Root Morphological Analysis of 10 Forest Tree Species in an Effort to

Design a Rooter System in the Bukit Barisan Forest

Budi Utomo, Hisar Manalu and Afifuddin Dalimunthe

Department of Silviculture, Faculty of Forestry, Jln. Tri Darma Ujung no. 1, Universitas Sumatera Utara,

Medan 20155, Indonesia

Keyword: Tree roots, behavior, flooding, rooter system, engineering.

Abstract: Forests have gave us an education in building a good ecosystem balance. This balance causes flooding

during the rainy season. This is contrary to conditions in urban areas which often experience flooding during

the rainy season. Therefore, the behavior of forest vegetation in treating nature needs to be studied further,

especially tree roots. Roots in trees are a very important foundation for tree growth and development. Not

only does it provide mechanical reinforcement to maintain the straight-up structure of a tree, but it is also

essential for the absorption of water and minerals. In its growth the roots are the most important part of the

tree to be able to maintain its life. Roots have the task of strengthening the establishment of plants,

absorbing water and nutrients dissolved in it from the soil, and sometimes as a place to store food. This

research can provide information about the root behavior of several forest tree species and the optimization

of land use. There were ten types of trees studied, namely Pinus (P. merkusii), Eucalyptus (E. grandis),

Jackfruit (A. heterophyllus), Jengkol (A. pauciflorum), Rambutan (N. lappaceum), Cinnamon (C.

burmannii), Petai (P. speciosa) and Meme (A. angustiloba). Parameters observed were root behavior, root

shape and root size. The results showed that the root behavior of each tree was different with varying

lengths and angles ranging from 10-65o, lateral root lengths ranging from 300-570 cm with root diameters

of mature trees 10-28.8 cm, taproot depth as deep as 1.5-2 m.

1 INTRODUCTION

Roots in trees are a very important foundation for

tree growth and development. Not only does it

provide mechanical reinforcement to maintain the

straight-up structure of a tree, but it is also essential

for the absorption of water and minerals. In fact, the

health and vigor of the root system strongly underlie

the overall health and vigor of the tree, so ideally,

silvicultural treatment should be based on balanced

root and crown characteristics. The root system is

relatively little known because of the unavoidable

difficulty of studying roots without at the same time

changing their growing conditions. Characteristics

of tree roots vary widely between species,

individuals within the same species, and even among

different roots within an individual tree. Lateral

spread of the root system is usually 2 to 5 times the

crown radius, becoming greater in poor growing

sites and in drier conditions. The extensive lateral

development of the tree's root system means that

generally the highest concentrations of food-

absorbing fine roots are present at some distance

from the trunk. This fact has a clear relationship

with fertilizer placement (Daniel et al, 1987).

Roots are the lower part of the plant axis and

usually develop below the soil surface, although

there are also roots that grow outside the soil. A

good root system allows plants to get the necessary

resources in sufficient quantities. Bahuguna and

Bhatia (2010) stated that dry matter from

photosynthesis is a source of energy for cell division

and enlargement which results in an increase in plant

height. Knowledge of root characteristics as

influenced by management and growing conditions

is very important for optimizing land use (Schroth,

1995).

According to Bahuguna and Bhatia (2010) in a

forest ecosystem, trees are vegetation that cannot be

separated from the area, trees are the largest carbon

sinks and become vegetation that plays a very

important role in maintaining ecosystems,

maintaining soil fertility, preventing erosion,

flooding and contributing the largest oxygen. . To

Utomo, B., Manalu, H. and Dalimunthe, A.

Root Morphological Analysis of 10 Forest Tree Species in an Effort to Design a Rooter System in the Bukit Barisan Forest.

DOI: 10.5220/0010137300002775

In Proceedings of the 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), pages 117-124

ISBN: 978-989-758-556-2

117

maintain the growth and development of the tree, the

root is one part of the tree that needs to be

considered, including the system, as well as the

behavior of the tree's roots. Because the system and

how the behavior of the roots on a tree greatly affect

its growth and development. The behavior of tree

roots needs to be known to study how forests treat

nature so that the balance of the ecosystem can be

maintained. The shape of the roots of this tree can be

imitated to create an optimal water absorption

system in order to prevent flooding in the city area.

2 MATERIALS AND METHODS

This research was carried out in the Bukit Barisan

National Park (TMBB) forest, precisely in the

Sibolangit Village area, Deli Serdang Regency. This

forest is located at an altitude of 700-1250 masl with

an annual average temperature of 19.60C and

humidity in the range of 85% - 89% and with an

average humidity of 87%. This research lasted for 3

months starting from April to June 2017.

The tools used in this study were hoe, meter,

digital camera, machete, spray and stationery. The

research material used was the roots of 10 dominant

tree species found growing in this forest area.

The trees studied consisted of 10 different

species, the most dominant species appearing in the

TNBB forest area which had the largest height and

diameter. Furthermore, data for all sample trees were

recorded, such as tree height, branch-free height and

tree diameter.

Excavations adjacent to tree roots were carried

out to examine the behavior of tree roots in forest

areas as deep as the roots of the tree to be studied.

Damage to the roots should not occur when

excavation is carried out to prevent damage to the

roots and the tree.

After doing the excavation, the root depth was

measured from the soil surface, measured the

diameter at the largest root, estimated the average

angle between the roots and the soil surface and

measured the length of the lateral roots. These

measurements were carried out with the aim of

knowing the relationship between rooting and tree

age in one species and knowing the relationship

between root behavior and optimization of land use

(Hidayat, 1995).

Observations were made on the behavior of tree

roots in penetrating the soil and adapting to the

horizon or differences in the soil layers, as well as

observing the behavior of roots towards growing

places dominated by rocks, to high humidity, to

fertile soil, to soils with a high level of drought and

to soils with high levels of drought. soil that is

difficult for the roots of the tree to penetrate.

Furthermore, observations were made on the

shape of the tree roots of each individual to be

observed, the shape of the roots on the taproot,

lateral roots and adventitious roots. Measurements

on the roots of the trees studied included lateral root

length and root diameter with a distance of about 30

cm from the base of the tree trunk and observed

changes in root colour along with the depth of the

soil that had been excavated. Observation activities

were carried out using descriptive methods, namely

observing directly in the field.

3 RESULTS AND DISCUSSION

The trees studied consisted of 10 different tree

species that were dominant in the TNBB forest. The

measurement results obtained from the 10 tree

species studied in the TNBB Forest are as follows:

Table 1. Characteristics of Trees Researched with Different Types and Ages in TNBB Forests

No Local Name Species Tree Age (Year)*

1 Pinus Pinus merkusii 20

2 Nangka Artocarpus heterophyllus 20

3 Rambutan Nephelium lappaceum 15

4 Petai Parkia speciosa 20

5 Jengkol Archidendron pauciflorum 20

6 Dadap Erythrina subumbrans 25

7 Eucalyptus Eucalyptus grandis 15

8 Alpukat Persea Americana 25

9 Meme Alstonia angustiloba 25

10 Kayu manis Cinnamomum burmanni 15

Note: *The age of the tree is known by receiving information directly from the community at the research site.

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The trees studied differ based on the type and age

level of the tree. The age of the tree is known by

asking directly to the people who are in the research

location. Each tree has an age ranging from 15 years

to 25 years. The purpose of taking tree age data was

to determine the relationship between tree age and

root diameter, root depth from the soil surface,

estimated total root depth, estimated average angle

and lateral root length. Tree age data collection also

aims to find out how it relates to root behavior and

root forms of the tree. After that, the root behavior

and root shape will be known at a certain age class.

Table 2. Characteristics of Tree Roots Researched Based on Tree Diameter, Tree Height and Branch-Free Height

No Local Name/Species Tree Diameter (cm) Tree Height (cm) Height of Free Branch (m)

Pinus (P. merkusii) 57.9 25 3

Nangka (A. Heterophyllus) 41.8 17.5 1.5

Rambutan (N. lappaceum) 33.1 13.5 4.5

Petai (P. speciosa) 39 17 5.5

Jengkol (A. pauciflorum) 28.7 12 2

Dadap (E. subumbrans) 52 18.5 2

Eucalyptus (E. grandis) 40.7 18.5 7.5

Alpukat (P. americana) 45.2 15.2 5

Meme (A. angustiloba) 44.1 14.5 4.5

Kayu manis (C. burmannii) 41 16.4 3.5

Tree diameter, tree height and branch-free height

were different among the ten tree species studied.

Based on field data, the species with the largest

diameter is Pinus (P. merkusii) and the species with

the lowest diameter is Rambutan (N. lappaceum).

The species with the largest tree height was Pinus

(P. merkusii) and the species with the lowest tree

height was Jengkol (A. pauciflorum). The species

with the largest free branch height was Eucalyptus

(E. grandis) and the species with the lowest free

branch height was Jackfruit (A. heterophyllus).

Measurements of tree diameter, tree height and

branch-free height were carried out to determine the

relationship with root behavior and root forms. The

difference in the size of tree diameter, tree height

and branch-free height between the ten tree species

caused a comparison between the behavior of the

root of one species and the behavior of the root of

another species could not be done. The behavior of

tree roots and root form will be known based on the

class of tree diameter, tree height and branch-free

height.

Table 3. Condition of Tree Roots Researched in TNBB Forest

Local Name/Species

Root depth from soil

surface (cm)

Estimated total

depth root (m)

Root diameter

(cm) *

Pinus (P. merkusii) 25 2 22.6

Nangka (A. Heterophyllus) 35 1.8 21.9

Rambutan (N. lappaceum) 3 1.5 7.3

Petai (P. speciosa) 35 2 22.4

Jengkol (A. pauciflorum) 35 2 14.3

Dadap (E. subumbrans) 30 1.8 22.6

Eucalyptus (E. grandis) 25 2 12.4

Alpukat (P. americana) 30 1.9 28.8

Meme (A. angustiloba) 25 2 16

Kayu manis (C. burmannii) 5 1.5 11.3

note: *Measured about 30 cm from the base of the tree trunk

The depth of the roots from the soil surface was

measured by measuring precisely from the top soil

surface until the topmost roots were visible.

Estimates of the total root depth are carried out when

the roots have shown a smaller diameter. Root

diameter was measured based on a distance of about

30 cm from the base of the tree trunk.

Root Morphological Analysis of 10 Forest Tree Species in an Effort to Design a Rooter System in the Bukit Barisan Forest

119

Measurement of root depth from the soil surface

is carried out to determine the relationship of roots

to the presence of other plants in the vicinity,

because the depth of tree roots is related to other

plants living in the vicinity. Measurement of the

total root depth was carried out to determine the

relationship of roots to the conditions of a barren

(hardened) or fertile growing place. In fertile soil

conditions root growth is shallower than in harder or

barren soil conditions. However, there are several

types of trees that are unable to penetrate the

compacted soil conditions, so that root growth

becomes shallow due to direct physical obstacles.

Measurement of root diameter was carried out to

determine root behavior based on certain root

diameter sizes.

Table 4. Characteristics of Tree Roots Under Study Based on Estimated Mean Angle and Lateral Root Length

No Local Name/Species Mean of root angle

(

)

Length of lateral root

(cm)**

1 Pinus (P. Merkusii) 30 510

2 Nangka (A. heterophyllus) 50 420

3 Rambutan (N. lappaceum) 15 65

4 Petai (P. speciosa) 35 470

5 Jengkol (A. pauciflorum) 30 330

6 Dadap (E. subumbrans) 65 570

7 Eucalyptus (E. grandis) 40 435

8 Alpukat (P. americana) 40 305

9 Meme (A. angustiloba) 40 350

10 Kayu manis (C. burmannii) 20 310

note: **Measured by adjusting the radius of the crown until the lateral root diameter is + 1 cm

The approximate mean angle is measured from

the soil surface to the top root. This measurement is

carried out to determine the direction of root growth

when it emerges from the base of the stem, which is

far below the soil or growing to the side. The lowest

angle indicates that the root growth is shallow and

the growth is inclined to the side. The highest angle

indicates that root growth is deep into the soil.

Lateral root length was measured by adjusting

the radius of the tree canopy, then observations were

made until the roots began to shrink with a diameter

of approximately 1 cm. Measurement of lateral root

length aims to determine its relationship with the

roots of other plants in the vicinity. The long lateral

roots will encounter the roots of other plants in the

vicinity, some types of trees interfere with the

growth of other tree roots and some species give

each other space in carrying out their functions.

1. Pinus (Pinus merkusii)

A B C

Figure 1. Trunk (A), Roots (B), Crossed and united roots (C)

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2. Nangka (Artocarpus heterophyllus)

A B C

Figure 2. Trunk (A), Roots (B), Roots about 30 cm below the soil surface (C)

3. Rambutan (Nephelium lappaceum)

A B C

Figure 3. Trunk (A), Roots (B), Small roots resembling fibrous roots (C)

4. Jengkol (Archidendron pauciflorum)

A B C

Figure 4. Trunk (A), Roots (B), There is a bending of the roots towards the top (C)

Root Morphological Analysis of 10 Forest Tree Species in an Effort to Design a Rooter System in the Bukit Barisan Forest

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5. Petai (Parkia speciosa)

A B C

Figure 5. Trunk (A), Roots (B), Overlapping roots (C)

6. Dadap (Erythrina subumbrans)



A B C

Figure 6. Trunk (A), Roots (B), Roots penetrate the roots of the surrounding trees (C)

7. Eucalyptus (Eucalyptus grandis)

A B C

Figure 7. Trunk (A), Roots (B), Roots penetrate the roots of other trees (C)

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8. Alpukat (Persea americana)

A B C

Fgure 8. Trunk (A), Roots (B), Roots bend upwards when they encounter hard soil in the form of rocks (C)

9. Meme (Alstonia angustiloba)

A B C

Figure 9. Trunk (A), Roots (B), Trees have buttress roots (C)

10. Kayu manis (Cinnamomum burmanii)



A B C

Figure 10. Trunk (A), Roots (B), Roots are mostly found on the soil surface (C)

The roots of the trees studied are often found

meeting with the roots of other trees in the vicinity

in the soil surface. Some of the 10 tree species

studied were found to have roots that damage the

roots of other trees growing in the vicinity, such as

cinnamon (C. burmanni) and Rambutan (N.

lappaceum) roots.

Several tree species that do not show interfering

behavior between roots are the roots of the Dadap

tree (E. subumbrans) crossing with the roots of the

Root Morphological Analysis of 10 Forest Tree Species in an Effort to Design a Rooter System in the Bukit Barisan Forest

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Jackfruit tree (A. heterophyllus) that grow close

together, the roots of the Dadap tree (E.

subumbrans) that penetrate roots of coffee plants,

roots of Eucalyptus (E. grandis) trees that intersect

with one of the local plants in the vicinity, but

provide each other with good growth space by

providing an opening to penetrate the soil layer to

get the nutrients needed.

Some of the trees studied did not have branches

around the base of the trunk and some had branches

around the base of the trunk. There are several types

of trees that do not have branches around the base of

the trunk, such as pine trees (P. merkusii),

eucalyptus (E. grandis), jackfruit (A. heterophyllus),

dadap (E. subumbrans) and Meme (A. angustiloba).

Meanwhile, trees with branches close to the base of

the trunk are rambutan (N. lappaceum), Petai (P.

speciosa), Jengkol (A. pauciflorum), Avocado (P.

americana) and Cinnamon (C. burmanii).

The tree under study had irregularly bent roots

and more often straight roots. Trees with irregularly

bent roots are rambutan (N.lappaceum), Pinus (P.

merkusii), and Cinnamon (C. burmanii), while trees

with more straight roots are Eucalyptus (E. grandis),

Jackfruit (A. heterophyllus), Dadap (E. subumbrans),

Meme (A. angustiloba), Petai (P. speciosa), Jengkol

(A. pauciflorum), and Avocado (P. americana).

The behavior of tree roots that grow less than 10

cm above the soil surface is more suitable for land

rehabilitation activities on flat (horizontal) land

conditions. The behavior of roots growing at a depth

of less than 30 cm above the soil surface and

penetrating physical barriers far down or to the side

is more suitable for land rehabilitation purposes on

sloping or rocky land conditions. (Bahuguna and

Bhatia 2010) stated that tree roots can function in

maintaining cliff stability through two mechanisms,

namely, gripping the topsoil (0-5 cm), and reducing

the driving force of the soil mass due to the rupture

of the soil clod. The role of tree roots in increasing

soil shear resistance is determined by tree age, total

root length and root diameter. Trees that have

intensive roots in the top layer are very effective in

helping to reduce the drift of the top layer (Lakitan,

1991).

Hairiah et al., (2007) stated that the most

appropriate strategy to increase the stability of cliffs

is to increase the diversity of trees planted in a land

to increase the network of strong roots in both the

top and bottom soil layers. Therefore, for the

conservation of landslide-prone cliff areas (steep

slopes with a slope of 80% or 40%) it is better to

reforest with plants with deep root systems.

The behavior of tree roots found at a depth of

more than 30 cm from the soil surface and never

turning to the surface is more suitable for

agroforestry purposes. (Brunner and Godbold, 2007)

stated that the inclusion of forest plants in the

agroforestry system has the potential to be able to

exploit nutrients that are not reached by seasonal

roots, capture nutrients that move down and move

laterally in the soil profile, and dissolve nutrients

that are not available to plants.

4 CONCLUSIONS

From the 10 types of trees studied in the age range

of 15-25 years, the root diameter of mature trees is

10-28.8 cm, depth is 1.5-2 m and the angle of

inclination from the ground surface is 10-65o. The

length of the lateral roots ranges from 300-570 cm.

ACKNOWLEDGEMENT

The author would like thanks to the Universitas

Sumatera Utara for the 2017 Non-PNBP research

funds.

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