Frankincense is one of the major commercial NTFPs in the Sudan produced by tapping the bark of Boswellia papyrifera (Del.) Hochst trees. It is one of the major NTFPs of the Sudan traded locally and internationally. The aims of the present study include: (1) to identify the chain actors and their functions (2) to estimate benefit distribution and value added along the chain; and (3) to determine the mechanisms by which actors control and maintain access to benefits. The study was conducted in the Rashad locality, South Kordofan state, Sudan in 2008/2009. A combination of Rapid Rural Appraisal tools including key informant interview, indepth semi-structured interviews, group discussion and direct observations were used for primary data collection. Eight major actors involved in the value chain were identified and their activities and characteristics examined. The average annual net income of tapper, producer, village trader, and urban merchant was estimated to be 74, 740, 1,300, and 11,230 USD, respectively. The results clearly demonstrate the upward skewed benefit distribution among the value chain actors. The total relative commercialization margin was 62.5% indicating that the actors involved in marketing of the product accrued higher proportion of the end market price. While those involved in the production activities, tappers and producers, receive less income counting about 37.5% of the end market price. The results also illustrate that there is limited value added processing in the commodity chain. Commercial benefits in the commodity chain are gained, maintained and controlled through different mechanisms. The study concludes that frankincense production and marketing is financially profitable for producers, village traders and urban merchants. However, frankincense tappers and producers receive less income. Technical, financial, and institutional support could result in an increase in local actors’ income and contribute to sustainability of the supply of the product.
The forests and woodlands of Sudan are potential source for large number of Non-Timber Forest Products (NTFPs) that support the livelihoods of rural community living in and around the forest areas as well as the national economy. The various NTFPs extracted from the woodlands of the country are consumed, traded locally for a variety of uses and/or exported to international markets. In this regard, gum Arabic is an important source of foreign exchange for the country. Sudan earned more than 100 million USD in 2006 and 2007 from the export of gum Arabic (CBOS 2006, 2007), accounting for about 10% of the annual non-oil export income. Other important NTFPs with international markets include Gum luban or olibanum from B. papyrifera which generated 153,000 USD in the year 2007 alone (CBOS 2007). The majority of the frankincense/olibanum produced in the country is consumed internally and therefore only a limited proportion is exported.
Boswellia papyrifera is among the dominant natural gum and resin bearing tree species in southern Sudan, covering large areas in the south of the traditional gum belt. The species occurs as a pure stand or mixed with other species such as Sterculia Setigera, Combretum Spp., Terminalia and Commiphora species on slopes and land hills (Salih et al. 2002). The area covered by Boswellia woodland is believed to be a very large portion of the country. B. papyrifera is known for its diverse ecological and economic benefits (Chikamai 2002). It is a multipurpose tree species almost all parts of the tree are used for different purposes. Its wood is used for pole and timber. The sweet smelling flowers, that appears when the tree fall its leaves, are important sources of nectar for honey bees (Fichtl and Admasu 1994).
The leaves and seeds are highly valued as dry season fodder for goats, camels and other livestock (Tilahun 1997; Adam 2003; Gebrehiwot et al. 2003). The leaves, bark, root and the resin are also used as traditional medicines for curing various diseases (Tucker 1986; Azene et al. 1993; Eshete et al. 2005). In economic terms, frankincense or gum olibanum is the most valued product of the tree species, as it has wider applications for cultural uses and modern industries (FAO 1995) and source of employment and cash income.
Frankincense or olibanum is the hardened, resinous wood exudate obtained from B. papyrifera by making incisions in the bark with a special tool called ‘Mingaf’ (FAO 1995). The word frankincense is derived from the old French word ‘francencens’ meaning ‘‘pure incense’’ (Tucker 1986). Although it is better known as ‘‘frankincense’’ the resin is also called olibanum, which may be derived from the Arabic ‘al-luba¯n’ (roughly translated: ‘‘that which results from milking’’), a reference to the milky sap tapped from the Boswellia tree. Detail account on the chemistry of frankincense is given in Tucker (1986). It is composed of about 5–9% essential oil, 65–85% alcohol-soluble resins, and the remaining water-soluble gums.
The essential oil extract from the resin obtained by steam distillation has wide applications in traditional medicine, perfumes and fragrances, aromatherapy, pharmaceuticals, as flavour in the food and beverage industries, for making adhesives, chewing gum (FAO 1995). Unprocessed frankincense is commonly used in cultural and religious ceremonies. Frankincense, along with gold and myrrh, was presented to the newborn Jesus Christ. This resin is widely used as incense in Sudan and the surrounding countries including the Middle East and in many churches worldwide. Frankincense is an ancient commercial forest product which currently remains an important commodity. Ethiopia, Eritrea, Kenya, Somalia and Sudan are the major producers and exporters of frankincense (Chikamai 2002). In addition to its environmental benefits, the production and marketing of frankincense offer diverse socioeconomic benefits at local, regional and national levels, including job opportunities and remarkable economic benefit for tappers, traders, exporters, and the national economy at large. Its contribution to the national economy is reflected in its status as one of the forestry export commodities.
More than 3,700 metric tonne of frankincense was exported from Sudan between 2000/2001 and 2006/2007 with the value of export more than 3.5 million USD from this export in the respective years (CBOS 2006, 2007; Ministry of foreign trade annual reports). However, despite the good resource potential of Boswellia stands in the country, its share of the market remains relatively small with regards to its resource potential (Salih et al. 2002). Rashad Locality is the major frankincense production area in South Kordofan. El Tahir and Gebauer (2004) estimated that the Rashad Locality has an average annual production potential of 8,000 tonne. Despite the potential for socio-economic and environmental benefits from the utilization of the resource, not much has been done to analyze the production and marketing systems of frankincense in the study area. Data from such studies is crucial for policy making to ensure the development and conservation objectives through commercialization of the product. Thus this study aims to: (1) identify and characterize the chain actors, their functions and interaction; (2) estimate benefit distribution and value added along the chain; and (3) determine the mechanisms by which actors control and maintain access to benefits.
Frankincense, also called olibanum (Arabic: , لبان lubbān , Mastic ), is an aromatic resin obtained from trees of the genus Boswellia, particularly Boswellia sacra (syn. B. carteri, B. thurifera), B. frereana, and B. bhaw-dajiana (Burseraceae). It is used in incense and perfumes.
There are four main species of Boswellia which produce true frankincense and each type of resin is available in various grades. The grades depend on the time of harvesting, and the resin is hand-sorted for quality.
Frankincense is tapped from the very scraggly but hardy Boswellia tree by slashing the bark and allowing the exuded resins to bleed out and harden. These hardened resins are called tears. There are numerous species and varieties of frankincense trees, each producing a slightly different type of resin. Differences in soil and climate create even more diversity of the resin, even within the same species.
Frankincense trees are also considered unusual for their ability to grow in environments so unforgiving that they sometimes grow directly out of solid rock. The means of initial attachment to the stone is not known but is accomplished by a bulbous disk-like swelling of the trunk. This disk-like growth at the base of the tree prevents it from being torn away from the rock during the violent storms that frequent the region they grow in. This feature is slight or absent in trees grown in rocky soil or gravel. The tears from these hardy survivors are considered superior due to their more fragrant aroma.
The trees start producing resin when they are about 8 to 10 years old.Tapping is done 2 to 3 times a year with the final taps producing the best tears due to their higher aromatic terpene, sesquiterpene and diterpene content. Generally speaking, the more opaque resins are the best quality. Dhofari frankincense (from Boswellia sacra) is said to be the best in the world, although fine resin is also produced more extensively in Yemen and along the northern coast of Somalia, from which the Roman Catholic Church draws its supplies. Recent studies have indicated that frankincense tree populations are declining due to over-exploitation. Heavily tapped trees have been found to produce seeds that germinate at only 16% while seeds of trees that had not been tapped germinate at more than 80%.
Flowers and branches of the Boswellia sacra tree, the species from which most
frankincense is derived
Frankincense has been traded on the Arabian Peninsula and in North Africa for more than 5000 years. A mural depicting sacks of frankincense traded from the Land of Punt adorns the walls of the temple of ancient Egyptian Queen Hatshepsut, who died in 1458 BCE. Frankincense was reintroduced to Europe by Frankish Crusaders. Although it is better known as “frankincense” to westerners, the resin is also known as olibanum, which is derived from the Arabic al-lubān (roughly translated: “that which results from milking”), a reference to the milky sap tapped from the Boswellia tree. Some have also postulated that the name comes from the Arabic term for “Oil of Lebanon” since Lebanon was the place where the resin was sold and traded with Europeans. Compare with Exodus 30:34, where it is named levonah, meaning either “white” or “Lebanese” in Hebrew.
The lost city of Ubar, sometimes identified with Irem in what is now the town of Shisr in Oman, is believed to have been a centre of the frankincense trade along the recently rediscovered “Incense Road”. Ubar was rediscovered in the early 1990s and is now under archaeological excavation.
The Greek historian Herodotus was familiar with Frankincense and knew it was harvested from trees in southern Arabia. He reports, however, that the gum was dangerous to harvest because of venomous snakes that lived in the trees. He goes on to describe the method used by the Arabians to get around this problem, that being the burning of the gum of the styrax tree whose smoke would drive the snakes away. The resin is also mentioned by Theophrastus and by Pliny the Elder in his Naturalis Historia.
Indirect burning of frankincense on a hot coal
Frankincense comes in many grades, and its quality is based on colour, purity, aroma, and age. Silver and Hojari are generally considered the highest grades of frankincense. The Omanis themselves generally consider Silver to be a better grade than Hojari, though most Western connoisseurs think that it should be the other way round. This may be due to climatic conditions with the Hojari smelling best in the relatively cold, damp climate of Europe and North America, whereas Silver may well be more suited to the hot dry conditions of Arabia.
Local market information in Oman suggests that the term Hojari encompasses a broad range of high-end frankincense including Silver. Resin value is determined not only by fragrance but also by color and clump size, with lighter color and larger clumps being more highly prized. The most valuable Hojari frankincense locally available in Oman is even more expensive than Somalia’s Maydi frankincense derived from B. frereana (see below). The vast majority of this ultra-high-end B. sacra frankincense is purchased by His Majesty Sultan Qaboos bin Said the ruler of Oman, and is notoriously difficult for western buyers to correctly identify and purchase.
Frankincense is used in perfumery and aromatherapy. Olibanum essential oil is obtained by steam distillation of the dry resin. Some of the smell of the olibanum smoke is due to the products of pyrolysis. Frankincense was lavishly used in religious rites. In the Book of Exodus in the Old Testament, it was an ingredient for incense (Ex 30:34); according to the book of Matthew 2:11, gold, frankincense, and myrrh were among the gifts to Jesus by the Biblical Magi “from out of the East.”
The Egyptians ground the charred resin into a powder called kohl. Kohl was used to make the distinctive black eyeliner seen on so many figures in Egyptian art. The aroma of frankincense is said to represent life and the Judaic, Christian, and Islamic faiths have often used frankincense mixed with oils to anoint newborn infants and individuals considered to be moving into a new phase in their spiritual lives.
The growth of Christianity depressed the market for frankincense during the 4th century AD. Desertification made the caravan routes across the Rub’ al Khali or “Empty Quarter” of Arabia more difficult. Additionally, increased raiding by the nomadic Parthians in the Near East caused the frankincense trade to dry up after about 300 AD.
Boswellia sacra tree, from which frankincense is derived, growing inside Biosphere 2
5- Traditional medicine
Frankincense resin is edible and often used in various traditional medicines in Asia for digestion and healthy skin. Edible frankincense must be pure for internal consumption, meaning it should be translucent, with no black or brown impurities. It is often light yellow with a (very) slight greenish tint. It is often chewed like gum, but it is stickier because it is a resin.
In Ayurvedic medicine Indian frankincense (Boswellia serrata), commonly referred to as “dhoop,” has been used for hundreds of years for treating arthritis, healing wounds, strengthening the female hormone system, and purifying the atmosphere from undesirable germs. The use of frankincense in Ayurveda is called “dhoopan”. In Indian culture, it is suggested that burning frankincense everyday in house brings good health.
Burning frankincense repels mosquitos and thus helps protect people and animals from mosquito-borne illnesses, such as malaria, West Nile Virus, and Dengue Fever.
6- Frankincense essential oil
The essential oil of frankincense is produced by steam distillation of the tree resin. The oil’s chemical components are 75% monoterpenes, sesquiterpenes, monoterpenoles, sesquiterpenols, and ketones. It has a good balsamic and sweet fragrance, while the Indian frankincense oil has a very fresh smell.
Olibanum is characterized by a balsamic-spicy, slightly lemon, and typical fragrance of incense, with a slightly conifer-like undertone. It is used in the perfume as well as cosmetics and pharmaceuticals industries.
8- Medical research
Standardized preparations of Indian frankincense from Boswellia serrata are being investigated in scientific studies as a treatment for chronic inflammatory diseases such as Crohn’s disease, ulcerative colitis, and osteoarthritis. Initial clinical study results indicate efficacy of incense preparations for Crohn’s disease. For therapy trials in ulcerative colitis, asthma, and rheumatoid arthritis there are only isolated reports and pilot studies from which there is not yet sufficient evidence of safety and efficacy. Similarly, the long-term effects and side effects of taking frankincense has not yet been scientifically investigated. Boswellic acid in vitro antiproliferative effects on various tumor cell lines (such as melanoma, glioblastomas, liver cancer) are based on induction of apoptosis. A positive effect has been found in the use of incense on the accompanying specimens of brain tumors, although in smaller clinical trials. Some scientists say the results are due to methodological flaws. The main active compound of Indian incense is viewed as being boswellic acid.
As of May 2008 FASEB Journal announced that Johns Hopkins University and the Hebrew University of Jerusalem have determined that frankincense smoke is a psychoactive drug that relieves depression and anxiety in mice.The researchers found that the chemical compound incensole acetate is responsible for the effects. In a different study, an enriched extract of “Indian Frankincense” (usually Boswellia serrata) was used in a randomized, double-blinded, placebo-controlled study of patients with osteoarthritis. Patients receiving the extract showed significant improvement in their arthritis in as little as seven days. The compound caused no major adverse effects and, according to the study authors, is safe for human consumption and long-term use. The study was funded by a company which produces frankincense extract,and that the results have not yet been duplicated by another study. In a study published in March 2009 by the University of Oklahoma Health Sciences Center it was reported that “Frankincense oil appears to distinguish cancerous from normal bladder cells and suppress cancer cell viability.”
9- Chemical composition
These are some of the chemical compounds present in frankincense:
- “acid resin (56 per cent), soluble in alcohol and having the formula
- gum (similar to gum arabic) 30–36%.
- 3-acetyl-beta-boswellic acid (Boswellia sacra).
- alpha-boswellic acid (Boswellia sacra).
- 4-O-methyl-glucuronic acid (Boswellia sacra).
- incensole acetate.
Description of the genus and species
Boswellia papyrifera (Del.) Hochst belongs to the family Burseraceae, which contains up to 600 species in 17 genera (Fichtl and Admasu 1994). One of the genera, Boswellia Roxb., contains about 20 species of shrubs or small to medium-sized trees. The genus Boswellia is distributed across the dry regions of the tropics, with its presence in the African mainland extending from Côte d’Ivoire to north-eastern Tanzania. It also grows in northern Madagascar and in India. Its centre of diversity is in north-eastern tropical Africa (Vollesen 1989, Kuchar 1995, Gachathi 1997). Six species of Boswellia occur in Ethiopia: B. microphylla, B. neglecta, B. ogadensis, B. papyrifera, B. rivae and B. pirrotae. All of these, except B. pirrotae, are tapped for gum olibanum.
Boswellia papyrifera is the chief source of frankincense produced in Ethiopia. Frankincense from northern Ethiopia is known and traded on international markets as Tigray (Eritrea) type frankincense (Lemenih and Teketay 2003). Boswellia papyrifera trees can attain a height of up to 20 meters.
The large compound leaves have 6–8 pairs of leaflets plus one at the tip. Each leaf is oval, 4–8 cm long and densely hairy underneath. The edges of the leaves are sharpor round-toothed, and sometimes double-toothed. The sweet-smelling flowers develop on loose heads at the end of thick branchlets (Figure), appearing before the new leaves. The red flower stalk, which can reach a length of up to 35 cm, bears white-pink flowers with 5 petals and 10 yellow stamens.
The pearshaped fruits are a red capsule of about 2 cm long, divided into 3 valves, each containing 1 hard seed. The fruits are borne at the ends of the reproductive branchlets. The outer bark often peels off in thin, papery flakes, and the inner bark is greenish. When wounded, the bark exudes a watery aromatic resin, which slowly hardens to a resin with exposure to air.
Figure . A B. papyrifera tree (centre), its flowers (upper left), leaves (right), bark with a frankincense
tear (lower left) and flaking bark (centre bottom)
Distribution of Boswellia species
Reported occurrence of Boswellia papyrifera
Figure . The distribution of B. papyrifera (Del.) Hochst in Africa
Source: Adapted from Hepper (1969) and Vollesen (1989).
In Ethiopia, Boswellia species grow naturally in various vegetation formations. The species are predominantly found in the Terminalia–Combretum broad-leaved deciduous woodlands, the Acacia– Commiphora small-leaved deciduous woodlands, and among lowland semi-desert and desert vegetation. These vegetation types are found in the northern, north-western, western, eastern, south-eastern and south-western lowlands as well as along the major river gorges such as Blue Nile, Tekeze and their tributaries.
Boswellia papyrifera is restricted to the Terminalia– Combretum broad-leaved deciduous woodlands of the north, north-west and some of the northern major river gorges. In these areas, it covers wide ecological and altitudinal ranges, occurring in areas at an elevation range of 220–1800 m above sea level, with an annual rainfall of 100–800 mm and a mean annual temperature of 25–40 °C. Boswellia papyrifera is predominantly found in Tigray, Amhara and Benishangul-Gumuz Regions, although its presence has been reported on a smaller scale in some parts of Oromiya and Afar Regions. According to available estimates, about 1.7 million ha of woodlands holding B. papyrifera as their main species occur in 3 administrative regions. In Africa generally, B. papyrifera is found in Cameroon, Central African Republic, Chad, Eritrea, Ethiopia, Nigeria, Sudan and Uganda.
Boswellia species grow on steep and rocky areas, exposed sites, gullies and lava flows or sandy river valleys with very shallow soils (Figure 3). They are well adapted to red sandy/rocky soils and do well in soils with poor fertility. They also grow densely on steeper and rocky (rather than gentle) slopes and on well drained landscapes.
Flowering, seed production and propagation
The B. papyrifera tree produces leaves with the first few showers of small rains, around April in northwestern Ethiopia. It sheds leaves at the beginning of the dry season, in October–November. Flowering commences in October. Most of the fruits begin to mature in November and fall from the tree before the second half of January. The sweet-smelling flowers on the red flower stalk (Figure) usually develop before new leaves. Recent observations have shown that B. papyrifera displays a slightly different phenology in different sites, according to environmental conditions, particularly rainfall. Thus, the phenological description given here may not apply to the whole geographical range of the species.
Figure. Female flowering of B.papyrifera, Rapanui, 2014.
2- Seed production
Normally, B. papyrifera bears seeds in abundance, with 44 000–64 000 seeds per kilogram. Purity is high, usually more than 90%. Boswellia papyrifera seeds germinate readily and have a high germination rate. They require no pre-treatment nor do they exhibit dormancy. However, treatment by soaking in cold water for 12 hours has been reported to induce greater and faster germination of the seeds (Eshete and Alem unpub.). By contrast, the treatment of seeds with boiling water or with concentrated sulphuric acid, as conventionally used, suppresses germination.
Inter-annual seed viability (germinability) differences have been observed in the species. This raises the concern that B. papyrifera might produce non-viable or dormant seeds in some years, an aspect that merits further investigation. A high incidence of insect attack and a high proportion of seeds without embryos have been observed in seeds from heavily tapped and old trees (Ogbazghi et al. 2006, Rijkers et al. 2006). Therefore, seed collection from old trees and intensively tapped stands should be avoided. Instead, seeds must be collected from medium-sized, healthy and untapped trees, if available. If not, seeds should be collected from sufficiently rested trees.
Seeds of B. papyrifera can be stored under various storage conditions such as at room temperature for a long period without significant loss of viability provided that the moisture content of the seed is kept low (6% or less) (Eshete et al. unpub.). For instance,
at a moisture content of 6%, germination of more than 94% was obtained after 1 year of storage at room temperature. This suggests that the seeds of B. papyrifera can be stored in rural nursery stores, which are convenient and cheap.
3- Propagating B. papyrifera
Boswellia papyrifera is known to propagate via several means: from natural seed germination (wildings), nursery seedling production and transplanting, rooted cuttings and root sprouts/suckers. However, artificial establishment of the species is not a common practice in Ethiopia.
3.1 Seed-based propagation
a.Seedling production in nurseries seedlings is limited
However, observations show that the seedlings can be raised in nurseries without problem (Figure ), as with many other dryland species. Seeds readily germinate and seedlings grow vigorously on various soil types. However, a higher proportion of sand than normally used in nursery soils is recommended (e.g. 3:3:1 soil ratio). This is because B. papyrifera demands a well-drained and aerated soil environment. Furthermore, watering should be less frequent than is usually applied to the seedlings of many other species. Because B. papyrifera
is a dryland species, it tends to develop a deep taproot in the nursery, with a ratio of root to stem growth of around 3:1. Hence, B. papyrifera seedlings require root pruning. On average, seedlings reach plantable size within 4–5 months.
Figure . Two-month-old seedlings of B. papyrifera in a nursery
b.Propagation from wildings
A large seedling population is often observed in the natural stands of B. papyrifera, particularly during the rainy season (Figure ). However, for reasons that are still largely unknown, most of the seedlings fail to survive during the dry season. This has resulted
in minimal recruitment in natural stands to replace old and dying trees. Boswellia papyrifera is highly palatable for livestock and wild herbivores, and the seedlings are frequently browsed and trampled due to uncontrolled grazing in Boswellia forests. Fire also causes considerable damage. Wildings can be saved by transplanting and replanting them in nurseries and managing them until they achieve significant strength for field replanting. In this way, wildings can be used in managing the natural stands of the species.
Fig. Betula papyrifera male catkin 2
Fig. Betula papyrifera female catkin
c.Planting and protecting seedlings and saplings
Seedlings of B. papyrifera must achieve sufficient vigour before being planted out. The seedlings should also be hardened off well before planting out as the juvenile seedlings may be unable to withstand the harsh environmental conditions of arid and semiarid
areas. Planted seedlings and saplings must be protected from grazing animals, termites, rats and fire. If possible, constructing fire breaks and fencing are recommended to protect seedlings. To protect planted seedlings from termites, use of insecticides, mainly bio-insecticides, is suggested.
3.2 Propagation through rooted cuttings
In experiments, planting of nursery-raised seedlings of B. papyrifera demonstrated a poor field establishment success rate. Even when protected against grazing and fire, seedlings failed to exhibit good survival. Vegetative propagation, particularly macro vegetative propagation with rooted cuttings, is expected to result in successful field establishment of the species including plantation forest establishments. As with most deciduous tropical plants, B. papyrifera propagates from branch cuttings (Figure 7). In fact, unlike other asexual propagation methods such as grafting, budding and micro propagation (tissue culture), macro cutting techniques are easy, cheap and quick. Macro cuttings can take root in an open environment when planted directly in the field.
To use rooted cuttings for propagation of B. papyrifera, the materials should be collected from healthy, mature and vigorous donor plants. Factors that significantly affect the success of rooted cuttings are the season when collection and planting are carried out and the dimensions of the cuttings. Collection and planting should be
done during the dry season when the donor trees are dormant. For instance, in Tigray and Metema, the best months to collect and plant cuttings are February and March. Cuttings used in this exercise were reported to be about 1.0–1.5 m long and with a
circumference of about 20 cm. Experiments have been initiated to explore options to minimize the height and diameter of cuttings required for successful vegetative propagation Branch cuttings should be planted immediately to protect them from desiccation/dehydration. Planting pits should be 45–60 cm deep with a diameter of at
least 20 cm. The thicker side of the branch cutting should be sliced at a slanting angle of about 45° and the cuttings should be inserted into the soil at a leaning angle in order to allow the cambial layer to fully touch the soil. The opposite end (the tip) must be
covered with water-repellent coatings and treated with fungicide to avoid decay and dehydration. The fine soils removed from the pit should be placed back into the pit and thoroughly packed to reduce air voids. The soil around the pits should be scrapped and heaped around the cutting to form a small mound to avoid water accumulation on the pit. Weeding and hoeing are necessary, and the cuttings should be protected from animals (e.g. by fencing) and insect pests such as termites (e.g. by using anti-termite chemicals). Latex from Euphorbia abyssinica can be used to treat B. papyrifera branch cuttings to stimulate and enhance rooting and survival. The latex is known to contain indoleacetic acid, an auxin controlling apical dominance and lateral rooting, as well as indoleacetic acid metabolites and conjugates (Negussie et al. 2009).
Figure. B. papyrifera established from cuttings at a research station in Tigray (a) and under field conditions in the Blue Nile gorge (b).
3.3 Propagation through root suckers
Boswellia papyrifera can also be reproduced using root suckers. This method appears to play a considerable propagation role in the natural environment of the species. In this type of B. papyrifera propagation, the exposed root of a mature tree can initiate a root
sprout, which, if protected against damage by animals and insects, can grow into a mature tree (Figure).
Figure. Root-sprouted B. papyrifera in its natural stand in Metema.
Tapping and post-harvest handling
Traditionally, frankincense from B. papyrifera is produced through artificial wounding of the trees, a process called tapping. Tapping is carried out during the dry season. However, it is not clear whether the dry season is chosen out of convenience for tappers or because it is dictated by the physiology of the tree. Traditional tapping1 involves slightly shaving the external layer of the bark and forming a circular wound of about 1–2 cm high, 1–1.5 cm wide and 0.5–1.0 cm deep. Usually 3 tapping spots are made on each side of the tree, starting at about 0.5 m from the base of the stem (Figure). More than 3 tapping spots can be made depending on the size of the tree.
Tapping is a cyclical operation that is repeated every 15–20 days after the first tapping. During the subsequent tapping cycles, older wounds are refreshed and the blaze is moderately widened by removing more bark from the upper edges of the former wound and by carving down 2 cm of the lower edge. Tapping continues until the onset of the rainy season. Thus, a tree is tapped 8–12 times a year, and at the end of the production year each wound may attain a width of about 10 cm or more (Figure).
Increasing the number of tapping spots in a tree increases the overall annual yield of frankincense per tree, but it affects the tree’s vitality and interferes with its reproductive biology. If a tree has too many wounds, it can produce tears of resin that are too fine or dusty, and thus less attractive to buyers. Indeed, an optimum tapping intensity needs to be applied to ensure a compromise between tear size, total frankincense yield and impact on the tree. The recommended tapping intensity per tree is a total of 6 spots for trees of < 20 cm diameter at breast height (DBH), a total of 12 spots (3 spots on each of the 4 sides) for trees of medium DBH (20–30 cm) and a total of 16 spots (4 spots on each of the 4 sides) for trees > 30 cm DBH.
Figure. Schematic presentation of recommended distances between tapping sites (left) and the tapping practice (right) (Figure: Girmay F., Photo: Wubalem T.).
Another important element in managing the tapping regime is renewing the wound at the correct interval of days. If wounds are not renewed at the correct intervals, the old wounds may heal completely. Wounding after the older wounds heal causes the tree to delay exuding the resin. This is almost equivalent to starting the whole process of tapping all over again, which will result in reduced overall annual yield and increased production costs.
Estimates of annual frankincense yield per B. papyrifera tree vary considerably. For instance, Tadesse et al. (2004) reported a range of 6.7–451.4 g frankincense per tree per year. Eshet and Alem (unpub.) reported a frankincense yield of 207–352 g per tree per year. The variation in yield per tree is attributed to tree size (DBH), tapping intensity and site conditions. Generally, trees with a bigger DBH provide higher frankincense yield than trees with a smaller DBH. Similarly, increased tapping intensity increases frankincense yield per tree. Frankincense yield can be doubled or tripled by increasing the number of tapping spots per tree from 4 to 12, but this may be unsustainable. For this reason, it is recommended that smaller trees be wounded in only a few spots, with a subsequent increase in the number of wounding spots as the tree increases in girth. Wide variability in frankincense yields is common among trees of similar sizes growing in the same environment (Tadesse et al. 2004). Research indicates a weak correlation between tree dimensions (e.g. DBH, height) and frankincense yield for any given tapping intensity (Tadesse et al. 2004, Eshete and Alem unpub.). Developing a predictive model to estimate frankincense yield for a tree or a production area using such weakly correlated relationships would be misleading.
2- Post-harvest handling
Using locally made collection vessels, tappers manually pick the tears of solidified frankincense resin from individual trees (Figure). These tears are seasoned by spreading them out on mats under temporary shades constructed in the field. Seasoning is an essential process for avoiding clumping of the tears. The seasoned tears are then packed in sacks and transported to permanent warehouses for further processing.
Figure. Frankincense tears oozing through a wound (a); tool and collection vessel for collecting frankincense (b); and product seasoning under shade at the production site (c)
Further processing at warehouses involves cleaning any foreign materials (such as grass, leaves or small stones) off the frankincense. During this process of manual sorting and grading, the frankincense is sorted into 7 grades based on colour and tear size (Table).
Cleaning, sorting and grading play an important role in improving product quality. However, current traditional post-harvest handling practices have several shortcomings that negatively affect product quality. Major problems include: improper storage; seasoning in unclean conditions; use of inappropriate or contaminated containers; and poor hygienic conditions during sorting and cleaning. One common problem, for example, is that frankincense is stored and/or transported with volatile substances such as petroleum products. Moreover, frankincense collected from trees is often kept in the field under high temperatures for a prolonged time in perforated (not airtight) containers. These improper post-harvest handling practices result in the loss of significant proportions of volatile essential oils and subsequent reduction in the quality of the frankincense.
Delivery of high-quality frankincense requires adherence to the following practices:
- Clean and appropriate vessels should be used for field collection and airtight containers for storage and transport of the product.
- Storage rooms/shades should be as clean as possible and kept at a relatively moderate temperature.
- Seasoning should be carried out on clean materials free from dust and grass.
- Storage or transport with substances such as petroleum, oil and salt should be avoided.
- Collectors and cleaners should maintain cleanliness to avoid contamination.
- Frankincense fallen from the trees and mixed with dust should be avoided if possible. If not, such products must be collected separately and cleaned thoroughly.”
Table. Grades of frankincense from B. papyrifera
Expected proportion from 1 quintal of unprocessed frankincense (%)
Size ≥ 6 mm; white
Size ≥ 6 mm; creamy white
Size 4–6 mm
Size 2–4 mm
Any size; brown
Any size; black
Powder and bark; no size limit
Following such best-practice guidelines will make it possible to supply better-quality, higher-value frankincense to the market.
Recent studies have failed to distinguish differences in chemical composition between the different grades of frankincense. This suggests to producers and exporters that the tradition of grading based on size and colour is merely a physical requirement and may have little to do with chemical composition. In fact, frankincense of all grades is processed into more or less the same end products. This indicates that at least partial value-added processing, such as essential oil extraction, will provide better returns than selling the raw frankincense, especially for products labelled as low grade and sold for lower prices. Essential oils can be extracted in many ways, such as by mechanical or solvent extraction, vacuum distillation and stem/hydro distillation.
Processing of frankincense for the production of essential oils is simple and does not require sophisticated equipment. The frankincense is placed in water in a distillation apparatus, and the water is maintained at boiling point. The steam containing the dissolved or vaporised volatile oils from the frankincense condenses and is collected in a basin, in which the oil floats on top of the water. This technology can be adopted at the farmer level using a prototype apparatus.
Measures for ensuring sustainable frankincense production
Boswellia papyrifera forests are facing several challenges. Four direct factors affecting Boswellia forests are: (1) clearance for crop production by commercial farmers and resettled smallholder farmers; (2) overgrazing; (3) intensive and improper tapping; and (4) increasing forest fire (Gebrehiwot et al. 2002, Eshete et al. 2005, Lemenih et al. 2007). Underlying factors are high population influx, mainly through resettlement schemes, coupled with a weak institutional environment for regulating access to and management of dry-forest resources. These factors have led to uncontrolled conversion and unregulated exploitation of Boswellia-dominated woodlands, resulting in widespread deforestation. Addressing these challenges is a major requisite to ensure sustainable production and supply of frankincense. Developing stronger local institutions, in which local communities take the lead, and establishing sustainable market links are essential steps to achieving successful frankincense-based enterprise development at the local level. Market links may also create an economic incentive for farmers to responsibly manage dry forests and sustain the environmental services from woodlands. The following sections present specific management-related measures for sustaining frankincense production.
1- Reducing conversion of woodlands
Agricultural land expansion as a result of human population pressure, mainly from state-sponsored resettlement programmes, is a growing threat to B. papyrifera forests. Conversion of B. papyrifera forests to farmland is taking place at an increasing rate each year (Figure 12). For instance, from 2003 to 2005, 18 586 households were officially settled in Metema district through the Amhara Regional State Resettlement Programme. Upon arrival, each household was allocated 2 ha of land for farming.
This means a total of 37 172 ha of the dry forest containing predominantly B.papyrifera was cleared. Furthermore, information obtained from Metema district office shows that during the past 20–30 years, an area equivalent to 303 180 ha of B. papyrifera woodland has been converted to cropland. Similarly, in Tigray Region, Gebrehiwot (2003) reported that more than 177 000 ha of Boswellia woodland had been destroyed during the previous 20 years. If this high rate of forest clearance continues, ensuring a sustainable supply and production of frankincense in the future will be difficult.
2- Managing forest fire
Controlled burning is part of a woodland management practice that serves many purposes. It is used to reduce bush encroachment in favour of grass and to control animal parasites such as ticks. However, in recent years, fires have been intensified in B. papyrifera woodland areas. Not only farmers but also tappers set fire just to clear the undergrowth or to reduce the risk of encountering snakes or other wild animals. Local people also set fires while harvesting wild honey or clearing woodlands for farmland. These fires can spread, causing damage to woodlands, including to emerging seedlings and saplings (Figure). As these areas have no organised fire control mechanism, damage recurs each time forest fire incidence occurs. It is therefore crucial to raise awareness and establish local institutions responsible for reducing fire incidence and damage in these areas.
Figure. Managing Forests and Fire in Changing Climates | Science
3- Improving tapping methods and timing
Tapping can cause damage to trees if done at high intensity or by inexperienced tappers. Damage arises because tapping exposes trees to infectious attack by insects and other pathogens (Figure), reduces tree vigour and increases susceptibility to windfall.
Moreover, increased tapping intensity of B. papyrifera trees reduces their sexual reproduction by affecting the carbon allocation between frankincense production, healing of wounds and fruit and seed setting (Rijkers et al. 2006). Tapping is practised only during the dry season, apparently because this season is convenient for collectors. Trees are in dormant state during this period, and there is a large carbon reallocation to frankincense production. This carbon reallocation greatly weakens the trees and limits their production of viable seeds. In general, intensively tapped stands produce less viable seeds, which can negatively affect natural regeneration. As untapped trees produced very healthy and viable seeds, it is recommended that, for all production systems, a selection of trees be left untapped to serve as seed sources (mother trees). If this is difficult to implement, then allowing a sufficient resting period of 3–5 years after trees/stands are consecutively tapped for a couple of years can enable the trees to regain vigour and vitality.
4- Maintaining a viable Boswellia population
Current mismanagement of B. papyrifera appears to be affecting the population structure of the species. In some sites, reports indicate that 65% of the total population falls in the diameter range of 10–20 cm (Gebrehiwot 2003). Under normal conditions the youngest population of less than 10 cm should have constituted the largest percentage of the population. The low density of individuals in smaller diameter classes suggests that regeneration and seedling recruitment are inadequate. This potentially poses a threat to sustainable resin production from B. papyrifera. Managing certain woodlands to support regeneration and recruitment of B. papyrifera, by controlling open grazing and fires and by nursing seedlings, is essential for maintaining viable populations, which, in the long run, is key to ensuring a sustainable supply of frankincense.
Figure. Effects of fire in B. papyrifera forests on trees, seedlings and saplings
Figure. Improper tapping (a) exposes the inner bole of the tree todecay (b) and predisposes the tree to parasite attack (c)
5- Other management-related recommendations
Generating sustainable benefits from the gums and gum resins subsector depends on the reconciliation of biological sustainability and commercial viability. Several possible approaches for increasing the production and quality of frankincense are available, such as using appropriate collection tools and methods, improving the management of natural stands and establishing plantations to increase production and improve productivity.
5.1 Improving harvesting methods
As discussed above, improper tapping adversely affects trees. However, in Metema area for instance, some companies bring in young and unskilled tappers, who do not treat the trees properly. Therefore, to minimise the impacts of improper tapping on the trees, it is necessary that workers be equipped with appropriate tools and adequate training on proper tapping practices. The lack of trained labourers in production areas is exacerbated by competition for labour from nearby commercial farms (Lemenih et al. 2007).
5.2 Management of natural stands for sufficient regeneration
At present, frankincense is produced from natural populations of B. papyrifera. Ensuring sustained production of frankincense from natural stands requires managing the resource in a responsible way. This involves, among others, managing the regeneration of B. papyrifera in natural forests, through appropriate management of the ecosystem. Management options that support adequate regeneration of B. papyrifera are regulated frankincense harvest and intensive management of the stands.
- Regulated harvesting. Regulating tapping, either by allowing a sufficiently long resting period or by reducing tapping intensity, or a combination of these, is necessary to promote regeneration. This technique is cheap and simple, but it has the drawback of reduced economic gains in the short term. To optimise economic gains, this management option can be integrated with other economic activities such as livestock production. Grass and browse, including B. papyrifera leaves, can be used as livestock feed. Alternative strategies for regulated harvesting are to adopt selective harvesting or rotational harvesting. Selective harvesting involves selectively leaving untapped a sufficient number of healthy parent trees throughout the landscape. These trees then serve as sources of viable seeds to enhance regeneration. These trees and their surroundings must be protected against fire and grazing to protect emerging seedlings. Rotational harvesting involves rotating production centres to allow some sites to sufficiently rest while production is taking place in other sites. The system can be based on collectors’ traditional knowledge as there is a lack of scientific research on the appropriate rotational period.
- Intensive management. This management option involves adjusting the intensity of harvesting using silvicultural practices to better manage natural propagation of the species. Such management involves site preparation, artificial seeding, shading and watering seedlings and protecting seedlings against grazing, fire, rats and termites. Other management applications such as thinning and coppicing can be applied to ensure rapid growth and high yields. However, knowledge on appropriate management techniques for the species is still very limited, and further research is needed to determine how best to manage the resource base.
5.3 Domestication and plantation establishment
Boswellia papyrifera has not yet been domesticated in Ethiopia. The domestication of the species and its widespread plantation on private farmlands, community forestlands and degraded wastelands could enhance the contribution of the subsector to local livelihoods and the national economy in general. Boswellia papyrifera must be domesticated to achieve sustainable frankincense production for export markets. As this species successfully establishes itself and thrives well even on marginal and degraded lands, it is more appropriate to plant the species on marginal lands and degraded community forestlands where cultivation of crops has little success. There exist some agroforestry systems where gum and incense tree species are integrated with other production systems such as crop or animal production or both. For instance, in the Sudan, A. senegal is intensively managed in agroforestry systems. Although to a very limited extent, in some parts of Tigray, B. papyrifera trees are maintained on farmlands as parkland agroforestry trees and used for the production of frankincense. There is huge potential in this regard, but this must be supported by action-oriented research that helps build local capacity and addresses possible constraints.
5.4 Improving product handling, quality control and value-adding
The most important aspect that needs to be addressed in frankincense production and marketing is quality control. This calls for improvement in storage, handling and transportation conditions. Important components of frankincense from B. papyrifera are the essential oils, which are partly volatile when exposed to the high temperatures prevalent in the production areas. Storing products under excessive temperatures should be avoided, and airtight containers are recommended to maintain volatile oils. Harvested quantities should be processed as soon as possible, packed in airtight containers and stored at relatively low temperatures. Once the products are properly collected, options for value-adding must be explored; those that are economically feasible need to be pursued.
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