Distribution and Conservation Status of the Endangered Pepperbark Tree Warburgia Salutaris (Canellaceae) in Swaziland

Distribution and conservation status of the Endangered pepperbark tree Warburgia salutaris (Canellaceae) in Swaziland

M ESHACK N. DLUDLU,PRISCILLA S. DLAMINI,GUGU F. SIBANDZE V USUMUZI S. VILANE and C LIFF S. DLAMINI

Abstract The Endangered Warburgia salutaris (Bertol. f.) medicinal plants (Van Wyk, ). Stem bark is the most Chiov. (Canellaceae), a sought-after medicinal plant in commonly used part of the tree, and leaves and roots are southern Africa, is on the verge of extinction as a result of also used. It is claimed to treat numerous illnesses, including overexploitation for illegal trade. As part of formulating a bronchial infections, colds, gastric ulcers, malaria, oral conservation strategy for the species in Swaziland we sought thrush, rheumatism, sinusitis and venereal diseases (Van to determine its distribution and population status and to Wyk, ; Maroyi, ; Leonard & Viljoen, ), and sev- revise its national conservation status. Field surveys were eral phytochemical and pharmacological studies attest to its conducted in all physiographic regions of Swaziland. medicinal value (Rabe & van Staden, ; Madikane et al., Eighteen locations of species presence were found, of ; Mohanlall & Odhav, ; Green et al., ). which  were new records. Three were within protected However, such popularity makes it a sought-after species, areas, and seven were in areas worthy of protection. The lar- resulting in overharvesting, mainly for illegal trade (Botha gest subpopulations occurred in two of the latter areas, et al., ). Consequently, it is categorized as Endangered Ngudzeni and Sitsatsaweni ( and  individuals, respect- on the IUCN Red List (Hilton-Taylor et al., ). In ively), and one unprotected area, Bulunga ( individuals). Zimbabwe it is categorized as Extinct in the Wild (Maroyi, Warburgia salutaris has a severely fragmented distribution ) and exists only in cultivated populations (Maroyi,  and an area of occupancy of  km .Of mature ). In South Africa it is categorized as Endangered and individuals % were ring-barked and % felled, and some is in continual decline (Williams et al., ), and in subpopulations had ring-barked juveniles. This indicates a Swaziland it is categorized as Critically Endangered plausible decline in number of mature individuals. Most (Dlamini & Dlamini, ). localities in unprotected areas are eroded and invaded by Priortothisstudytherewereonlyfouroccurrencere- alien plants, indicating a decline in habitat quality. Our cords of W. salutaris in Swaziland, at Bulunga findings indicate that W. salutaris should be categorized (Compton, ), Malolotja Nature Reserve (Dlamini & as Endangered nationally based on criteria Bab (iii,v). Dlamini, ), Shewula and Mlawula (Loffler & Loffler, Although this status implies a lower level of threat than ), and no specimens were held in the Swaziland the previous national categorization as Critically National Herbarium. However, discussions with foresters, Endangered, it does not imply an improved conservation ef- traditional healers and local people revealed that subpopu- fort in the country, but rather a more accurate assessment lations existed at other locations in the country. We con- based on more data. We have clarified the conservation sta- ducted a country-wide survey to map the distribution of tus of W. salutaris in Swaziland, discovered some previously the species, estimate its population size, record threats, undocumented subpopulations and identified potential and revise its conservation status. This was done as part conservation interventions. We recommend that this infor- of formulating a conservation strategy to ensure sustain- mation be used in setting priorities to ensure conservation able utilization of the species and maintenance of genetic of the species. diversity. Given the widespread use of traditional medicine in Swaziland (Amusan, ), such a popular medicinal Keywords Africa, medicinal plants, pepperbark tree, pro- plant is vulnerable to overexploitation and ultimately tection-worthy area, Swaziland, Warburgia salutaris extinction. – arburgia salutaris is a popular medicinal tree in Field surveys were conducted during November  southern Africa, where there is widespread use of December in representative areas of all physiographic W regions of Swaziland. Five park rangers and  local people (traditional healers, herdsmen and plant enthusiasts) as-  MESHACK N. DLUDLU (Corresponding author), PRISCILLA S. DLAMINI,GUGU sisted with surveys in five protected areas and unprotected F. SIBANDZE,VUSUMUZI S. VILANE and CLIFF S. DLAMINI Swaziland Institute for areas, respectively. These study sites were identified through Research in Traditional Medicine, Medicinal and Indigenous Food Plants, discussions with reserve managers and community leaders. University of Swaziland, Private Bag 4, Kwaluseni, Swaziland E-mail [email protected] As W. salutaris is popular and easy to identify, they had no Received  July . Revision requested  December . difficulty leading the researchers to its exact locations, and Accepted  February . First published online  June . some suggested potential locations beyond their villages,

Oryx, 2017, 51(3), 451–454 © 2016 Fauna & Flora International doi:10.1017/S0030605316000302 Downloaded from https://www.cambridge.org/core. IP address: 170.106.34.90, on 30 Sep 2021 at 11:41:29, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0030605316000302 452 M.N. Dludlu et al.

TABLE 1 Locations of Warburgia salutaris in Swaziland (Fig. ), with habitat protection status, number of patches per location, and numbers of mature and juvenile individuals.

No. of Mature Juvenile Total Location Protection status patches Ring-barked Felled Total (ring-barked) (mature + juvenile) Malolotja Nature Protected 6 0 0 38 40 78 Reserve* Mhlumeni Protected 4 0 0 21 46 67 Mlawula Nature Protected 5 0 0 39 6 45 Reserve* Ekuvinjelweni Protection-worthy 1 0 0 0 16 16 KaKholwane Protection-worthy 1 20 4 24 6 30 KaPhunga Protection-worthy 4 11 15 46 20 66 Mambane Protection-worthy 1 0 0 10 20 30 Ngudzeni Protection-worthy 14 27 0 101 250 351 Nyonyane Ranch Protection-worthy 1 10 3 17 14 31 Sitsatsaweni Protection-worthy 18 22 15 108 122 230 Bulunga* Unprotected 19 84 2 155 95 (26) 250 Lomahasha Unprotected 1 27 13 40 12 52 Mafutseni Unprotected 2 10 0 10 25 35 Manzini Unprotected 1 0 0 1 0 1 Nkwene Unprotected 2 2 0 2 21 23 Shewula* Unprotected 3 6 0 28 23 51 Sibovini Unprotected 1 40 0 56 40 96 Timphisini Unprotected 1 4 0 4 8 12 Total 85 263 52 700 764 1,464

*Previously known locations

which turned out to be correct. Eighteen voucher specimens in two protection-worthy areas, Ngudzeni and Sitsatsaweni were collected and deposited in the Swaziland National ( and  individuals, respectively), and in one unprotect- Herbarium. Geographical coordinates, habitat characteris- ed area, Bulunga ( individuals) (Table ). We conclude tics, number of individuals (mature and juvenile), and phys- that the previously sparse number of records of the species ical damage to the plants were recorded. Semi-structured was attributable to lack of research rather than a paucity of interviews were conducted with the rangers and local people the species in Swaziland. to ascertain the uses of W. salutaris, threats to the species, Seven hundred mature individuals were recorded, of which and its conservation status.  (%) had been ring-barked and % were felled and de- We assessed the extinction risk of W. salutaris in barked(Table ).Juvenileswerealsoring-barkedwheremature Swaziland using IUCN guidelines (IUCN, a,b), apply- individuals had been destroyed (Table ). Such indiscriminate ing criterion B, which considers the species’ geographical harvesting was observed only in unprotected areas, and all re- range, number of subpopulations, decline in habitat quality spondents attributed it to illegal trade. The need for supple- and number of mature individuals. Unlike other criteria, all mentary income to alleviate poverty (%), poor law data required for criterion B were available, facilitating an enforcement (%), and ignorance of the value of biodiversity accurate assessment. A distribution map was plotted using (%) were cited as drivers of the illegal trade. A decline in the QGIS v. .. (QGIS Development Team, ). The area of number of mature individuals is inevitable if such indiscrim- occupancy (AOO) and extent of occurrence (EOO) were inate harvesting persists. Soil erosion and invasive alien plants calculated using the GeoCAT tool (Bachman et al., ). were prevalent in most of the unprotected areas, indicating a Eighteen locations of W. salutaris were found,  of decline in habitat quality, and the occurrence of W. salutaris in which were new records (Table , Fig. ). The species occurs small isolated subpopulations constitutes a severely fragmen- in small isolated patches, with – patches per location ted distribution. Thus, despite not being as rare as previously (Table ). Three locations (.%) were in protected areas, supposed, the species is threatened. and seven (.%) were in unprotected areas worthy of pro- The AOO and EOO were calculated to be  and  tection, as defined by Roques () based on biological and ,. km , respectively. Although the EOO falls below social importance and threats to biodiversity. Formal pro- the threshold for the Vulnerable category, the AOO corre- tection of these protection-worthy areas would thus con- sponds to the Endangered category. Considering the on- serve at least % of the species’ locations, provided going decline in number of mature individuals and habitat harvesting was curbed. The largest subpopulations occurred quality, the severely fragmented distribution, and the EOO

Acknowledgements

Funding was provided by Bioversity International, through the Abdou-Salam Ouédraogo Fellowship to MND, and the University of Swaziland. We thank the Swaziland National Trust Commission for providing access to protected areas and allowing their rangers to participate in the study. We also acknowledge the various individuals from local com- munities who readily participated in surveys.

References

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