The strength with which a plant resists uprooting from erosion is influenced by a number of morphological traits including the stem basal diameter. The objective of this study is carry out in-situ lateral uprooting tests for various plant species and develop models that relate uprooting resistance to plant stem basal diameter. The study area is the erosion prone land of Nguzu Edda in Ebonyi State, Nigeria. Several lateral uprooting tests were carried out to determine the uprooting forces for twelve plant species. The stem basal diameters of the plants were also measured. Linear, quadratic and cubic regression models were used in data analysis. The results showed that maximum uprooting force has a linear relationship with stem basal diameter with coefficients of determination ranging from 0.900 to 0.999. The r2 value was 0.900 for Saccharum officinarum, 0.975 for chrysopogon zizanioides and 0.980 for paspalum notatum while other plants studied had r2 values ranging from 0.996 to 0.999. The p-values for all species using linear regression were less than 0.05 hence the model results are significant at 95% confidence level for all plant species studied

1. http://www.iaeme.com/IJCIET/index.asp 129 editor@iaeme.com
International Journal of Civil Engineering and Technology (IJCIET)
Volume 7, Issue 3, May–June 2016, pp. 129–135, Article ID: IJCIET_07_03_013
Available online at
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=3
Journal Impact Factor (2016): 9.7820 (Calculated by GISI) www.jifactor.com
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
© IAEME Publication
RELATING UPROOTING RESISTANCE TO
STEM BASAL DIAMETERS OF PLANTS
FOR EROSION MITIGATION
Nwoke, H.U., Dike, B.U., Nwite, S.A., Nwakwasi, N.L.
Department of Civil Engineering,
Federal University of Technology, Owerri. P.M.B 1526 Owerri, Imo State, Nigeria.
ABSTRACT
The strength with which a plant resists uprooting from erosion is
influenced by a number of morphological traits including the stem basal
diameter. The objective of this study is carry out in-situ lateral uprooting tests
for various plant species and develop models that relate uprooting resistance
to plant stem basal diameter. The study area is the erosion prone land of
Nguzu Edda in Ebonyi State, Nigeria. Several lateral uprooting tests were
carried out to determine the uprooting forces for twelve plant species. The
stem basal diameters of the plants were also measured. Linear, quadratic and
cubic regression models were used in data analysis. The results showed that
maximum uprooting force has a linear relationship with stem basal diameter
with coefficients of determination ranging from 0.900 to 0.999. The r2
value
was 0.900 for Saccharum officinarum, 0.975 for chrysopogon zizanioides and
0.980 for paspalum notatum while other plants studied had r2
values ranging
from 0.996 to 0.999. The p-values for all species using linear regression were
less than 0.05 hence the model results are significant at 95% confidence level
for all plant species studied
Key words: Lateral Uprooting, Basal Diameter, Uprooting Force, Erosion,
Statistical Analysis.
Cite this Article: Nwoke, H.U., Dike, B.U., Nwite, S.A., Nwakwasi, N.L.,
Relating uprooting Resistance to Stem Basal Diameters of Plants for Erosion
Mitigation, International Journal of Civil Engineering and Technology, 7(3),
2016, pp. 129–135.
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=3

2. Nwoke, H.U., Dike, B.U., Nwite, S.A., Nwakwasi, N.L.
http://www.iaeme.com/IJCIET/index.asp 130 editor@iaeme.com
1. INTRODUCTION
The role played by lateral roots and root hairs in promoting plant anchorage and
specifically resistance to uprooting forces cannot be over emphasized in
Bioengineering. In terms of flash flood mitigation, it refers to the combination of
biological, mechanical and ecological concepts to reduce or control erosion, protect
soil and stabilize slopes using vegetation (Finney, 1993). The effects of roots in
protecting the soil from being eroded can therefore not be neglected (Gray and Sotir,
1996). Resistance to uprooting for plants could be resolved into series of events
associated with the breakage of individual roots. When a plant is pulled from the soil,
force is transmitted to the root system, which will fail at a point determined by the
strength of the root, the soil shear strength and soil bond. In non woody roots, such
failure generally occurs in the proximal region of the roots (Ennos, 1993). The role of
both lateral and tap roots in the anchorage of a plant remains unquantified. Stokes et
al. (1996) used wire model to predict that branching should increase uprooting
resistance, however, the rigid wire models are obviously not close mimics of non-
woody roots and indeed models that bent during uprooting behaved differently.
In most plants, a single force applied to stem will be transmitted to numerous roots
either because of lateral branching or because of adventitious roots from the stem
base. This allows more efficient transfer of the load to the soil because many narrow
roots have a greater surface area than a single thick one (Ennos, 1993). Quantifying
the role of laterals and more generally, root architecture on anchorage will allow a
better understanding of the relative importance in determining the evolution of the
diversity of root system form (Fitter, 1985). It has been demonstrated that when
subjected to mechanical stress, some species of plant have higher number of roots and
greater lateral root branching (Stokes et al, 1997, Mickovski and Ennos, 2002). It
should also be pointed out that other traits such as root stiffness (Mickovski et al,
2007), changes in cell wall properties (Scippa et al, 2006) and root system asymmetry
(Nicoll and Ray, 1996) can also play roles in plant anchorage.
2. MATERIALS AND METHODS
This study was conducted in Nguzu-Edda Erosion site of Ebonyi State, Nigeria.
Twelve plant species from the local vegetation were sampled as shown in Table 1.
Table 1 sampling and classification of plant species
S/N Species Family Growth form Sampling site
1 Oxytenanthera abyssinica Poaceae Shrub 1
2 Vernonia amygdalina Asteraceae Shrub 1
3 Saccharum officinarum Poaceae Shrub 1
4 Pennistum purpureum Poaceae Herb 2
5 Paspalum notatum Poaceae Herb 1
6 Chrysopogon zizanioides Poaceae Herb 1
7 Cynodon dactylon Poaceae Herb 2
8 Citrus sinensis Rutaceae Tree 1
9 Mangifera indica Anacardiaceae Tree 2
10 Anacardium occidentale Anacardiaceae Tree 1
11 Azadirachta indica Meliaceae Tree 1
12 Milicia excels Moraceae Tree 2

3. Relating uprooting Resistance to Stem Basal Diameters of Plants for Erosion Mitigation
http://www.iaeme.com/IJCIET/index.asp 131 editor@iaeme.com
The species selected represent different families and were at juvenile stage of
growth. Uprooting tests were carried out at the peak of vegetative growth. During the
experiment, plants were selected to represent different stem-root basal diameters and
thus to represent species’ anchorage strength and morphology throughout the range of
diameters studied (2-20mm). Lateral in-situ uprooting tests were done using a scale
force gauge which measures the uprooting force. The tests were performed on six
samples per specie. Before each test, the superficial litter layer was removed to clear
the stem base. A non-stretch rope was bound to the stem base at one end and to a
portable force gauge at the other end. A horizontal traction force was then applied
slowly and regularly manually until the plant was uprooted. During the valid tests, the
maximum force (in each case) reached before uprooting was noted. To prevent soil
moisture content differences, the tests were carried out in the morning hours, about
two days after a rainfall of high intensity. Soil shear strength at 5cm and 10cm depths
were measured to determine the soils mechanical properties.
After uprooting, the plants were cleaned using stream of water to remove soil
particles, the stem basal diameters were measured using venire caliper and
micrometer screw gauge. Statistical tools were used in the analysis of results obtained
from the tests. The linear, quadratic and cubic models were applied to establish the
relationship between plant uprooting resistances and stem basal diameters as
presented in Equations 1 to 3.
+ (1)
(2)
(3)
Where a0, a1, a2 and a3 are regression coefficients.
3. RESULTS AND DISCUSSION
Result of the soil’s shear strength measured at two points in the study area is
presented in Table 2. The result shows that the soil cohesion increased with soil depth
but there was no significant difference in soil shear strength between the two
locations.
Table 2 Soil shear strengths (KPa) at two points on the site
Depth Characteristics Point 1 Point 2
5cm Mean 58.8 47.1
Standard error 3.6 3.6
10cm Mean 121.4 150.8
Standard error 9.2 10.9
The results of the maximum uprooting forces ( ) and the stem basal diameters
(D) of the twelve species studied are shown in Table 3.

4. Nwoke, H.U., Dike, B.U., Nwite, S.A., Nwakwasi, N.L.
http://www.iaeme.com/IJCIET/index.asp 132 editor@iaeme.com
Table 3 Maximum Uprooting forces and stem basal diameters
Species Test No 1 2 3 4 5 6
O. abyssinica 790.0 210.0 847.0 669.0 390.0 387.0
D(mm) 18.0 15.5 19.2 14.5 10.4 10.0
C. Sinensis 735.0 480.0 570.0 193.8 197.4 225.0
D(mm) 15.9 13.5 14.2 12.7 13.6 14.5
V. amygdalina 630.0 610.0 480.0 640.0 830.0 634.0
D(mm) 16.2 17.1 12.5 14.6 17.9 17.0
C.dactylon 20.5 28.7 20.0 21.5 5.5 8.5
D(mm) 4.0 6.5 3.9 4.5 2.0 2.2
P. Purpureum 68.8 28.3 42.5 34.0 35.4 32.6
D(mm) 7.2 6.0 7.0 6.5 6.8 6.5
S. officinarium 180.0 125.0 95.0 140.0 184.9 246.0
D(mm) 15.5 11.5 10.0 12.5 10.6 16.9
M. indica 837.0 285.0 450.0 405.0 225.0 276.0
D(mm) 18.6 14.5 18.2 17.5 10.5 13.0
A. occidentale 300.0 225.0 270.0 855.0 195.0 210.0
D(mm) 12.3 11.5 16.2 18.0 11.0 11.2
A. indica 741.0 561.0 525.0 570.0 540.0 195.0
D(mm) 19.5 19.0 15.5 17.5 17.3 12.0
M.excelsa 780.0 645.0 501.0 570.0 585.0 246.0
D(mm) 18.5 18.0 11.5 16.5 15.0 10.5
P.notatum 43.0 47.5 92.5 49.3 32.5 22.5
D(mm) 6.2 8.0 12.4 4.5 7.3 7.0
C.zizanioides 35.0 18.4 15.0 18.0 17.0 10.0
D(mm) 13.5 9.0 6.0 6.5 5.0 4.2
Tables 4 and 5 show the linear, quadratic and cubic regression models obtained
for various plant species using the data presented in table 3. The coefficients of
determination and p-values for the various models are also presented. The r2
- values
are positively correlated with Fmax for all models. However, the linear model had the
highest coefficient of determination and lowest p-values (P<0.05) which implies that
the model results are significant at 95% confidence level for all plant species studied.
Therefore, the linear regression model can be applied in the determination of
maximum uprooting force using stem basal diameter.

5. Relating uprooting Resistance to Stem Basal Diameters of Plants for Erosion Mitigation
http://www.iaeme.com/IJCIET/index.asp 133 editor@iaeme.com
Table 4 Regression and statistical parameter for various plant species
Specie Linear Quadratic Cubic
Saccharum
Officinarum
+
r2
=0.90 r2
=0.65 r2
=0.69
P=0.003197 P=0.02776 P=0.022921
Mangifera indica +50.2
r2
=0.99 r2
=0.98 r2
=0.93
P=0.000001495 P=0.000191 P=0.01731
Anacardium
Occidentale
+69.8
r2
=0.99 r2
=0.98 r2
=0.99
P=0.00000037 P=0.0001451 P=0.000001495
Azadirachta indica +60.9
r2
=0.99 r2
=0.99 r2
=0.91
P=00000037 P=0.00003358 P=0.002740
Milicia Excelsa +
r2
=0.99 r2
=0.99 r2
=0.99
P=0.00000037 P=0.00002992 P=0.0000369
Paspalum
Notatum
+
r2
=0.98 r2
=0.89 r2
=0.83
P=0.0001451 P=0.003812 P=0.00833

6. Nwoke, H.U., Dike, B.U., Nwite, S.A., Nwakwasi, N.L.
http://www.iaeme.com/IJCIET/index.asp 134 editor@iaeme.com
Table 5 Regression and statistical parameter for additional plant species
Specie Linear Quadratic Cubic
Oxytenanthera
abyssinica
+
r2
=0.99 r2
=0.88 r2
=0.713
P=0.000000375 P=0.00474 P=0.0202
Citrus Sinensis
+156
r2
=0.99 r2
=0.99 r2
=0.65
P=0.00000037 P=0.0000718 P=0.02814
Vernonia
Amygdalina
+43.2
r2
=0.99 r2
=0.88 r2
=0.92
P=0.00000037 P=0.00004605 P=0.001211
Cynodon Dactylon +5.1
r2
=0.99 r2
=0.99 r2
=0.94
P=00000336 P=0.00001337 P=0.00115
Penniston Purpureum +
r2
=0.99 r2
=0.98 r2
=0.99
P=0.00000596 P=0.0001312 P=0.00006203
Chrysopogon
Zizanioides
+
r2
=0.98 r2
=0.72 r2
=0.25
P=0.0002249 P=0.020016 P=0.0828
4. CONCLUSION
It has been the practice in most erosion devastated areas for people to use plants for
mitigation and control of the erosion. However, the strength of such plants in resisting
uprooting by erosion has been given little or no consideration. This study therefore
focused on establishing the relationship between the uprooting forces and the basal
diameters of plants used in erosion control. Twelve plant species were studied. This
involved measuring the uprooting forces and the basal diameters of the plants. Six

7. Relating uprooting Resistance to Stem Basal Diameters of Plants for Erosion Mitigation
http://www.iaeme.com/IJCIET/index.asp 135 editor@iaeme.com
independent tests were carried out on each of the twelve species selected. Regression
analysis was employed to establish the relationship between maximum uprooting
forces and stem basal diameters. It was observed from the result that though some
quadratic and cubic models related the variables well, the linear models gave the best
relationships in all cases. These results will help in informed choice of plants for
erosion and flood control.
REFERENCES
[1] Ennos, A.R (1993), “The Scaling of Root Anchorage”, J. TheorBiol 161: 61-75.
[2] Finney, K. (1993), “Landscape Architect,” 11th
Annual California salmonid
Restoration Federation Conference in Eureka.
[3] Fitter, A.H. (1985), “Functional Significance of Root Morphology and Root
System Architecture” Ecological Interactions in soil. Blackwell Scientific,
Oxford, UK, pp 87-106
[4] Gray, D.H. and Sotir, R.B. (1996),“Biotechnical and Soil Bioengineering Slope
Stabilization,” John Wiley and sons, New York.
[5] Mickovski, S.B., Bengough, A.G., Bransby, M.F., Davies, M.C. and Haallett,
P.D. (2007), “Material Stiffness, Branching Pattern and Soil Matrix Potential
affect Pullout Resistance” European Journal of Soil Science 58: 1471-1481.
[6] Mickovski, S.B. and Ennos, A.R. (2002), “A Morphological and Mechanical
study of the Root Systems of Suppressed Crownscots Pine Pinussylvestris,” Tree
(Berl) 16: 274-280.
[7] Nicoll, B.C. and Ray, D. (1996), “Adaptive Growth of Tree Root Systems in
Response to Wind Action and Site Conditions,” Tree physiol 16: 891-898.
[8] Scippa, G.S., Di Michele, M., Di Lorio, A. (2006), “The Response of
Spartiumjunceum Roots to Slope: Anchorage and Gene Factors,” Ann Bot (Lond)
97: 857-866.
[9] Stokes, A., Ball, J. and Fitter, A.H. (1996), “An Experimental Investigation of the
Resistance of Model Root Systems to Uprooting,” Ann Bot (Lond) 78: 415-421.
[10] Stokes, A., Nicoll, B., Coutts, M.P. and Fitter, A.H. (1997), “Responses of
Young Sitka Spruce Clones to Mechanical Perturbation and Nutrition: Effects on
Biomass Allocation, Root Development and Resistance to Bending,” Can J.
Res27: 1049-1057.
[11] Nwoke H.U, Dike B.U, Okoro B.C and Nwite S.A., Uprooting Resistance
Andmorphological Traits of Plants Used In Erosion Mitigation, International
Journal of Civil Engineering and Technology, 7(3), 2016, pp. 104–110.