207

ORIGINAL PAPER

Aboveground Dynamics and Productivity of Major
Mangrove Communities on Pohnpei Island,Federated States of Micronesia
Kiyoshi FUJIMOTO1*, Ryuichi TABUCHI2, Yasumasa HIRATA2, Kenji ONO3,
Shingo TANIGUCHI4 and Saimon LIHPAI5
1

Faculty of Policy Studies, Nanzan University, 27 Seirei-cho, Seto, Aichi 489-0863, Japan
Forestry and Forest Products Research Institute (FFPRI), Tsukuba, Ibaraki 305-8687, Japan
3
Tohoku Research Center, FFPRI, Morioka, Iwate 020-0123, Japan
4
Faculty of Agriculture, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
5
Division of Forestry & Marine Enforcement, Pohnpei State Government,
Kolonia, Pohnpei 96941, Federated States of Micronesia*e-mail: kfuji@nanzan-u.ac.jp

20Abstract
The aboveground dynamics, biomass, productivity and carbon storage rate of major mangrove communities on Pohnpei Island, Federated States of Micronesia, were estimated using census data obtained from two
1-hectare permanent plots during about two decades. The aboveground biomass increased from 526 t ha-1
in 1994 to 572 t ha-1 in 2010 for the plot situated in a coral reef-type habitat, referred to as PC1, and from
637 t ha-1 in 1994 to 744 t ha-1 in 2011 for the plot situated in an estuary-type habitat, referred to as PE1. Bothwere higher than any other estimates for mangrove forests throughout the world, though the tree density
decreased from 1,558 trees ha-1 to 1,074 trees ha-1 in PC1 and from 651 trees ha-1 to 473 trees ha-1 in PE1. The
ratio of trees cut by local residents to all deceased trees was higher in PC1 (35%) than PE1 (15%) because ofdifferent accessibility. The potential rates of aboveground carbon storage were estimated at 1.66 t C ha-1 yr-1
for PC1 and 2.79 t C ha-1 yr-1 for PE1. The difference was considered to have resulted from different stages ofsuccession and site environments, such as soil water EC, ground elevation and frequency of submergence bytides.
Key words: aboveground biomass, carbon storage, forest dynamics, forest productivity, mangrove

1. Introduction
Micronesian mangrove forests situated in the midtropics are expected potentially to have the highest
productivity among the earth’s mangrove forests becauseof optimal climatic conditions for the growth of mangrove trees. Studies of tree biomass and productivity
contribute to the creation of a sustainable forest management system and evaluation of the ability of forests toabsorb carbon dioxide. Komiyama et al. (2008) investigated the tree biomass and productivity of mangrove
forests by reviewing 23 and 11 papers, respectively, onthese topics, published since the 1960s, which constituted
almost all of studies published in the field as of that time.
The biomass study areas were distributed worldwide intropic-subtropical regions, though Micronesian mangrove forests were not included. The productivity study
areas, however, were limited to South to Southeast Asia,
Central America and Florida.
Global Environmental Research
17/2013: 207-214
printed in JapanThe USDA Forest Service conducted forest inventories of Micronesian mangrove forests between 1985 and1996 (e.g., MacLean et al., 1986, 1988; Devoe, 1992;
Devoe & Cole, 1998; Ewel et al., 1998). The inventories
established 65 permanent plots that were randomly
located in >12,500 ha of mangrove forests in the Federated States of Micronesia and Palau (Cole et al., 1999).
Cole et al. (1999) estimated tree volumes and diameter
growth rates of major mangrove species on Micronesianislands using these data. The biomass and productivity ofthe main mangrove communities, however, were notcalculated.
We established two 1-hectare permanent plots in the
major mangrove communities of Pohnpei Island in theFederated States of Micronesia in 1994 to observe theforest dynamics and productivity (Fujimoto et al., 1995).
This paper describes the forest dynamics, estimates
aboveground productivity, and discusses the carbon sequestration ability of these forests.
©2013 AIRIES208

K. FUJIMOTO et al.

2. Regional Settings
Pohnpei is a high oceanic island of about 35,500 ha
consisting of Tertiary volcanic rocks and is surroundedby barrier reefs (Fig. 1b). The average annual rainfall is
4,745 mm with no apparent dry season, and the annual
mean temperature is 27.1ºC with less than 1ºC of annual
variation (Western Regional Climate Center, 2012). The
mean tidal range at Pohnpei Harbor is about 70 cm, andthe diurnal tidal range is approximately 104 cm (NOAA,
2010).
Mangrove habitats have developed mainly on the reef
flats fringing the island, although some of them are situated in estuaries (Fig. 1b). The former habitat is referred
to as the coral reef type and the latter as the estuary type(Fujimoto et al., 1995). The substrata of these mangrove
habitats mainly consist of peat (Miyagi & Fujimoto,
1989; Fujimoto & Miyagi, 1993; Fujimoto et al., 1995,
1999). The mangrove forests on Pohnpei Island have notsignificantly suffered from human impact; therefore aclear zonation of mangrove communities can be found.
Based on the phytosociological method, the mangrove forests in Pohnpei have been classified into threecommunity types, along with six subcommunities andfive subunits, by Mochida et al. (2006). The community
types are as follows:
I. the Rhizophora stylosa community, with three subcommunities:(1) the typical subcommunity,(2) the Enhalus acoroides subcommunity, and(3) the Bruguiera gymnorrhiza subcommunity.
II. the Sonneratia alba community, andIII. the Rhizophora apiculata – B. gymnorrhiza community, with three subcommunities:(1) the typical subcommunity,(2) the S. alba subcommunity, with three subunits:a) the typical subunit, b) the Xylocarpus
granatum subunit, and c) the Lumnitzera littorea
subunit, and(3) the X. granatum – Heritiera littoraris subcommunity, with two subunits:a) the typical subunit and b) Barringtonia
racemosa subunit.
Communities I and II develop along the seaward edgeof coral reef-type habitat. Communities III(1) and III(2)adevelop in coral reef-type habitat with a mangrove peat
layer less than 1 m thick, and community III(2)b, which
occupies the widest area of the mangrove forests in
Pohnpei, develops in coral reef-type habitat with amangrove peat layer more than 1 m thick, usually around
2 m, and estuary-type habitats with a deep mangrove peat
layer, usually 3 to 5 m. Communities III(2)c and III(3) areusually found in landward and relatively high elevation
areas (Fujimoto et al., 2006).

Fig. 1 Map showing the location of Pohnpei Island (a), landformof Pohnpei Island and distribution of mangrove habitats(b; after Fujimoto et al., 1995) and the location of thepermanent plots (c; satelite photo taken by QuickBird on
Aug. 15, 2003).

Aboveground Dynamics and Productivity of Major Mangrove Communities on Pohnpei Island

2010

Dead trees
200m
190
180
170
160
150

140
130
120

R. apiculata

130
100

20-

90

30-

80

4050-

70

B. gymnorrhiza

70

90
80

120

10-

100

100
90
80
70

110

0-

110

110

140

140

Diameter (cm)

120

130

150

150

160

160

170

170

180

180

190

190

200 m

200 m

1994

209

50
40

60

1020-

50

50
40

60

60

0-

40
30

20-

30

30

30-

S. alba

0

10

20

30

40

50 m

10

50-

10

100-

0

20

20

40-

0

0

10

20

30-

0

10

20

30

40

0

50 m

10

20

30

40

50 m

Fig. 2 Distribution of living trees by species and diameter in 1994 and 2010 and locations of trees that died or were
harvested between 1994 and 2010 in PC1. The 0 m line of the vertical axis is situated in the direction of the sea.

3. Methods
Two permanent plots 50 m wide and 200 m long were
set up in a III(2)a community in a coral reef-type habitat
at right angles to the coast line and a III(2)b community
in an estuary-type habitat at right angles to the river channel, located in the eastern part of Pohnpei Island, andwere named PC1 and PE1, respectively (Fig. 1c).
Tree censuses were carried out in February 1994,
March 1997, December 1999, and September 2002, 2004
and 2010 for PC1 and in February 1994, March 1997,
December 1999, August 2003, and September 2005 and2011 for PE1. All trees taller than 1.3 m were numbered,and their position, species and stem diameter, at 30 cm
above the root collar for R. apiculata and DBH for theother species, were recorded. Tree height was calculatedusing equations created from the relationship between
diameter and height of sample trees for each species(Tabuchi et al., 2006). Tree biomass was estimated using
allometric relationship equations from Komiyama et al.
(1988).

(trees)
500
450
400
350
300
250
200
150
100
50
0

Ra

1994

0200
180
160
140
120
100
80
60
40
20
0

2010

5-

10-

15-

20-

25-

30-

35-

5-

10-

15-

20-

25-

30-

35-

100-

120-

Bg

014
12

Sa

10

4. Results

8

4.1 Forest dynamics
In PC1, three mangrove species, i.e., R. apiculata, B.
gymnorrhiza and S. alba, were found (Fig. 2). Tree density decreased from 1,558 trees ha-1 in 1994 to 1,074 trees
ha-1 in 2010 (R. apiculata: from 1,173 to 896 trees ha-1, B.
gymnorrhiza: from 351 to 146 trees ha-1, S. alba: from 34
to 32 trees ha-1). In particular, B. gymnorrhiza smaller
than 10 cm in diameter and R. apiculata smaller than

4

6

2
0
0-

20-

40-

60-

80-

Diameter class (cm)Fig. 3 Frequency distribution of diameter classes ofrespective species in PC1 in 1994 and 2010.
Ra: R. apiculata, Bg: B. gymnorrhiza, Sa: S. alba.

210

K. FUJIMOTO et al.

15 cm in diameter dramatically declined from 264 to 81
trees ha-1 and from 256 to 46 trees ha-1, respectively (Fig.
3). The average tree diameters of each species increased
from 18.6 to 22.0 cm for R. apiculata, from 8.6 to 13.7
cm for B. gymnorrhiza and from 53.9 to 60.1 cm for S.
alba during the period.
Sixty-five percent of the dead trees had been killed bynatural factors such as dieback and windfall, while 35%of them had been cut by local residents. Looking at thecauses of death by species and diameter class, natural
deaths of B. gymnorrhiza (hereafter referred to as DeadBg) and R. apiculata (hereafter referred to as Dead Ra)
occurred most frequently for trees of less than 10 cm indiameter and between 10 and 20 cm in diameter, respectively. Harvested B. gymnorrhiza (hereafter referred to as
Cut Bg) and R. apiculata (hereafter referred to as Cut Ra)
were most frequently less than 10 cm in diameter andaround 10 cm in diameter, respectively (Fig. 4). The
average diameters of Dead Bg, Dead Ra, Cut Bg and Cut
Ra were 5.5 ± 3.5 cm, 14.9 ± 4.1 cm, 7.6 ± 3.9 cm and11.9 ± 4.0 cm, respectively. Significant differences indiameter were found between Dead Bg and Dead Ra(p<0.001, Welch’s t-test), Dead Bg and Cut Bg, Cut Bg
and Cut Ra, and Dead Ra and Cut Ra (p<0.001, Student’s
t-test).
In PE1, four mangrove species, i.e., R. apiculata, B.
gymnorrhiza, S. alba and X. granatum, were found(Fig. 5). Tree density decreased from 651 trees ha-1 in
1994 to 473 trees ha-1 in 2011 (R. apiculata: from 369 to
285 trees ha-1, B. gymnorrhiza: from 184 to 110 trees ha-1,
S. alba: from 34 to 31 trees ha-1, X. granatum: from 64 to
47 trees ha-1). Most dramatically, B. gymnorrhiza smaller
than 10 cm in diameter declined from 81 to 29 trees ha-1,
X. granatum smaller than 15 cm in diameter declined
from 16 to 4 trees ha-1, and R. apiculata smaller than
20 cm in diameter declined from 156 to 45 trees ha-1
(Fig. 6). The average tree diameters of each species
increased from 21.8 to 27.6 cm for R. apiculata, from
23.1 to 32.3 cm for B. gymnorrhiza, from 86.6 to 99.3 cm
for S. alba and from 28.9 to 37.0 cm for X. granatum
during the period.
Eighty-five percent of dead trees had been killed by(trees)100
Cut Bg80

Dead Bg

60

Cut Ra40

Dead Ra

20
01015Diameter class (cm)

20-

25-

Fig. 4 Frequency distribution of diameter classes of
deceased trees by species and causes in PC1
between 1994 and 2010. Cut Bg: harvested B.
gymnorrhiza, Dead Bg: B. gymnorrhiza that dieda natural death, Cut Ra: harvested R. apiculata,
Dead Ra: R. apiculata that died a natural death.

2011

Dead trees
200 m
190

50-

S. alba
3040-

60

50-

130

140

150

160

170

180

40-

120

140
130
110
100
90
80
70

110
100
80
60

70

90

120

0102030-

110

140
130
120

B. gymnorrhiza

100010203040-

150

150

160

R. apiculata

90

180
170

Diameter (cm)

80

180
160

170

190

190

200 m

200 m

1994

70

5-

60

0-

50

50

50

100-

20

30

40

50 m

0

10

20

30

40

50 m

40
30
20

20
10
0
10

10

20
10
0
0

4050-

0

0102030-

30

30

40

40

200-

X. granatum

0

10

20

30

40

50 m

Fig. 5 Distribution of living trees by species and diameter in 1994 and 2011 and locations of trees that died or were
harvested between 1994 and 2011 in PE1. The 0 m line of the vertical axis is situated in the direction of the sea.

Aboveground Dynamics and Productivity of Major Mangrove Communities on Pohnpei Island

natural factors, while 15% had been cut by local residents.
Looking at the causes of death by species and diameterclass, Dead Bg and Dead Ra were most frequently lessthan 10 cm in diameter and between 10 and 20 cm indiameter, respectively, though larger dead trees were also
found, and Cut Bg and Cut Ra were most frequently lessthan 10 cm in diameter and between 5 and 10 cm indiameter, respectively (Fig. 7). The average diameters of
Dead Bg (one at 64.8 cm was declared an outlier bySmirnov-Grubbs rejection test (P<0.01)), Dead Ra, Cut
Bg (one at 40.6 cm was declared an outlier bySmirnov-Grubbs rejection test (P<0.001)) and Cut Ra
were 14.6 ± 12.3 cm, 15.8 ± 6.8 cm, 5.9 ± 2.0 cm and10.9 ± 2.3 cm, respectively. Significant differences in the
average diameter were found between Dead Bg and Cut
Bg (p<0.001, Welch’s t-test), Cut Bg and Cut Ra(p<0.001, Student’s t-test), and Dead Ra and Cut Ra(p<0.001, Welch’s t-test).

(trees)
120

Ra

100

1994

2011

80
60
40
20
0
0-

10-

20-

30-

40-

50-

60-

70-

10-

20-

30-

40-

50-

60-

70-

10-

20-

30-

40-

50-

60-

70-

50

Bg
40
30
20
10
0
0-

4.2 Aboveground productivity
In PC1, the total aboveground biomass increased
from 526 t ha-1 in 1994 to 572 t ha-1 in 2010 (R. apiculata:
from 396.5 to 425.4 t ha-1, B. gymnorrhiza: from 26.6
to 26.9 t ha-1, S. alba: from 102.7 to 120.1 t ha-1) (Fig. 8).
The average annual increment rate between 1994 and2010 was calculated to be 2.81 t ha-1 yr-1. On the other
hand, the aboveground necromass arose at a rate of
3.67 t ha-1 yr-1 during the period, including the harvested
necromass, which arose at a rate of 0.88 t ha-1 yr-1
(Fig. 9a). Dead Ra accounted for 69% of total annual
necromass emergence.
In PE1, the total aboveground biomass increased from
637 t ha-1 in 1994 to 744 t ha-1 in 2011 (R. apiculata: from195.8 to 238.2 t ha-1, B. gymnorrhiza: from 109.3 to121.9 t ha-1, S. alba: from 287.9 to 331.7 t ha-1, X.
granatum: from 44.1 to 51.9 t ha-1) (Fig. 8). The averageannual increment rate between 1994 and 2011 was calculated to be 6.06 t ha-1 yr-1. The aboveground necromass
arose at a rate of 3.34 t ha-1 yr-1 during the period,
including harvested necromass, which arose at a rate of
0.13 t ha-1 yr-1 (Fig. 9b). The ratios of Dead Ra, Dead Bg
and Dead Sa to total annual necromass emergence were35%, 27% and 26%, respectively.

12
10

Xg

8
6
4
2
0
010

Sa
8
6
4
2
0
20-

40-

60-

80- 100- 120- 140- 160- 180- 200-

Diameter class (cm)Fig. 6 Frequency distribution of diameter classesof respective species in PE1 in 1994 and 2011.
Ra: R. apiculata, Bg: B. gymnorrhiza,
Xg: X. granatum, Sa: S. alba.
(trees)40

Cut BgDead Bg

30

Cut Ra20

Dead Ra
Dead Xg

10
0
0-

5-

10-

15-

211

20-

25-

30-

35-

40-

45-

50-

55-

60-

Diameter class (cm)Fig. 7 Frequency distribution of diameter classes of deceased trees by species and causes in PE1 between 1994 and2011. Cut Bg: harvested B. gymnorrhiza, Dead Bg: B. gymnorrhiza that died a natural death, Cut Ra: harvested
R. apiculata, Dead Ra: R. apiculata that died a natural death, Dead Xg: X. granatum that died a natural death.

212

K. FUJIMOTO et al.
(t/ha)
600

5. Discussion

PC1
526

542

545

500

555 561

572

400
300
200
100
0
1990

1995

2000

2010

2015 (AD)PE1(t/ha)
800
700

2005

697
637
660

600

744

703

678

total

500

Sa

400

Ra

300

Bg

200

Xg

100
0
1990

1995

2000

2005

2010

2015 (AD)Fig. 8 Changes in aboveground biomass in PC1 and PE1.
Ra: R. apiculata, Bg: B. gymnorrhiza, Sa: S. alba, Xg:
X. granatum.

(t/ha/yr)
6.0

PC1

5.0
4.0
3.0
2.0
1.0
0.0

(t/ha/yr)
8.0

PE1

7.0
6.0

Dead Xg

5.0

Dead Sa

4.0
3.0
2.0

Dead Bg
Dead RaCut Bg1.0
0.0

Cut RaFig. 9 Aboveground necromass occurrence rate between
censuses and the average. Cut Bg: harvested B.
gymnorrhiza, Dead Bg: B. gymnorrhiza that died anatural death, Cut Ra: harvested R. apiculata,
Dead Ra: R. apiculata that died a natural death,
Dead Xg: X. granatum that died a natural death.

5.1 Differences in forest structure, dynamics andproductivity between different community types
PC1, which is situated in a III(2)a community, has amangrove peat layer less than 1 m thick, while PE1 situated in a III(2)b community has a mangrove peat layer
more than 2 m thick (Fujimoto et al., 1995). The radiocarbon ages obtained from the mangrove peat of PE1
indicate that the habitat is older than 2000 years(Fujimoto et al., 1999), while that of PC1 is estimated tobe younger than 1,000 years (Fujimoto et al., 2006). The
presence or absence of X. granatum, which is in PE1 but
is not in PC1; and differences in tree density, which ishigher in PC1 than PE1, and tree size, which is smaller in
PC1 than PE1, seem primarily to be due to differences instage of primary succession associated with habitat age.
Additionally, disturbance by huge typhoons, such as in1905, may have caused secondary succession partially(Imanishi & Kira, 1944).
Human impact has also affected the forest structures.
The ratio of cut trees to all deceased trees was higher in
PC1 than PE1, probably because of a difference inaccessibility, namely, PC1 is located in a place which isapproached easily from land, while PE1 can only beapproached from the sea by boat. The high density of R.
apiculata, which is a less shade-tolerant species (Kitao
et al., 2003) and usually dominates at relatively lower
elevations than B. gymnorrhiza (Mochida et al., 1999), in
the landward part of PC1 (Fig. 2) seems to have beencaused by severe human impact such as clear cutting.
The average diameter of Dead Ra was around 15 cm
in both plots, while that of Dead Bg differed between
PC1, at around 5.5 cm, and PE1, at around 15 cm. The
main factor in natural deaths of R. apiculata in both plots
and B. gymnorrhiza in PE1 was windfall, while that of B.
gymnorrhiza in PC1 was dieback because most of themwere shrubs of small diameter (Fig. 4).
Potential aboveground productivity, which is calculated by adding the rate of harvesting to the increment
rate of aboveground biomass, was estimated to be
3.69 t ha-1 yr-1 for PC1 and 6.19 t ha-1 yr-1 for PE1,
excluding litter production, which was estimated to be
15 t ha-1 yr-1 for PC1 by the litter trap method (Ono et al.,2006). The difference in productivity between the twoplots seems to have been caused by a difference in stageof primary or secondary succession and some site
environmental factors, such as soil water EC, groundelevation and submergence frequency by tides. The soil
water EC at 20 cm depth in 1994 (Fujimoto et al., 1995)
was significantly higher in the seaward part (up to the
50 m line from the seaward edge of the plot) of PC1,
45.5 ± 1.9 mS cm-1, than that of PE1, 37.4 ± 2.4 mS cm-1
(p<0.01, Student’s t-test), while no significant difference
was found in the landward part. The ground elevation in1994 was higher in PC1 than PE1, which means that thesubmergence frequency was lower in PC1 than PE1(Fujimoto et al., 1995). The ground elevation in PC1,
especially in the landward part, where R. apiculata

Aboveground Dynamics and Productivity of Major Mangrove Communities on Pohnpei Island

dominates unnaturally, is possibly too high for optimal
conditions for the growth of R. apiculata.
5.2 Carbon sequestration ability
The aboveground biomass was estimated to be
572 t ha-1 in 2010 for PC1 in a middle stage of primarysuccession and 744 t ha-1 in 2011 for PE1 at almost theclimax stage of succession. These values were higher
than any other estimates for mangrove forests in theprevious studies compiled in Komiyama et al. (2008).
The highest estimate in the previous studies was
460 t ha-1 for an R. apiculata dominant forest in Matang,
Malaysia, by Putz and Chan (1986).
Pohnpei mangrove forests also store the largest
amount of carbon in sediments in the Asia-PacificRegion, reaching about 650 t C ha-1 up to 1 m deep
(Fujimoto, 2004). These facts suggest that among theearth’s mangrove forests, Pohnpei’s mangrove forests
store the greatest amount of carbon per unit area.
The potential rates of aboveground carbon storage
are estimated to be 1.66 t C ha-1 yr-1 for PC1 and
2.79 t C ha-1 yr-1 for PE1, supposing that the carbon
content of a mangrove tree is 45% of its dry weight. The
below-ground carbon burial rates during the stable andrising sea-level phases in Pohnpei were estimated to be
0.6 to 0.9 t C ha-1 yr-1 using radiocarbon ages obtained
from bulk samples of mangrove peat (Fujimoto, 2004).
Higher-precision estimates of the formative age of mangrove peat using the AMS radiocarbon dating method for
non-reworked samples such as bark, excluding roots, andclarification of the mechanism of below-ground production and decomposition are needed in order to enableevaluation of the carbon sequestration abilities of themangrove ecosystem accurately.
The constant increment of aboveground biomass inboth plots suggests that the mangrove forests of Pohnpei
have been managed sustainably at least during the lasttwo decades. However, the sea-level rise induced by
global warming, which is already observed to have been
+1.8 mm yr-1 between 1974 and 2004 and +16.9 mm yr-1
between 2002 and 2010 at Pohnpei, though the cause of
the rapid rise in recent years is not clear (Bureau of
Meteorology, Australian Government, 2010), is possibly
affecting the productivity and habitat conditions.
Continuous monitoring of the permanent plots is neededin order to detect the effects of sea-level rise on mangrove ecosystems.

Acknowledgments
We are grateful to Mr. Benly Lucios, Director of the
Department of Land and Natural Resources, Mr. Herson
Anson, former Chief of the Division of Forestry andMarine Resources, and all of staff of the Division ofForestry and Marine Enforcement, Pohnpei State
Government, for their dedicated collaboration with our
joint project and heart-warming hospitality during ourstay in Pohnpei. This study was financially supported by
the Special Coordination Funds for Promoting Science213

and Technology of the Science and Technology Agencyof Japan (Bilateral International Joint Research; FY 1993,
1996 and 1999) and a Grant-in Aid for Scientific
Research (A) of the Japan Society for the Promotion of
Science (No. 14255011; FY 2002-2005 and No.
22255009; FY 2010-2013).
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Kiyoshi FUJIMOTO
Kiyoshi FUJIMOTO is a Professor at the Facultyof Policy Studies, Nanzan University. He hasstudied mangrove ecosystems from the viewpoint of geomorphology and ecology since 1987,
mainly in the Asia-Pacific region, to predict andmonitor the effects of sea-level rise and toevaluate the carbon sequestration abilities. He is
also a representative director of an NGO called Nan-yu no Kai (Hoi Nam
Du in Vietnamese) for mangrove planting in Vietnam.

Ryuichi TABUCHI
Ryuichi TABUCHI is a senior researcher at theForestry and Forest Products Research InstituteJapan. Since studying in Thailand under a fellowship of the Thai Government when he was a
graduate school student, he has continued to be
attracted by the topic of forest ecosystems in thetropics and has been involved in several forest
ecological studies in Southeast Asia and Pacific islands. His major interest
is in swamp forests, particularly mangroves, which involve human activity
as an important component and sustain the livelihood of local residents.

Yasumasa HIRATA
Yasumasa HIRATA is head of the Climate Change
Office, Forestry and Forest Products ResearchInstitute (FFPRI), Japan. He is studying remotesensing applications for forest monitoring andmanagement. He is working on developing
methodologies for forest carbon monitoring
based on the UNFCCC scheme in Southeast
Asia and South America.

Kenji ONO
Kenji ONO is a Senior Researcher at the Forestry
and Forest Products Research Institute (FFPRI)
in Japan. His interest is in humification processes of organic materials in forest ecosystems.
He is studying peat accumulation processes invarious types of mangrove ecosystems.

Shingo TANIGUCHI
Shingo TANIGUCHI is a Professor in the Department of Subtropical Agro-Environmental
Sciences, Faculty of Agriculture, University of
the Ryukyus. He has worked at this university
since 2006, and has expertise in the fields ofsilviculture, forest ecology and tree physiological ecology. His research interest is in thephysiological ecology of mangroves. His recent research has focused on
the salt tolerance mechanisms of mangroves and he is working on analysisof stable isotope distributions in breeding resources among trees native tothe subtropical Ryukyu islands. He has been involved in a study on carbon
accumulation of a natural mangrove forest on Pohnpei Island, Federated
States of Micronesia, since 2010.

Saimon LIHPAI
Saimon LIHPAI is Chief Forester at the Divisionof Forestry and Marine Enforcement, Department of Land and Natural Resources,
Pohnpei State Government, Federated States ofMicronesia. He earned his Bachelor of Science
degree in Forestry from the Visayas State
College of Agriculture in the Philippines in
1995. He has collaborated with our joint research project on mangrove
forests since 1997.

(Received 12 June 2013, Accepted 22 July 2013)