703 11.2 2.17 723 5.6

Japan

1970s 9.61 346 36.0 14.22 608 42.8

1980s 10.23 497 48.6 13.56 676 49.9

1990s 10.34 668 64.6 13.26 727 54.8

2000s 10.33 810 78.4 13.31 805 60.5

Net change 0.72 464 42.4 �0.91 197 17.7



increased from 12.9% to 24.2% in the 2000s (Table 3).

Meanwhile, the regrowth of these young forests also

made a significant contribution to the C gain: the bio-

mass C density of planted forests increased by 11.2 Mg

C ha�1, from an initial density of 15.1 Mg C ha�1 to

26.3 Mg C ha�1 in the 2000s. For natural forests, how-

ever, forest area had a slight increase (2% increment),

but the biomass C density increased remarkably, with a

net gain of 5.6 Mg C ha�1 (13.9%). Therefore, regrowth

of existing forests was found to be the dominant factor

related to C sequestration (87.0% vs. 13.0% for biomass

density vs. area) (Fig. 2b).

Japan’s forest is the second largest C sink with a total

C sink of 661 Tg C over the four decades. However, for-

est area was reduced by 0.18 9 106 ha, indicating that

increased biomass density contributed the entire C sink

for all forests in Japan (Fig. 2a; Tables 2 and S3). Within

Japan’s forests, over 70% of the total biomass C accu-

mulation (464 Tg C) was derived from planted forests

(Table 3). During the study period, biomass C density

of planted forests increased by 42.4 Mg C ha�1 and

the area of planted forests slightly increased by

0.72 9 106 ha (Table 3). Therefore, the regrowth of

planted forests dominated this large C sink with a con-

tribution of 91.1% (Fig. 2b). Despite a decrease

(0.91 9 106 ha) in forest area over the four decades,

total biomass accumulation of 197 Tg C was found in

natural forests. Therefore, the C sink was due entirely

to the regrowth of natural forests, with a net increase of

17.7 Mg C ha�1 of biomass C density during the study

period (Fig. 2b; Table 3).

In South Korea, total forest biomass C stocks

increased by 189 Tg C over the four decades mainly

due to the regrowth of existing forests. There was a net

increase in biomass C density of 30.3 Mg C ha�1, or 3.6

times, from an initial density of 8.4 Mg C ha�1 to a den-

sity of 38.6 Mg C ha�1 in the 2000s. As a result,

increased biomass density was largely responsible for

this C sink (98.6%) and areal expansion made a small

contribution (1.4%) due to a slight increase in total

forest area over the four decades (0.11 9 106 ha or

2% increment) (Fig. 2a; Tables 2 and S3).

In contrast, forests in both North Korea and Mongo-

lia acted as C sources because of deforestation, but the

mechanisms causing the C loss were different in these

two countries. In North Korea, land-use change (con-

verting forests to croplands) and harvest of firewood

were major causes of the decrease in forest area (Lee,

2006), while in Mongolia, the combined effects of tim-

ber cutting, forest fires, pests, and diseases had

resulted in the decrease in forest area and biomass C

density (United Nations Environmental Programme

and Mongolian Ministry of Nature and Environment,

2002).

Factors affecting C sink strength among the countries

As shown in Tables 2 and 3, China’s forest has been the

largest C sink (1426 Tg C) over the last four decades,

followed by that of Japan (661 Tg C) and South Korea

(189 Tg C). Compared with China’s much larger forest

area, however, forests in Japan and South Korea

showed greater C sink strength (C sink per area), with

0.35, 0.93, and 1.01 Mg C ha�1 yr�1 in China, Japan,

and South Korea, respectively. This may be attributed

to two major factors: forest age structure and growth

conditions. We discuss these factors below, focusing on

the forests of China and Japan because information was

not available for South Korea.

First of all, the age structures of forests (especially for

planted forests) are much different in the two countries.

In Japan, large-scale plantation and restoration of natu-

ral forests had been conducted since the late 1950s and

early 1960s (after World War II) (Japan Agency of For-

estry, 2000), while afforestation campaigns have been

occurring in China since the end of 1970s (Fang et al.,

2001; Xiao, 2005). As a result, Japan’s forests are about

20 years older than China’s forests, suggesting that

Japan’s forests are mostly in the middle- to premature-

aged growing stage in which trees grow fast, while for-

ests in China are young- to mid-aged stands. Although

we do not have detailed information on forest age for

each study period for both countries, we have some data

to support this. In China, national inventories report

timber volume for each age class for some forest types

and forests were divided into five age classes: young,

middle, premature, mature, and overmature-aged clas-

ses (Xiao, 2005). In this classification, the age span

changes with forest types, but at the national level, this

could be generalized as: young- (<20 years), mid- (20–35 years, or 20–40 years), premature- (35–60 years), and

mature-aged forests (>60 years) (for practically, we

combined mature and overmature-aged classes into a

single mature-aged class for comparison of the two

countries). In China’s planted forests in 2000, the area of

young-, mid-, premature-, and mature-aged forests was

40.2%, 37.2%, 13.7%, and 8.9% of the total forest area,

respectively (China State Administration of Forestry,

2005). In comparison, the respective numbers were

12.8%, 35.0%, 43.7%, and 8.6% (Japan Agency of For-

estry, 2003), suggesting that a majority of forest stands

were in the mid- and premature-aged classes in Japan.

The younger age structure of China’s forests likely

contributed to lower biomass C densities and smaller C

sink strength when compared with Japan’s forests.

Table 3 shows this clearly. The area in planted forests

in China increased by 19.71 9 106 ha over the

study period, from 16.44 9 106 ha in the 1970s to

36.15 9 106 ha in the 2000s; likewise, the area of natural



forests increased by 2.17 9 106 ha. In comparison, the

area of Japan’s plantations fluctuated between

10.23 9 106 ha and 10.34 9 106 ha during the 1980s–2000s, and the area of natural forests showed a slight

decrease (Table 3). With such changes in forest age

structure, China’s forests have much lower biomass C

density than that of Japan’s forests. For example, bio-

mass C density of planted forests in China was only

15.1 Mg C ha�1 in 1970s and 26.3 Mg C ha�1 in the

2000s, while that in Japan was 36.0 and 78.4 Mg C ha�1,

respectively.

Growing conditions (or site quality) differ consider-

ably among East Asian countries. Japan has a typical

oceanic climate, with abundant precipitation and warm

temperature that favor the relatively fast growth for

forests as compared with China and other countries

(Kira, 1991; Fang et al., 2005, 2010). Consequently, bio-

mass density of both planted and natural forests in

Japan generally increases faster than that in the other

countries, even at the same forest ages. Because we do

not have direct measurements of growing conditions

and because remotely sensed NDVI data can be a surro-

gate to indicate integrative growing conditions (Potter

et al., 1993; Field et al., 1995; Fang et al., 2003), we used

the NDVI time series data set to compare integrative

growing conditions for forests among the different

countries. Specifically, we explored possible causes of

the large biomass C density and high productivity of

Japan’s forests relative to the other countries. In gen-

eral, a large NDVI value and a positive NDVI trend

over time imply good site quality and favorable grow-

ing conditions for forests.

Figure 3 shows interannual variation in growing sea-

son NDVI (May to September) of forested areas in

China, Japan, South Korea, and North Korea (data for

Mongolia were not available). Table 4 lists statistics for

the NDVI attributes. Japan had the largest 30 years

averaged NDVI (0.672 units), followed by South Korea

(0.638), China (0.606), and North Korea (0.583)

(Table 4). The NDVI trends also showed a similar order

as did the averaged NDVI (but Japan and South Korea

showed a similar value of the trend, or 9.59 9 10�4 vs.

9.61 9 10�4). Together, these suggest that Japan has the

best growing conditions for forests, followed by South

Korea, China, and North Korea. This order is the same

as that of biomass C density and C sink (Table 2), sug-

gesting that NDVI and its change over time can not

only indicate the growing conditions for forests but also

act as good measures to show biomass C density and

vegetation production (or C sink strength). Note that

the NDVI in North Korea did not exhibit an increasing

trend (R2 = 0.000, P = 0.938) and coincidently did not

show an increase in biomass C density (ranging from

36.1 to 36.8 Mg C ha�1) over the last 40 years.

Implications of forest C sinks in East Asia

Although we estimated the changes in forest biomass C

accumulation in East Asia over the last four decades,

we could not estimate the total C budget for this region

because we lacked the estimates for the four other

important C pools of the forest system: dead wood, lit-

ter, soil organic C, and harvested wood products (Pan

et al., 2011). Here, we use the ratios of different C pools

in US forests to make an approximate account for the C

budget of the whole forest sector in East Asia. Similar

to forest of the United States, those of East Asia have

experienced a long history of forest clearing, agricul-

tural expansion, and subsequent abandonment; cur-

rently, forests are still recovering from such activities

(Perlin, 1991; Brown et al., 1997; Fang et al., 2005; Li

et al., 2010; Pan et al., 2011). The ratio of net change

among different C pools of the forest sector in the Uni-

ted States was 0.49: 0.11: 0.01: 0.02: 0.37 for living vege-

tation: dead wood: litter: soil organic C: harvested

forest products (Woodbury et al., 2007). By applying

these ratios to our data, we obtained an average C sink

rate of 136.5 Tg C yr�1 for the whole forest sector in

East Asia over the four decades.

Table 4 Statistics for NDVI attributes over 30 years between

1982 and 2011 for forested areas in East Asian countries

Country Mean � SD

Trend

(910�4) R2 P value

China 0.606 � 0.124 7.49 0.163 0.027

Japan 0.672 � 0.124 9.59 0.164 0.027

North Korea 0.583 � 0.065 0.26 0.000 0.938

South Korea 0.638 � 0.069 9.61 0.173 0.022

Fig. 3 Interannual variation in growing season NDVI of for-

ested area for four countries (China, Japan, North Korea, and

South Korea) in East Asia from 1982 to 2011. Other than North

Korea, all countries show a significant NDVI increase. Mongolia

was not included because data were not available.



We used national fossil-fuel CO2 emissions data pro-

vided by the Oak Ridge National Laboratory of the

United States Department of Energy (Boden et al., 2012)

to estimate average CO2 emissions from fossil fuels in

each country and the entire region over the last four

decades (Table 5). The C sink rate averaged 47.5, 22.0,

and 6.3 Tg C yr�1 in living forests of China, Japan, and

South Korea over the last four decades, respectively,

which offsets 6.3, 7.5, and 8.9% of total fossil-fuel CO2

emissions of the respective countries over the study

period (Table 5). However, over the same period, living

biomass of forests in North Korea and Mongolia

released 3.6 and 5.4 Tg C yr�1, equaling to 9.2% and

270.0% of total fossil-fuel CO2 emissions of these two

countries, respectively. Overall, the net C sink (66.9 Tg

C yr�1) in living biomass in East Asian forests has off-

set 5.8% of the total fossil-fuel CO2 emissions in this

region over the last 40 years. If the four other C pools

mentioned above were also included in the account,

then the forest sector in this region could offset 11.8%

of its contemporary fossil-fuel CO2 emissions.

Uncertainty of estimations

The most important uncertainty may come from the

quality of forest area and timber volume data from the

forest inventories and FAO. For China, Japan, and

South Korea, forest inventory data used in our study

specified the precision requirement in the sampling

design: in China, the forest area and timber volume pre-

cision were required to be >90% in almost each province

(>85% in Beijing, Shanghai, and Tianjin) (Xiao, 2005); in

Japan, the error of timber volume in the inventories at

the national level was <3% (Japan Agency of Forestry,

2000); and in South Korea, the error in total timber

volume at the provincial and national levels was <5%(Li et al., 2010). For Mongolia, data on forest area and

timber volume for 1990–2010 were collected from sev-

eral official documents (Enkbayar, 1997; GOM, 2004,

2009). Although the quality of the data source was

ranked moderate by FAO, we could still obtain reason-

able information. For North Korea, the main source of

data was the publication ‘State of the Environment

2003-DPR Korea’ by the United Nations Environment

Programme. Although the quality of the data source for

the country was ranked high by FAO, large uncertainty

in estimating forest area and timber volume still existed.

Uncertainty may also arise from the estimation of

national biomass stocks using the BEF method. The R

square values of the BEF equations used to convert tim-

ber volume to biomass for most dominant tree species

or forest types were above 0.8, 0.9, and 0.7 for China,

Japan, and South Korea, respectively (Table S2). The

empirical relationships with high R square values in

China were applied to convert timber volume to bio-

mass at the provincial level for North Korea and Mon-

golia because of the lack of detailed information on

forest area and timber volume for major forest types in

these two countries. Therefore, the method used in this

study has relatively high precision. Previous studies

have reported that the estimation error of biomass

stocks at the national level should be less than 3% in

China (Fang et al., 1996) and ranged from �2.8% to

4.3% in Japan (Fang et al., 2005).

In conclusion, forest biomass C accumulation in East

Asia has increased from 36.4 Tg C yr�1 in the 1970s to

95.5 Tg C yr�1 in the 2000s, with an average of 66.9 Tg

C yr�1 over the last four decades. Among the five coun-

tries, China, Japan, and South Korea each contributed

to the region’s forest C sink by 71.1%, 32.9%, and 9.4%,

respectively, although the mechanism driving the

increased C differed among the countries. In China,

areal expansion was the major contributor to the C

sinks for all (60.0%) and planted (58.1%) forests, while

increased biomass density was the major contributor

for natural forests (87.0%). In Japan, increased biomass

density dominated the contribution of C sink for all

(101.5%), planted (91.1%), and natural (123.8%) forests.

In South Korea, increased biomass density contributed

98.6% of the total forest C sink during the study period.

Relative to these three countries, shrinking forests in

both North Korea and Mongolia caused a C loss at an

average rate of 9.0 Tg C yr�1, equal to 13.4% of the total

region’s forest C sink.

Acknowledgements

This publication was a product of the A3 foresight program oncarbon cycle in terrestrial ecosystems in East Asia jointly sup-ported by the three funding agencies, National Natural ScienceFoundation of China (NSFC), Japan Society for the Promotion ofScience (JSPS), and National Research Foundation of Korea(NRF). We are grateful to the subject editor and four anony-mous reviewers for their insightful comments and suggestions

Table 5 The percentage of the national fossil-fuel CO2 emis-

sions offset by East Asia’s living forests during the 1970s–

2000s

Region

C sink

(Tg C yr�1)

Fossil-fuel

emission

(Tg C yr�1)*

Offset

percent

(%)

China 47.5 749 6.3

Japan 22.0 292 7.5

North Korea �3.6 39 �9.2

South Korea 6.3 71 8.9

Mongolia �5.4 2 �270.0

East Asia 66.9 1153 5.8

*The mean fossil-fuel emission during 1970s–2000s.



on an earlier version of this manuscript. We thank X. Zhao forassistance in NDVI data analysis. We also thank Benjamin O.Knapp for his editing on the manuscript. This study was alsopartly supported by the National Basic Research Program ofChina on Global Change (2010CB950600), National Natural Sci-ence Foundation of China (31321061 and 31330012), StrategicPriority Research Program of the Chinese Academy of Sciences(XDA05050300), and State Forestry Administration of China.

References

Beck HE, McVicar TR, van Dijk A, Schellekens J, de Jeu RAM, Bruijnzeel LA (2011)

Global evaluation of four AVHRR-NDVI data sets: intercomparison and assess-

ment against Landsat imagery. Remote Sensing of Environment, 115, 2547–2563.

Birdsey RA, Pregitzer K, Lucier A (2006) Forest carbon management in the United

States: 1600-2100. Journal of Environmental Quality, 35, 1461–1469.

Boden TA, Marland G, Andres RJ (2012) Global, Regional, and National Fossil-Fuel CO2

Emissions. doi 10. 3334/CDIAC/00001_v2012. Carbon Dioxide Information Analysis

Center, Oak Ridge National Laboratory, US Department of Energy, Oak Ridge,

TN.

Bonan GB (2008) Forests and climate change: forcings, feedbacks, and the climate

benefits of forests. Science, 320, 1444–1449.

Brown S, Lugo AE (1984) Biomass of tropical forests: a new estimate based on forest

volumes. Science, 223, 1290–1293.

Brown S, Lugo AE (1992) Aboveground biomass estimates for tropical moist forests

of Brazilian Amazon. Interciencia, 17, 8–18.

Brown SL, Schroeder PE (1999) Spatial patterns of aboveground production and mor-

tality of woody biomass for eastern U.S. forests. Ecological Applications, 9, 968–980.

Brown S, Schroeder P, Birdsey R (1997) Aboveground biomass distribution of US

eastern hardwood forests and the use of large trees as an indicator of forest devel-

opment. Forest Ecology and Management, 96, 37–47.

Brown SL, Schroeder P, Kern JS (1999) Spatial distribution of biomass in forests of the

eastern USA. Forest Ecology and Management, 123, 81–90.

China State Administration of Forestry (2005) Forest Resources Report of China. China

Forestry Publishing House, Beijing, China.

Chinese Ministry of Forestry (1977) Forest Resource Statistics of China (1973–1976).

Department of Forest Resource and Management, Chinese Ministry of Forestry,

Beijing, China.



Beijing, China.



Beijing, China.



Beijing, China.



Beijing, China.



Beijing, China.

Chinese Ministry of Forestry (2010) Forest Resource Report of China - The 7th National

Forest Resources Inventory. China Forestry Publishing House, Beijing, China.

Choi SD, Lee K, Chang YS (2002) Large rate of uptake of atmospheric carbon dioxide

by planted forest biomass in Korea. Global Biogeochemistry Cycles, 16, 1089.

Enkbayar K (1997) Protection Use and Restoration of Forest in Mongolia. A paper pre-

sented in “Reforestation Workshop 1997”.

Fang JY, Chen AP (2001) Dynamic forest biomass carbon pools in China and their sig-

nificance. Acta Botanica Sinica, 43, 967–973.

Fang JY, Wang ZM (2001) Forest biomass estimation at regional and global levels,

with special reference to China’s forest biomass. Ecological Research, 16, 587–592.

Fang JY, Liu GH, Xu SL (1996) Biomass and net production of forest vegetation in

China. Acta Ecology Sinica, 16, 497–508.

Fang JY, Wang GG, Liu GH, Xu SL (1998) Forest biomass of China: an estimation

based on the biomass–volume relationship. Ecological Applications, 8, 1084–1091.

Fang JY, Chen AP, Peng CH, Zhao SQ, Ci LJ (2001) Changes in forest biomass carbon

storage in China between 1949 and 1998. Science, 292, 2320–2322.

Fang JY, Piao SL, Field CB et al. (2003) Increasing net primary production in China

from 1982 to 1999. Frontiers in Ecology and the Environment, 1, 293–297.

Fang JY, Oikawa T, Kato T, Mo W, Wang ZH (2005) Biomass carbon accumulation by

Japan’s forests from 1947–1995. Global Biogeochemistry Cycles, 19, GB2004.

Fang JY, Guo ZD, Piao SL, Chen AP (2007) Terrestrial vegetation carbon sinks in

China, 1981–2000. Science in China (Series D), 50, 1341–1350.

Fang JY, Tang YH, Son Y (2010) Why are East Asian ecosystems important for carbon

cycle research? Science China Life Science, 53, 753–756.

FAO (2006) Global Forest Resources Assessment 2005: Progress Towards Sustainable Forest

Management. FAO Forestry Paper No. 147. Rome, Italy.

FAO (2010a) Global Forest Resources Assessment 2010: Main Reports. FAO Forestry

Paper No. 163. Rome, Italy.

FAO (2010b) Global Forest Resources Assessment – Country Reports: the Democratic

People’s Republic of Korea. Rome. 53. Available at: http://www.fao.org/

forestry/fra/67090/en/prk/ (accessed 4 January 2014).

FAO (2010c) Global Forest Resources Assessment – Country Reports: Mongolia. Rome.

136. Available at: http://www.fao.org/forestry/fra/67090/en/mng/ (accessed

4 January 2014).

Fensholt R, Proud SR (2012) Evaluation of Earth Observation based global long term

vegetation trends – comparing GIMMS and MODIS global NDVI time series.

Remote Sensing of Environment, 119, 131–147.

Field CB, Randerson JT, Malmstrom CM (1995) Global net primary production: com-

bining ecology and remote sensing. Remote Sensing of Environment, 51, 74–88.

GOM (2004) Mongolian Forest. A country report submitted to Regional meeting of

National Correspondents in November 2004. Bangkok, Thailand.

GOM (2009) State of Forest Resources in 2008. Report of Forestry Agency, Ministry of

Nature, Environment and Tourism. Rome, Italy.

Goodale CL, Apps MJ, Birdsey RA et al. (2002) Forest carbon sinks in the northern

Hemisphere. Ecological Applications, 12, 891–899.

Guo ZD, Fang JY, Pan YD, Birdsey R (2010) Inventory-based estimates of forest bio-

mass carbon stocks in China: a comparison of three methods. Forest Ecology and

Management, 259, 1225–1231.

Hansen M, DeFries R, Townshend JRG, Sohlberg R (1998) UMD Global Land Cover

Classification, 8 Kilometer, 1.0. Department of Geography, University of Maryland,

College Park, Maryland, 1981-1994.

Hansen M, DeFries R, Townshend JRG, Sohlberg R (2000) Global land cover classifi-

cation at 1 km resolution using a decision tree classifier. International Journal of

Remote Sensing, 21, 1331–1365.

IPCC (2007) Climate change 2007: the physical science basis. In: Contribution of Work-

ing Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate

Change (eds Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB,

Tignor M, Miller HL), pp. 1–18. Cambridge University Press, Cambridge, UK and

New York, NY, USA.

Ito A (2008) The regional carbon budget of East Asia simulated with a terrestrial

ecosystem model and validated using AsiaFlux data. Agriculture and Forest Meteo-

rology, 148, 738–747.

Janssens I, Freibauer A, Ciais P et al. (2003) Europe’s terrestrial biosphere absorbs 7 to

12% of European anthropogenic CO2 emissions. Science, 300, 1538–1542.

Japan Agency of Forestry (1978) Forest Resources of Japan 1975. Japan Agency of

Forestry, Tokyo, Japan.

Japan Agency of Forestry (1982) Forest Resources of Japan 1980. Japan Agency of

Forestry, Tokyo, Japan.

Japan Agency of Forestry (1987) Forest Resources of Japan 1985. Japan Agency of For-

estry, Tokyo, Japan.

Japan Agency of Forestry (1992) Forest Resources of Japan 1990. Ministry of Agriculture,

Forestry and Fisheries, Tokyo, Japan.







Kauppi PE, Mielikainen K, Kusela K (1992) Biomass and carbon budget of European

forests, 1971 to 1990. Science, 256, 70–74.

Kauppi PE, Ausubel JH, Fang JY, Mather AS, Sedjo RA, Waggoner PE (2006) Return-

ing forests analyzed with the forest identity. Proceedings of the National Academy of

Sciences of the United States of America, 103, 17574–17579.

Kira T (1991) Forest ecosystems of east and southeast Asia in a global perspective.

Ecological Research, 6, 185–200.

Korean Ministry of Agriculture and Forestry (1975) Agriculture and Forestry Statistical

Yearbook. Korea Forest Service, Seoul, Republic of Korea.











Kramer PJ (1981) Carbon dioxide concentration, photosynthesis, and dry matter pro-

duction. BioScience, 31, 29–33.

Lee SH (2006) Forest and other biomass production in the DPRK: current situation

and recent trends as indicated by remote sensing data. DPRK energy experts study

group meeting. Available at: http://www.nautilus.org/projects/dprk-energy/

2006-meeting/papers-and-presentations (accessed 3 January 2014).

Lei JF (2005) Forest Resources of China. Chinese Forestry Publisher, Beijing.

Li X, Yi MJ, Son Y, Jin G, Han SS (2010) Forest biomass carbon accumulation in Korea

from 1954 to 2007. Scandinavian Journal of Forest Research, 25, 554–563.

Liski J, Korotkov AV, Prins CFL, Karjalainen T, Victor DG, Kauppi PE (2003)

Increased carbon sink in temperate and boreal forests. Climatic Change, 61, 89–99.

Malhi Y, Meir P, Brown S (2002) Forests, carbon and global climate. Philosophical

Transactions of the Royal Society of London Series A-Mathematical and Physical Sciences,

360, 1567–1591.

McKinley DC, Ryan MG, Birdsey RA et al. (2011) A synthesis of current knowledge

on forests and carbon storage in the United States. Ecological Applications, 21, 1902–

1924.

Mongolian Ministry of Environment, Nature and Tourism (2009) Mongolia: Assessment

Report on Climate Change 2009 (MARCC 2009). Ministry of Environment, Nature

and Tourism, Ulaanbaatar, Mongolia.

Nabuurs GJ, Goodale C, Schelhaas MJ, Mohren GMJ, Field CB (2003) Temporal evolu-

tion of the European forest sector carbon sink from 1950 to 1999. Global Change

Biology, 9, 152–160.

Pan YD, Birdsey RA, Fang JY et al. (2011) A large and persistent carbon sink in the

world’s forests. Science, 333, 988–993.

Perlin J (1991) A Forest Journey: The Role of Wood in the Development of Civilization.

Harvard University Press, Cambridge, MA.

Persson R (1974). World Forest Resources: Review of the World’s Forest Resources in the

Early 1970s. Department of Forest Survey, Reports and Dissertations, No. 17. Royal

College of Forestry, Stockholm.

Potter CS, Randerson JT, Field CB, Matson PA, Vitousek PM, Mooney HA, Klooster

SA (1993) Terrestrial ecosystem production: a process model based on global satel-

lite and surface data. Global Biogeochemical Cycles, 7, 811–841.

Schroeder P, Brown S, Mo J, Birdsey R, Cieszewski C (1997) Biomass estimation for

temperate broadleaf forests of the United States using inventory data. Forest

Science, 43, 424–434.

Turner DP, Koepper GJ, Harmon ME, Lee JJ (1995) A carbon budget for forests of the

conterminous United States. Ecological Applications, 5, 421–436.

United Nations Environmental Programme and Mongolian Ministry of Nature and

Environment (2002) State of the Environment Mongolia 2002. UNEP Regional

Resource Centre for Asia and the Pacific, Panthumthani, Thailand.

Waggoner PE (2008) Using the Forest Identity to grasp and comprehend the swelling

mass of forest statistics. International Forestry Review, 10, 689–694.

Wang Y, Fang JY, Kato T, Guo ZD, Zhu B, Mo WH, Tang YH (2011) Inventory-based

estimation of aboveground net primary production in Japan’s forests from 1981 to

2005. Biogeosciences, 8, 2099–2106.

Watson R, Nobel IR, Bolin B et al. (2000) Land Use, Land-Use Change and Forestry.

A Special Report of the IPCC. Cambridge University Press, Cambridge.

Winjum JK, Dixon PK, Schroeder PE (1993) Forest management and carbon storage:

analysis of 12 key forest nations. Water, Air and Soil Pollution, 70, 239–257.

Woodbury PB, Smith JE, Heath LS (2007) Carbon sequestration in the US forest sector

from 1990 to 2010. Forest Ecology and Management, 241, 14–27.

Xiao XW (2005) Forest Resource Inventory of China. China Forestry Publishing House,

Beijing, China.

Supporting Information

Additional Supporting Information may be found in theonline version of this article:

Table S1. Forest area and its proportion in 2010 for eachcountry in East Asia. Data are provided by FAO (2010a).Table S2. Parameters of the BEF equation for major foresttypes in China, Japan, and South Korea.Table S3. Change rates of forest area, biomass C density,and total C stock, and their relative ratio to the changes oftotal C stock (C sink) for all, planted, and natural forests inChina and Japan, and for all forests in South Korea, from1970s to 2000s.



forest biomass carbon sinks in east asia, with special reference to the relative contributions of...

Documents