全 文 ：Architectural Plasticity in Response to Soil Moisture in the
Stoloniferous Herb , Duchesnea indica
LUO Xue_Gang1 , 2 , DONG Ming1 ＊
(1.Laboratory of Quantitative Vegetation Ecology , Institute of Botany , The Chinese Academy of Sciences , Beijing 100093 , China;
2.Southwest University of Science and Technology , Mianyang 621000 , China)
Abstract:　Architectural plasticity of clonal plants may enhance exploitation of soil moisture heterogeneity by
the plants.The plasticity of clonal architecture in response to soil moisture in the stoloniferous herb , Duch-
esnea indica Focke , was investigated in an experiment with different soil moisture contents as treatments , i.e.
40%, 60%, 80%, 100% of the maximum moisture content of soil(MMCS).As soil moisture content in-
creased , the spacer length , ramet density , branching intensity and branching angle of D.indica plants
changed by quadratic curve.And the optimum habitat for the plants was at 80%of the MMCS.This architec-
tural plasticity in D.indica was simulated through the Dynamic Logistic Model.The imitative effect was sta-
tistically satisfactory.Its architectural plasticity observed here may allow the species to show foraging behavior
in its habitat where soil moisture is patchily distributed.
Key words:　Duchesnea indica;clonal plant;soil moisture;clonal architecture;plasticity
　　Clonal plants can produce more than one genetically
identical individual in their habitats through clonal growth
and occupy a large area
[ 1-3] .Spatial distributional pattern
of ramets is referred as clonal architecture
[ 4] .The archi-
tecture of clonal plants with larger between_ramet distance
is called as “guerilla” , while that with smaller between_
ramet distance as “ phalanx” .Guerilla and phalanx are
two extreme types of clonal architecture , and there are
many between them.One of the basic properties of the
habitat is heterogeneity
[ 5-8] .Water is one of the compo-
nents of plants and a medium in their biological process.
It is not only an important prerequisite for their survival
but also an important environmental factor.Only with
proper moisture contents can plants grow and develop.
The essential resources such as light , water and mineral
nutrients for plants maintenance , growth and reproduc-
tion are distributed heterogeneously in space and can be
observed even on small scales
[ 5 , 6] .The clonal architecture
of plants may differ not only among species
[ 1]
but also
among populations of the same species growing in different
habitats
[ 9, 10] .This means plasticity of clonal architecture
of plants can adjust their countermeasures to exploit dif-
ferent heterogeneously distributed water resources
[ 2 , 3, 11] .
The architecture of a clonal plant is mainly deter-
mined by three morphological traits , including spacer
length(the distance of clonal organs such as stolons and
rhizomes between adjacent interconnected ramets),
branching intensity (the branch number produced by a
genet)and branching angle (the angle between axial ra-
mets and its branches and the angle between sister ra-
mets)[ 12] .Generally , clonal architecture with long spac-
er , low branching intensity and large branching angle
tends to be guerrilla.Otherwise , it tends to be phalanx.
So we can investigate the architectural plasticity of clonal
plants through the above_mentioned morphological traits.
Previous experiments and simulation models show that the
response of branching angle to environmental changes was
very weak
[ 12] , that branching intensity increased with the
increase of resource availability , and that the responses of
the spacer length with the increase of resources varied
among species
[ 12] .Therefore , the insight into the plastici-
ty of clonal architecture , in terms of spacer length ,
branching intensity and branching angle , needs investiga-
tion for more different clonal plant species.
Duchesnea indica , a stoloniferous herb of Rosaceae
in the subtropical area of China , was used in a control ex-
periment in which the plants were subjected to four levels
of soil moisture.The responses of its spacer length ,
branching intensity , branching angle and ramet density
were measured.
1　Materials and Methods
1.1　Materials
Duchesnea indica Focke (Rosaceae), a perennial
rosette herb , distributes in the south of Liaoning Province
in China and grows in hillside , bank , grassland and other
kinds of moist fields no higher than 1 800m above the sea
level.This plant shows clonal growth by producing long
stolons
[ 13] .The experimental plant materials were collect-
ed from the undergrowth of a Masson pine forest in Long-
men Mountain (31°34′N;104°42′E), Mianyang City ,
Sichuan Province , China.The altitude there is 396 m.
The annual average temperature is 14.7-16.3 ℃, an-
nual precipitation is 963.2-1 417 mm and the total solar
radiation is 320.91-388.28 kJ·cm-2·a-1.The soil is
Received:2000-11-08　Accepted:2001-08-03
Supported by the State Key Basic Research and Development Plan of China (G2000046804);National Science Fund for Distinguished Young Scholar of China
(39825106).
＊Author for correspondence.E_mail:.
植　物　学　报　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　
Acta Botanica Sinica　2002 , 44(1):97-100
yellow soil with 1.27% of organic matter.The nitrogen ,
phosphorus and potassium content and pH of the soil was
0.087%, 0.052%, 1.98% and 7.6 , respectively.
1.2　Experimental design
The experiment was conducted on an open area close
to where the experimental plants were collected from
Sept.30 , 1999 to June 30 , 2000.The plants were grown
in containers of 3 m wide ×5 m long × 0.5 m deep
filled with yellow brown soil , and the largest water capac-
ity was 47%.The soil contained 1.16% organic matter ,
0.079%N , 0.047% P , 1.54%K and had a pH of
7.4.Soil moisture was adjusted to 40%, 60%, 80%
and 100% of the largest water capacity by spraying at in-
terval of every three to five days depended on the soil wa-
ter content.The container had an area of 15 m2 and the
density with which the plants were planted was 1 genet·
m
-2 .There were three replicates in each treatment.
1.3　Measurements and analyses
We measured the number of ramets , the number of
stolons , the stolon internode length and the branching an-
gles (using organic glass protractor with diameter of 30
cm)for every genet.The angle between the neighbor
branch stolons was measured as the branching angles
[ 14] .
The data were analyzed by means of Duncan and Mar-
quardt following the Statistical Analysis System(SAS)[ 15 ,16] .
1.4　Modeling analysis and fitting of data
Sub_sectioned Logistic curve was used to describe
the seasonal changes of population in biology and
groups
[ 17] .The hypothesis is that the change characteriza-
tion N(t)of the clonal architecture of Duchesnea indica
has intrinsic ratio of change r 0 before and after soil mois-
ture fc , it changes as r1 , the kinetic model of N(t)un-
der different soil moisture is presented as follows accord-
ing to the Logistic Model.
dN
df
= r 0N(1-N K)
r 1N(1-N K) 　　
ff≥fc (1)
K is environmental capacity.fc is the changing
point to initial value N(t0)=N 0.Equation(1)can be
showed as the following one in order to fit model parame-
ter:
dN
df =[ r0+(r1-r0)(f-fc)hazard(f-fc)N(1-NK)] (2)
Hazard is an index of risk.When the result was less
than 0 , it turns to 0 , while when the result was more than
0 , it turns to 1.After integration of equation (2), it
comes out as:
N=K (1+K-N(f 0)
N(f 0) exp R) (3)
where ,
R =-r 0(f-f 0)+(r 1-r 0)(f-f 0)hazard (f-f 0)]
If α=lnK -N(f 0)
N(f 0) +r0 f 0 , β=-r0 , γ=r1-r0 , then:
N= K
1+exp[ α+βf+γ(f-fc)hazard (f-fc)] (4)
And equation(4)can be used to imitate the correla-
tion of clonal architecture and test for fitting.
2　Results
2.1　Experimental results
The spacer length , ramet density , branch angle and
branch intensity changed as quadratic curve with the in-
crease of soil moisture(Fig.1).They reached either the
maximum or the minimum values on the curve at the 80%
of MMCS.The spacer length , ramet density , branch an-
gle and branch intensity show significantly different at var-
ious moisture levels(P =0.05).When soil moisture was
at 40%, 60%, 80% and 100% of the MMCS , the
spacer length was 10.2 cm , 7.8 cm , 5.9 cm and 8.9
cm , the branch ramet density was 19.1 , 41.2 , 59.3 and
28.6 individual m2 , the branch angle was 71.2°, 49.8°,
38.9°and 63.5°, and the branch intensity was 4.7 ,
7.4 , 9.8 and 6.0 individual , respectively.The minimal
value of spacer length and branch angle , and the maxi-
mum value of branch ramet density and branch intensity
were all at 80%of the MMCS.If the soil moisture devi-
ates from 80% of MMCS , the spacer length and branch
angle increase gradually , but the increase was greater
when the soil moisture rises than lowers from 80% of
MMCS.Likewise , the ramet density and the branch in-
tensity decrease gradually but the decrease was greater
when the soil moisture rises than lower from 80% of
MMCS.The branch intensity seemed to be negatively cor-
related with the branch angle while positively correlated
with the ramet density (Fig.1 B , C , D).
Fig.1.　Spacer length(mean±SD)(A), ramet density(mean±
SD)(B), branch angle (mean ±SD)(C) and branch intensity(D)of Duchesnea indica grown at 40%, 60%, 80% and 100%
levels of soil moisture content.For soil moisture levels see the Mate-
rials and methods.For each of the panels , the bars sharing the same
letter are not different at P=0.05.
2.2　Simulation results and testing for goodness of fit
The model of clonal architecture relevent to soil
moisture was created according to Equation(4)by using
Marquardt in SAS and estimating the parameter of Logistic
model.Simulations of clonal architecture to spacer
length , ramet density , branch angle and branch intensity
under different soil moisture contents were conducted ac-
cording to Equations(5), (6), (7)and(8)(Table 1).
The testing for goodness of fit shows a highly significant
level(F=384.97).The Logistic model had good simula-
tion effect on the clonal architecture in terms of those
characters.
98　 植物学报　Acta Botanica Sinica　Vol.44　No.1　2002
N spacer=301.10 {1+exp[ -0.06+0.02f-0.05(f-79.95)hazard (f-79.95)]} (5)
N density =76.87 {1+exp[ 3.42+0.06f+0.14(f-79.47)hazard (f-79.47)]} (6)
N angle =454.22 {1+exp[ 0.94+0.02f-0.05(f-78.18)hazard (f-78.18)] } (7)
N intensity =139.92 {1+exp[ 2.21+0.04f+0.10(f-79.73)hazard (f-79.73)]} (8)
Table 1　Observed and simulated values of clonal_architecture_de-
termined morphological traits of Duchesnea indica in response to dif-
ferent soil moisture levels
Soi l
moisture
level
Spacer
length(cm)
Ramet density
(ramets·m-2)
Branch
angle
Branching intensity
(stolons·genet -1)
O S O S O S O S
40% 10.2 10.18 19.1 19.52 71.2° 70.84° 4.7 4.72
60% 7.8 7.87 41.2 42.24 49.8° 51.21° 7.4 7.33
80% 5.9 5.94 59.3 58.91 38.9° 39.41° 9.8 9.77
100% 8.9 8.93 28.6 28.30 63.5° 63.82° 6.0 5.98
O , observed;S , simulated.
3　Discussion
In this paper , we focused on the plastic changes of
clonal architecture of Mock_strawberry , Duchesnea indi-
ca , in terms of spacer length , branch intensity , branch-
ing angle and ramet density in response to different soil
moisture contents.The changes could be expressed , elu-
cidated and simulated using the Logistic Model.Previous
researches on clone plant ecology revealed that plasticity
of the branch angle in response to heterogeneity of re-
sources like soil nutrients , illumination was very weak ,
suggesting that branch angle of plant clone contributed
less to spatial positioning of ramets
[ 12] .Therefore less at-
tention was paid to plasticity of branch angle in response
to resource heterogeneity .In this study , however , the
branch angle of the Mock_strawberry growing in the Chi-
nese subtropics changed significantly in response to vari-
ous soil moisture contents.Soil moisture content (per-
centage of MMCS).
The branch angle changed by quadratic curve as the
soil moisture content increased.When soil moisture cont-
ent changed from 40%to 80% of MMCS , the branch an-
gle decreased gradually.When soil moisture content
changed from 80%of MMCSs to 100%, the branch angle
increased.These results implicate that the response of
branch angle had considerable contribution to the archi-
tectural plasticity of Mock_strawberry clone.Therefore ,
the plasticity of the branch angle should receive attention
in ecological researches of clone plants.
Previous study showed that branch intensity and
ramet density increased with increase of soil nutrients and
light intensity
[ 12] , while the plasticity of spacer length dif-
fered among species.For example , the spacer length of
Fragaria chiloensis
[ 18] , Ranunculus repens[ 4] and Duch-
esnea indica
[ 19]
etc.showed no significant changes to re-
source levels.While the spacer length of leguminous
Trifolium repans
[ 20 , 21]
and gramineous Cynodon da-
ctylon
[ 22]
tended to be longer under higher than lower soil
nutrient level.In this study , change of the spacer length
of the Mock_strawberry followed the quadratic curve.
Therefore , a further study seems necessary to focus on re-
vealing the difference among species , among populations
and even among genets using the methods of comparative
ecology.
In this study , changes of the spacer length , branch
angle , branch intensity and ramet density of Duchesnea
indica follow the quadratic curve.The branch intensity
was correlated negatively with branch angle , while posi-
tively with ramet density.With the increase of soil mois-
ture content , the spacer length , branch angle , branch in-
tensity and ramet density reached either the maximum or
the minimal value as the soil moisture content was 80%of
MMCS which was a turning point.When the soil moisture
was 60% of MMCS , the spacer length and branch angle
increased gradually while the branch intensity and ramet
density decreased gradually , suggesting the plants were
under moderate drought or water stress
[ 23] .When the soil
moisture was 40% of MMCS , the spacer length and
branch angle had the maximum values while the branch
intensity and ramet density had the minimal values , sug-
gesting the plants were under drought or wither index
[ 24] .
When the soil moisture content changed from 80% to
100%of MMCS , the spacer length and branch angle in-
creased gradually , while the branch intensity and ramet
density decreased gradually , indicating the plants were
under soaked or water_logged condition.We found the
plasticity changed at the point of 80%of MMCS.The ef-
fect of soil moisture content on clonal architecture of the
species seemed stronger while the moisture content was
increasing than decreasing.
The horizontal distribution of soil moisture in a habi-
tat is often heterogeneous.When a plant extends from one
spot to another by clonal growth , the change in clonal ar-
chitecture may have significance of ecological adaptabili-
ty.The resources and conditions in a patch may affect not
only the ramets in the patch but also the connected ramets
in different patches because of the between_ramet trans-
port of information and substances.Consequently in a
patch with proper soil moisture (about 80% of MMCS in
this case study), the clonal architecture tended to be
phalanx with higher ramet density.When the plants grow
in a patch with improper soil moisture(less than 60% or
more than 80%of MMCS in this case study), the clonal
architecture tended to be guerilla with lower ramet densi-
ty.This plasticity of clonal architecture may favour the
plant to exploit water resource efficiently , showing the for-
aging behavior in the habitat
[ 25] .
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匍匐茎草本蛇莓克隆构型对土壤水分的可塑性反应
罗学刚1 , 2 　董　鸣1 ＊
(1.中国科学院植物研究所植被数量生态学开放研究实验室 ,北京 100093;2.西南科技大学 , 绵阳 621000)
摘要:　克隆植物构型的可塑性有可能促进它对斑块性分布土壤水分资源的利用 ,因而可能具有生态学意义。在
田间实验中 , 匍匐茎草本蛇莓(Duchesnea indica Focke)经历了不同土壤水分水平(土壤最大含水量的 40%、60%、
80%、100%等)处理 ,以研究土壤水分对蛇莓克隆构型的影响。结果表明:间隔子长度 、分株密度 、分枝角度和分枝
强度呈二次曲线变化 ,土壤含水为最大含水量的 80%的生境为最适。在不同土壤水分水平生境中 , 蛇莓克隆构型
相关特征的可塑性变化可用动态 Logistic模型进行模拟和预测 ,拟合效果较好。结合植物对环境异质性的利用对
策 ,对所揭示的蛇莓克隆构型可塑性进行了讨论 。
关键词:　蛇莓;克隆植物;土壤水分;克隆构型;可塑性
中图分类号:Q948.113　　　文献标识码:A　　　文章编号:0577-7496(2002)01-0097-04
收稿日期:2000-11-08　接收日期:2001-08-03
基金项目:国家重点基础研究发展规划项目(G2000046804);国家杰出青年科学基金(39825106)。
＊通讯作者。E_mai l:.
(责任编辑:崔金钟)
100　 植物学报　Acta Botanica Sinica　Vol.44　No.1　2002