**2. The ecology of marula trees in Swaziland**

Marula is a wild indigenous fruit tree (see **Figure 1**) which is a member of the floral family *Anacardiaceae* [41]. *Sclerocarya birrea caffra* (the species found in Swaziland), is one of three species of *Sclerocarya—*the others being *S. gillettii* and *S. multifoliolata* [18, 60]. Marula is endemic to Africa and occurs in a diversity of vegetation types; mainly open woodland, deciduous savannah and semi-deciduous forest [14, 18, 22]. It grows well in altitudes ranging from sea level to 1800 m above sea level in areas that are frost-free, as the species is generally sensitive to frosty conditions [25, 47]. Marula trees also prefer areas where temperatures vary between 10°C

**Figure 1.** A marula tree (picture taken by first author, December 2013).

(in high altitudes) and 40°C (in low altitudes) [9]. Such wide-ranging temperatures are beneficial for marula seed germination, which happens usually at temperatures between 27 and 37°C [19]. The marula tree species is relatively drought-tolerant and grows well in areas that are humid to subhumid with wide-ranging amounts (200–1500 mm) of annual rainfall [18, 19].

local populations [5, 44]. Therefore, Hugo [24] rightly emphasizes that the sustainable management and use of such resources require an interdisciplinary approach and sound knowledge of each resource, while the ecological and socio-economic factors related to their use must be sorted out as well. Furthermore, since the long-term success of any initiative hinging on the utilization of natural resources depends on local benefit and support, it is imperative that local livelihoods and poverty reduction are considered during the formation and man-

Currently, there are growing concerns about the effects of people on ecosystems and the reciprocal impact of ecosystem degradation on the quality of human life [30, 38, 72]. The degradation of ecosystems in terms of loss of biodiversity has particularly become a major concern, especially when the harvesting of the species in question and/or its products has become commercialized as is the case of marula harvesting in Swaziland. This chapter focuses on the recently introduced practice of commercial harvesting of marula products in Swaziland, and reports on some of the findings of a study conducted to explore the impact of commercial harvesting on the future availability of marula. The study aimed at identifying challenges faced by the harvesting of marula products and to explore opportunities for the sustainability of the

Marula is a wild indigenous fruit tree (see **Figure 1**) which is a member of the floral family *Anacardiaceae* [41]. *Sclerocarya birrea caffra* (the species found in Swaziland), is one of three species of *Sclerocarya—*the others being *S. gillettii* and *S. multifoliolata* [18, 60]. Marula is endemic to Africa and occurs in a diversity of vegetation types; mainly open woodland, deciduous savannah and semi-deciduous forest [14, 18, 22]. It grows well in altitudes ranging from sea level to 1800 m above sea level in areas that are frost-free, as the species is generally sensitive to frosty conditions [25, 47]. Marula trees also prefer areas where temperatures vary between 10°C

agement of such initiatives [3, 31, 45, 74].

304 Selected Studies in Biodiversity

marula species and harvesting of its products.

**2. The ecology of marula trees in Swaziland**

**Figure 1.** A marula tree (picture taken by first author, December 2013).

In Swaziland, marula trees grow abundantly in the lowveld and in the lower parts of the middleveld. The UNDP [70] estimated that about 2 million marula trees are growing in Swaziland and that each tree can produce up to 500 kg of fruits per year. Marula is a dioecious tree that grows to about 15 m in height with spreading crowns and dense foliage [41, 60]. When ripe, the marula fruits (see **Figure 2**) and kernels are edible and are rich in minerals, proteins, oils and vitamins [17]. The kernels are normally eaten fresh, mixed and cooked with other foods or stored for later consumption. This, according to Shackleton et al. [60] and also Wynberg et al. [75], makes marula an integral part of the diet, tradition and culture of rural communities in many southern African communities. Apart from playing an important role in cultural practices in Swaziland, Marula is also sought after for many commercial initiatives across the African continent and beyond.

Marula plays a fundamental role in the ecosystems and provides a number of important services to human beings and other living organisms. Being a keystone species, marula plays a significant role in the ecology of other plants and animals [22]. The marula tree is large and, usually, it is considered a community-dominant species [27, 47]. It also provides valuable shade that produces large areas with cool subcanopy environments that are good habitats for other plant and animal species. Marula is also a favorite food of numerous birds, mammals and insects [15, 22, 25, 42]. Therefore, removal of this large dominant species can threaten biodiversity and result in loss of many important subcanopy species such as mistletoes which grow on marula branches and wood roses that are often used by rural curio traders [10].

The leaves of the marula trees are also browsed by domestic and game animals, such as cattle, goats, impala, zebras and kudu. These trees are also host to various insect species such as butterflies and moths. The larvae of the edible kinds of these insects such as the mopane

**Figure 2.** The marula fruit (picture taken by first author, December 2013).

worm (*Imbrasia belina*) and the African moon moth (*Argema mimosa)* are used as food by many tribes in southern Africa [16, 21, 42, 55, 76]. The Swazis and Zulus also traditionally use the tough silk pupa cases of the moon moth for anklet rattles used in tribal dances such as the annual reed dance and *Buganu* ceremonies practiced in Swaziland. The barks of the marula trees are used by elephants and rhinoceros. The marula fruits, which are rich in vitamin C, are also eaten by animals, such as elephants, warthogs, porcupine, monkeys, baboons, millipedes, domestic cattle and goats and, thus, creating an intricate ecological linkage between the marula trees and other animal species [21, 27, 55].

proportion of people live on an income below US\$2 per day [40, 48, 57, 73].From time immemorial, people in Swaziland have harvested marula fruits and seeds for livelihoods in the form of food and for producing a traditional brew (*Buganu*). The brew is largely consumed during traditional festivals or sold to local customers to generate an income [34, 36, 49]. The people of Swaziland have used the marula kernels in relishes, eating the fresh fruits and seeds, using the bark for relieving stomach aches and also for spiritual reasons [64]. Marula products also feature in traditional ceremonies, such as the *Buganu* ceremony, celebrated annually where people gather with their King (The *Ingwenyama*) and Queen Mother (The *Indlovukazi*) to celebrate [34, 36, 49]. This ceremony normally marks the start of the *Buganu* season whereby, after the ceremony, every Swazi is free to drink the *buganu* brew [26, 63]. Recognizing its social, cultural and economic values, the Queen Mother in 2004 established two commercial processing plants (Swazi Secrets and Swaziland Marula) as initiatives to economically empower rural women through enterprising on marula harvesting and processing. In Swaziland, marula is traditionally harvested almost exclusively by women who pick up the fruits from the ground when ripe. The UNDP [70] has observed that the Swazi Secrets project alone is supporting 2400 rural women who earn a living through selling seed

Commercial Harvesting of Marula (*Sclerocarya Birrea*) in Swaziland: A Quest for Sustainability

http://dx.doi.org/10.5772/intechopen.76606

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The establishment of commercial processing plants for marula is an initiative to augment the battle for economic growth and poverty alleviation in Swaziland. The challenges for economic growth in Swaziland have been compounded by the global economic meltdown that started in 2008, the reduction in Southern African Customs Union (SACU) revenue as of 2011, and the environmental challenge of global climate change which is impacting developing countries the most [4, 12, 58]. The consequences of climate change in turn present one of the most fundamental threats to biodiversity and the functioning of ecosystems [54]. Swaziland is therefore faced with two dilemmas: the grapple with the challenge of marrying economic growth and poverty alleviation; and at the same time, it is expected to exert efforts for environmental conservation and resource sustainability, among others of

The past few decades have seen marula and its products gaining popularity in the international market due to demand for its many by-products, such as marula oil and the well-known Amarula cream liqueur [7, 8, 60, 64, 75]. The increased demand for marula products, coupled with the high incidence of poverty, especially among rural women in Swaziland, led to the establishment of the two marula processing plants in 2004. These initiatives have attracted a large number of Swazi women to scout the forests and fields around their homesteads in search of marula fruits and seeds to sell and earn an income. This commercially induced harvesting of marula fruits and seeds poses a potential threat to the marula tree species as more and more of the seeds that would support regeneration and recruitment of new marula trees

According to Peters [56], when the bark, fruits, seeds, wood and other parts of a species are harvested for processing into various products at household and/or commercial levels, there may be significant impacts on the population structure and distribution of the species, depending on the nature and intensity of the harvest. This imposes a potential threat to the species in the sense that it might be driven to depletion and/or extinction if proper sustainability measures are not put in place. Therefore, it is clear that the potential depletion or extinction

kernels from marula trees.

the marula species.

are removed through increased harvesting.

The water-filled holes in the trunks of marula trees are very important breeding grounds for mosquitoes and other animals such as amphibians. These interrelationships such as the overbrowsing by animals can destabilize the population structure of marula trees as it affects the growth of marula seedlings and, thus, impacts on its successful regeneration and recruitment potential [19, 27, 55]. Marula seedlings are also susceptible to fire which also impact on its regeneration potential [23, 25].
