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African Sandalwood (Osyris lanceolata Hochst.)
The increasing demand for ornamental, cosmetic and pharmaceutical products is driving exploitation of plant species globally. Sub-Saharan Africa harbours unique and valuable plant resources and is now a target of plant resource depletion. African Sandalwood (Osyris lanceolata), a multi-purpose and drought-tolerant species, has seen increased exploitation for the last thirty years and is now declared endangered.
The high global demand for ornamental, cosmetic and pharmaceutical products is driving exploitation of plant species all over the world . Sub-Saharan Africa harbours an important stock of unique and valuable plant resources, and therefore is a target of expanding plant resource exploitation . African sandalwood ( Osyris lanceolata Hochst. & Steud. ) is a multipurpose, drought-tolerant and hemiparasitic tree, well known for its essential oils used in perfumery industries . It emerged as a potential commercial species in Africa due to significant decline in original sources of sandalwood oil, e.g., Santalum album L. (Indian subcontinent) and Santalum spicatum (R.Br.) A. DC. (Australia) in the 1990s, and the increasing demand for sandalwood oil over the years . Dwindling of the species populations in Africa is attributed to overexploitation and lack of robust management strategies . Some populations in Uganda, Kenya, Tanzania and South Sudan have completely disappeared due to illegal harvesting and smuggling of tree logs despite the species being protected under Appendix II of the Convention on International Trade in Endangered Species (CITES) . O. lanceolata is assigned an automated status of least concern (LC)  with an unknown population trend but acknowledging decline in east Africa due to over exploitation .
Apparently, the lack of adequate information to reliably manage a sound resource base for O. lanceolata makes it very difficult to implement informed strategies for in situ and ex situ conservation in Africa . Previous emphasis on plantations (ex situ strategy) and in situ measures for conservation have not succeeded due to information gaps on the species ecology, population dynamics and genetics . Additionally, identification of suitable sources for genetic resource improvement is difficult without adequate scientific information on the species . Knowledge of non-random distribution of genes from these studies may be even more important for conservation of the species . Information on species population structure and demographic data help to predict the future stability of a species population amidst environmental and anthropogenic disturbances .
Whereas the ecology, population genetics and phylo-geography of other economically important species like Prunus africana. (Hook.f.) Kalkman. are documented in Africa , similar information is lacking for Osyris lanceolata . There are peculiar ecological and genetic aspects of O. lanceolata which need to be understood and aligned with strategies for responsible management, in particular hemiparasitism, complex distribution patterns and low survival rate . These broad attributes raise the following questions which require critical analysis: (i) What is the distribution, taxonomy and ethnobotany of O. lanceolata ? (ii) Which environmental factors influence the species distribution and hemiparasitic relationships across habitats? and (iii) How do such factors impact on characteristics of the species population structure, genetic diversity and conservation status in Africa? Understanding these questions contributes to informed conservation strategies.
This review analyses the missing links in population dynamics, ecology, taxonomy and genetic diversity of Osyris lanceolata using the available literature with a special interest in populations in Sub-Saharan Africa. We present the species taxonomy and ethnobotanical uses and discuss the role of hemiparasitism, while identifying emerging questions for further research. A global scope of the species distribution is provided and factors influencing its spatial distribution are explored. Further, we discuss the role of population structure assessment and general trends in the species population in Africa. Finally, the relevance of genetic diversity assessment, the extent of genetic studies on the species and implications for further research and conservation of O. lanceolata in Africa are proposed.
2. Taxonomy of Osyris sp.
3. Ecology: Habitats and Drivers for Distribution of African Sandalwood
4. Implications for Conservation of Osyris lanceolata in Sub-Saharan Africa
The entry is from 10.3390/plants10091780
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