全 文 ：Received 26 Aug. 2003 Accepted 10 Feb. 2004
Supported by the National Natural Science Foundation of China (30230030, 39800012) and Cooperative Project Futian-CityU Mangrove
Research and Development Centre.
* Author for correspondence. E-mail: .
http://www.chineseplantscience.com
Growth Dynamics and Self-Thinning of the Dominant Populations
in the Mangrove Community
LIAO Wen-Bo1*, LAN Chong-Yu 1, ZAN Qi-Jie1, WONG Yuk-Shan2, Nora Fung-Yee TAM2
(1. School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China;
2. City University of Hong Kong, Hong Kong, China)
Abstract : Consecutive investigations in 1994, 1996, 1998, and 2002 in the permanent plots established
in Futian Mangrove Reserve of Shenzhen, Guangdong Province, revealed that the breaking, drying and
death of the individual plants or branches in the mangrove communities were significant and the number of
plants in plots covering an area of 200 m2 was 417, 341, 196 and 132; the average density of population per
square meter is 2.08, 1.70, 0.98 and 0.66; the death rate between the interval of two investigations is
18.2%, 42.5% and 32.6% respectively. The individuals of population exhibit an obvious diameter at breast
height (DBH) growth. For example, the maximum increment of individual DBH was up to 3.63, 2.45, and 4.52
cm in the dominant populations Aegiceras corniculatum (L.) Blanco (Ac), Kandelia candel (L.) Druce (Kc),
and Avicennia marina (Forsk.) Vierh. (Am), respectively. At the same time, growth of individual height was
also prominent. In the second investigation, 233 out of the 341 individuals exhibit a height growth; whereas
the number under the third and fourth investigations was 127 out of 196 and 74 out of 132, respectively.
During a 2-year interval, the maximum height growth was 1.5 m in Ac, 1.9 m in Kc, and 1.8 m in Am. The
biomass also showed a relative change in the mangrove communities. The total biomass of stems and
leaves decreased with time but occasionally an increase was found in the second and third investigations
and finally a decrease in the fourth investigation. However, the average biomass of the survived individuals
usually increased with time. In terms of the total biomass, the results of the four investigations were
similar to the previous research in which the data were calculated by the methods of standardized timbers,
etc. being 7.57, 8.36, 5.15 and 7.71 kg/m2 during 1994, 1996, 1998 and 2002, respectively. The above
analysis indicates that self-thinning of mangrove communities is an important evolutionary process,
characterized by drying, breaking, and death of individuals/ramifications. During the process of evolution,
fewer new seedlings deve loped, and individual height growth, DBH growth , breaking and death from
dryness maybe closely related to the composition, structure and density of population in the mangrove
communities.
Key words : mangrove; Aegiceras corniculatum ; Kandelia candel ; Avicennia marina ; self-thinning;
growth dynamic
Despite the large body of materials and references con-
cerning the research of seashore mangrove in China in the
as pects of s pecies compos it ion and geograph ical
distribution, vegetation types, community structure, popu-
lation patterns of mangrove plants , and ecological and
physiological feature of mangrove communities (Chang et
al., 1957; Lin , 1987; 1997; Chen and Miao, 1994; Li et a l.,
1994; Fang and Liang , 1995; Miao and Chen, 1997; Wong
and Tam, 1997), very few studies have been reported on the
population and community dynamics, and evo lut ion of
mangrove.
Permanent plo ts can be used to study the dynamics of
plant communities because it is easy for observing the indi-
vidual characters and life proces s in ecosystem, i.e. the
continuous changing process in time and space; as well as
observing the population change and development of com-
munity in ecos ystem, and its environmental relation . And
mangrove is a community type with higher productivity and
higher recession rate, in which the species are of simpler
composition, higher ecological dominance, lower diversity
index and evenness; as well as with clumped pattern of domi-
nant population distribution (Chen et al., 1994b; Li et a l.,
1994). Therefore, it is o f importance to examine the dy-
namic p roces s o f the dominant populat ions by des ign-
ing permanent plots in the mangrove ecosys tem for long-
term eco log ical research.
The authors designed a piece of permanen t plot cover-
ing an area of 200 m2 and completed an eigh t-year’s
Acta Botanica Sinica
植 物 学 报 2004, 46 (5): 522-532
523LIAO Wen-Bo et al.: Growth Dynamics and Self-Thinning of the Dominant Populations in the Mangrove Community
observation. The chief objective of this study was to in-
vestigate the biomass growth , individual plant growth in
height and diameter at breast heigh t (DBH), and demo-
graph ic change in the mangrove communities, as a basis
for further inspection on the population dynamics o f the
local mangrove.
1 Natural Geographical Condition
The mangrove of Shenzhen Futian-Neilingding National
Nature Reserve of Guangdong Province, China, covers an
area of 300 hm2, including 13 mangrove plant species, more
than 100 semi-mangrove and seashore plant species, and
more than 190 bird species (Deng et a l., 1986; Yang and
Shen, 1992a; 1992b; Wang et al., 1993; Chen et al., 1994a;
Chang et al., 1998). Especially, it is an important bird habitat,
where sometimes there are as many as ten thousand birds.
Based on Chen’s (1994b) and Li’s (1994) research, the spe-
cies diversity index (Shannon-Wiener index) of Futian man-
grove communities is 0.78, the evenness index is 0.49, the
importance value of the dominant population Aegiceras
corniculatum (Ac), Kandelia candel (Kc) and Avicennia
marina (Am) is 0.72, 0.19 and 0.09 respectively. The simple
composition and structure of the mangrove community are
advantageous for further inspecting and observing the re-
lationship between species and community evolution (Chen
et al., 1994b; Li et al., 1994).
Our selected permanent plot is situated in the northeast
Futian Nature Reserve Mangrove in Shenzhen, with a geo-
graphical position at about 22°32′N and 114°05′E, be-
longing to an area of lower-subtropical oceanic monsoon
climate. The mean annual temperature is 22.55 ℃, mean
monthly temperature is 15.0 ℃ in January, and 28.72 ℃ in
Ju ly . The annual p recipitat ion is 1 794.14 mm, and annual
daily sunshine is 2 209 h exhibiting an obvious alternation
of arid and humid seasons. In the Shenzhen bay and man-
grove distribution area, the tide is the semi-diurnal with an
average tidal range of 1.36 m, being maximal at about 2.8 m.
The average salinity of seawater is < 1.5%, with a pH of 7.6.
The physical and chemical properties of soil are as follows:
organic compound, 22.3 g/kg; available N, 49.5 mg/kg; avail-
able P, 50.9 mg/kg; available K, 951.2 mg/kg; so il salin ity,
2.1%. Among the clunch deposit, 6.31% of the grain com-
position is > 0.25 mm, 24.87% of which is 0.25-0.01 mm and
67.35% of which is < 0.01 mm (Li et a l., 1994; Tam et a l.,
1995a; Chang et al., 1998; Huang et al., 2000).
2 Materials and Methods
2.1 Plot design
In 1994 we selected two zones, A and B, in a natural and
typical mangrove community in the south of Shazui village
of Shenzhen bay. Each zone was 10 m in width and 180 m in
length extending towards the beach. The zones were 150 m
apart. A 0.3 m concrete bat was built on each side-border of
A-zone. A-zone was then irrigated and drained with living
waste-water at the time after daily ebb-tide weekly for one
year. B-zone was served as control. Four permanent plots
A-S1 to A-S4 and B-S1 to B-S4 were set up in A- and B-zone
respectively. In each zone the four plots (each plot cover-
ing an area of 5 m× 5 m) extended in sequence from the
bottomland towards the beach, the total plot area was 200
m2. The first plot A-S1 in A-zone (likewise B-S1 in B-zone)
was 20 m away from bottomland. A-S2, A-S3 and A-S4 in A-
zone (B-S2, B-S3 and B-S4 in B-zone) were located in se-
quence further away from the bottomland. The space be-
tween the neighboring plots was identically 10 m.
2.2 Plot investigation
Plants with height of over 1.3 m, including all branches
with DBH over 1 cm, that had branched from the t runk at
levels below 1.3 m above-ground were accounted. Indi-
vidual plant was identified with plastic-sealed ID (with the
code number). The ID cards were tagged on individual tree/
branch at the height of 1.3 m. Measurements included the
tree/branch height (H, or length (L)), trunk circumference at
breast height (expressed as DBH by divid ing the breast
circumference by 3.14), coord inate position of individuals
(X, Y); and from which all data were computerized into
database (Li et al., 1987; Yu et al., 1993; Wang et al., 1996).
The tree/branch height was measured at the highes t (the
longest) part and the breast circumference was measured
around trunk at 1.3 m above-ground us ing a measuring
tape. Four consecutive invest igations were carried out in
January of 1994, 1996, 1998 and 2002.
It is preferab le to take a 5 m× 5 m -s ized s ite as an
individual plot, since a plot with an area o f 25 m2 usually
includes three main dominant populations in the mangrove
community. In addition, the number of individual plants in
the eight plots, ranging from 41 to 65, represented a suit-
able density fo r study. Moreover the population in the
community, being different from those in the land fo rest,
grow in clusters with luxurian t branches from short and
stout bases. During the developmental process, the base
changes much s lower than the b ranches. Therefore it is
much easier to inspect the change of populations in man-
grove community by measuring the total area at 1.3 m breast
height (ABH; ABH = p (DBH/2)2) of plants/branches than
the total area at bas e, as the measurement of the latter is
very difficult and could be inaccurate. Furthermore, as the
permanent p lots were des igned in the core region of the
Acta Botanica Sinica 植物学报 Vol.46 No.5 2004524
mangrove community , they actually occupied only
20+5+10+5+10+5+10+5 = 70 m among the 180 m from the
bottomland extending to the beach. There was still a 30-40
m conservation zone (of the same community), and another
30-40 m zone o f annual herbaceous plan t Acanthus
ilicifolius L. (Ai), and also a 30 m zone of sporadic distribu-
tion zone at the beach side (Wong et al., 1995a).
2.3 Data analysis
The following equations were employed in analyses.
Index of the area ABH: ABH-Index = Total of all indi-
vidual ABH in community or plots / Total area of all commu-
nity or plots;
Biomass of mangrove community: W = a×DBH2×H
×b (W is weight of total biomass; DBH is diameter at breast
heigh t; H is tree height (length); a and b are constan ts),
based on an analysis of Futian mangrove communities, the
a and b values are confirmed by Tam et al. (1995b), i.e.:
Ac: LogW = 1.496+0.465 Log(DBH2×H)
Kc: LogW = 2.814+1.053 Log(DBH2×H)
Am: LogW = 2.092+0.529 Log(DBH2×H)
where W is the total b iomass of the above-ground parts
(kg), DBH is diameter at breas t heigh t (m), H is height
(length) (m).
3 Results and Analysis
3.1 Characters of communities in the plots
In the eight plots A-S1, A-S2, A-S3, A-S4, B-S1, B-S2, B-
S3 and B-S4, generally speaking, the vertical stratification
of communities was not significant with crown density of
about 0.90-0.96. The dominant populations examined in
1994 included Ac with a maximal DBH of 7.6 cm, Kc with a
maximal DBH up to 12.1 cm, and Am with a maximal DBH of
9.6 cm, and other biennial herbaceous species such as Ai.
The number o f Kc and Ac were overwhelming in the
mangrove. And Am was a minor species, but it could be-
come dominant in some sectional areas. Ai was particularly
dominant in B-S3 and B-S4, d istributed s catteredly o r in
clusters; As they exhibited a rapid life cycle only its height
and number were recorded.
In A- and B-zone, according to Chen’s (1994b) and
Li’s (1994) research , the degree o f correlat ion among
the dominan t populat ions (Ac, Kc and Am) was les s
sign ifican t than their complexity, reflect ing a relative
stab ility o f the mangrove community. In addit ion, the
calcu lat ing un it of total biomass in the mangrove com-
munit ies approximated 12.14 kg/m2 (Tam et al ., 1995b).
Based on a detailed investigation in 1994, the main char-
acters of the plot communities were as follows:
(1) Plo t A-S1 The Ac community, composed of Ac
solely, contained a total of 17 clusters with 54 main branches.
Since Ac grows in clusters and all main branches usually
grow directly from the root (or base), therefore they were
recorded as the same coordination, but for those branches
grown above 1.3 m, from a main trunk they were accounted
as the same individual plant.
(2) Plot A-S2 The Ac + Kc community contained five
clusters of Ac with 41 branches and two clusters of Kc with
eight branches.
(3) Plot A-S3 The Ac community contained 19 clusters
with 41 branches.
(4) Plot A-S4 The Ac + Kc community contained 21
clusters of Ac with 43 branches and one cluster of Kc with
four branches.
(5) Plot B-S1 The Ac + Kc community contained 27
clusters of Ac with 48 branches and four clusters of Kc
with 16 branches.
(6) Plot B-S2 The Ac + Kc + Am community contained
16 clusters o f Ac with 50 branches, th ree clusters of Kc
with 10 branches, and one plant of Am (one branch).
(7) Plot B-S3 The Ac + Kc + Am community contained
two clusters of Ac with 16 branches, six clusters of Kc with
12 branches, six clusters of Am with nine branches, and the
Ai included nine clusters with height ca. 1.5 m and six clus-
ters with height ca. 2 m.
(8) Plot B-S4 The Kc + Ac + Am community contained
nine clusters of Ac with 13 branches, 20 clusters of Kc with
47 branches, two clusters of Am with six branches, and Ai
more than 200 single branches.
3.2 Growth dynamics of population
3.2.1 Growth of population Based on the four consecu-
tive investigations in January of 1994, 1996, 1998, and 2002,
the individual change of A- and B-zone is shown in Table 1.
From Table 1, it is shown that in A-zone, the population
Ac exhibited the highest branch death rate being 10.6% in
1994 and up to 36.9% in 1998, and that of Kc was minimal as
no death was found in 1996, and only one branch died
(8.3%) in 1998.
In B-zone, the branch-death rate was still the highest in
the Ac population, accounted for 31.7% in 1996 and 73.2%
in 1998. Eighty-six out of 126 individual plants survived in
1996 and 23 survived in 1998. Branch death rate of Am
population ranked the second highest, being 31.2% in 1996,
45.4% in 1998, and 33.3% in 2002. The death rate of Kc was
higher than that in A-zone, accoun ted fo r 14.3% in 1996,
23.6% in 1998 and 20.0% in 2002.
3.2.2 DBH growth As shown in Table 2, in the 1994
investigation o f A-zone, the DBH of the Ac population
ranged 1.46-7.64 cm with an average increment of 0.37,
525LIAO Wen-Bo et al.: Growth Dynamics and Self-Thinning of the Dominant Populations in the Mangrove Community
0.22 and 0.49 cm in 1996, 1998 and 2002 respectively. Com-
paratively that of the Kc population ranged 3.66-12.10 cm
with an average increment of 0.76, 0.50 and 1.23 cm
respectively, indicat ing a more rapid g rowth o f the Kc
population.
In the B-zone, the average DBH of Ac, Kc and Am popu-
lation in 1994 was 0.99-6.37 cm, 1.43-10.19 cm, and 3.03-
9.55 cm, increasing 0.27, 0.74 and 1.00 cm in 1996, 0.11, 0.38
and 0.31 cm in 1998, and 0.38, 1.01 and 1.42 cm in 2002
respectively. Their growth was obviously increased in the
order of Am > Kc > Ac.
3.2.3 Height growth There was an obvious growth in
height in the main population of the mangrove community
and that branch breaking, blight or death leading to nega-
tive growth was also apparent (Table 3). From 1994 to 1996,
the height growth of Ac increased 1.5 m in A-zone and that
of Kc increased 1.9 m in B-zone.
Further analys is showed significant growth difference
among the dominant populations Kc, Ac and Am in A-zone
and B-zone. During the four invest igat ions , the to tal
Table 1 Demographic change in mangrove plots under different investigations*
Year / Individuals 1994 1996 Second death rate** 1998 Third death rate** 2002 Fourth death rate**
A-zone Ac 179 160 10.6% 101 36.9% 63 37.6%
Kc 12 12 0 11 8.3% 11 0
TI 191 172 10.0% 112 34.9% 74 33.9%
B-zone Ac 126 86 31.7% 23 73.2% 10 56.5%
Kc 84 72 14.3% 55 23.6% 44 20.0%
Am 16 11 31.2% 6 45.4% 4 33.3%
TI 226 169 25.2% 84 50.3% 58 31.0%
T I in A- and B-zone 417 341 18.2% 196 42.5% 132 32.6%
*, number in 2000 not available; **, the death rate was calculated by using number of individuals in the former investigation as the cardinal
number. Ac, Aegiceras corniculatum ; Am, Avicennia marina; Kc, Kandelia candel; T I, total individuals.
Table 2 Individual diameter at breast height (DBH) growth in mangrove plots under different investigations*

Population
DBH
1994 1996
Increment
1998
Increment
2002
Increment
(cm) (cm)** (cm)** (cm)**
A-zone Ac TI 179 160 - 101 - 70 -
Maximum 7.64 8.82 3.63 9.49 1.43 10.35 4.68
Minimum 1.46 1.43 -0.29 0.80 -0.35 2.99 -0.51
Average 4.15 4.58 0.37 5.12 0.22 5.80 0.49
SD 1.569 1.878 0.478 1.821 0.304 1.835 0.990
Kc TI 12 12 - 11 - 11 -
Maximum 12.10 12.68 1.27 13.12 0.76 14.45 6.18
Minimum 3.66 3.82 0.16 6.53 0.19 7.64 -0.92
Average 7.42 8.18 0.76 9.08 0.50 10.31 1.23
SD 2.215 2.331 0.276 2.059 0.208 2.262 0.789
B-zone Ac TI 126 86 - 23 - 10 -
Maximum 6.37 7.80 2.55 8.12 0.70 9.04 0.96
Minimum 0.99 1.27 -0.41 2.55 0 1.91 -0.80
Average 3.02 3.46 0.27 4.35 0.11 4.28 0.38
SD 1.075 1.262 0.416 1.437 0.160 1.892 0.764
Kc TI 84 72 - 55 - 43 -
Maximum 10.19 10.99 2.45 11.78 1.46 14.01 11.46
Minimum 1.43 2.23 -0.35 2.55 -0.06 3.92 -0.79
Average 3.78 4.81 0.74 5.48 0.38 6.52 1.01
SD 1.500 1.553 0.590 1.779 0.395 2.028 1.114
Am TI 16 11 - 6 - 3 -
Maximum 9.55 14.08 4.52 14.65 1.27 16.15 2.55
Minimum 3.03 3.09 -0.16 6.37 -0.06 9.14 0.70
Average 5.10 6.66 1.00 9.55 0.31 12.21 1.42
SD 2.066 3.602 0.825 3.233 0.527 3.181 0.819
*, all dead plants and branches were excluded from statistical analyses; **, positive increment > 0, zero increment = 0, negative increment <
0 (That the stem of individuals dur ing the process of branch drying and breaking shrank slightly results in a negative increment of the DBH
growth and leads to ultimate death). Abbreviations are the same as in Table 1.
Acta Botanica Sinica 植物学报 Vol.46 No.5 2004526
number of individuals decreased from 417 to 341, 196 and
132 res pectively. In the second investigation, among 341
individuals 286 exhibited positive DBH growth, 22 individu-
als had no growth and 33 had negative growth (DBH
const riction). However, in the third investigation, 137 of
the 196 individuals exhibited positive DBH growth, 47 had
no growth and 12 had negative growth. As for the height
growth , in 1996, 233 of the 341 individuals had increased
height growth, 20 had no growth and 88 had negative height
growth. From 1996 to 1998, 145 individuals died, including
68 from the 88 with negative height growth counted in 1996.
And among the rest 196 survived individuals, 127 had in-
creased height growth, 39 ceased growth and 30 had nega-
tive height growth.
3.3 Self-thinning of population and succession of com-
munities
Death of branches in mangrove plants initiated from the
apex, expanded to the base and finally broke off. A common
phenomenon is that firstly the branch stopped growing in
length and then in DBH. Many of the breaking and drying
branches migh t become s omewhat stouter near the t ree
crown and then shrank and eventually died and broke off.
The process of branch-death could extend slowly down to
1.3 m above ground.
The drying, breaking and dying of branches of man-
grove population is a natural self-thinning process as well
as an ecological phenomenon of forest gap formation which
is closely related to population composition, community
cons truction, age construction and nature geograph ical
position. In the Futian mangrove region of Shenzhen City,
the mangrove population was of a cluster growth. Both Ac
and Am had abundant branches, thus, their branch death
obviously could affect space change, although the base
diameter o f the plants showed relat ively little change as
being expressed in the disappearance of only nine coordi-
nat ions in A-zone but 17 coordinations in B-zone which
was inves tigated in 1996, reflecting a change of ground
stratum indeed.
Moreover, the forest gap formation of mangrove com-
munity was different from that of the land forest commu-
nity such as the lower sub-tropic monsoon evergreen broad-
leaved forest in South China, which generally resulted from
death of various populations. In contrast, the self-thinning
proces s in the mangrove popu lat ion, becaus e of those
Table 3 Individual height growth in mangrove plots during eight years*

Population
Height
1994 1996
Increment
1998
Increment
2002
Increment
(m) (m)** (m)** (m)**
A-zone Ac TI 179 160 - 101 - 63 -
Maximum 5.800 6.500 1.500 6.500 1.300 6.200 0.800
Minimum 1.400 0.800 -4.000 0.600 -3.800 1.300 -2.500
Average 4.180 4.180 -0.044 4.470 -0.164 4.400 -0.230
SD 0.992 1.565 0.884 1.480 0.726 1.465 0.259
Kc TI 12 12 - 11 - 11 -
Maximum 5.500 6.300 1.100 6.400 0.200 6.500 0.600
Minimum 4.400 5 0.300 5.100 0 5.100 -0.400
Average 5.000 5.700 0.650 5.880 0.127 6.000 0.164
SD 0.387 0.496 0.215 0.485 0.065 0.563 0.277
B-zone Ac TI 126 86 - 23 - 10 -
Maximum 5.200 5.900 1.800 6.900 1.000 5.800 1.000
Minimum 1.300 0.600 -3.900 2.600 -1.100 1.500 -3.900
Average 3.570 3.630 -0.044 4.490 0.070 4.050 -0.590
SD 0.933 1.332 0.959 0.903 0.370 1.283 1.500
Kc TI 84 72 - 55 - 44 -
Maximum 5.100 5.400 1.900 6.400 1.200 6.700 3.000
Minimum 2.200 0.600 -3.500 3.500 -0.500 1.300 -2.800
Average 3.620 4.190 0.399 4.720 0.253 5.820 1.057
SD 0.820 0.992 0.872 0.632 0.266 1.079 1.254
Am TI 16 11 - 6 - 4 -
Maximum 5.700 6.700 1.800 6.900 0.600 6.200 0.500
Minimum 1.300 1.400 -2.600 4.000 -2.500 4.500 -0.700
Average 3.850 4.680 0.364 5.400 -0.717 5.700 -0.025
SD 1.165 1.942 1.314 1.178 1.309 0.850 0.499
*, dead plants and branches were excluded from statistical analyses through all investigations; **, positive increment>0, zero increment = 0,
negative increment <0. Abbreviations are the same as in Table 1.
527LIAO Wen-Bo et al.: Growth Dynamics and Self-Thinning of the Dominant Populations in the Mangrove Community
plants with abundant branches and bigger base diameter,
was usually carried out by continuous drying and breaking
of branches.
The forest community in Shenzhen mangrove Nature
Res erve, in part icular, has developed into a mature and
stable one, where the young plants of the abundant popu-
lations did not occur, and the seedlings were also seldom
found, it was likely that the natural renew may be attributed
to the formation of forest gap after the death of individuals.
Nevertheless, if the formation of forest gap and self-thin-
n ing was related to ind iv idual death from natural
senescence, the colon ized dist ribu tion of population in
mangrove community would become randomized, and the
communities will eventually undergo a stage of decay (Chen
et a l., 1994b; Li et a l., 1994). An increas e of dry ing and
breaking branches and the sparsity of young trees and
seedlings in the community indicate that this community
was at a special stage, or a s ub-climax stage. On the other
hand, based on a recent research (Zhong et al., 1996), the
age of Shenzhen mangrove community could rough ly be
about 20 years, and it was approved that the evolut ion
cycle of mangrove community could be rather rapid and
short.
3.4 Dominance of communities and their change in
biomass
The dominance of communities were usually expressed
by the total ABH of the populations (Table 4).
From 1994 to 1996, the DBH of the main populations in
A- and B-zone was obviously increased, whereas much
more decreased by 1998 indicating a marked strengthening
of self-thinn ing activity. In the development process of
mangrove community, the total individuals were obviously
deceased, while the ABH of each individual was increased
during the eight years, thus it was considered that the self-
thinn ing was mainly res ulted from the individual diminu-
tion and in turn reduction of population density. The self-
thinning p rocess varied among three populations of the
community, characterized by an individual d iminution of
Ac and increment of ABH (no obvious change of number)
of Kc in the A-zone and apparent individual diminution of
both Ac and Kc in the B-zone, as if there was less DBH
change of Ac and Kc in the B-zone than in A-zone. Appar-
ently there was a negative correlation between the change
of ABH and individual number in Ac of A-zone as well as in
Ac and Kc of B-zone. As for the Am in B-zone, there was an
increase of ABH and no obvious decreas e of individual
number, because unlike Ac, it has a major trunk with few
branches.
Generally speaking, taking the land forest ecosystem as
an example, a maximum ABH index and a minimum plant or
branch density may give rise to a higher community value.
In fact, the evaluating index is related to various methodol-
ogy and validation of the fo rest community. For example,
an increase of the ABH and ABH-index indicates a growth-
climax or -s ubclimax of the community fo llowed by a
declination trait and eventually an trend to decline, an
Table 4 Change of total area at breast height (ABH) in mangrove plots during the eight years
Year / Individuals 1994 1996 1998 2002
A-zone Ac Total individuals 179 160 101 64
TABH (cm2) 2 635.09 2 885.81 2 256.90 1 793.90
AABH (cm2)* 14.72 18.04 22.35 28.51
Kc Total individuals 12 12 11 11
TABH (cm2) 560.66 677.53 744.63 958.00
AABH (cm2) 46.72 56.46 67.69 87.09
Subtotal Total individuals 191 172 112 75
TABH (cm2) 3 195.76 3 563.34 3 001.54 2 753.90
B-zone Ac Total individuals 126 86 23 10
TABH (cm2)** 1 014.87 913.49 317.84 169.54
AABH (cm2)*** 8.05 10.62 16.43 16.95
Kc Total individuals 84 72 55 44
TABH (cm2) 1 088.84 1 440.73 1 432.12 1 606.15
AABH (cm2) 12.96 20.01 26.04 36.50
Am Total individuals 16 11 6 4
TABH (cm2) 377.40 485.41 470.98 492.21
AABH (cm2) 23.59 44.13 78.50 123.05
Subtotal Total individuals 226 169 84 58
TABH (cm2) 2 481.11 2 839.63 2 280.94 2 267.90
*, negative corr elat ion of tota l indiv iduals (P < 0.05 ); **, sign ificant po sitive corr elat ion of tot al indiv iduals (P < 0.05 ); * **, high ly
significant negat ive co rrelation of tot al individuals (P < 0.0 1). AABH, average ABH; TABH, to tal ABH.

529LIAO Wen-Bo et al.: Growth Dynamics and Self-Thinning of the Dominant Populations in the Mangrove Community
mangrove community. Comparing with the results in Table
1, the death rate was positively related to the popu lation
density.
4.2 Dynamics of population growth in A-zone and B-zone
Based on the resu lts demonstrated in Tab les 1-4 and
Fig.4, the difference in the dynamics of population growth
was also obvious. In 1995, plots in A-zone was experimen-
tally treated with living waste-water irrigation and drainage
after ebb-tide at weekly interval for one year, receiv ing a
total volume equaling 2 600 m3 in the plots o f ca. 1 800 m2
(A-zone, an area of 180 m× 10 m). B-zone was served as
control. By comparing the two kinds of plots, we might find
some evidence whether the mangrove forests and man-
grove plants could develop some anti-pollution endurance
that is of important significance in ecological and environ-
ment conservation.
4.2.1 Comparison of population mortality (Table 1) In
A-zone, the death rate was 10.0% in 1996 and 34.9% in
1998, and was 25.2% and 50.3% in B-zone, indicating a
higher death rate in the latter. Furthermore, the treatment of
waste-water irrigation and drainage in A-zone exerted no
impact on its population mortality. In further analysis, the
death rate of population in A-S1, A-S2, A-S3 and A-S4 of A-
zone in 1996 was 7.4%, 10.2%, 17.1% and 6.4% respectively,
with an average of 10.0%; and that of B-S1, B-S2, B-S3 and
B-S4 of B-zone was 21.9%, 26.2%, 25.0% and 27.7%
respectively with an average of 25.2%. Noticeably, B-zone
had a higher and more even death rate among plots, while
A-zone showed great disparity in death rate of population,
averaged from 6.4% to 17.1%. The analysis suggested that
the death process could mainly be related to the s pecies,
branch composition and population construction.
4.2.2 Comparison of DBH growth The average DBH
increment of Ac in A-zone was 10.36% in 1996 and 11.79%
in 1998; and that of Ac in B-zone was 14.09% in 1996 and
22.65% in 1998 (Table 2). The average increment o f DBH
growth of Kc in A-zone was 10.24% in 1996 and 11.00% in
1998; and that o f B-zone was 26.56% and 13.99%
respectively. Both Ac and Kc exhib ited a dominant DBH
growth in B-zone. Moreover, in B-zone Am also showed a
remarkable average increment of DBH growth of 30.59% in
1996 and 43.39% in 1998.
4.2.3 Comparison of height (length) growth The aver-
age growth increment of heigh t o f Ac in A-zone was
-0.95% (negative growth) in 1996, and 6.94% in 1998; and
was 1.69% and 22.72% respectively in B-zone. The average
increment of height growth o f Kc was 13.10% in 1996 and
3.16% in 1998 in A-zone and 14.80% and 12.65% res pec-
tively in B-zone (Table 3). Obviously the height growth of
both Ac and Kc in B-zone was more significant. Likewise
the Am population also had significant height growth in B-
zone, being 21.56% and 15.38% respectively.
On the whole, the more obvious change in B-zone was
related to the original status (density, ABH, absolute height
Table 5 Comparison of population density in mangrove plots during eight years*
Year / Individuals 1994
Population
1996
Population
1998
Population
2002
Population
density density density density
A-S1 Ac 54 2.16 50 2.00 39 1.56 22 0.88
A-S2 Ac 41
1.96
36
1.36
23
1.24
20
1.12
Kc 8 8 8 8
A-S3 Ac 41 1.64 34 1.36 14 0.56 7 0.28
A-S4 Ac 43
1.88
40
1.76
25
1.60
14
0.68
Kc 4 4 3 3
B-S1 Ac 48
2.56
35
2.00
4
0.68
2
0.60
Kc 16 15 13 13
B-S2 Ac 50 34 15 8
Kc 10 2.44 10 1.80 9 1.00 7 0.64
Am 1 1 1 1
B-S3 Ac 16 8 4 0
Kc 11 1.44 11 1.08 10 0.76 6 0.36
Am 9 8 5 3
B-S4 Ac 12 9 0 0
Kc 47 2.60 36 1.88 23 0.92 18 0.72
Am 6 2 0 0
TI** in A- and 417 2.08 341 1.70 196 0.98 132 0.66
B-zone
*, in the different plots of 5 m×5 m in A- and B-zone, density change (individuals/m2) was the result of population difference. Abbreviations
are the same as in Table 1.
Acta Botanica Sinica 植物学报 Vol.46 No.5 2004530
of plant or branch, etc.) in the population and community.
In the first investigation in 1994, the average DBH of Ac
was 4.15 cm in A-zone and 3.02 cm in B-zone s howing a
difference of 1.13 cm, and the latter was 37.42% less than
the former. In respect of average height, Ac was 4.18 m in
A-zone and 3.57m in B-zone respectively with a difference
of 0.61 m, then the height of Ac in B-zone was 17.09% less
than that in A-zone. Ev idently populations of B-zone ex-
hibited much more growth potential both in DBH and height.
At the s ame time, the individual death rate in B-zone was
higher, indicating that pollu tion may no t be the ess ential
cause for the disparity between the two zones. On the other
hand , one might consider if was te-water irrigation might
provide some nourishment for the vegetation could be
considered. Some recent studies (Tam et al., 1995a; Wong
et a l., 1995a; Huang et a l., 2000) have revealed that the
to tal organic C and P in s oil had no sign ificant change
before and after waste-water discharge in A-zone and the
leaf conten ts of total organic C, P, and N were similar as
well.
5 Conclusion
An 8-year consecutive and comprehensive survey and
analysis of the typical mangrove plots in Shenzhen Futian
Mangrove Nature Reserve had demonstrated that the total
number of individuals and population density in mangrove
community decreased progres sively with relevant ind i-
vidual death, branch-breaking and growth of DBH, height
as well as biomass. This indicates that this mangrove com-
munity has been developing with a pos itive process of
evolution characterized by the following features:
(1) Self-thinning of the Shenzhen Futian mangrove com-
munity is an important evolutionary process characterized
by frequent plant and branch death, drying and breaking.
But the clustered development of mangrove plants has
much less impacts on positional change of ground surface.
(2) Growth in DBH and height of mangrove population
was quite significant. Generally speaking, the total above-
ground biomass usually decreased, nevertheless, the aver-
age individual biomass was increased. For example, the
average individual biomass of Ac in A-zone was 3.18, 3.50,
4.98 and 4.46 kg /p lan t in 1994, 1996, 1998 and 2002
res pectively ; that of Kc was 16.78, 23.2, 28.66 and 38.50
kg/plant respect ively ; and that o f Am in B-zone was
11.13, 17.06, 25.73 and 34.12 kg/plant respectively.
(3) The change in growth of height and DBH, individual
and branch death is direct ly related to the original state
(composition and st ructu re construction) of populat ion
during the evolutionary process of the community.
(4) Nonetheless, the potential physiological impacts of
the environmental pollution to the mangrove community
merits further consideration and investigation.
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(Managing editor: HAN Ya-Qin)