Botanical Studies (2006) 47: 403-408.
*
Corresponding author: E-mail: jchang@zju.edu.cn; Tel &
Fax: +86-571-8820-6465; Mobil: 133-9658-0523.
INTRODUCTION
Light is one of the most important environmental fac-
tors affecting plant survival, growth, reproduction, and
distribution. First, light intensity affects photosynthesis,
and this, in turn, is related to the accumulation of organic
matter and biomass. Moreover, to sustain higher photosyn-
thetic capacity or survival, plants modify their morphol-
ogy and biomass allocation at different light conditions
(Sims and Pearoy, 1992; Den Dubbleden and Oosterbeek,
1995; Feng et al., 2004). For example, plants grown at
low light intensities have higher specific leaf areas (SLA)
and leaf area ratios (LAR), and lower biomasses and root
shoot ratios (R/S) (Semb, 1996; Lentz1 and Cipollini,
1998; Kremer and Kropff, 1999). Different species, how-
ever, respond differently to light intensity. Light-demand-
ing species are more flexible in both morphology and
biomass allocation in response to light change than shade-
tolerant species (Lortie and Aarssen, 1996; Valladares et
al., 2000). Ryser and Eek (2000) suggested the adaptive
phenotypic plasticity differences among species may
contribute to their different abilities to occupy variable
and diverse habitats in the nature. Thus, studies on the
plasticity responses of plants, especially endangered and
rare species, to light environments will contribute to
our understanding of the ecological mechanism of plant
distribution and assist in the development of conservation
approaches to endangered and rare species.
Mosla is an annual herb in the family Labiatae. As
an endemic plant in China, M. hangchowensis only has
several small local populations, which were found along
the coast in China¡¦s subtropical zone. It has become en-
dangered because the number and size of its distribution
areas are decreasing quickly due to recent human activities
(Chang et al., 1999; Ge and Chang, 2001). Mosla chinen-
sis is distributed in the southern Yangtze River drainage
area in China, and it is usually the concomitant species in
a community because it has just a few individuals in each
population (Guan et al., 2003, 2004). In contrast, M. dian-
thera and M. sacbra are widely distributed in most parts
of the subtropical and tropical zones in China and in other
countries in East and Southeast Asia, where they are often
dominant in their communities (Fang et al., 1989). In the
field ecology studies, we found that the habitats of the four
species were open land, forest edge, and forest understory.
But M. hangchowensis, M. dianthera and M. chinensis are
mainly distributed in open land or forest edge with ample
sunlight while M. scabra is often found in shaded and
moist conditions, such as the forest understory (Zhang and
Xu, 1988). In this study, we grew the four Mosla species
under three light intensities. The objectives were to com-
PHYSIOLOGY
Effects of light intensity on growth of four Mosla species
Jian-Xiong LIAO
1,2
, Xiao-Yan ZOU
1
, Ying GE
1
, and Jie CHANG
1,
*
1
College of Life Sciences, Zhejiang University, 368 Zijinghua Road, Hangzhou 310058, P.R. China
2
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P.R. China
(Received February 22, 2005; Accepted April 11, 2006)
Abstract. We compared the growth characteristics of four Mosla species that occurred under three light
conditions that simulated shaded forest understory, forest edge, and open land. Root mass (M
root
), stem
mass (M
stem
), leaf mass (M
leaf
), total mass (M
total
), root mass ratio (RMR), and root shoot ratio (R/S)
all decreased with decreasing light intensity while specific leaf area (SLA), leaf area ratio (LAR), and
height ratio (HR) increased as growth light declined. At low light intensity, M. scabra, acclimating to a
shade environment, had the highest biomass, RMR, R/S, SLA, and LAR, but its plasticity in response to
light intensity was lower than that of the other three shade-intolerant species. The results supported the
hypothesis that shade-intolerant species have greater plasticity than shade-tolerant species. Compared with
M. scabra and M. dianthera, M. hangchowensis and M. chinensis had lower competitive ability for water,
nutrients and light (indicated by lower RMR, R/S and HR values), which could cause their endangerment
and rarity, respectively.
Keywords: Endangerment; Growth; Light intensity; Molsa chinensis; M. dianthera; M. hangchowensis; M.
scabra; Plasticity; Rarity.
pg_0002
404
Botanical Studies, Vol. 47, 2006
pare the effects of light intensity on the plants¡¦ biomass,
biomass allocation, and morphological characters, to ana-
lyze the relative importance of these characters in response
to light intensity, and to find reasons for the endangerment
of M. hangchowensis and the rarity of M. chinensis.
MATERIALS AND METHODS
Plants and treatments
The research was conducted at the plantation of Zhe-
jiang University, Hangzhou, Southeast China (120o10¡¦
E, 30o15¡¦N). Four Mosla species were grown in 17 ¡Ñ 15
cm (depth ¡Ñ diameter) pots (three plants per pot) with a
mixture of field soil and vermiculite (2:1 v/v) at the end
of May 2003 until the seeds germinated and the seedlings
reached 5 cm. One week later, they were transferred to
three different light conditions: high light (full ambient
light, approximately 56.2 mol m
-2
day
-1
), medium light
(about 70% full ambient light, 39.3 mol m
-2
day
-1
), and
low light (25% full ambient light, 14.0 mol m
-2
day
-1
). The
light was controlled by different layers of nylon-net shade
(placed 2 m above ground) to simulate the light condi-
tions of open land, forest edge, and forest understory, re-
spectively. The seedlings were irrigated at regular periods
depending on the weather and soil moisture status. Each
treatment was performed thrice.
Measurements and calculation
At the vigorous vegetation growth period of the four
species (mid-July), six individuals of each treatment and
species were harvested from the three replication¡¦s pots.
The height of the individuals was measured before harvest.
Leaf area (LA) was determined using a portable leaf area
meter (Li-cor-3000, Lincoln, NE, USA). Then all samples
were dried in an oven at 80¢XC for at least 72 h. Leaf mass
per unit of total mass (leaf mass ratio, LMR), branch mass
per unit of total mass (branch mass ratio, BMR), root mass
per unit of total mass (root mass ratio, RMR), root mass/
shoot mass (root shoot ratio, R/S), leaf area per unit leaf
mass (specific leaf area, SLA), leaf area per unit of total
mass (leaf area ratio, LAR), and height per unit of total
mass (height ratio, HR) were calculated according to Hunt
(1978) and Sakai (1995).
Statistical analysis
Statistical analysis was conducted using SPSS 13.0
for Windows (SPSS Inc., Chicago, USA). Differences
of the twelve parameters¡Xroot mass (M
root
), stem mass
(M
stem
), leaf mass (M
leaf
), total mass (M
total
), LMR, BMR,
RMR, R/S, LA, SLA, LAR and HR¡Xamong species,
light treatments, and interactions were tested by two-
way ANOVA. When species effects were significant,
significant differences between species in the same
treatment and those between treatments in the same
species were tested by Duncan¡¦s multiple range test. When
species ¡Ñ light interactions were significant, plasticity
index was calculated for each significant variable and spe-
cies according to Valladares et al. (2000), by dividing the
difference between the minimum and the maximum mean
values among the three light treatments by the maximum
mean value.
Hierarchical cluster analysis was used to determine the
relative similarity between the four species or between
species clusters based on above twelve parameters. Cluster
amalgamation was done with the single linkage method,
and the results were plotted as a dendrogram.
RESULTS
Biomass
There were no significant species ¡Ñ light interactions
in M
root
, M
stem
, M
leaf
and M
total
, but they tended to decrease
with decreased growth light intensity (Tables 1-2). Mosla
scabra had the highest M
root
, M
stem
, M
leaf
and M
total
under
low light conditions, but the differences from the other
three species were insignificant at high light. M
stem
, M
leaf
and M
total
did not differ among M. hangchowensis, M. chi-
nensis and M. dianthera at the same light intensity, but for
M
root
, M. dianthera was higher than both M. hangchowen-
sis and M. chinensis under medium light conditions (Table
2).
Biomass allocation
There were no significant differences between species
and interactions in LMR and BMR (Table 1). RMR and
R/S of four Mosla species decreased with decreasing light
intensity (Figure 1). Under low light conditions, RMR
Table 1. Two-way ANOVA of biomass, biomass allocation,
and morphological characters parameters of four Mosla species
grown at three light conditions.
Parameters Species
Light Species ¡Ñ Light
M
root
(g)
0.004
0.000
0.128
M
stem
(g)
0.010
0.000
0.063
M
leaf
(g)
0.000
0.000
0.602
M
total
(g)
0.002
0.000
0.279
LMR (g g
-1
) 0.276
0.034
0.971
BMR (g g
-1
) 0.759
0.000
0.536
RMR (g g
-1
) 0.019
0.000
0.013
R/S
0.002
0.000
0.001
LA (cm
2
)
0.000
0.000
0.037
SLA (cm
2
g
-1
) 0.000
0.000
0.028
LAR (cm
2
g
-1
) 0.000
0.000
0.144
HR (cm g
-1
) 0.000
0.000
0.000
M
root
, M
stem
, M
leaf
, M
total
: the mass of root, stem, leaf, and total,
respectively; LMR: Leaf mass ratio; BMR: branch mass ratio;
RMR: root mass ratio; R/S: root shoot ratio; LA: leaf area;
SLA: specific leaf area; LAR: leaf area ratio; HR: height ratio.
The bold P-values are statistically significant at P < 0.05.
pg_0003
LIAO et al. ¡X Effects of light on growth of
Mosla
species
405
and R/S of M. scabra were significantly higher than the
other three species. At high and medium light conditions,
however, M. dianthera had the highest RMR and R/S
(Figure 1).
Morphological characters
LA of the four species was the largest under medium
light conditions. For M. hangchowensis, M. dianthera and
M. chinensis, LA was significantly larger at high light than
that at low light. In M. scabra, however, no difference in
LA between high and low light emerged (Table 3). SLA
and LAR of the four species increased with decreasing
light intensity. Under medium light conditions, SLA and
LAR showed no significant differences among four spe-
cies. Under high and low light conditions, however, M.
scabra had the highest SLA and LAR, followed by M.
hangchowensis, and the lowest for M. chinensis and M.
dianthera (Table 3). HR of the four species also increased
with decreasing light intensity. Under the same light con-
ditions, M. dianthera had the highest HR, but there were
no significant differences among other three species (Table
3).
Table 2. Comparison of the root mass (M
root
), stem mass (M
stem
), leaf mass (M
leaf
), and total mass (M
total
) of four Mosla species
grown under high (full ambient light), medium (about 70% full ambient light), and low (about 25% full ambient light) light condi-
tions.
Biomass parameters Light intensities
Species
M. hangchowensis M. chinensis
M. dianthera
M. scabra
M
root
(g)
High
0.75¡Ó0.09
aA
0.79¡Ó0.21
aA
0.89¡Ó0.22
aA
0.88¡Ó0.25
aA
Medium
0.59¡Ó0.20
aAB
0.47¡Ó0.09
bB
0.64¡Ó0.12
bA
0.60¡Ó0.05
bA
Low
0.11¡Ó0.06
bB
0.11¡Ó0.04
cB
0.12¡Ó0.08
cB
0.31¡Ó0.05
cA
M
stem
(g)
High
1.08¡Ó0.24
aA
1.07¡Ó0.17
aA
1.18¡Ó0.16
aA
1.07¡Ó0.12
aA
Medium
1.08¡Ó0.20
aAB
0.92¡Ó0.21
aB
0.93¡Ó0.29
aB
1.24¡Ó0.21
aA
Low
0.50¡Ó0.17
bB
0.49¡Ó0.11
bB
0.53¡Ó0.25
bAB
0.75¡Ó0.24
bA
M
leaf
(g)
High
1.22¡Ó0.28
aA
1.10¡Ó0.12
aA
1.09¡Ó0.15
aA
1.23¡Ó0.18
aA
Medium
1.19¡Ó0.13
aAB
1.02¡Ó0.24
aB
1.02¡Ó0.14
aB
1.24¡Ó0.23
aA
Low
0.51¡Ó0.18
bB
0.46¡Ó0.19
bB
0.44¡Ó0.15
bB
0.75¡Ó0.18
bA
M
total
(g)
High
3.05¡Ó0.60
aA
2.96¡Ó0.49
aA
3.15¡Ó0.48
aA
3.18¡Ó0.52
aA
Medium
2.86¡Ó0.51
aAB
2.40¡Ó0.52
aB
2.59¡Ó0.45
aAB
3.08¡Ó0.49
aA
¡@
Low
1.12¡Ó0.40
bB
1.05¡Ó0.33
bB
1.10¡Ó0.33
bB
1.81¡Ó0.48
bA
The data are the means ¡Ó SD (n = 6). Different small letters indicate significant differences among three light conditions of the same
species (P < 0.05). Different capital letters indicate significant differences among four species under the same light conditions (P <
0.05).
Figure 1. Comparison of root
ma s s ra tio (RMR; A), root
shoot ratio (R/S; B) of four
Mosla species grown unde r
high (full ambient light), me-
dium (about 70% full ambient
l ight), a nd low (about 25%
full ambient light) light condi-
tions. The data are the means
¡Ó SD (n = 6). Different small
letters in each graph indicate
significant differences among
three light conditions of the
same species (P < 0.05). Dif-
ferent capital letters in each
g rap h i ndi ca te s ign ifi ca nt
differences among four spe-
c i es un de r t he s am e l ig ht
conditions (P < 0.05).
pg_0004
406
Botanical Studies, Vol. 47, 2006
Plasticity index
There were significant interactions of species ¡Ñ light in
RMR, R/S, LA, SLA and HR (Table 1). For most of the
five parameters, M. dianthera had the greatest phenotypic
plasticity, followed by M. chinensis and M. hangchowen-
sis, with M. scabra being the lowest (Table 4). The same
trend was found in the mean plasticity index, but the mean
plasticity index of M. scabra was significantly lower than
for other three species, and M. dianthera, M. hangchowen-
sis and M. chinensis exhibited no significant differences.
DISCUSSION
Phenotypic plasticity is the environmental modifica-
tion of genotypic expression and an important means by
which individual plants respond to changing environment
(Macdonald et al., 1988). In the present study, light in-
tensity strongly affected the biomass, biomass allocation,
and morphological characters of the four Mosla species
(Table 1). M
root
, M
stem
, M
leaf
, M
total
, RMR and R/S decreased
with decreasing light intensity while SLA, LAR, and
HR increased as growth light declined. These latter are
very plastic growth traits and strongly affected by light
availability (Jeangros and Nosberger, 1992; Sakai, 1995;
Pothier and Prevost, 2002). Decreasing light intensities
caused an increase in LAR with the result that light cap-
tured by the leaves increased (Semb, 1996). SLA may re-
flect the leaf thickness to some extent (Augspurger, 1984;
Jones and Mcleod, 1990), and it is the most important
component affecting LAR (Kremer and Kropff, 1999).
Generally, an increase in SLA with decreasing light in-
tensity might compensate for the reduced photosynthesis
per unit leaf area and cause overall photosynthesis per
plant to be equal (Kremer and Kropff, 1999). Significantly
lower photosynthesis at low light intensity was found in
the four Mosla species in our previous study (Liao et al.,
Table 4. Plasticity indices for root mass ratio (RMR), root shoot ratio (R/S), leaf area (LA), specific leaf area (SLA), and height ra-
tio (HR) in four Mosla species.
Parameters
M. hangchowensis
M. chinensis
M. dianthera
M. scabra
RMR (g g
-1
)
0.60
0.61
0.62
0.38
R/S
0.67
0.69
0.69
0.46
LA (cm
2
)
0.53
0.54
0.55
0.30
SLA (cm
2
g
-1
)
0.42
0.46
0.47
0.41
HR (cm g
-1
)
0.51
0.52
0.54
0.49
Mean ¡Ó SD
0.54¡Ó0.09
a
0.56¡Ó0.09
a
0.58¡Ó0.08
a
0.41¡Ó0.08
b
Different letters indicate significant differences (P<0.05).
Table 3. Comparison of leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR) and height ratio (HR) of four Mosla species
grown under high (full ambient light), medium (about 70% full ambient light), and low (about 25% full ambient light) light condi-
tions.
Morphological
characters
Light intensities
Species
M. hangchowensis M. chinensis
M. dianthera
M. scabra
LA (cm
2
)
High
151.03¡Ó20.81
bB
113.34¡Ó20.19
bC
109.28¡Ó16.78
bC
173.62¡Ó21.93
bA
Medium
228.25¡Ó26.78
aA
191.34¡Ó24.64
aB
188.57¡Ó25.24
aB
247.35¡Ó26.74
aA
Low
108.11¡Ó19.66
cB
88.11¡Ó19.15
cB
85.07¡Ó20.43
cB
179.19¡Ó25.36
bA
SLA (cm
2
g
-1
)
High
123.80¡Ó13.80
bB
103.25¡Ó14.70
bC
100.57¡Ó13.56
bC
141.72¡Ó14.00
cA
Medium
191.81¡Ó17.33
aA
188.15¡Ó13.86
aA
184.78¡Ó14.60
aA
199.48¡Ó21.50
bA
Low
211.98¡Ó18.70
aB
192.92¡Ó15.68
aBC
191.34¡Ó12.78
aC
240.18¡Ó17.13
aA
LAR (cm
2
g
-1
)
High
49.52¡Ó6.14
bA
38.28¡Ó4.96
bB
34.69¡Ó4.96
bB
54.60¡Ó7.25
cA
Medium
79.81¡Ó8.57
aA
79.63¡Ó9.96
aA
72.75¡Ó8.22
aA
80.31¡Ó13.12
bA
Low
96.53¡Ó16.4
aAB
83.68¡Ó8.80
aBC
77.48¡Ó9.96
aC
99.00¡Ó13.78
aA
HR (cm g
-1
)
High
11.28¡Ó3.10
bB
13.44¡Ó2.29
bB
21.59¡Ó3.85
cA
12.97¡Ó2.21
bB
Medium
14.43¡Ó2.53
bB
15.56¡Ó2.65
bB
35.57¡Ó4.80
bA
15.00¡Ó2.55
bB
¡@
Low
23.07¡Ó4.16
aB
27.73¡Ó4.71
aB
47.22¡Ó4.97
aA
25.66¡Ó4.36
aB
The data are the means ¡Ó SD (n = 6). Different small letters indicate significant differences among three light conditions of the same
species (P < 0.05). Different capital letters indicate significant differences among four species under the same light conditions (P <
0.05).
pg_0005
LIAO et al. ¡X Effects of light on growth of
Mosla
species
407
2005). In this study, therefore, higher SLA and LAR under
low light conditions could be parts of the strategy the four
Mosla species use to acclimate to the shade environment,
but lower M
root
, RMR, and R/S would reduce nutrient and
water absorption capacity.
Under 25% full ambient light conditions, M. scabra
had higher biomass, RMR, R/S, SLA and LAR than the
other three species. This was consistent with the shade
and moist in the natural habitat of M. scabra, as well as
the ample sunlight conditions for the other three species.
In the three shade-intolerant species, the endangered M.
hangchowensis and rare M. chinensis had M
stem
, M
leaf
and
M
total
similar to M. dianthera at the same light intensity, but
their lower M
root
, RMR and R/S under full and 70% full
ambient light conditions might be the cause of their lower
competitiveness for water and nutrients in their favorable
habitats than M. dianthera. Moreover, the significantly
lower HR indicated the competitiveness for light of M.
hangchowensis and M. chinensis was lower than M. di-
anthera because higher HR means more competition for
light when total mass is similar (Sakai, 1995; Pothier and
Prevost, 2002).
In general, significant species ¡Ñ light interaction in-
dicates that species respond differently to growth light
(Gonzalez and Gianoli, 2004). In this study, significant
interactions in RMR, R/S, LA, SLA and HR were found,
and their plasticity indices were lower in M. scabra than
in the other three Mosla species. This is consistent with
the hypothesis that shade-tolerant species have lower
plasticity than shade-intolerant species (Lortie and Aars-
sen, 1996; Valladares et al., 2000). Moreover, the highest
values of biomass, RMR, R/S, SLA and LAR in a low
light environment caused M. scabra to separate from the
other three species at 25% ambient light intensity (Figure
2C). For the other three shade-intolerant species, M.
hangchowensis and M. chinensis were separated from M.
dianthera under full ambient light and 70% ambient light,
their favorite light intensities (Figures 2A and B). This was
because M. hangchowensis and M. chinensis had lower
M
root
, RMR, R/S and HR and thus had lower competitive
ability for water, nutrients, and light, which may have
reduced their abilities to extend their populations, hence
causing them to be endangered and rare, respectively.
Acknowledgements. We are grateful for the funding pro-
vided by the National Science Foundation of China (No.
30570113 and 39970058) and the Postdoctoral Research
Foundation of China (No. X90401).
LITERATURE CITED
Augspurger, C.K. 1984. Light requirements of neotropical tree
s eedlings: A comparative study of growth and survival.
Ecology 72: 777-795.
Chang, J., K. Liu, Y. Ge, and G.Q. Qing. 1999. Features of the
photosynthesis of Mosla hangchowensis and the response
of photosynthesis to soil water status. Acta Phytoecol. Sin.
23: 62-70.
Den Dubbleden, K. and M.J. Oosterbeek. 1995. The availability
of external support affects allocation and morphology in
herbaceous climbing plants. Funct. Ecol. 9: 628-634.
Fang, Y.Y., J.X. Wang, Z. Wei, C.F. Zhang, Y.Q. He, C.Z. Zheng,
Q. Lin, S.Y. Zhang, and B.L. Qiu (eds.). 1989. Flora of
Zhejiang (V). Zhejiang Science and Technology Publishing
House, Hangzhou, pp. 289-290.
F eng, Y.L., K.F. Cao, and J.L. Zhang. 2004. Photosynthetic
characteristics, dark respiration, and leaf mass per unit area
in seedlings of four tropical tree species grown under three
irradiances. Photosynthetica 42: 431-437
Ge, Y. and J. Chang. 2001. Existence analysis of populations
of Molsa hangchowensis, an endangered plant. Bot. Bull.
Acad. Sin. 42: 141-147.
Gonzalez, A.V. and E. Gianoli. 2004. Morphological plasticity
in respons e to shading in three Convolvulus species of
different ecological breadth. Acta Oecol. 26: 185-190.
Guan, B.H., Y. Ge, and J. Chang. 2004. Phenotypic plasticity of
Mosla chinensis and M. scabra (Labiatae) response to soil
water status. Bot. Bull. Acad. Sin. 45: 229-236.
Guan, B.H., Y. Ge, M.Y. Fan, X.Y. Niu, Y.J. Lu, and J. Chang.
2003. Phenotypic plasticity of growth and morphology in
Mosla chinensis responds to diverse relative soil water con-
tent. Acta Ecol. Sin. 23: 259-263.
Hunt, R. 1978. Plant Growth Analysis. Edward Arnold, London.
Jeangros, B. and J. Nosberger. 1992. Comparison of the growth
response of Rumex obtusifolius L. and Lolium perenne L. to
photon flux density. Weed Res. 32: 311-316.
Jones, R.H. and K.W. Mcleod. 1990. Growth and photosynthetic
responses to a range of light environments in Chinese tal-
Figure 2. Dendrogram of hierarchical cluster analysis of four
Mosla species bas ed on 12 parameters at high (full ambient
light, A), medium (about 70% ambient light, B) and low (about
25% ambient light, C) light conditions. M.c, M. chinensis; M.d,
M. dianthera; M.h, M. hangchowensis; M.s, M. scabra. H, M, L
in parentheses indicates high, medium, and low light conditions,
respectively.
pg_0006
408
Botanical Studies, Vol. 47, 2006
lowtree and Carolina ash seedlings. Forest Sci. 36: 851-862.
Krem er, E. and M.J. Kropff. 1999. Comparative growth of
triazine-susceptible and -resistant biotypes of Solanum ni-
grum at different light levels. Ann. Bot. 83: 637-644.
Lentz1, K.A. and D.F. Cipollini. 1998. Effect of light and simu-
lated herbivory on growth of enda ngered northeas tern
bulrush, Scirpus ancistrochaetus Schuyler. Plant Ecol. 139:
125-131
Liao, J.X., Y. Ge, C.C. Huang, J. Zhang, Q.X. Liu, and J. Chang.
2005. Effects of irradiance on photosynthetic characteristics
and growth of Mosla chinensis and M. scabra. Photosyn-
thetica 43: 111-115.
Lortie, C.J. and L.W. Aarssen. 1996. The specialization hypothe-
sis for phenotypic plasticity in plants. Int. J. Plant Sci. 157:
484-487.
Macdonald, S.E., C.C. Chinnappa, and D.M. Reid. 1988. Evolu-
tion of phenotypic plasticity in the Stellaria longipes com-
plex: comparisons among cytotypes and habitats. Evolution
42: 1036-1046.
Pothier, D. and M. Prevost. 2002. Photosynthetic light response
and growth analysis of competitive regeneration after par-
tial cutting in a boreal mixed stand. Trees 16: 365-373.
Ryser, P. and L. Eek. 2000. Consequences of phenotypic plastic-
ity vs. interspecific differences in leaf and root traits for ac-
quisition of aboveground and belowground resources. Am.
J. Bot. 87: 402-411.
Sakai, S. 1995. Evolutionarily stable growth of a sapling which
waits for future gap formation under closed canopy. Evol.
Ecol. 9: 444-452.
S emb, K. 1996. Growth characteris tics of spring barley and
selected weeds. I. Effect of irradiance in growth chambers.
Weed Res. 36: 339-352.
Sims, D.A. and R.W. Pearoy. 1992. Responses of leaf anatomy
and photosynthetic capacity in Alocasia macrorrhiza to a
transfer from low to high light. Am. J. Bot. 73: 445-449.
Valladares, F., S .J. Wright, E. Lasso, K. Kitajima, and R.W.
Pearcy. 2000. P lastic phenotypic response to light of 16
congeneric shrubs from a Panamanian rainforest. Ecology
81: 1925-1936.
Zhang, S.A. and B.S. Xu. 1988. A study on the variation patterns
of Mosla in the Yangtze delta on population level. Acta Bot.
Yunnan. 10: 409-421.