Prof. Mahmoud Yaish
Department of Biology, College of Science
Every 31 October, Oman pauses to celebrate its trees. The occasion was designated by the late Sultan Qaboos bin Said to recognise the importance of trees to individuals, society and the environment. Mangroves and date palms often take center stage, but this year two lesser-known trees deserve our attention: the Alalan of the high mountains and the Shoua of the wadis. One survives in the cold air near Oman’s highest summit; the other thrives in some of the hottest, driest terrain on the Arabian Peninsula.
The Alalan, or Zeravschan juniper (Juniperus seravschanica, formerly treated as part of Juniperus excelsa), is important in Oman, which is the country’s only native coniferous tree and, in Arabia, grows only in the western Hajar Mountains: Al-Jabal Al-Akhdar and Jabal Shams, with additional stands on Jabal Qubal and Jabal Kawr. Oman’s trees also form the species’ southernmost population in the world, where its main range lies much farther north, across Iran and Central Asia. This aromatic evergreen grows slowly and lives for a very long time, and local tradition holds that some trees are thousands of years old, with many bearing scars and twisted, weathered trunks, often caused by lightning strikes during mountain storms. Its wood has long been burned as incense in Omani homes, much like frankincense, which has also been used to repel insects, and parts of the tree feature in traditional remedies.
The Alalan also plays an important role in nature and is considered a keystone species in Oman. Juniper communities in the Al-Hajar highlands support about 30% of the country’s flora, including 14 endemic taxa. Yet this ancient survivor faces serious pressure: many trees have sparse, unhealthy foliage, and few saplings are taking root. Research in Al-Jabal Al-Akhdar and Jabal Shams range found that temperature and moisture, rather than grazing or harvesting, best explained the decline, suggesting climate change is the main cause. Its conservation status changed from Vulnerable in 2008 to Endangered in 2015, and researchers are now investigating fungal dieback in the remaining stands.
Far below these cold summits, the Shoua (Moringa peregrina) tells a very different story. It grows in rocky wadis, on hillsides, and in arid regions across much of Oman. Its range stretches from Egypt to northeastern tropical Africa, and from Syria to the Arabian Peninsula. In spring, its slender, almost leafless branches burst into pinkish-white blossoms, a sight Omanis call Walh al-Shoua.
What makes the Shoua remarkable is how much it gives back. Its seeds contain about 50% oil, prized as “ben oil” and considered comparable in quality to olive oil. In Oman, oil from the pods was traditionally used in medicine and perfumery; today, it is still used for massage, skincare, and relief from joint pain. The seeds can also purify water: a protein in them causes suspended particles to clump together. The tree is just as striking for its resilience; among its relatives, it grows in the most arid and inhospitable habitats, yet can reach 3 to 4 m tall in a single year when it has enough moisture. Communities are responding with tree-planting initiatives, including the planting of thousands of Shoua seedlings in South Al-Batinah, as well as nurseries that sell Omani Shoua seedlings to the public. Still, there is cause for concern. Ben oil production appears to be declining, while excessive harvesting for firewood has contributed to the depletion of Shoua populations across the region.
The Alalan’s Omani population has been isolated at the southern edge of its range for a very long time. It may carry adaptations to heat and drought found nowhere else, which could be vital as the climate warms. Scientists studying the species recommend identifying genotypes with greater tolerance to heat and drought and planting only more mature nursery trees. That is impossible without first mapping and safeguarding genetic diversity. Shoua populations from different wadis may likewise differ in oil quality and hardiness. Holding seeds from more than one population provides better insurance against loss and allows study of differences in their active compounds.
Oman has made significant progress in protecting its native trees. The national initiative to plant ten million wild trees, conservation efforts in Al-Jabal Al-Akhdar, and the Oman Botanic Garden, whose seed bank holds seeds from nearly half of the country's plant species, reflect a growing commitment to preserving the nation's botanical heritage. Research supported by the Ministry of Education (formerly the Ministry of Higher Education, Research and Innovation), including DNA barcoding to identify and document native plant species, further contributes to these efforts. These initiatives deserve recognition. Yet planting trees, protecting habitats, and identifying species are only part of the solution. We must also safeguard the genetic diversity within these species, particularly the locally adapted genetic variation that has enabled them to survive in Oman's harsh environments.
On this Tree Day, Oman should go further. It needs genetic surveys of both species across their full Omani range. It also needs well-documented seed and living collections stored in multiple locations, along with nurseries that grow seedlings from local, genetically diverse parents.
Trees that have outlasted empires should not be lost on our watch.