Uprooting resistance of plants by erosion is influenced by morphological traits. This study established the mathematical relationship between uprooting resistance and morphological traits for various plants. Several lateral uprooting tests were carried out to determine the uprooting forces for twelve different plant species. Measurement of the surface and underground traits of the plants was carried out using basic measurement devices .The soil shear strength was determined at various depths of in two different locations. Statistical tools like ANOVA, regression, correlation, discriminant and t-test were employed in the analysis of data obtained.

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International Journal of Civil Engineering and Technology (IJCIET)
Volume 7, Issue 3, May–June 2016, pp. 104–110, Article ID: IJCIET_07_03_010
Available online at
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Journal Impact Factor (2016): 9.7820 (Calculated by GISI) www.jifactor.com
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
UPROOTING RESISTANCE AND
MORPHOLOGICAL TRAITS OF PLANTS
USED IN EROSION MITIGATION
Nwoke H.U, Dike B.U, Okoro B.C and Nwite S.A
Department of Civil Engineering,
Federal University of Technology, P.M.B 1526 Owerri,
Imo State, Nigeria
ABSTRACT
Uprooting resistance of plants by erosion is influenced by morphological
traits. This study established the mathematical relationship between uprooting
resistance and morphological traits for various plants. Several lateral
uprooting tests were carried out to determine the uprooting forces for twelve
different plant species. Measurement of the surface and underground traits of
the plants was carried out using basic measurement devices .The soil shear
strength was determined at various depths of in two different locations.
Statistical tools like ANOVA, regression, correlation, discriminant and t-test
were employed in the analysis of data obtained. The soil cohesion increased
with soil depth from 65.5KPa to 125.5KPa at 5cm and 10cm but there was no
significant difference in the soil shear strength between locations. The
computed t-value (tc =9.54) of uprooting resistance at α of 5% is greater than
t-value obtained from table (tt=5.60). This shows that there is significant
difference between uprooting resistance of plants of different species with a
range of 2.92 between species. The discriminant analysis shows that the
percentage fine roots less than 0.5mm, root slenderness ratio, relative root
volume, relative root dry weight with r values of 0.745, 0.714, 0.714 and 0.772
have more contributions to uprooting resistance than plant slenderness ratio,
percentage tap root dry weight, root density and specific root length with r
values of 0.617, 0.501, 0.599 and 0.63. The relationship between uprooting
resistance and morphological traits was found to be nonlinear with r2
value of
0.96 for O. Abbyssinica and 0.95 for S. Officinarium at probability levels of
0.0006 and 0.0009 respectively.
Key words: Lateral Uprooting, Morphological Traits, Erosion, Statistical
Analysis

2. Uprooting Resistance and Morphological Traits of Plants Used In Erosion Mitigation
http://www.iaeme.com/IJCIET/index.asp 105 editor@iaeme.com
Cite this Article: Nwoke H.U, Dike B.U, Okoro B.C, Nwite S.A, Uprooting
Resistance and Morphological Traits of Plants Used In Erosion Mitigation,
International Journal of Civil Engineering and Technology, 7(3), 2016, pp.
104–110.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=3
1. INTRODUCTION
Plant morphological traits such as root form, tap root length, the proportion of fine
lateral roots, stem biomass and root biomass have dominant influence on uprooting
resistance. It is important to identify traits that contribute to plant’s stability. Such
knowledge can be incorporated in designs to check erosion. Stokes et. al., (1996)
conducted an experiment on the influences of architectural and anchorage efficiency
of plant root systems on resistance to uprooting using artificial root models subjected
to lateral force. Plant anchorage depends on a combination of root system type, root
system morphology, soil properties and type of constraint (Ennos, 1990, Ennos,
1993, Dupuy et. al., 2005). Among plant traits, plant size, root system size, root length
and root branching are the most important traits related to plant anchorage (Goodman
and Ennos, 1997). It is also important to note that root stiffness and root system
asymmetry can play a role in plant anchorage (Nicoll and Ray, 1996; Mickovski and
Ennos, 2002, Crook and Ennos, 1993; Goodman et al; 2001; Mickovski et. al., 2005).
Most of the studies on plant anchorage carried out over the last twenty years were
geared towards gaining information on the anchorage mechanics of single specie or to
investigate the influence of one specific factor such as branching pattern, lateral roots
or root hairs on anchorage efficiency. Many of the factors related to anchorage, such
as diameter, biomass and root number vary with regards to plant size and age.
Consequently, the results available in literatures are often valid for one specie and do
not always enable relevant inter-specie comparison. Moreover, a large number of
studies investigated trees, herbaceous dicots and grasses but very few studies have
focused on shrubby species which are dominant species in Eastern Nigeria. The
objectives of study are to investigate the effects of morphological traits on uprooting
resistance and establish a mathematical relationship between uprooting resistance and
morphological traits.
2. MATERIALS AND METHODS
Twelve plant species from the local vegetation found within Nguzu-Edda erosion site
in Ebonyi State of Nigeria were chosen for the study. This consist of five trees
(Anacardium occidentale, Mangifera indica, Milicia 105xcels, Citrus sinensis and
Azadirachta indica), three shrubs (Oxytenanthera abyssinica, Vernonia amygdalina
and Saccharum officinarum) and four herbaceous species (Pennistum purpureum,
Cynodon dactylon, Paspalum notatum and Chrysopogon Zizanioides). Uprooting tests
and trait measurements were carried out at the peak of vegetative growth. During the
tests, plants were selected to represent species anchorage strength and morphology for
a range of diameters between 2mm and 20mm. A scale force gauge was used in
measuring the uprooting force. Uprooting tests were performed on six samples per
specie. The maximum force reached before uprooting was noted for each of the
samples. To prevent soil moisture content differences, the tests were carried out in the
morning under same moisture effect. Soil shear strengths at 5cm and 10cm depths
were measured. Eight morphological traits were investigated and six juvenile plants
tested per plant type. The week following harvest, the plants were cleaned using a
stream of water to remove soil particles. The plant height (H) and stem basal diameter

3. Nwoke H.U, Dike B.U, Okoro B.C, Nwite S.A.
http://www.iaeme.com/IJCIET/index.asp 106 editor@iaeme.com
(D) were measured thereafter. Root samples were separated into tap root and lateral
roots. Basic measurement tools such as tape rule, vernier caliper, micrometer screw
gauge and weighing scale were employed to measure the morphological traits of the
uprooted plants. The morphological traits of specimens studied are plant slenderness
ratio (cm.cm-1
), root slenderness ratio (cm.cm-1
), relative root volume (cm3
.cm-1
),
relative root dry weight (g.cm-1
), percentage of root system representing tap root (%),
root tissue density (g.cm-3
), specific root length (m.g-1
), and proportion of root length
with diameter less than 0.5mm (%). An analysis of variance (ANOVA) was used to
test for differences between species in uprooting resistance and traits. Discriminant
analysis was performed to determine which traits best discriminate between the
species. Trait differences between species were investigated using ANOVA. Multiple
regression and correlation analysis were used to investigate relationship between
uprooting resistance and plants morphological traits.
3. RESULTS AND DISCUSSIONS
Table 1 shows the shear strength of soil at 5cm and 10cm depths at 2 different sites.
The soil cohesion increased with soil depth but there was no significant difference in
the soil shear strength between locations. Therefore there is strong indication of
homogenous nature of soil between the two sites.
Table 1 Soil shear strength (Kpa) at 5cm and 10cm depths
Depth Statistical measures Site 1 Site 2
5cm
Mean 65.5 58.2
Standard error 3.15 3.15
10cm
Mean 125.5 150.5
Standard error 8.9 9.5
The method of analysis of variance serves as useful purpose in performing the test
of significance on difference between species in terms of their uprooting resistances
as shown in Table 2. The uprooting resistances of six samples each of the twelve
species under study were computed by dividing each uprooting force by the respective
basal area.
Table 2 Test for differences between species in uprooting resistance
Plant Species Uprooting Resistances (N/mm2
) Row
Average
Variance
1 2 3 4 5 6
O. abyssinica 3.10 1.11 2.93 4.05 4.59 4.93 3.45 1.94
C. sinensis 3.70 3.35 3.60 1.53 1.36 1.36 2.48 1.38
V.amygdalina 3.06 2.66 3.91 3.82 3.30 2.79 3.26 0.27
C. dactylon 1.63 0.86 1.67 1.35 1.75 2.34 1.60 0.24
P. purpureum 1.69 1.00 1.10 1.02 0.97 0.98 1.13 0.08
S. oficinarium 0.95 1.20 1.21 1.14 2.10 1.10 1.28 0.17
M.indica 3.08 1.73 1.73 1.68 2.94 2.08 2.21 0.41
A. occidentale 2.52 2.46 1.31 3.36 2.05 2.13 2.31 0.45
A.indica 2.48 1.98 2.78 2.37 2.30 1.72 2.27 0.14
M.excelsa 2.90 2.53 4.82 2.61 3.31 2.84 3.18 0.72
P.notatum 1.42 0.94 0.77 3.10 0.78 0.58 1.27 0.89
C.zizanioides 0.24 0.29 0.53 0.54 0.87 0.72 0.53 0.06
Column Average 2.23 1.68 2.20 2.21 2.19 1.96

4. Uprooting Resistance and Morphological Traits of Plants Used In Erosion Mitigation
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The combined variance of uprooting resistance is computed as
(1)
This implies that;
S2
=
Range = 3.45 – 0.53 = 2.92
The modified studentised range of uprooting resistance is computed as
(2)
Where R= Range
Hence Sr = 9.54
The percentage point of studentised range of uprooting resistance at 5% level of
significance with 60 degree of freedom (from t-table) is given as
Sr (t-table) = 5.60
By comparison, Sr (calculated) is greater than Sr 0.05 (table) which confirms that
there is a significant difference between the uprooting resistance of plants of different
species. The major application of Discriminant analysis is to distinguish between sets
of morphological traits based on their contribution to the uprooting resistance of the
plant species tested. The morphological traits that were investigated are plant
slenderness Ratio (Ps), Root slenderness ratio (Rs), Root relative volume (Rv),
relative root dry weight (Rw), percentage tap root dry weight (Tw), specific root
length (RL), percentage fine roots less than 0.5mm (Rf) and Root density (Rd). The
summary of ANOVA on these traits of the twelve species studied separately and
when grouped into two depending on their resistance to lateral uprooting is presented
in Table 3.
Table 3 Morphological Traits of the Uprooted Samples
Group
I
Plants
Ps
(cm/cm)
Rs
(cm/cm)
Rv
(cm3
/cm)
Rw
(g/cm)
Tw
(%)
Rd
(g/cm3
)
RL
(cm/g)
Rf
(%)
O. abyssinica 46.58 21.43 0.62 0.36 0.15 0.58 3.38 62.20
V. amygdalina 35.23 71.50 0.50 0.28 0.50 0.56 3.59 45.50
M. excelsa 40.33 72.00 0.22 0.11 0.88 0.50 3.04 36.00
C. Sinensis 34.68 37.20 0.24 0.14 0.63 0.58 2.61 42.50
A. occidentale 33.84 53.10 0.33 0.13 0.70 0.59 2.25 38.50
A. indica 28.87 45.80 0.18 0.14 0.75 0.52 2.38 34.60
M. indica 35.44 46.90 0.34 0.26 0.58 0.76 2.88 42.20
II
C. dactylon 42.08 21.70 0.24 0.08 0.25 0.33 4.70 80.90
S. officinarium 37.61 34.60 0.11 0.06 0.26 0.55 3.87 79.60
P. notatum 31.68 24.00 0.20 0.07 0.25 0.35 4.98 88.80
P. purpureum 51.09 26.80 0.30 0.10 0.22 0.30 5.13 73.20
C. zizaniodes 34.60 22.50 0.11 0.04 0.23 0.36 4.40 89.50
ANOVA between species 0.37 24.38 24.48 38.94 16.61 7.74 5.18 21.78
r (traits with uprooting
resistance σmax)
0.62 0.71 0.71 0.77 0.50 0.60 -0.63 -0.75

5. Nwoke H.U, Dike B.U, Okoro B.C, Nwite S.A.
http://www.iaeme.com/IJCIET/index.asp 108 editor@iaeme.com
O. Abbyssinica was selected from a plant group with high uprooting resistance.
These plants are characterized by high root slenderness ratio, high relative root dry
weight, high percentage tap root dry weight, high root density, low specific root
length and low percentage fine roots. S. officinarium was selected from a plant group
with low uprooting resistance that are characterized by low length and biomass in the
tap root with high specific root length and percentage of fine roots. To establish a
relationship between the uprooting resistance and the morphological traits, a non-
linear regression model of the form below was assumed
(3)
Where max = Maximum uprooting resistance
C,a,b,c,d,e,f,g, = model coefficients
Ps=H/D = Plant slenderness ratio
Rs=LR/D = Root slenderness ratio
Rv=V/D = Relative root volume
Rw=DWR/D = Relative root dry weight
Tw= DWR = Percentage tap root dry weight
RL=SRL = Specific root length
Rf= FR – Percentage fine roots less than 0.5mm
Taking the logarithms of both sides of Equation (3)
(4)
Let log max = Y; Log C = a0; log Ps = X1, log Rs = X2, log Rv = X3, log Rw = X4, log Tw =
X5, log RL = X6, log Rf = X7.
Hence,
(5)
Considering the variation of morphological traits and uprooting resistance for O.
Abyssinica as presented in Table 4, the application of Equation 5 will result in the
relationship presented in Equation 6 below
Table 4 Variation of uprooting resistance with morphological traits of O. Abyssinica
Morphological
traits
Uprooting Resistance
Test numbers
1 2 3 4 5 6
Y 0.4914 0.4530 0.4669 0.6075 0.6618 0.6928
X1 1.6741 1.5040 1.6758 1.7223 1.7072 1.7243
X2 1.4219 1.3570 1.4499 1.3280 1.1838 1.1667
X3 - 0.1192 - 0.1810 - 0.0860 - 0.2076 - 0.3570 - 0.3768
X4 - 0.3565 - 0.4200 - 0.3280 - 0.4437 - 0.5850 - 0.6021
X5 - 0.7447 - 0.7960 - 0.6990 - 0.8239 - 0.9590 - 1.0000
X6 0.6201 0.5550 0.6474 0.5263 0.3820 0.3636
X7 1.4780 1.6220 1.4609 1.6513 1.7163 1.7443
(6)

6. Uprooting Resistance and Morphological Traits of Plants Used In Erosion Mitigation
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Equation (6) has a coefficient of determination (r2
) of 0.96 showing a good fit at a
probability level of 0.0006.
Similarly S. Officinarium was selected for regression and correlation analysis
using the data in Table 5. Solving Equation (5) using the data in Table 5 produces
Equation 7.
Table 5 Variation of uprooting resistance with morphological traits of S. officinarium
Morphological
traits
Uprooting Resistance
Test numbers
1 2 3 4 5 6
Y 0.0223 0.0792 0.0828 0.0569 0.3222 0.0414
X1 1.6848 1.6383 1.6532 1.7160 1.6604 1.6912
X2 1.6212 1.4915 1.4309 1.5278 1.4562 1.6582
X3 -0.8539 - 1.0000 - 1.0458 - 0.9586 - 0.3565 - 0.3768
X4 - 1.1549 -1.3010 - 1.3010 - 1.2218 - 1.3010 - 1.0969
X5 - 0.5229 - 0.6576 - 0.7212 - 0.6198 - 0.6778 - 0.4685
X6 0.6702 0.5403 0.4800 0.5763 0.5051 0.7059
X7 1.8180 1.8896 1.9186 1.8534 1.9830 1.9236
(7)
Equation (7) has a coefficient of determination of 0.95 which shows a good fit at a
probability level of 0.0009.
4. CONCLUSION
This study focuses on establishing the relationship between plant uprooting resistance
to erosion and their morphological traits. This will provide informed choices of plants
that will be used for erosion mitigation. The results from tests carried out established
that the morphological traits of plants such as root slenderness ratio, shoot slenderness
ratio, relative root volume, relative root dry weight, percentage tap root dry weight,
percentage fine roots, relative root dry weight and specific root length have bearing
effects on the resistance of plants to uprooting. Anon linear relationship was
established mathematically between morphological traits and uprooting resistance in
this study. It is recommended that plant species with the desirable traits of high root
slenderness ratio, high values of shoot slenderness ratio, high values of relative root
dry weight, high values of percentage tap root dry weight, high values of root density,
low values of percentage fine roots and low values of specific root length be bred and
incorporated into the use of vegetation for erosion mitigation, flood control and land
reclamation projects.
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