1Bahir Dar Environment and Forest Research Center, Ethiopia
2Ethiopian environment and Forest Research Institute, Ethiopia
3Gondar Agricultural Research center, Ethiopia
Submission: September 23, 2019; Published: November 01, 2019
*Corresponding author: Ambachew Getnet Asfaw, Bahir Dar Environment and forest research center, P. O. Box: 2128, Bahir Dar, Ethiopia
How to cite this article: Ambachew Getnet Asfaw, Tatek Dejene, Kibruyesfa Sisay, Hadera Kahasay, Elliyas Cherent, Bihonegne Akalu. Influence of Resting
from Tapping on the Survival and Frankincense Yield of Boswellia Papyrifera Trees in Ethiopia. Int J Environ Sci Nat Res. 2019; 22(2): 556085.
About half of the total landmass in Ethiopia is arid to be semiarid , with no marginal agricultural potentials. Nevertheless, several indigenous trees and shrubs in these vast arid and semiarid lowlands of the country have been known to yield economically valuable products since several millennia. Ethiopian natural vegetation resources include several species of potential importance. For instance, the Acacia-Commiphera woodlands in the dry lands of the country that are dominated by Acacia, Boswellia, and Commiphera species are well known for their economically valuable products, largely oleo-gum resins such as gum arabic, frankincense, myrrh, and karaya [2-5].
The potential area covered by natural gum and resin-bearing species is believed to be very high in Ethiopia. Preliminary mapping and assessments show that the resource is found in eight regions covering an area of about 2.9 million ha. . Tigray and Amhara National Regional State (ANRS) constitute the leading natural gum and resin bearing forest resource base, 32.9 % and 23.8 % respectively. Vast areas of land, ca. 51%, in Ethiopia are arid to semiarid (Le Houérou, 1996; Tamerie Hawando, 1997)  with marginal or no agricultural potentials. Including the dry sub-humid area, the total dry landmass of the country amounts 860,000km2 (ca. 71%) (Tamerie Hawando, 1997). Nevertheless, many of the indigenous trees and shrubs in these vast arid and semi-arid lowlands hold known or potential promise for the production of economically valuable products, principally oleo gum resins such as gum acacia (gum arabic and gum talha), frankincense, myrrh, hinna, and gum karaya (Stiles, 1988; EFAP, 1993; Kuchar, 1995; FAO, 1995; Mulugeta Lemenih et al. in press).
Boswellia papyrifera is an indigenous gum producing multipurpose perennial tree species that grow in drier parts of Africa from Nigeria in the west to Eritrea and Ethiopia in the east. In ANRS, the woodlands dominated by B.papyrifera stands are identified in nine zones covering 34 woredas and 151 PAS. It is found abundantly in Metema, Quara and Armachiho woredas of North Gondar Zone (NGZ). Boswellia has an immense ecological and economic significance . It is found to be highly suitable for future reforestation establishments or restoration efforts in moisture deficit arid and semi-arid areas . This species produces frankincense, an oleo-gum resin valued for its industrial, folk medicine, cultural and religious uses . It has wide demand in domestic and international markets.
At present, Boswellia papyrifera is threatened as the result of several interrelated factors. Increasing population pressure has resulted in the conversion of woodlands to agricultural land while unregulated grazing by which young seedlings are either eaten or trampled by livestock, is hindering the natural regeneration. Another factor causing the decline of Boswellia papyrifera is suggested that the exploitation system. Trees are tapped every year in the dry season. The frankincense tapers are paid based on the amount of gum collected. This easily can lead to over tapping. Intensive tapping is thought to have resulted in the death of many trees, especially during the period of drought. Furthermore, there are indications that over-tapping may lead to poor flower and seed production and hence poor regeneration. All these factors deceasing Boswellia stand at alarming rate in the study area. Therefore, proper planning, for the development, conservation and sustainable utilization of this potential resource is urgently required. Therefore, the main objective of this study was examining the influence of resting on the survival and frankincense yield of matured Boswellia papyrifera trees. More specifically to determine the annual yield of frankincense that can be harvested from a tree per year and recommend the best season for high yielding of frankincense.
Metema woreda is located about 900km northwest of Addis
Ababa and about 180km west of Gondar town. Metema woreda
has an international boundary of more than 60km long distance
between Ethiopia and Sudan. It is found North of Quarra and Alefa,
west of Chilga south of Tach Armachoho woredas and east of
Sudan border. It is one of the 18 woreda in North Gondar Zone.
According to the woreda Plan for 2004, there are 15,675 rural Agricultural
households (excluding the newly resettled households)
and about 4,991 urban households. According to this estimate, the
total population of the woreda is 91,216 people. Out of the total,
3918 are rural and 1497 are urban women households. The original
residents of the area are Gumuz. Until recently, they practice
slash and burn and hunting wild animals. They produce sorghum
as the staple crop and remain to be the major food crop in the
area. Since the settlement programmes of the last and current
governments, the area is populated, and the natives became small
in number. They are concentrated in few areas and live close to
each other. They are found in only three PAs (Kumer Aftit, Tumet
and Shinfa). The total number of the indigenous people would be
around 500 households. Hence much of the area is recently settled
by newcomers from the highlands. During the group’s visit to
the woreda, it was known that 11,000 settlers would be received
during 2004/05. About 3,000 settlers were received when the
team was in the woreda.
The altitude of Metema ranges from as low as 550 to 1608m.
a.s.l while the minimum annual temperature ranged between
22oC and 28oC. Daily temperature becomes very high during the
months of March to May, where it may get to as high as 43oC. Nearly
all of the land in the woreda is in the lowlands except some
mountain tops which fall outside. At the time of the visit, the
temperature was around 36oC. Metema is one of the woreda in
the country where the climate is harsh, and government allows a
30% hardship allowance. According to the available digital data,
the mean annual rainfall for the area ranges from about 850 to
around 1100mm. These values are not in agreement with what
has been reported by the OoA. Based on this digital data, about
90% of the woreda receives mean annual rainfall of between 850
and 1000mm. Metema has a unimodal rainfall. The rainy months
extend from June until the end of September. However, most of the
rainfall is received during the months of July and August. Rainfall
during these months is erratic, combined with the poor workability
of most of the soils, farm operations are also affected. The soils
in the area are predominantly black and some are soils with vertic
properties. Due to the season, soils in most of the areas visited
were observed with excessive cracks, which could be as deep as
0.75m in some places.
Homogeneous site was delineated for the selection of trees.
Trees which have similar tapping history and be tapped one year
before the experiment started were selected. Within each area,
trees having diameters of 10-20 and >20cm were randomly selected.
For each diameter class, twenty-five trees taken and labeled.
These trees then allocated to five different tapping resting
categories (n=5 per tapping resting categories) i.e. tapped in each
years, tapped one year and rest one year, tapped for two years and
rest one year, tapped for three years and rest one year and the
remaining are left without being taped. Following the traditional/
local practices each category was taped according to the time
allocated for each trial i.e.1, 2, 3 and 4 years. Each sampled tree
was tapped eleven times every year (T1-T11). The gum obtained
from each tree then collected and compared to see the impact of
resting on the yield of gum from the trees. Analysis of variance
was performed to assess variations among Treatments. Lsd mean
separation method was employed if significant differences are
found among experimental variables. And the result is presented
in means and graph forms
From the frankincense yield collected from tapping of matured
Boswellia papyrifera tress, it has been possible to identify the high
yielding time from the trees. Since frankincense production is the
response of physiological responses of the tress to stress, it is important
to identify the best time for the trees to response actively
in order to maximize frankincense yield from tapping of the trees.
Accordingly, this study identified that the trees has been more
responsive to tapping when they tapped from tapping period of
four) (Figure 1) up to ten according to the local taping practice
of the farmers in the study area. Beginning December to the mid
of April were the peak period to tape the high yield from the matured
Boswellia papyrifera trees (Figure 2).
At this time, it has been possible to collect the maximum yield
from the trees. Thus, this indicated that trees have to be tapped
effectively at this time in order to collect maximum yield of frankincense
from the trees in the study area
The result indicated that as the trees are tapped continuously
without resting will have negative effect on the survival of the
tapped trees. Therefore, it is easily understood that resting of
Boswellia trees is a must in order to protect the trees from death
Of tapped trees, ten of them from small five trees and large five
trees sized trees has been assigned to be tapped for one year and
got rest for one year and then tapped to see the effect of one year
tapping and one year resting on the survival of matured Boswellia
papyrifera tress in the study area. The results of this tapping
schedule indicated that tapping of trees for one year and provide
rest one year regularly after one tapping year will provide better
survival or provide less mortality to the tapped tress in the study
area (Table 2).
Of tapped trees, ten of them from small (5trees) and large (5
trees) sized trees has been assigned to be tapped for two years
and got rest for one year and then tapped to see the effect on the
survival of matured Boswellia papyrifera tress in the study area.
The results of this tapping schedule indicated that tapping of trees
for two continuous years and provide rest for one year regularly
will provide is high mortality of tapped trees as compared to those
trees tapped one year and gets one-year rest (Table 3).
Of tapped trees, ten of them from small (5trees) and large (5
trees) sized trees has been assigned to be tapped three years continuously
and left for one year resting. The result of this tapping
category indicated that there a high mortality to the tapped trees
next to the continuously tapped trees category in the study area
The result indicated that there were significant differences
among those treatments (Large trees one year tapped one-year
rest, large trees three years tapped and one-year rest, and Small
trees three years tapped and one-year rest). From trees having
large diameter one year tapped and one-year rest obtained high
mean yield followed by large trees three years tapped and oneyear
rest. But trees having small diameter and every year tapped
have lower yield followed by trees Small trees Two years tapped
and one-year rest and large trees every year tapped (Table 5).
Based on the result, trees that has been collected from tapping
of matured small and large sized Boswellia papyrifera trees,
the frankincense production potential of the study area is found
to be 77.6 to 535.3gm/tree/year respectively. This figure ranges
from 77.6 to 282.5gm/tree/year and 151.86 to 535gm/tree/
year for small and large sized trees respectively. Different scholars
reported that on their study different frankincense yield for
instance Tadesse et al. (2004) reported a range of 6.7-451.4gm/
tree/year, Abeje & Asmamaw  reported a frankincense yield
of 207-352gm/tree/year and Girmay  reported 500gm/tree/
year of frankincense to be collected from Boswellia papyrifera
tree under normal frankincense production techniques. A similar
study on the yield potential of Boswellia papyrifera in the Metema
area (Wubalem et al. 2004) Asmamaw & Abeje , revealed the
potential of 67.5kg of frankincense production from a hectare of
Boswellia woodland, and; Mesfin et al.  also reported frankincense
production per hectare from open and closed area in Tigray
to be 254.18kg and 169.08kg respectively. This figure indicated
that frankincense yield production is highly influenced by the tree
size of the stand thus the higher yield has been obtained from the
larger sized matured Boswellia papyrifera trees as compared to
the small sized matured tress in the study area. Generally, from
the stand analysis of the Boswellia dominated woodland of Metema
woreda, in a hector of land it is possible to find cal. 250 to
300 matured Boswellia papyrifera tress. Therefore, it is likely to
harvest frankincense yield on the average of cal. 45.1kg/ha/year
in the range between cal. 19.4 to 70.6kg/ha/year from small sized
matured trees and average yield of cal. 85.89kg/ha/year in the
range between cal. 37.96 to 133.82kg/tree/year from large sized
trees depending on the site condition and density of the tree in
the study area.
From the beginning December to the mid of April were the
peak period to tape the high yield from the matured Boswellia
papyrifera trees. From this study tapping period of four (T4) up
to ten (T10) gave more yield than other period. It also indicated
that tapping (T 7) highest yield approximately 0.1kg /tree/yr and 0.032kg/tree/yr for large and small matured Boswellia trees
respectively. Trees tapped three years and one-year rest indicated
that there is a high mortality for both diameter classes in the
study area. Trees for one year tapped and one-year rests regularly
had shown better survival or provide less mortality. Trees having
large diameter one year tapped and one-year rest obtained high
mean yield of 0.535kg/tree/year and followed 0.404kg/tree/year
for large trees three years tapped and one-year rest. Trees having
small diameter and every year tapped have lower yield followed
by trees Small trees Two years tapped and one-year rest and large
trees every year tapped. Since tapped trees continuously without
resting had negative impact on the survival of trees therefore resting
period for Boswellia papyrifera is a must. Tapping of one year
and allowing one year resting have higher survival and frankincense
yield therefore resting period should be done accordingly.
A scientific guideline for frankincense production and on different
tapping techniques shall be developed and implemented. Moreover,
further training shall be given for the local community and
gum and resin producing organizations.
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