Vol1 no2 4

JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2012, 1(2), 26-34

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Abstract— The objective of the study was to determine whether

the A.seyal variety seyal (A.seyal) is able to produce healthy wood

(rebellious to A.seyal borer), suitable to be used in building poles,

firewood and charcoal when applying particular type of felling

process, in particular period. The study confirmed the possibility,

of producing endurable amount of A.seyal wood, not infested by

A.seyal borer, when felled during April and June using charcoal

felling process, and October and January when girdling process

was used. The study also revealed that, the moisture content in

A.seyal wood has noticeable effect; on the revival of the insect

activity i.e. A.seyal borer was active only when the moisture

content was in the range of 27-30% in the wood which seldom

occurred in autumn due to rainfall frequency.

Index Terms— Acacia seyal, Felling process, Endurable A.seyal

wood, Revival of the insect activity, A.seyal borer

I. INTRODUCTION

cacia seyal predominantly a tree of the cracking clay soil

found in large almost pure stands or mixed with A.

senegal and Balanites aegyptiaca under rainfalls of 250

to 1000 mm. under low rainfalls on water- receiving sites and

depressions. Confined in the Flood Region to low elevation

intermittently flooded by rain. It is also found in depressions

on sandy soils derived from Nubian Sandstone under rainfalls

of 200 mm or above. It occurs in northern Sudan fringing the

flood plains of rivers and in basins at the upper edge of Acacia

nilotica forests. It tolerates high pH and salinity [1].

Acacia seyal is considered as tree number one in Sudan, as

reported by [2] that has potential never been fully explored,

but they are promising. The global demand for A.seyal gum is

to be noted. The species is an important multipurpose tree for

the rural population. In Sudan, the tree varieties occur

naturally in the low rainfall savannah zone and extend from

Gadarif, Blue Nile and White Nile to the clay plains around

Nuba Mountains and the Darfur Region. In the savannah

* corresponding author

region of Sudan Acacia seyal has been subjected to large scale

deforestation from mechanized farming, over grazing, fires

and other human factors [3; 4]. It produces a gum arabic

known as “talha”, which is of inferior quality to that produced

by A. senegal making about 10% of Sudan’s gum arabic

exports. The gum is produced from cracks or wounds caused

by drought, fire, insects or wounds. Pods and bark contain

about 20% tannin and smoke from the wood is a good insect

repellent. Women use the aromatic smoke to tan and perfume

their skin. The tree does not respond to tapping, and the gum

is collected from natural exudation. There are numerous

medicinal uses, mainly bark, and leaves [1 and 5].

A.seyal poles were widely used for telegraph poles during the

war II era. The Forest and Plant Protection Authorities

resorted to submerging poles in the river instantaneously after

felling to leach as much carbohydrates as possible.

The limited research and studies which were subsequently

investigated the varies ways of seasoning, for protecting

A.seyal wood against damage by A.seyal borer. [6, 7]. The

susceptibility of A.seyal wood insect borer required more

considerable efforts [2]. A.seyal borer (Sinoxylon senegalense

) infects A.seyal wood immediately after felling , turning it into

powder in short time in such a manner that render it useless,

even for firewood or charcoal, let alone to building poles. The

borer also infested sap wood of most wood species and

bamboo. The most destructive agents to forests and their

products are insects, particularly of the orders Coleoptera,

Isoptera and Thoptera which affect growth of trees, quality

and quantity of wood products [2]. Over 40 species of insects

are reported associated with A. seyal. These include 10 species

of bruchid beetles which may damage high proportion of

stored seeds. The relationship between the wood moisture

content and the insect attack was investigated by [8] who

stated that, there are two types of pests, one lives only in green

timber, but other do not appear until the wood is at least

seasoned to 30% moisture content. In case of the first type of

insect who live in green timber its activity feeble as the wood

dries out. Wood seasoned below 30% moisture content is less

susceptible to insect attack.

Assessing the Effect of Timing and Felling

Techniques on the Susceptibility of Acacia

seyal (Del) to Wood Borers.

Mohamed T. A. Eltayb¹ and Talaat D. Abdel Magid*² ¹ Forest National Corporation Sinnar State E-mail: [email protected]

² University of Bahri, College of Natural Resources and Environmental Studies,

E-mail: [email protected]

(Received: October 15,2012, Accepted: November 6, 2012)

A


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A.seyal wood has a wide range of uses in Sudan, particularly in

rural areas, where villagers or peasantry people use A.seyal

wood for hut construction, charcoal, firewood. Branches and

pods are used as fodder for their animals. Insect causes a large

damage to A.seyal wood which may cause complete

destruction to tree plantation by chewing and chambering

inside the main stems and branches. Then trees enormously

completely damaged and fall down. FNC loss plenty of its revenues due to this damage caused by the borer against

A.seyal wood. As peasantries are perturbing of this insect, they

have used several types of treatments to protect A.seyal wood

against insect. In Gedarif, Blue Nile and Sennar States, the

villagers when cut A.seyal trees, emerged the wood

immediately after cut into river or lagoon for six weeks, before

used for hut. Sometimes set fire, on dry grass covered it

immediately, after cutting and before using it.

Charcoal and firewood producers in Gedarif State, said that

when you need to avoid the attack of borer insect to A.seyal

wood, you have to cut it avoid moony days i.e. not under the

moon light. Other people reputed that, the best period of

felling A.seyal trees is during the rainy season (July and

August) when the wood left to direct rainfall, until the end of

rainy season (end of October), by the end of rainy season the

wood collected and the bark should be removed, this process

will give a healthy wood, suitable for fire wood, building, and

charcoal. Some people cut trees; split the wood dry them under

direct sunlight, this type of wood use as bundles for firewood.

Art of killing trees by girdling the stems as a process was

stated by [9 and 4]. They reported that the reduction of

moisture content in girdling occurs slowly and the death of

trees may take place during a period of a year. Stem girdling

usually result in killing the roots of tree, but the degree of

killing depends on root´s nutrient storage and the degree of

exhausting it. So girdling should be done when the tree in

feeble condition and the death of upper part should be done

gradually [10, 11] stated that insects attack the wood but

durability may be improved by water storage.

This study is aimed to determine, the best period and type of

harvesting A.seyal trees, to produce healthy wood, suitable for

fire wood, building poles and other uses.

II. MATERIALS AND METHODS

Location of study area

The study was located in Rawashda forest, Gedarif state

eastern Sudan. It lies between latitude 12º 45´ and 14º 15´ N,

longitude 34º to 37º E and altitude 600 m above sea level. Two

experiments were used; field and laboratory experiments.

Field experiment

One Feddan (60×70m) (Feddan = .024ha) was selected in

Rawashda forest, well stocked by A.seyal trees plate (1). The

area was fenced, using metallic posts and barbed wire. The site

was divided, into nine plots of the same dimension (20× 23.3)

m. The trees in each plot were sorted and classified according

to their bark color. All trees were numbered, measured for

their diameters at breast height (DBH) using caliper.

Plate (1): View shows the selected site of experiment.

The mean diameters at breast heights were calculated for each

plot. Two types of felling were used for harvesting A.seyal

trees, charcoal felling (CF) in which the tree was completely

felled, left only 30 cm stump above ground level. The other

treatment of killing tree was girdling (G) where the tree’s bark

was removed completely, encircling the stem at a point 30 cm

above ground level , and left it stand, to be killed gradually

like dieback disease. The first felling of both treatments (CF

and G) were applied in two plots, selected randomly in April,

plot A1CF and A2G, where ten trees in each plot were treated.

The second treatment was done in June plot B1 and B2 and the

treatments (B1 C F and B2 G) were used for ten trees in each

plot. The first treatment (April period) was called summer

treatment and here the trees had already shed their leaves. The

second treatment (June period) was called autumn treatment,

in which the trees returned their leaves back. The third

treatment was done in October, two plots (C1F and C2 G) were

treated, during that time the trees were starting dropping their

leaves. The last treatment (January) was done in plots (D1F

and D2G) where trees were shed their leaves, and called it

winter treatment. Two plots were used for each period of

felling, and ten trees were treated for each type of felling. One

plot was used as standard plot, Figure 1.Temperature and rain

fall were recorded during the period of the experiment. The

damage occurred, by insect borer in A.seyal wood, in each plot

was observed and recorded.

D2 B1 A2

C1 Standard C2

A1 D1 B2

Figure (1): Design of experiment

Laboratory experiment


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Ten pieces, of the same length, of A.seyal wood were cut, from

green healthy trees, five pieces, from white bark tree (B) and

the other five from red bark tree (A) on October, Plate (2) in

Rawashda Forest.

Plate (2): Specimens for experiment.

The weight of each specimen was determined every day, with

well observations, to A.seyal borer attack to them. The weights

and observations were recorded, until we reached constant

weight, of each piece of specimen. Data were analyzed to

determine, the optimum or ideal moisture content, for insect

borer to attack A.seyal wood. The same treatments were used,

for other specimens, in the period of June, during the rainy

season and data were recorded and analyzed.

III. RESULTS AND DISCUSSION

Field study

The result of this study revealed that, the relation between the

period of felling and type of treatment, for producing healthy

A.seyal wood was reversal i.e. when specific type of felling

produced healthy wood, in specific period of treatment, the

other type of felling, produced badly wood in the same period

of felling (Table 1). The girdling felling process in the period

of April and July. Figure. 2 produced A.seyal wood infected

with various rates by A.seyal borer. While charcoal felling in

the same period Figure 3 produced healthy wood suitable for

fire wood, charcoal and building poles (plate 3, 4 & 5).

January and October girdling felling period, produced healthy

wood suitable for building poles, fire wood (plate 6) Figure 2.

The result showed that the girdling process, gave reversal

results, with that of charcoal felling process where April and

July treatment, produced badly A.seyal wood, with high

damaged by borer insect 100% loss. While October and

January produced 100% healthy wood, suitable for all type of

uses. The result showed that, the death of tree in girdling

process, required about one year and the girdling trees during

October and January period were receiving the supply of water

and food material from the root, while the leaves exhausted the

storage material in the trunk and branches, reduced the

carbohydrates in the wood [9] beside that the death of trees

were occurred in the rainy season, that help on washing more

of carbohydrates and increase the moisture content above the

ideal moisture content of the insect to attack the wood.

This result in line with [9 and 4] who stated that the death of

tree in girdling, may take place during a period of a year, and

the reduction in moisture content secured by girdling occurs

slowly while the leaves exhaust some of the water and the food

substances present in the trunk causing gradually death to the

tree. The result also in agreement with that reported by [10] on

girdling process. From this result we found that the best

period of felling by charcoal process was June (during rainy

season) to produce healthy A.seyal wood (98%). This was in

agreement, with the thoughts of charcoal and fire wood

producers that said, cutting of A.seyal tree, during the rainy

season, is possible for producing healthy wood, protected

against A.seyal borer. Because the trees were cut, after they

had exhausted some quantity of storage carbohydrates, for

building their leaves. Besides that, the frequency of direct

rainfall on the wood help on washing away some part of

carbohydrate, and increasing or rising up moisture content of

wood above the optimum point of the borer insect (plate 7

and 8).

Plate (3): Charcoal felling process (April period) produced

Healthy wood (fire wood) and forks.


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Table (1)

Effect of period, and felling techniques on quality of A.seyal wood

Period of

felling

Tree diameter class

cm

No. of treated

trees

Ave.

temp.(◦C)

Wood %age attack

(loss)

red white red white

April A1CF 8-23 5 5 35 0.00 0.10

A 2G 6.6-12.3 5 5 100.0 100.0

July B 1Cf 9-14 5 5 34 0.02 0.02

B 2G 7.2-16.7 5 5 100.0 100.0

October C 1CF 9.1-14 5 5 36.3 20.00 20.00

C 2G 7-16.5 5 5 0.00 0.00

January D 1CF 5.6-17.8 5 5 36 48.00 50.00

D 2G 6.6-15 5 5 0.00 0.00

Figure 2: Effect of period and type of felling (GF) of Acacia seyal tree in production of healthy A.seyal wood.

Plate (4): Charcoal felling process (April period) produced healthy wood


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Figure 3: Effect of period and type of felling (CF) of Acacia seyal tree in production of healthy A.seyal wood.

Plate (5): Charcoal felling process, (July period) produced healthy wood.

Plate (6): Girdling process, (October period) produced healthy wood.


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Plate (7): Larvae of A.seyal borer (Sinoxylon seneglense), the active impaired stage of A.seyal wood.

Plate (8): The borer insect, penetrated inside the wood, laid its eggs, hatched and damaged the

A. seyal sapwood, converted it into powder.

Laboratory study

The result in this study showed that the insect of A.seyal borer

Sinoxylon senegelense had attacked A.seyal wood only, when

the moisture content of the wood had been in the range of 27-

30%. This is the ideal point of moisture content, for insect to

corrode the wood and laid their eggs inside. The larvae live

inside the wood and damaged it (plates: 7and 8) .The result

revealed that, moisture content has a marked effect, on the

revival of the insect activity, to damage A.seyal wood. (Figure

4, 5, 6 and 7) from these figures, it was clearly observed, the

attack of insect was happened, when the specimen moisture

content in the range of fiber saturated point (27 -30%)

particularly in October felling specimen, without any

difference between red and white tree bark. While July felling,

the attack was completely slight, in view of the fact that the

optimum point of moisture content was fluctuated, difficult to

be attained because of the rainfall. (Figure 8 and 9).This

result is in agreement with [8], who stated that wood that

seasoned below 30% moisture content (fiber saturation point),

is less susceptible to insect attack and also supported by [12, 1,

11].

This result is also supported and consolidate the peasantry

presumption and traditional type of treatments, that used by

local people, to preserve A.seyal wood against insect, like

emerging wood in water, or set fire on it immediately after


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felling, in addition to that, report of [2] on reserved process, of

A.seyal poles against borer by The Forests and Plant

Protection Authorities during war II was laid in the same trend

of the result of this study.

Figure 4: Effect of A.seyal wood’s moisture content (on October felling) on revival of A.seyal borer attack.




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Figure 7 : effect of A.seyal wood’s moisture content (on October felling) on revival of A.seyal borer attack.

Figure 8: Effect of A.seyal wood’s moisture content (on July felling) on revival of A.seyal borer attack.

Figure 9: Effect of A.seyal wood’s moisture content (on June felling) on revival of A.seyal borer attack.


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IV. CONCLUSIONS

The abundance of the tree means that it is one of the most

important sources of fuel wood in the Sudan. The charcoal is

of good quality. Branches are used to make thorny fences and

for forage. Pods and bark contain tannin and smoke from the

wood is a good insect repellent. Women use the aromatic

smoke to tan and perfume their skin.

The result of this study indicated that Acacia seyal variety

seyal is a reasonable species as indigenous tree in the Sudan

that can be managed, to produce protected A.seyal wood

against A.seyal borer (Sinoxylon senegalense ), suitable for

fire wood and building poles. However, April and July should

be a reasonable period for felling, using charcoal felling

process, to produce healthy wood, further more girdling of

trees should be applied during October and January periods

to attain healthy wood. According to the result of this study the

favorable period and suitable technique of felling Acacia seyal

trees to produce healthy wood well preserve against a

devastated insect (Sinoxylon senegalense) is April and July for

charcoal felling techniques and January October for girdling

felling. These periods and felling techniques showed

significant measures to be used to manage Acacia seyal stands.

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