Dhofar: Oman’s vertical fog oasis on the edge of the unknown

James and Thibaud Aronson report from Dhofar, in southern Arabia. This remarkable region is a biogeographical and historical crossroads at a critical moment of change.

The Sultanate of Oman doesn’t figure on most people’s mental map. But once told that it sits on the southeastern rim of the Arabian Peninsula, between Yemen to the west, and Saudi Arabia and the Emirates to the north, they may visualize an endless sea of sand with pack camels ambling towards an oasis dotted with date palms. A large part of the country – which is half the size of France – does look like this and is part of the fabled Empty Quarter of Arabia – Rub al Khali.  But we have come here to see Dhofar, the monsoon-affected and heavily wooded fog oasis that harbors some of the most unexpected and spectacular landscapes and ecosystems in arid lands worldwide.

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One of the beautiful landscapes of Dhofar, southern Oman, in the remote Wadi Ahjawt.

From mid-June to mid-September, every year, Dhofar is thoroughly drenched by the southwesterly monsoon – khareef in Arabic. Not what you expect in a desert region! The steady stream of drizzle and fog, aka “horizontal precipitation”, during this period recharges hundreds of springs and temporary rivers (wadis in Arabic), supporting dense, lush woodlands and forests on the south-facing slopes, dominated by large and varied trees more typical of east and north-east Africa. This constitutes a giant vertical oasis of sorts, but as the monsoon goes over the ridgetops, it is stopped by the hot desert winds coming from the interior and the vegetation transitions to a sparse desert scrub in a matter of meters, in one of the best illustrations of an ecotone – or ecological frontier – imaginable.

The stark contrast between the slopes which receive the monsoon fogs, and the plateaux beyond the escarpments, where the moisture is stopped by the desert wind. Djebel al Qamr, near the Yemeni border.

The stark contrast between the slopes which receive the monsoon fogs, and the plateau beyond the escarpments, where the moisture is stopped by the desert wind. Jebel al Qamr, near the Yemeni border.

It is there, right on the threshold of the desert, that are found the Boswellia sacra trees that produce the finest frankincense in the world. This tree resin was one of the most prized commodities in ancient times, throughout Asia, Europe, and Arabia, and it is still highly prized today for many uses, including incense, ritual ceremonies, bath oils, and perfumes.

A wild Boswellia sacra tree in Wadi Aful.

A wild Boswellia sacra tree in Wadi Aful.

Indeed, two thousand years ago, Oman was the meeting point for maritime traders and spice caravans, who traded between the Mediterranean region, east Africa, India, and China. They came to Dhofar to buy the Frankincense harvested by the Jibbali tribes of the escarpments, who to this day manage the Boswellia trees in a sophisticated agro-forestry system, where the ownership of each tree is carefully recorded. You can read about this in detail in Gary Nabhan’s excellent book, Camels, Cumin and Caravans: A Spice Odyssey.

Moreover, as one would expect in such a major historical crossroad, there are many intriguing questions here, for those with an interest in human ecology. For example, Wadi Hinna, connecting the coastal foothills east of Salalah and Jebel Qara, hosts a beautiful population of very old baobab trees, as well as equally ancient tamarind trees. Are they relicts, the last remnants of once much larger populations, or were they brought here as seeds or young transplants by traders and returning travelers hundreds of years ago? Together with our colleagues at the Oman Botanic Garden, we are working on a study of these and other enigmatic trees of Arabia, on which we will report more in due course.

Ancient baobab trees (Adansonia digitata) in Wadi Hinna, eastern Dhofar, the only population of the species found in Oman.

Ancient baobab trees (Adansonia digitata) in Wadi Hinna, eastern Dhofar, the only population of the species found in Oman.

Equally ancient Tamarind trees (Tamarindus indica) in Wadi Hinna,

Equally old tamarind trees (Tamarindus indica) in Wadi Hinna,

and in Wadi Ahjawt. These are often the sign of ancient human settlements.

and in Wadi Ahjawt. Both these trees are often found near ancient human settlements.

Besides its value for traders, Oman’s geographic position also makes it a genuine biogeographical crossroad for fauna and flora. Indeed, thanks to the monsoon, the humid slopes and wadis of Dhofar may be home to one of the last remnants of a belt of seasonally dry tropical forest that once stretched from sub-Saharan Africa to India, but which was almost entirely severed as Arabia became drier. Indeed, among the 900 species of plants found there, Dhofar hosts quite a few species whose nearest relatives – or populations of the same species, are more than 1000 km away, across the Red Sea in Africa or otherwise found only in India, Pakistan and Iran. There is also quite a large number of plants that are unique to the region, with over sixty endemic species and 2 genera endemic to Dhofar.  For animals, it is also a haven for many species, such as the critically endangered Arabian leopard, and the fascinating Arabian chameleon.

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The beautiful desert rose (Adenium obesum, Apocynaceae), which is in fact related to the common oleander.

The beautiful desert rose (Adenium obesum) which is related to the common oleander.

The Arabian chameleon (Chamaeleo arabicus), found only in Dhofar and southern Yemen.

The Arabian chameleon (Chamaeleo arabicus), found only in Dhofar and southern Yemen.

However, despite its lush appearance, Dhofar’s vegetation is not doing well, for many reasons. This – like much of the world – is a region in transition. Over-grazing is worse than ever. Throughout the Middle East – and Africa, it is a sign of status for a man to have a large herd of animals. However, many Omanis today actually hold sedentary jobs in the cities and simply employ shepherds – often from Bengal, Pakistan or Bangladesh – to look after their livestock for a very small wage. Further, they feed the animals fodder, which is subsidized by the government and which is of dubious value long-term. This enables them to maintain their herds at unsustainably large numbers, and as they roam over the slopes, the cattle, goats and camels graze the vegetation well past the threshold of sustainability. As a result, in many areas, you will see trees with no leaves under 3 m (the height camels can reach), with additional branches cut, bent and often broken to bring them within reach of the domestic animals, and an understory cropped to less than one cm above ground level.

The effect of large, essentially uncontrolled herds of camels and other browsers on an Omani landscape.

The effect of large, essentially uncontrolled herds of camels and other browsers on an Omani landscape.

Note the 3m high browse line, marking the limit of the camel’s reach into the tree canopy and the all but extinguished understory.

Note the 3m high browse line, marking the limit of the camel’s reach into the tree canopy and the all but extinguished understory.

Farmers then go further by breaking higher branches to bring them within reach of the animals. This technique, which can be applied with varying degrees of care, is illustrated here with a particularly unsustainable example.

Shepherds then go further by breaking higher branches of trees, in this case the dominant species Anogeissus dhofarica, to bring them within reach of domestic animals. This technique, which can be applied with varying degrees of care, is illustrated here with a particularly regrettable example.

When the animals are kept out, as we saw in a few fenced off plots maintained by the Department of Forestry, you see instead rapid regrowth of tall native grasses, often over a meter high, hopping with insects and birds, in amazing contrast to the silent, rocky moonscape outside the exclosure. This is actually an interesting problem, from a restoration perspective. Indeed, as recently as the 1980s, parts of Dhofar were dominated by tall grasslands, the easternmost extension of a habitat type more characteristic of East Africa. These are the ecosystems most affected by the increasing grazing pressure and today they are all but gone. However, according to Dr. Annette Patzelt, Director of the Oman Botanic Garden, it is likely that these grasslands were anthropogenic, and only arose following local clearing of woodland and forest. Therefore, did they exist for long enough to become an integral part of the Dhofari landscapes, which would make them a valid target for restoration, or should they instead be abandoned, to focus on the woodlands they replaced?

The only way to prove the effects of livestock on a landscape is to keep the animals out. The result speaks for itself.

The only way to prove the effects of overstocking livestock on a desert landscape is to keep the animals out. In Dhofar, the result speaks for itself.

Dhofar faces other problems as well, such as rampant road building and urbanization. But it is conceivable that better policies relating to further development could be implemented and accepted with relative ease.  This issue of livestock, however, is a systemic problem pertaining to people’s perception of themselves and their relationship to land, which is a lot more complex to address and change.

One ray of hope is the terrific work in education and outreach being done by the team at the Oman Botanic Garden, who are documenting the flora and vegetation of the whole country and tracking its changes over recent times. They are also learning how to propagate hundreds of native species that have never before been cultivated as they prepare a monumental desert park and garden that will demonstrate all the ecosystems found in the country and help Omanis to better understand the richness of their country’s natural heritage. It is a first step for desert ecosystem restoration, which is emerging not only in the Middle East, but throughout the world.

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Jordan III. Black, blue, and green: Life near water in the desert of northeastern Jordan.

James and Thibaud Aronson post their third report from Jordan, as they continue to study prospects for ecological restoration in deserts, with special focus on trees and the animals that use them.

Trees never lie.  Michael Zohary.

As you travel east from Amman, Jordan’s capital, you quickly leave behind cultivated landscapes and enter the hammada, a desert of black basalt gravel with very little rainfall. Large tracts are devoid of any vegetation at all; in the few places where water occurs, the abundance of life is remarkable.

A 'densely' vegetated (sic!) tract of Hammada near Shaumari Resreve, 100 km east of Amman.

A ‘densely’ vegetated (sic!) tract of Hammada near Shaumari Reserve, 100 km east of Amman.

The first place we visit is Wadi Butum, 26 km east of Amman. This is an ephemeral river, or wash (Wadi or Oued in Arabic). It is lined along 30 km by a gallery forest of magnificent Pistacia atlantica trees (Butum in Arabic). Judging by the trees, and the ancient architectural remains at this site, this entire region looked vastly different a mere millennium or so ago. Back then, clearly, it was inhabited by many people, at least along some rivers, and there were many wild animals, such as gazelles, ibex, probably lions and much more. In addition to the trees, one can visit the bath house associated with the Amra Palace, Qasr Amra, in Arabic, built during the reign of the Umayyad Caliphat, (661-750 CE). Archeological and historical records show that 1300 years ago, this site was maintained with a large staff and regularly used as a hunting lodge and pleasure palace for nobles who traveled 200 km south from the Caliphat’s capital in Damascus. Water was drawn from a hand-dug well 25 meters deep.

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Bathhouse at Amra Palace, Wadi Butum, eastern Jordan. Building to the right contains the well and water wheel (nuria).

Its ornately decorated bath house shows scenes of daytime and nocturnal hunts, as well as dancing women, musicians, and much more that contrast starkly with the environment here today.

Murals inside the bathhouse, Amra Palace, Wadi Butum. A hunting scene

Murals inside the bathhouse, Amra Palace, Wadi Butum. A hunting scene.

A bather.

A bather.

Dead wood from nearby trees and abundant shrubs, including branches from the Butum trees, surely provided most of the wood necessary for heating the water for the bathhouse.

And panels showing people cutting wood.

Panels showing people cutting wood, presumably harvested nearby.

Pistacia atlantica, in Wadi Butum, eastern Jordan.

Pistacia atlantica, in Wadi Butum, eastern Jordan.

If it is true that trees never lie, as quoted above from Michael Zohary, these multi-secular trees strongly suggest there was once a much more extensive gallery forest along this Wadi – and the others – than we can easily imagine… Without them, one could easily assume that the frescoes in the bathhouse represent scenes from elsewhere in the Omayyad Caliphat’s dominion. Yet because of the Butum trees, we suppose these scenes depicted what the visiting nobles saw and hoped to experience in the immediate environs.

Twenty kilometers further east is Azraq, and a much sadder tale of human water use. “Azraq” means “blue” in Arabic, and was named after a large oasis, which was once 26 km2. A beacon in the desert, it attracted up to 350,000 migrating birds, who stopped there on their long journey between their breeding grounds in northern Europe and their wintering areas south of the Sahara.

A photo of Azraq, a large wetland in the desert, as it was in the early 1960s.

A photo of Azraq, a large wetland in the desert, as it was in the early 1960s.

However, the abundant water also came to be viewed as a resource for human use. In the 1960s, water began being extracted to feed the growing cities of Amman and Irbid, the two largest cities in the country. By 1975, water was extracted twice as fast as it could replenish itself, and hundreds of illegal private wells were taking an additional  toll on the oasis. By 1991, it had entirely dried up. The Azraq killifish (Aphanius sirhani) – Jordan’s only endemic vertebrate – almost disappeared, and only survived ex-situ. Still, pumping continued, directly from the aquifer. It was only in 1994 that the Jordanian government took steps to stop water extraction. Yet, it only finally stopped because of brackish water infiltration, which rendered the water unsuitable for human consumption or irrigation. What once was a lush oasis is now a dry husk. In 2000, a census counted 1200 birds in the entire migrating season, a third of one percent of what there once was.

Then, in 2011, the sad and sorry site was designated a nature reserve, to be administered by the Royal Society for the Conservation of Nature or RSCN. They began a restoration and rehabilitation project, with a goal of recovering 10% of the original wetland, including both permanent and seasonal areas. An agreement was signed with the Jordanian Ministry of Water, and each year since then, between 1.5 and 2.5 million cubic meters of water are pumped back into the oasis to provide habitat for birds and allow observations of spontaneous recovery of native plants.

In April 2015, at the time of our visit, there were 5 permanent pools, covering 3 ha, and a total of 170 ha of wetlands which are seasonally flooded. The system is very far from being stable, and if water stopped being pumped, the wetlands would surely dry out, as there are still many illegal wells in the area. However, even without any plantings, Tamarisk trees and reeds have recolonized the area, and bird numbers are increasing each year.

Restored permanent pools at Azraq reserve.

Permanent pools at the Azraq reserve, undergoing restoration and rehabilitation.

A few kilometers to the south is Shaumari, another RSCN reserve, which tackles another problem. Due to heavy hunting, Jordan’s ungulate populations have been severely depleted; several species disappeared altogether in the 20th century. The reserve now serves as a breeding center for Arabian oryx, onager, and Dorcas gazelle. The first two are already breeding freely in the reserve, and a few oryx have also been introduced to Wadi Rum, in the south of the country.

Arabian oryx (Oryx leucoryx) in breeding enclosures at Shaumari reserve.

Arabian oryx (Oryx leucoryx) in breeding enclosures at Shaumari reserve.

Clearly, the RSCN, the RBG Jordan, and other NGOs working for conservation in Jordan have a long way to go in their valiant efforts to protect and restore this country’s marvelous landscapes and preserve its biological richness. As in so many other countries, a paradigm shift towards sustainable resource use and nature conservation is needed. Still, a few pilot projects such as those described here, and a growing interest in ecological restoration, led by the RBG Jordan, are harbingers of change.

Jordan, II: Wadi Hasa to the Arava-Dead Sea-Jordan Rift valley.

From Wadi Hasa, we ascended a long road of switchbacks, up to 1000 m.a.s.l., while still travelling west, and from the town of Al Karak, we descended, for a mere 20 linear km, to the Dead Sea, lowest place on Earth and part of the Dead Sea Rift, a fault line between the Arabian and African tectonic plates. Here, just 80 kms from the montane forests where we started, in the so-called Feifa Forest, which more resembles a savanna, we admired Afro-tropical vegetation dominated by tree species commonly found in the Sahel region, south of the Sahara desert, but almost nowhere else in Jordan or Israel.

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Afro-tropical, or “Sudanian” vegetation near the Dead Sea, with Acacia tortilis, Acacia raddiana, Balanites aegyptiaca, and Maerua crassifolia.

Travelling north along the Dead Sea shore, we also saw shrubby forms of Salvadora persica, and date palm, Phoenix dactylifera, growing wild in the rocks…Finally at one site only, called Zara, 10 km north of the Mujib bridge, we were thrilled to see a dozen or more huge Moringa trees and a few tree-like Capparis decidua, in a small abandoned field surrounded by fields planted with vegetable crops.

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Moringa peregrina & JA. Zara, Jordan.

In all three segments of our Med-Dead transect, we observed canopies that were fragmented, but clearly visible and hosting mixed communities of trees in natural associations. These provide marvelous reference systems for those who would engage in restoration in this country or any of its neighbors where the same patterns and ecosystem types occur.

In many cases, we found tree species showing a remarkable degree of plasticity, or malleability, both in shape and in habitat, including Rhus tripartita, Retama raetam, Amygdalus arabica and Rhamnus palaestina. We also saw near ubiquitous signs of the ravages of goats and sheep. Only in a few places during our trip, and most notably at the Ajloun nature reserve, did we see places spared their impact.

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12 Sheep

All over Jordan, domestic but unruly goats and sheep eat most of the herbaceous vegetation, and tips of trees and shrubs, leaving only the taller adult trees and unpalatable shrubs to grow and prosper.

Having recently been on Guadalupe Island, Mexico, where goats were eradicated a mere 7 years ago, and where vegetation is leaping back, we can’t help but wish it were possible to do large scale experiments here…

But just like Mexico, the socioeconomic situation is complex and conservation and restoration are challenging. Woodcutting for firewood is one major problem, because most people rely on wood as their sole source of energy for heating and cooking.

Haloxylon persicum in a wadi having suffered a bit of wood extraction.

Haloxylon persicum in a wadi having suffered a bit of wood extraction.

Invasive plants are another problem, such as the South American mesquite tree, intentionally introduced and now spreading widely, with help of sheep, goats, and camels that relish the fleshy pods.

Mesquite, Prosopis juliflora , well known as a noxious weed in Africa, Asia and Australia, it is worrisome to find it spreading rapidly and without control at low altitudes throughout western Jordan. Shown here in a wadi near the Dead Sea, sopping up much of the available moisture in the riverbed and crowding out native trees and shrubs.

Mesquite, Prosopis juliflora , well known as a noxious weed in Africa, Asia and Australia, it is worrisome to find it spreading rapidly and without control at low altitudes throughout western Jordan. Shown here in a wadi near the Dead Sea, sopping up much of the available moisture in the riverbed and crowding out native trees and shrubs.

Despite these obstacles, the Royal Society for the Protection of Nature (RSPN), an NGO, and its Botanic Garden, are cause for hope, not only here, but throughout the Middle East. Here’s to Jordan, where all trees are protected by law, and to the RSPN and RBG Jordan, and here’s a tribute in particular to HRH Basma Bint Ali, the Garden’s founder. In the context of the Ecological Restoration Alliance of Botanic Gardens, there is indeed hope for the future.

Trees of Jordan I: ancient cypress, red juniper and the noblest of Pistacias, not to mention the mysterious and unexpected Rosewood of Sind.

James and Thibaud Aronson post here the first part of a 3-part report from The Hashemite Kingdom of Jordan, mid-April, 2015.

As part of an epic project undertaken with our very dear friend in France, Edouard Le Floc’h, and now with expert help from our friend Delphine Vinck, we are working on an ambitious book about trees that grow in deserts, their role in ecosystems there, and their not-to-be underestimated role in the vast number of ecological restoration projects and programs waiting to be undertaken in the vast deserts of the world, and on their ‘shores’, the even vaster semiarid regions of the earth.

This trip started with an inspiring meeting attended by James, in Amman, as part of the fourth gathering of the Ecological Restoration Alliance of Botanic Gardens, and a visit for Thibaud in southern Israel to observe, in some awe, the annual south-to-north bird migration along one of the major flyways of the western Palearctic.

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Steppe buzzards (Buteo buteo vulpinus) and black kites (Milvus migrans) flying over Aqaba, Jordan. That day, about 10000 birds flew over in 4 hours.

And some mammals along the way.

Foxes

Five pups of Arabian red fox (Vulpes vulpes arabica) in front of their den. Kibbutz Lotan, Israel.

We reunited in Aqaba, to begin a 4 x 4 road trip together with Hatem Taifour, chief botanist at the Royal Botanic Gardens of Jordan. Jordan and Israel form an incredible crossroads where the floras, faunas and cultures of three continents meet, Africa, Asia and Europe.

Map of the world as a cloverleaf, with Jerusalem at its centre. By Henricus Bünting. Itinerarium Sacrae Scripturae. Helmstedt, 1581.

Map of the world as a cloverleaf, with Jerusalem at its center. By Henricus Bünting. Itinerarium Sacrae Scripturae. Helmstedt, 1581.

According to Avinoam Danin (1999), southwestern Jordan is the ideal place for tracing transects as huge variations in climate, geology, flora, and fauna can be seen over short distances, and remarkable Mediterranean relicts and dozens of endemics occur there, far more so than in Israel and Sinai.

Therefore, our goal was to describe ecological transects following gradients of aridity, from relatively wet mediterranean climate regions at high-elevations with cypress, pine, oaks and pistacia, westward to steppe-desert with juniper and other trees of its own, into the hot, tropical desert of the Rift Valley. The Acacia-dominated vegetation found from the Red Sea to the Dead Sea, and the Jordan Valley, from the Dead Sea to the Sea of Galilee, represents a ‘tongue’ of so-called Sudanian flora, rich in trees. To one side is a colder desert with a Saharo-Arabian flora dominated by shrubs. On the other, is a tongue of penetration coming in from the east and the north of the so-called Irano-Turanian steppe, which experiences hot summers and very cold winters.

We began our trip with a morning visit to the justly celebrated archaeological site of Petra (looking at the trees along the way). We then drove up to Dana Nature Reserve – a jewel of the Mediterranean Basin by any standards and full of endemics and relicts of the Mediterranean vegetation that is now rare in the Near East. We visited rich montane Mediterranean forests, with a real canopy of evergreen oaks and Red Juniper, with populations of Atlantic Pistacia and a small, venerable and unquestionably wild population of Mediterranean Cypress – the only one in all the Near East. To our knowledge, its only other wild populations are in Cyprus and Cyrenaica, Libya. Two of these cypress trees are estimated to be roughly 800 years old.

1 Old cypress

Giant Mediterranean Cypress trees (Cupressus sempervirens) Dana and nearby, a younger stand, with spontaneous regeneration taking place, amidst Juniperus phoenicea, Pistacia atlantica. Near Dana Nature Reserve, 1500 meters above sea level (masl).

Giant Mediterranean Cypress tree (Cupressus sempervirens) and nearby, a younger stand, with spontaneous regeneration taking place, amidst Juniperus phoenicea, Pistacia atlantica. Near Dana Nature Reserve, 1500 meters above sea level (masl).

From there, in just 22 km as the crow flies, we descended to semi-arid steppes at 300 m above sea level, where the vegetation was dominated by red juniper and Rhus tripartita.

Steppe dominated by Juniperus phoenicea.

Steppe dominated by Juniperus phoenicea.

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And Rhus tripartita, on the road leading north from Dana towards the Dead Sea.

Then, Hatem led us down a steep dirt road to a site he had discovered, at 100 m.a.s.l., in remote Wadi Hasa, far from any town or garden. Growing there amidst native poplar and willow, we saw a population of Dalbergia sissoo, where we would never have expected to find it. This tree is native to India, Pakistan, southern Iran, Afghanistan and Oman (Tengberg & Potts 1999) and widely cultivated elsewhere. Danin (1999) reports it occurring in oases near the Dead Sea in Israel, and there are reports of it occurring in Sudan. In Jordan, Hatem Taifour has never seen it anywhere except in this location in Wadi Hasa and in one other wadi.

How then did this wind-dispersed tree get here? Is this a relict from earlier times when climate was different and the species was more widespread, and the tree was widely used for a range of purposes and perhaps intentionally introduced throughout the Near East? There is no clear answer to date….But it certainly added spice to our field trip and food for thought for restorationists working in Near Eastern deserts.

5 Dalbergia

 Dalbergia sissoo, commonly known as Indian Rosewood, far from its center of distribution on the Indian subcontinent and southern Iran.

Dalbergia sissoo, commonly known as Rosewood of Sind or Shisham, far from its center of distribution on the Indian subcontinent and southern Iran. Commonly introduced elsewhere around the world, it frequently escapes cultivation and becomes naturalized. However, both in Jordan and in Israel, there are a few populations that seem possibly quite ancient. This is a mystery to be explored.

References.

Danin, A, 1999. Desert rocks as plant refugia in the Near East. The Botanical Review 65: 93-170.

Tengberg, M. & D. T.  Potts 1999. mes.mii-gan-na (Dalbergia sissoo Roxb.) at Tell Abraq [Oman]. Arabian Archaeology and Epigraphy 10:129-133.