The Olive Highlands: a unique "island" of biodiversity within the Hajar Mountains of the United Arab Emirates.
This report is intended to describe, for further scientific and public policy attention, a remote and little known high elevation area of the Hajar Mountains that has been identified as an environmental refuge for rare plant and animal species and recommended as a conservation priority on biodiversity grounds.
The area that is here called the Olive Highlands, after its most distinctive species, is shown in Fig. 1. It comprises an area of high elevation terrain (600 to 1050 metres) in the south-east of the Hajar Mountains of the UAE. To the south-east, it corresponds to the Jebel Qitab ridge (Figs. 2 and 3), which forms the south-west flank of Wadi Mayy, south-west of Fujairah city. To the north and west, it encompasses the mountain ridges which separate Wadi Hiluw (to the south), Wadi Sfai (to the north-west), and Wadi Saham and Wadi Hayl (to the north-east). The northern extent of the area is marked by Jebel Samah, east-north-east of the village of Sfai, which now overlooks the new Sheikh Khalifah bin Zayed Freeway (not shown in Fig. 1).
Jebel Qitab itself, ca. 1030 metres high, lies near the south-eastern end of a ca. 6 km ridge, overlooking the village of Mayy. Near the other end of the ridge, ca. 4 km to the north-west, is a second summit, unnamed, also ca. 1030 metres. In between, the ridge rises and falls gently, with intermittent exposures of its rocky spine, but is never lower than ca. 900 metres. Further to the north-west, the summits of Jebel Al-Iyeli and Jebel Sfai both approach 1050 metres, and Jebel Samah is ca. 950 metres. [The elevations given here are those shown on the 1982 topographic map of Fujairah produced under the direction of the U.K. Director of Military Survey (Director of Military Survey 1982).]
A number of inter-related factors contribute to the ecological distinctiveness of the Olive Highlands. Foremost are probably its size and elevation. The nearly continuous chain of 800 to 1050 metre ridgetops in most of this area encompasses an estimated 13 [km.sup.2], making it, by far, the largest such high area in the UAE, outside the Ru'us al-Jibal (the mountains of the Musandam peninsula). The contiguous area above 600 metres (shown in Fig. 1) is estimated at ca. 78 [km.sup.2]; above 500 metres it is ca. 132 [km.sup.2]. (By way of comparison, the Shimayliyah area to the north, between Masafi and the Gulf of Oman coast, includes three individual peaks that exceed 1100 metres, but otherwise the ridges in the Shimayliyah area are generally much lower, reaching 900 metres at only a few points, and they are invariably narrower and more precipitous, often knifelike.) At these elevations there are no roads and no present day agriculture, although intermittent cultivated areas extend up to nearly 500 metres in Wadi Hiluw, Wadi Al-Iyeli and Wadi Sfai, and a graded road on the western margin of the designated area rises to ca. 550 metres and connects the villages of Sfai and Al-Iyeli (Fig. 4).
Geologically, the Olive Highlands consist almost entirely of gabbro (British Geological Survey 2006a, 2006b), a coarse grained igneous rock. Geologists classify igneous rocks as acid, intermediate, basic or ultrabasic on the basis of their (decreasing) content of silica (Si[O.sub.2]), the fundamental building block of igneous rocks. Gabbro, with a relatively low silica content, is said to have a "basic" composition. In this respect the Olive Highlands are geologically and geochemically distinct from most of the Hajar Mountains to the north (e.g., Wadi Wurayah National Park and surrounding areas) and to the south (e.g., the Hatta area southward to Wadi Jizzi and beyond), which are composed primarily of a rock called harzburgite. Harzburgite is extremely low in silica and is therefore classified as "ultrabasic".
Ultrabasic bedrock is typically associated with the development of poor soils that are deficient in important nutrients (e.g., calcium, nitrogen and phosphorus) and high in toxic heavy metals (e.g., chromium and nickel), so this distinction is potentially significant for plant life (Harrison & Kruckeberg 2008). Moreover, in arid climates, groundwater in ultrabasic bedrock can become extremely "basic" in the traditional chemical sense as well (i.e., high alkalinity), with groundwater pH in excess of 11, adding to the potential difficulties of the ultrabasic environment.
Within and adjacent to the Olive Highlands, ultrabasic bedrock (harzburgite) is found only just outside the periphery in the north-east, in upper Wadi Hayl and Wadi Saham, at elevations well below the main ridges, but some ultrabasic rock types can be found within what is mapped as a mixed unit, along the short ridge west of the Jebel Qitab summit ridge (separating uppermost Wadi Hiluw from Wadi Hayl) and continuing north along the lower slopes of the Olive Highlands, east of Jebel Sfai and Jebel Samah (British Geological Survey 2006a, Thomas et al. 2006).
Physiographically, weathering of the gabbro bedrock produces gentler slopes and broader summit ridges than weathering of the harzburgite, resulting in relatively greater physical area at high elevations and facilitating soil development, creating a more hospitable and diverse edaphic environment for most plant species. (See, e.g., Figs. 3, 4 and 6.)
Climatically, the elevation of the Olive Highlands offers relief from the worst of the region's high temperatures. But in addition, the Olive Highlands, and the Jebel Qitab ridge in particular, have the ability to make their own weather. They are high enough, and oriented at a sufficient angle to the coast, that they can and do trap and precipitate moisture from Indian Ocean (Gulf of Oman) air as cloud or fog (Figs. 5and 6). The development of easterly clouds against the summits in this region can frequently be seen from the west flank of the Hajar Mountains. This additional moisture undoubtedly contributes to the support of a distinctive floral community.
As in any mountain plant community, many individual species are selective in their choice of habitat, in terms of substrate, slope, exposure, orientation and other factors. Within the Olive Highlands, north-facing slopes and wadis generally have a more abundant and more diverse flora than south-facing ones. This can be seen very well along the Jebel Qitab ridge, where the more moist and sheltering north-east facing slopes and ravines feature large species such as Olea europaea, Ehretia obtusifolia and Grewia tenax (Fig. 6), as well as many of the other characteristic species discussed below, whereas even at higher elevations the south-west facing slopes tend to have a more typical Hajar Mountain flora. The north-east slopes of the Jebel Qitab ridge also have a steeper profile and a greater descent to base level than other areas of the Olive Highlands, descending ca. 800 metres to Wadi Mayy (at ca. 200 metres) in only about 2.5 kilometres horizontal distance.
The Jebel Qitab ridge, more than six kilometres long, can be thought of as the core of the Olive Highlands, because it constitutes by far the largest contiguous area at 900 metres or more elevation and because the summit of the ridge and its north-east facing slopes have been found to contain the densest concentrations of most (but not all) of the plant and animal species that make the area unique from the standpoint of biodiversity, as further discussed below.
The distinctive flora of the Olive Highlands was first reported nearly two decades ago (Feulner 1997), but the area remains largely unheralded and unexplored to this day. There are still no major roads in the immediately surrounding areas and (with the recent exception of rough tracks to three communications towers) the summit areas are accessible only on foot. Even among generally knowledgeable UAE naturalists, few know anything about the area, as evidenced, for example, at habitat mapping sessions held in the course of the Local, National Regional Biodiversity Rapid Assessment exercise conducted by Abu Dhabi Global Environmental Data Initiative in 2012 (AGEDI 2013).
Mountain environments are typically diversified on a relatively fine scale, and the Olive Highlands are no exception. It may nevertheless be helpful to attempt to categorise the area in terms of five major habitats, which, however, grade into each other at the margins.
Ridgetops. At first glance, the rounded summit ridges of the Olive Highlands appear to be almost barren (Figs. 3 to 5). The ridgetops themselves are all but devoid of trees and are dominated by dwarf shrubs and annuals (in season) (Fig. 7). The largest shrubs are Ochradenus arabicus and Ephedra pachyclada. Other common shrubs include Convolvulus acanthocladus, Fagonia schimperi, Glossonema varians, Gymnocarpos decandrus, Helianthemum lippii, Leucas inflata, Melhania muricata and Trichodesma enetotrichum. Ridgetop annuals include Asphodelus tenuifolius, Cuscuta planifora, Oligomeris linifolia, Pallenis hierochunticus (syn. Asteriscus hierochunticus), Plantago amplexicaulis, Senecio breviflorus (formerly considered S. flavus), Viola cinerea and Volutaria sinaica.
Subsidiary ridges. From the summit ridges, subsidiary ridges descend to wadi level. On the north-east slope of the Jebel Qitab ridge, and to a lesser extent on the slopes east of upper Wadi Sfai, the subsidiary ridges are arranged in parallel, like ribs along the summit spine. Elsewhere, the pattern of subsidiary ridges and the ravines between them is more dendritic (Fig. 8). The subsidiary ridges are moderately steep and rocky, featuring blocky weathering of the gabbro bedrock and large boulders. Plant life thrives in the shelter of the rocks and boulders, where thin soil can accumulate. A broad range of characteristic Hajar Mountain species can be found in this environment, as well as some of the rarer species described separately below. A representative sampling includes: Abutilon fruticosum, Aristida adscensionis, Cenchrus ciliaris, Desmidorchis arabicus (syn. Caralluma arabica), Echiochilon persicum, Erodium neuradifolium, Euphorbia larica, Fagonia brugueri, Filago desertorum, Iphiona scabra, Lavandula subnuda, Leucas inflata, Periploca aphylla, Phagnalon schweinfurthii, Plantago afra, Pulicaria glutinosa, Reichardia tingitana, Rumex vesicarius, Salvia aegyptiaca and Senecio breviflorus.
Upper ravines & summit cliffs. The subsidiary ridges are separated by ravines. The ravines are typically steepest at their heads, which sometimes end in blocky cliffs, especially on north and north-east facing slopes (Figs. 9 and 10). These cliffs provide shelter from the sun, they trap moisture from the sea (see above) and they allow soil accumulation. This environment hosts a mix of trees and large shrubs (Olea europaea, Ehretia obtusifolia, Ephedra pachyclada, Grewia tenaxand Ochradenus arabicus), dwarf shrubs (e.g., Abutilon fruticosum, Aerva javanica, Convolvulus acanthocladus, Geranium sp., Gymnocarpos decandrus, Launaea bornmuelleri (formerly considered L. spinosa) and Lavandula subnuda) and small annuals (e.g., Erodium neuradifolium, Plantago afra, Senecio breviflorus, Sisymbrium erysimoides and Spergula fallax). Where the upper slopes of a ravine are made of loose rubble or scree, the flora may resemble what is described below for the lower slopes. Where the ravines are fed by more gentle channels from the ridgetop, accumulations of stunted Dodonaea viscosa shrubs may be found along the channel banks.
Lower slopes of ravines. The lower slopes of the ravines are typically less steep than the upper slopes, and are more likely to have a cover of rubble or scree. They are home to diverse species (Fig. 11) including, e.g., Aerva javanica, Anagallis arvensis, Echinops erinaceus, Forsskaolea tenacissima, Launaea bornmuelleri, Leucas inflata, Moringa peregrina, Nanorrhinum hastatum (syn. Kickxia hastata), Rumex vesicarius, Salvia aegyptiaca, Salvia macrosiphon (syn. S. spinosa) and Teucrium stocksianum.
Ravine beds. In the centre of the main watercourses gabbro bedrock is often exposed, but the central wadis may also consist of large, rounded to sub-rounded boulders in a bed of well rounded cobbles and pebbles. Plants in this environment must be able either to withstand periodic torrents or to grow, flower and reproduce in between them. So it is primarily a realm of annual herbs and grasses (e.g., Anagallis arvensis, Campanula erinus, Castellia tuberculosa, Geranium mascatense, Misopates orontium and Spergula fallax) and larger, more deeply rooted shrubs, trees and tussock grasses (e.g., Dodonaea viscosa, Grewia tenax, Lycium shawii, Olea europaea, Pennisetum divisum and Ziziphus spina-christi). Trees are sometimes draped with the climber Cocculus pendulus. Soil may accumulate in or around boulders and debris above the lowest level of the bed, and will support species more typically found on wadi banks or the lower slopes of the ravines, e.g., Acacia tortilis, Echinops erinaceus, Lavandula subnuda and Physorrhynchus chamaerapistrum (Fig. 12).
Other habitats. One major habitat found in UAE mountain wadis generally that is not well represented within the Olive Highlands is the lower wadi environment, characterised by a relatively broad, flat wadi with a bed of stones, cobbles and small boulders, usually with subterranean water flow, flanked by thick terraces of alluvial gravel. The 600 metre contour, chosen here to define the Olive Highlands for discussion, excludes most such environments except for small areas in the upper reaches of Wadi Hiluw and Wadi Sfai. Species primarily associated with that environment, such as Chrozophora oblongifolia, Ficus cordata salicifolia, Rhazya stricta, Saccharum griffithii and Tephrosia apollinea, are correspondingly rare within the Olive Highlands, although Wadi Sfai is broad enough at some points in its upper reaches that the ghaftree, Prosopis cineraria, can be found there up to ca. 700 metres.
A few plant species generally common in the Hajar Mountains of the UAE may be rare or absent in the Olive Highlands because they have evolved to thrive best in areas of ultrabasic bedrock rather than gabbro. Among the species suspected to be in that category are, e.g., Diplotaxis harra, Pteropyrum scoparium and Salvia macilenta. Conversely, some of the species found in the Olive Highlands appear to be intolerant of ultrabasic bedrock. Three well supported examples are Dicoma schimperi, Echiochilon persicum and Lycium shawii (the Desert Thorn). The relationship between plant biogeography and bedrock geology within the Hajar Mountains is a focus of the author's current research (e.g., Feulner, in prep.).
In visits to areas within the Olive Highlands on more than 30 occasions over the past 20 years, at intervals of two years or less, the author has recorded at least 162 plant species there. (For this purpose, all plants recorded on mountain slopes or in wadis at elevations greater than ca. 600 metres have been included.) This figure compares respectably with figures from dedicated botanical surveys of Wadi Wurayah National Park (200+ species) (Feulner, in prep.) and of natural habitats within the Wadi Helo (a/k/a Wadi Hiluw) Protected Area (147 species) (ElKeblawy 2011). Both of the latter surveys included terrain at all elevations, and therefore lower wadi environments as well.
But more important than the number of species recorded is the fact that the Olive Highlands constitute an ecologically unique 'island' of biodiversity, characterised by a distinctive high elevation flora and fauna that includes a number of plant species and at least one animal species that are not found elsewhere in the UAE, as well as other plant and animal species that are not found outside the Ru'us al-Jibal.
The following is an annotated list of many of the plant and animal species that make the Olive Highlands a unique environment within the Hajar Mountains of the UAE.
Abutilon fruticosum (Malvaceae) (Fig. 13): The northeast slopes of Jebel Qitab are the only known UAE locality for this species with relatively large and showy flowers. Specimens were found at various elevations, including just below the summit.
Arenaria serpyllifolia (Caryophyllaceae): This "chickweed" species is locally common at higher elevations in the Ru'us al-Jibal (Feulner 2011). It has been considered very rare elsewhere in the UAE (Jongbloed 2003, Karim & Fawzi 2007) but in the Olive Highlands it is at least occasional on stony slopes at elevations of ca. 800 metres and above.
Astragalus fasciculifolius (Fabaceae): This large shrub. one of the UAE's most attractive when in flower, is common on slopes and wadi banks in the Ru'us al-Jibal but very rare in the Hajar Mountains. Small numbers have been found in uppermost Wadi Zikt, within Wadi Wurayah National Park. A few specimens have been recorded in the Olive Highlands, in the vicinity of Jebel Sfai (pers. obs.) and in upper Wadi Hiluw (El-Keblawy 2011).
Bromus pectinatus (Poaceae): This coarse grass was recorded by the author not far below the summt of Jebel Al-Iyeli, at ca. 1000 metres, and by ElKeblawy (2011) from Wadi Hiluw, also on upper slopes. Otherwise it is known in Eastern Arabia only from a single collection in the UAE and several in Northern Oman (Cope 2007).
Campanula erinus (Campanulaceae) (Fig. 14): This small annual was found in a steep wadi bed on the north-east flank of Jebel Qitab. It is locally common in the Ru'us al-Jibal, but there are only two other Hajar Mountain records, from different locations in Wadi Wurayah National Park.
Castellia tuberculosa (Poaceae) (Fig. 15): This rarely recorded grass was found at various elevations in the bed of a major ravine draining the northeast flank of Jebel Qitab. Only two other UAE records are known, both from areas now within Wadi Wurayah National Park.
Convolvulus acanthocladus (Convolvulaceae): This intricately twisted, spiny Convolvulus is one of the most common plants of the Ru'us al-Jibal, above ca. 1000 metres (Feulner 2011), but it is otherwise unknown in the UAE, except at higher elevations in the Olive Highlands, where it is found as occasional scattered plants. On the other hand, C. virgatus, a less robust spiny Convolvulus that is one of the most common species of lower slopes in much of the Hajar Mountains of the UaE (e.g., Wadi Wurayah and neighbouring wadis), is virtually absent within the Olive Highlands. [NB: C. acanthocladus as discussed here should not be conflated with the spiny but rectilinear form of Convolvulus, also professionally identified to date as C. acanthocladus but readily distinguishable in the field by appearance and habitat, and limited geographically to the west flank of the Hajar Mountains in northernmost Oman. See also Feulner (2011) at Sec. 14.]
Desmidorchis flavus (Asclepiadaceae) (Fig. 16): This yellow-flowering, cactus-like succulent (formerly Caralluma flava) is found occasionally in the northern part of the Olive Highlands, from upper Wadi Hiluw to Jebel Samah, including the slopes of the ridge that separates Wadi Sfai (to the west) from Wadi Saham (to the east). It is otherwise unknown in the UAE, although it is a close relative of the more widespread, purple-flowering Desmidorchis arabicus (formerly Caralluma arabica). The Olive Highlands population may represent the northernmost extent of its global range.
Dicoma schimperi (Asteraceae): This small shrub (formerly Hochstetteria schimperi) can be identified by its erect, ribbed stems. Western (1989) first recognised that its local distribution is limited to the south-eastern portion of the mountains of the UAE. This suggests that it is intolerant of the ultrabasic bedrock that prevails elsewhere. It is locally common in Wadi Hiluw, on gentle slopes at relatively low elevation (ca. 500600 metres), but it has also been recorded from near the summit of Jebel Jabsah (ca. 900 metres), north of Wadi Ham on the outskirts of Fujairah city.
Echiochilon callianthum (Boraginaceae): This is the pink-purple flowering species described in Jongbloed (2003) as E. thesigeri (see Feulner 2011, Appendix at Echiochilon persicum). It has been recorded in the UAE only from the Olive Highlands and the outlying carbonate massif of Jebel Hafit in Al-Ain.
Ehretia obtusifolia (Boraginaceae) (Figs. 6, 17): This large, drooping shrub is often found splayed out beneath other large shrubs or trees on slopes or cliffs. Its only known UAE locality is among the olive trees on the north-east facing slopes of the Jebel Qitab ridge, where on several occasions it has been observed in flower and fruit in January and February. A single erect, tree-sized specimen was found in a ravine below, at ca. 650 metres. Both the olive trees and E. obtusifolia appeared to suffer from extended drought during the 2000s but when seen most recently, in February 2014, E. obtusifolia appeared refreshed and was flowering and fruiting.
Ephedra pachyclada (Ephedraceae): One of the UAE's only two gymnosperms (both Ephedra spp.), this leafless shrub is otherwise found in Eastern Arabia only in the Ru'us al-Jibal (where it appears at ca. 900 metres and becomes more common above ca. 1200 metres) and in the high Jebel Akhdar (above ca. 2000 metres) (Ghazanfar 1992).
Fagonia schimperi (Zygophyllaceae) (Fig. 18): This species is occasional and locally common on the upper north-east facing slopes of Jebel Qitab. Scattered individual specimens have been found elsewhere within the Olive Highlands. It is otherwise known in Eastern Arabia only from higher elevations in the Ru'us al-Jibal (Feulner 2011). The author has also observed a probable specimen near the summit of the 1800-metre carbonate peak of Jebel Ra'is in Northern Oman, above upper Wadi Hawasina.
Grewia tenax (Tiliaceae) (Figs. 19a, b): The Olive Highlands are the only known UAE site for this species. It has been found in small numbers in company with the wild olive and Ehretia obtusifolia on the north-east facing cliffs and ravines of Jebel Qitab. G. tenax closely resembles its more common congener, G. erythraea, but unlike G. erythraea, which is often browsed to a cushion, G. tenax usually achieves the size of a large shrub or small tree. Scattered specimens are known from Northern Oman, including the Ru'us al-Jibal (Jongbloed 2003).
Launaea omanensis (Asteraceae): This uncommon daisy is endemic to the Hajar Mountains of the UAE and Northern Oman. It was first recorded from the UAE in early 2014, in the course of a botanical survey of Wadi Wurayah National Park, commissioned by Emirates Wildlife SocietyWWF and sponsored by HSBC. It is recognisable by its very thin, profusely toothed basal rosette of leaves, its rubbery, leafless stems and its greygreen colour (N. Kilian, pers. comm.). In the Olive Highlands, several specimens have been found on the rocky ridges on the north-east slopes of the Jebel Qitab ridge.
Melhania muricata (Sterculiaceae) (Fig. 20): This distinctive species is the UAE's only representative of the Sterculiaceae (the cacao family). It is occasional at higher elevations in the Olive Highlands, especially along the summit ridge of Jebel Qitab, but it is otherwise unknown in the UAE and northernmost Oman, with the exception of a single record from Jazirat alGhanem in the Strait of Hormuz. Circumstantial evidence suggests that M. muricata may be the larval foodplant of the Arabian Grizzled Skipper butterfly, another species so far known in the UAE only from Jebel Qitab (Feulner & Roobas 2014).
Monsonia cf. heliotropioides (Geraniaceae) (Fig. 21): M. heliotropioides is widespread but rare along the west flank of the Hajar Mountains in the UAE and is also recorded from the hills of the Batinah coast and the Dhofar region of Oman. The species found on the north-east slopes of Jebel Qitab in the Olive Highlands (and also recorded from Wadi Wurayah to the north) resembles M. heliotropioides in having sepals tipped with a purple mucro and relatively short petals, but the mericarp does not resemble either M. heliotropioides or M. nivea as shown in Flora of Egypt (Boulos 2000). Instead, the mericarp features a pit and furrow resembling that of Erodium neuradifolium, but with a weak septum dividing the pit.
Olea europaea (Oleaceae) (Figs. 22a to h): The north and east facing slopes of the Olive Highlands, principally those drained by Wadi Mayy, Wadi Hayl and Wadi Saham, are home to the UAE's only population of wild olives, which the author estimated in the late 1990s to number ca. 500 trees. The olive trees are concentrated along the north and east-facing rocky cliffs and in the steep ravines below. A small number of trees grow in the shelter of north-facing cliffs on Jebel Al-Iyeli and on the north slopes and ravines of Jebel Sfai. Single small specimens have been found at wadi level in Wadi Hayl (M.A.R. Khan, pers. comm.) and Wadi Mayy. Outside this area, only two wild olives have been found in the UAE, a pair of very small trees (<1.5 metres tall) situated high on the north slope of Jebel Jabsah, north of Wadi Ham on the outskirts of Fujairah city.
Pennisetum orientale (Poaceae): Large clumps of this grass (syn. Pennisetum setaceum) were recorded below the north-east facing cliffs along the summit ridge of Jebel Qitab. Only a single other UAE record is known, from Jebel Masafi. P orientale is similarly rare in the Ru'us al-Jibal, where it was recorded only on a damp cliff face at a major spring (Feulner 2011).
Phagnalon schweinfurthii (Asteraceae) (Fig. 23): This distinctive composite favours higher elevation. It features erect white stems, bright green leaves and compact, dull pinkish-purple flowerheads on long stalks. It is occasional in the high Ru'us alJibal, where it may be suppressed due to preferential browsing. To the south, however, it has been recorded only from Jebel Masafi and Jebel Qitab, each at elevations above ca. 600 metres, and at elevations above 1000 metres in the mountains south of Hatta. P. viridifolium has recently been synonymised with P. schweinfurthii (Feulner 2011).
Volutaria sinaica (Asteraceae): This generally rare but unpredictable ruderal species (syn. Amberboa lippii) was locally common on the Jebel Qitab summit plateau in March 2014, especially in silt accumulations, although it had not been recorded on previous visits to the same locality.
Spialia mangana (Arabian Grizzled Skipper) (Fig. 24): S. mangana is an uncommon and little known butterfly having its principal range from south-west Arabia to East Africa (Yemen through Ethiopia and Somalia to Uganda and Kenya) with two localities reported from the Dhofar region of Oman (T.B. Larsen, pers. comm.). In 2006-2007, S. mangana was found in the mountains of Northern Oman as well, on the middle slopes of the Jebel Akhdar and Jebel Kawr at elevations of ca. 1000-1400 metres. In February 2014 it was recorded on the summit ridge of Jebel Qitab by a team led by the author. Circumstantial evidence suggests that its preferred larval foodplant may be the similarly restricted Melhania muricata (Sterculiaceae). A full account is published separately in this volume of Tribulus (Feulner & Roobas 2014).
Pseudophilotes vicrama (Baton Blue butterfly) (Fig. 25): Once thought to be limited in Arabia to the Ru'us al-Jibal, local populations of this Lycaenid or "Little Blue" butterfly have been discovered in Wadi Sfai (Feulner 2008) and Wadi Hiluw (Kh. Rafeek, pers. comm. 2011), more than 80 kilometres south of the southernmost previous records, and at lower elevations (ca. 500-550 metres in Wadi Sfai and ca. 350-375 metres in Wadi Hiluw). Because of the sedentary character of this species, the Olive Highlands records are believed to represent long-term resident populations (T.B. Larsen, pers. comm.).
Junonia orythia (Blue Pansy butterfly) (Figs. 26a, b): The widespread Blue Pansy butterfly is generally considered to be represented in the UAE by the subspecies J.o. here. Local populations are somewhat variable but with only very rare exceptions the ground colour of the dorsal hindwing of females is blue, nearly but not quite as blue as the males (Fig. 26a). However, in a major ravine on the north-east slopes of Jebel Qitab, on a sunny day in March 2014, the author and Binish Roobas observed the phenomenon of a steady migration of hundreds of individual Blue Pansy butterflies down the ravine. Many of these stopped briefly to bask on large boulders and, although they were difficult to approach, they were reasonably easy to observe with ready binoculars. In all of the two dozen or so females observed, the ground colour was brown, without any hint of blue (Fig. 26b). These observations suggest that the Olive Highlands may harbour some secrets in this regard as well.
Targeted investigation can reasonably be expected to reveal at least a small number of additional invertebrate species that are localised in the Olive Highlands, particularly sedentary ones (e.g., burrowing species) that are sensitive to climate and/or elevation, and others, especially insect species, that may be associated with the wild olive trees. The author has looked specifically, but so far without success, for the land snail Pseudonapaeus jousseaumei, which replaces the more common and widespread Zootecus insularis at higher elevations in the Hajar Mountains to the south.
Fauna - Vertebrates - Herptiles Duttaphrynus dhufarensis (Dhofar Toad): This toad species is the rarer of two found in the UAE. It is primarily nocturnal and is sometimes found far from permanent water, including high on mountain slopes in the Ru'us al-Jibal (Cunningham & Feulner 2001). It was recorded once from Jebel Qitab, at ca. 700-800 metres in a wadi draining the summit ridge, where it was flushed during a late afternoon descent. A second individual was encountered by night, crossing the vehicle track at the base of the mountain, along Wadi Mayy. At a dam ca. 5 kilometres downstream in Wadi Mayy, a juvenile was observed and adults were heard calling in late fall. A juvenile was also identified in upper Wadi Sfai. Its occurrence in mountain slope environments suggests that D. dhufarensis must be able to breed successfully in ephemeral pools in steep, boulder-filled mountain wadis.
Pristurus celerrimus (Bar-Tailed Semaphore Gecko) (Fig. 27): The Jebel Qitab summit ridge supports a relatively large and conspicuous community of this diurnal species, similar to what can be seen on plateaux in the high Ru'us al-Jibal. It seems likely that this gecko is a major prey species for the Persian Horned Viper.
Pseudocerastes persicus (Persian Horned Viper) (Fig. 28): A specimen was observed in mid-afternoon on the ridge near the summit of Jebel Qitab, on open ground among scattered boulders. It retreated to shelter under a nearby boulder when approached but was subsequently exposed and observed more closely. This is understood to be the only confirmed sighting of P. persicus within the Hajar Mountains of the UAE. Other UAE sightings have been either from the Ru'us al-Jibal or from Jebel Hafit (Cunningham 2002, Gardner 2013, J. Els, pers. comm., Feulner, pers. obs.). Because this species has generally been found only at elevations above ca. 700 metres, the possibility should be investigated that the Jebel Qitab summit ridge supports a self-sustaining population. The relative abundance of the gecko Pristurus celerrimus could constitute a major food source, although this would require the viper to feed at least in part diurnally.
It was the impression of the observers that the distinctive black, wormlike tip of this viper's tail was very likely to be used as a lure to attract prey, as has been speculated by others (e.g., Cunningham 2002). In addition to the closely similar appearance of the tail tip to images of other species known to use tail luring (e.g., Dressler, showing Peringuey's Adder), that inference is further supported both by the coiling posture adopted by the snake, which left the tail positioned to the fore, and by the recent recognition of an even more elaborate caudal lure in a close Iranian congener, the Spider-Tailed Horned Viper P. urarachnoides (Bostanchi et al. 2006).
A shed snakeskin was collected from ca. 1000 metres on the ridge above uppermost Wadi Sfai, not far from Jebel Al-Iyeli. The shedding was examined by Johannes Els, Head of Department, Herpetology and Freshwater Fish, at the Breeding Centre for Endangered Arabian Wildlife in Sharjah. particularly to determine whether it might constitute an additional record of P persicus. His examination of the dorsolateral scales indicates that it probably represents Echis omanensis, but DNA confirmation will be sought (J. Els, pers. comm). The site is atypical for E. omanensis, on an open ridge and distant from water. Subsequently, a second, similar shed skin was collected adjacent to a gulley in the same area, at ca. 900 metres.
The only other snake so far confirmed from the Olive Highlands is the Sand Snake Psammophis schokari, which was recorded once at 700-800 metres and suspected at ca. 1000 metres on Jebel Qitab, among vegetated boulders below cliffs along the summit ridge. A "racer" was also recorded on the summit ridge of Jebel Sfai, which was probably either P schokari or Platyceps rhodorachis.
The best explanation for the presence of most of the above species of plants, invertebrates and herptiles in relative isolation in the Olive Highlands is that they represent relicts of more widespread populations that flourished in the more mesic climate of an earlier time, perhaps as recently as ca. 6,000-10,000 years ago during the so-called climatic optimum, and that the Olive Highlands has served as a biological refuge. The situation is somewhat different for birds and for larger mammalian species, which can migrate more easily. These are discussed below.
The author's records include some 30 bird species from visits to the Olive Highlands - all of them typical Hajar Mountain residents or visitors - including several species that are more common below the 500 metre contour (e.g., Green Sandpiper, Grey Francolin and Indian Roller).
Human observers are well exposed in the open terrain of the summit ridges, which probably diminishes the number of bird records from that environment, but it is reasonable to suppose that the overall lack of human disturbance and the shelter of the north-east facing cliffs and ravines which harbour the wild olive trees could make the upper slope areas potential breeding sites for raptors such as Short-Toed Snake Eagle, Bonelli's Eagle and Booted Eagle (R.J. Hornby, pers. comm.), and for other species as well.
Many more birds were typically recorded during visits to the Olive Highlands in the wet mid-1990s than in the drier 2000s. It is tempting to speculate that the difference might be due not only to the more congenial mountain environment of the mid-1990s, but also to the relative absence of alternative "green" sites for avian visitors to the UAE at that time. It may, however, reflect in equal or greater measure the author's increasing attention over time to non-avian fauna, at the expense of avian records.
The most dramatic avian record was a close encounter, at eye level, with an oncoming Griffon Vulture, which appeared suddenly around the corner of a summit cliff on Jebel Samah, aimed directly towards the observer. It was difficult to grasp immediately what this large but silent, unfamiliar silhouette could be. For its part, the bird displayed no emotion as it glided past, changing course almost imperceptibly to follow the trend of the ridge. It could be identified only at a distance, when it had descended slightly, making visible its distinctive mantle.
Fauna - Vertebrates - Mammals No wild mammals have yet been observed in the summit regions within the Olive Highlands, but there are limited records from the surrounding slopes and wadis.
Gazella gazella cora (Mountain Gazelle): Sightings or traces of the Mountain Gazelle G. gazella cora are known from at least three areas on the periphery and lower slopes of the Olive Highlands. On New Year's Day 1992, a group of four animals was observed on upper slopes above the head of Wadi Hayl (Hellyer 1992), at elevations estimated to be ca. 700 metres or more. This is the same area where Arabian Tahr were reported later in the decade (see below). In the mid-1990s and the early 2000s, then-recent gazelle droppings were observed at several places along the upper reaches of Wadi Hiluw, on the south-west slopes of the Jebel Qitab ridge, both on lower slopes and on long-abandoned agricultural terraces adjacent to the upper wadi, all at elevations of ca. 550-700 metres. Gazelle droppings were also observed in a tributary wadi to the west of Jebel Samah.
For the Mountain Gazelle, the Olive Highlands may represent marginal habitat to which it has been driven by human encroachment and hunting pressure. The 1992 account referenced above quotes a senior Fujairah government official to the effect that there were still a substantial number of this elusive species in the remoter parts of the Hajar Mountains, and that they were still subject to a limited amount of hunting, despite Emiri instructions to the contrary (Hellyer 1992). Arabitragus jayakari (Arabian Tahr) (formerly Hemitragus jayakari): Because the gabbro terrain is relatively easy for both humans and larger quadrupeds to access and navigate (the presence of feral donkeys, discussed below, is indicative), and because there is no permanent surface water within most of the Olive Highlands (the only known permanent surface water is at ca. 550 metres in upper Wadi Sfai), this area was probably never prime habitat for the Arabian Tahr. In the late 1990s, surveys by the Arabian Leopard Trust revealed Arabian Tahr on the upper slopes of Wadi Hayl (M. Sawaf pers. comm.), at the edge of the Olive Highlands, in the mixed harzburgite/gabbro unit, from where permanent water feeds plantations below, but Arabian Tahr have not yet been recorded from areas of gabbro bedrock.
Feral donkeys: Feral donkeys were conspicuous on the Jebel Qitab summit ridge on the author's first visit in late 1994. Live sightings included groups of 5 and 3 donkeys, including juveniles. There were also many fresh trails, droppings and dust baths, as well as recent bones. The observed donkeys, however, were possibly sufficient to account for all such circumstantial evidence. On subsequent visits in the wet mid-1990s, donkeys were less conspicuous although droppings were seen and smaller numbers (2 to 7) were observed. A group of 4 donkeys was also seen at high elevation on Jebel Sfai during the same period. Numbers apparently dwindled during the turn-of-the-century drought (1999-2003) (see Feulner 2006) but a single donkey was seen on the Jebel Qitab summit ridge in early 2003. However, on a subsequent visit in late 2006, the donkey droppings and dustbaths looked old, and by 2014 a visit to the same area did not record evidence of mammals, except some silt patches that may have originated as dusting baths.
Feral donkeys have always been more common in the lower, flatter reaches of Wadi Hiluw and Wadi Sfai, not far from the traditional plantations from which they or their ancestors were probably released. In upper Wadi Sfai, small numbers of feral donkeys continue to range up to 700 metres and more, probably due to the regular presence of surface water at that elevation. Evidence of their presence can also be found higher, along the summit ridge of Jebel Al-Iyeli, but as of late 2014, the existing donkey trails there appeared to have fallen into disuse, and donkey droppings were both scarce and old.
Feral goats: Feral goats and goat droppings have always been scarce in most of the Olive Highlands, and particularly on the summit ridges and upper slopes. The author's only record of a goat above 600 metres was of a large, heavychested male on the Jebel Qitab summit ridge in early 2003. Before that time, the wild olive trees in the summit regions showed evidence of heavy browsing, but that could be accounted for by the donkey population. In the ravines, where donkeys could not easily reach, browsing was less evident. The absence of feral goats at higher elevations in the Olive Highlands may be due primarily to local animal husbandry practices, specifically the failure to release domestic goats to forage in the wild for extended periods, as has been suggested for the distinction between the mountains of the Musandam peninsula, where feral goats are common, and the environmentally similar Jebel Akhdar, where they are rare (R. Wood, pers. comm.).
Carnivores: Field evidence of mammalian carnivores in the Olive Highlands is scarce. Fox droppings are rare and mostly found at lower elevations. They have appeared to be droppings of Red Fox Vulpes vulpes arabica as opposed to the typically insectrich droppings of Blanford's Fox Vulpes cana. The droppings of a large carnivore were observed only once, along the summit ridge south of Jebel Sfai. The most likely candidate is the Caracal Caracal caracal, which is undoubtedly present and may be ecologically significant (R.J. Hornby, pers. comm). A caracal was killed by farmers in Wadi Mayy in ca. 2005 (M. Ziolkowski, pers. comm.).
Small Mammals: Small mammals such as Egyptian Spiny Mouse Acomys cahirinus, Wagner's Gerbil Gerbillus dasyurus and Brandt's Hedgehog Paraechinus hypomelas are likely to be present throughout the Olive Highlands. All are nocturnal. A single Wagner's Gerbil was observed at length during a nighttime investigation on the slopes of a low hill in upper Wadi Sfai, at ca. 550 metres, but otherwise no evidence of tracks, skeletons or skins of small mammals has yet been encountered.
Status and Threats
The Olive Highlands have seen changes over the two decades since they were first recognised, but for the most part those changes appear to have been wrought by nature, not by man - a somewhat unusual situation in the UAE. One of the most noteworthy characteristics of the Olive Highlands environment, apart from its unique biodiversity, is the absence of significant human encroachment.
The author's visits to areas within the Olive Highlands have spanned the period from late 1994 through 2014, at irregular intervals of several weeks to almost two years, amounting to more than 30 visits and including two traverses of the length of the Jebel Qitab summit ridge, the core of the area. On early visits, in the wet mid-1990s, the olive trees on the north-east slope of the Jebel Qitab ridgetop appeared to be thriving (Figs. 22a & b). However, no saplings could be found and browsing of lower branches was evident (Figs. 22b & c), and even of some whole shrubs (Fig. 22d), leading to uncertainty whether the population could be said to be self-sustaining under those conditions.
In many UAE mountain and wadi environments, donkeys have been reflexively blamed for environmental damage more plausibly attributable to goats and camels - perhaps because, unlike goats and camels, donkeys have no economically vested constituency - but in the case of the wild olives on Jebel Qitab, the conclusion is inescapable that donkeys were the culprits and that the browsing levels seen in the mid-1990s were a threat to continued regeneration of the olive population.
The extreme drought of the early 2000s (see Feulner 2006, see especially Figs. 1 and 5 therein), which persisted in a less extreme form through most of the decade, appeared to take its toll of the donkey population, but also of the highest and most exposed olive trees. In early 2003, the olive trees on the summit cliffs of Jebel Qitab had only sparse leaves, and when visited thereafter, in late 2006, the older branches were barren (Fig. 22e). Recovery has yet to come; in March 2014 whole trees were barren, despite two consecutive rainy winters (Fig. 22f).
Within limits, these climatic vicissitudes may represent a contingency for which the wild olives are evolutionarily prepared. Fig. 22g shows the largest (by girth) and presumably oldest tree in the Jebel Qitab summit population; in this March 2014 photo it appears all but lifeless. However, Fig. 22b shows the same tree, revealing that it featured a major "dead" trunk even when it was first photographed, otherwise in full leaf, in 1996.
Downslope, olive trees continue in or adjacent to the wadis that drain the summit, down to an elevation of ca. 550 metres, and most have appeared to remain in good condition.
Not surprisingly, different species have reacted somewhat differently to the changing environmental conditions over the past two decades. For example, when seen in the early and mid-2000s, the score of drooping Ehretia obtusifolia shrubs associated with the cliff-top olive trees looked equally dismal, but in March 2014, unlike the olives, they appeared very much refreshed (after two consecutive rainy winters) and were in flower and fruit (Figs. 17, 22e). On the other hand, it was the author's impression that Ephedra pachyclada is much less in evidence currently, in 2014, than it was in the 1990s, suggesting a failure to thrive.
What is certain, in any case, is that plant and animal species such as those localised in the Olive Highlands are among the species at greatest risk from broader global or regional climate change in the form of increasing temperatures and decreasing rainfall. These species have already "retreated" uphill and have no place else to go. To that extent, their fate may ultimately be independent of any local conservation efforts. But at the moment there appear to be no other immediate threats to the environment of the Olive Highlands. Specifically, the feral donkeys of the 1990s have not returned, so over-browsing is not a problem, and the level of human encroachment, although incipient, remains extremely low by UAE standards.
This arguably imposes an added responsibility on the human stewards of the area not to tip the balance. The current situation is positive in that regard. There is almost no evidence of either historical or recent human visitation or exploitation anywhere within the Olive Highlands, except the construction in the past decade of three communication towers. The earliest of the three was at the north-western extremity of the Jebel Qitab ridge; a rough service road now ascends to the tower from Wadi Hiluw. The road had been allowed to fall into disrepair when it was investigated in 2008 but it has subsequently been gated at the bottom (reportedly by military, not communications, authorities) and is evidently still used for maintenance or other official purposes. Unfortunately the road was constructed with little attention to environmental considerations. In the kilometre or so before it reaches the summit ridge, the steep road cuts on the uphill side create an extended barrier to access or passage by humans or large quadrupeds. A more recent tower constructed on the ridge north of Wadi Mayy, apparently a standard microwave installation, is shown in Fig. 29.
The low pass (ca. 700 metres) from Wadi Sfai to Wadi Saham, east of the village of Sfai, was a historical route from the interior of the mountains to the East Coast, but it has become obsolete in the modern era. A single instance of boulder art has been found along that route. No examples of stone structures or other human artifacts are known from the ridgetops or from other passes in the Olive Highlands, although the 900-metre pass from Wadi Sfai to Wadi Hiluw is a relatively straightforward walking route and small, disused terraced fields are found as high as ca. 700 metres on the Wadi Sfai side. Those fields, however, are located near an area where water collects in a chain of pools after rain, and the presence there of mineral water bottles, plastic bags and other litter indicates that local residents know the site and visit at least occasionally. Other instances of human use are trivial. Once, in March 1998, the author encountered a middle-aged local couple from Wadi Mayy on the slopes of Jebel Qitab, collecting a favoured plant (or possibly the local 'truffle', shahmateen). On another occasion, in 2001, greetings were exchanged near the summit of Jebel Samah with two European ladies, both volunteers at Fujairah's maternity clinic, who had hiked up from Wadi Saham for exercise and diversion.
Geological prospecting has revealed no mineral deposits of economic value within the Olive Highlands and their surrounding areas, although minor excavation for chromite was undertaken in the ultrabasic rocks of upper Wadi Hayl (Thomas et al. 2006), in ca. 2000. These areas have also been spared, so far, from the depredation of quarrying for crushed stone. Small scale exploitation of minor copper-bearing veins may have occurred in premodern times on the fringes of the Olive Highlands, e.g., in upper Wadi Hiluw, near the 500 metre contour (M. Ziolkowski, pers. comm.), and at slightly higher elevation in upper Wadi Sfai (pers. obs.), but there is as yet no evidence of significant mineralisation, excavation, or milling or smelting operations in these areas. However, the nearby archaeological site at Harrah, in Wadi Hiluw at ca. 350-375 metres, was a major copper mining locality from which large quantities of metal were extracted over an extended period of time, from mineralised veins that spanned the wadi (J. Kuetterer, pers. comm.).
In view of the extensive list of distinctive flora (and to a lesser extent, fauna) set out above, it should not be necessary to say more to make the case that the Olive Highlands deserve high priority from a conservation standpoint, in order to preserve their unique array of high elevation species. It is difficult to identify a mountain area in the UAE (other than the high Ru'us al-Jibal) that is more distinctive in terms of its contribution to the biodiversity of the UAE.
Moreover, it is equally difficult to identify a mountain area in the UAE that is easier and simpler to preserve. The Olive Highlands are today largely in their natural state. Human visitation and use remain almost nonexistent. All that is required to preserve the area is to ensure that it continues be left alone, free of 'development' - roads, quarrying, construction, landscaping or other exploitation or molestation. Fences are not required: the habitat itself constrains resident species, and remoteness has protected them effectively to date. Active 'management' is also not required, only a modest regime of monitoring and supervision, including monitoring for the possible return of feral donkeys or the advent of feral goats to the high areas in significant numbers. This function could be performed in part by local residents in the surrounding villages. The expense of simply leaving the area undisturbed is almost negligible; it would be hard to get more biodiversity bang for the buck.
It was for many years the author's personal opinion that the best way to protect the Olive Highlands (and many other areas of natural history importance in the UAE) was through benign neglect - including minimal publicity. However, the pace and unpredictability of development in recent years, e.g., the rapid and all but uncontrolled expansion of quarrying, the discussion and implementation of potentially intrusive conservation-themed projects in nearby areas, and the temptations that could arise from the existence of access roads to the three communications towers, all make it important now to ensure public and official recognition of the special nature of the Olive Highlands.
That process has been initiated by identifying and prioritising the Olive Highlands as part of the Local, National Regional Biodiversity Rapid Assessment exercise conducted in 2012 by the Abu Dhabi Global Environmental Data Initiative, in conjunction with Hyder Consulting (AGEDI 2013), and thereafter by informal communication with representatives of the Government of Fujairah, where long-term strategic land use planning is currently underway. However, the Olive Highlands also include substantial territory within the Emirates of Ra's al-Khaimah (the Wadi Sfai watershed) and Sharjah (the Wadi Hiluw watershed), so it is important to raise the awareness of the concerned authorities in those Emirates as well, independent of the AGEDI initiative.
In Fujairah and Ras al-Khaimah, extensive quarrying has destroyed many mountain front areas, but the interior, including the Olive Highlands, remains all but untouched. The recent pipeline and highway routes across the mountains have sensibly followed lower terrain to the north. The upper watershed of Wadi Sfai was among a dozen or so areas recommended informally in the mid-2000s to an adviser to the Ra's al-Khaimah Department of Industrial Development and Environmental Protection, as deserving of special protection for natural history reasons, but the focus of concern for that office at the time was on areas in the periphery of urban Ra's al-Khaimah.
Sharjah's record of environmental awareness is excellent, and much of upper Wadi Hiluw (a/k/a Wadi Helo or Helow) was declared a protected area in 2007, for the stated purpose of protecting the mountain and wadi environment. As elsewhere in the UAE, however, development has often outpaced conservation efforts, with the result that most of Wadi Hiluw below 400 metres elevation is almost unrecognisable from what it was just two decades ago. In addition, a number of farms in Wadi Hiluw up to ca. 500 metres, disused during the wet 1990s due to inaccessibility, have been re-vitalised in the 2000s following the construction and maintenance of an improved vehicle track (Fig. 30).
Inter-governmental conservation cooperation has proven to be a challenge within Arabia generally, just as it has elsewhere. But where there is challenge there is also opportunity. Here, the case for conservation is clear and the solution is straightforward and inexpensive, but the devil is in the details. The most important priorities are that the Olive Highlands be recognised for their unique status as an island of biodiversity and that they be treated accordingly by all concerned.
Given that the relevant inter-Emirate borders essentially bisect the main summit ridges within the Olive Highlands, including the critical summit ridge of Jebel Qitab, a provincial approach, or worse, a turf war, would be disastrous for a satisfactory conservation result. It would destroy the integrity of the very habitat most in need of protection, effectively cutting the baby in half.
Perhaps in these circumstances a supportive role can be played by federal authorities as well; to the extent that military jurisdiction exists over the area of the communications tower at the north-western end of the Jebel Qitab ridge, the involvement and cooperation of federal authorities may be not only appropriate but necessary.
A more hopeful prognosis is that preservation of the Olive Highlands can serve as an opportunity to establish fruitful cooperation among Emirates in the service of an unquestionably worthwhile conservation goal.
The author wishes to thank the individuals who have accompanied him on field excursions to various locations in the Olive Highlands over the years, and who contributed their own valuable observations, including particularly the late Martin Parker, John Martin and Binish Roobas. Binish Roobas deserves special acknowledgment since he was responsible for the record of Pseudocerastes persicus atop the Jebel Qitab summit ridge, which would almost certainly have gone unnoticed without him, and he freely shared his thinking and subsequent research about P persicus. Johannes Els provided an authoritative examination of a shed snakeskin suspected to represent P persicus. Dr. Richard Hornby read and commented thoughtfully on a draft of this paper, as he has on others in the past. Richard Flemmings very kindly prepared the map of the Olive Highlands presented here as Fig. 1.
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[NB: Tribulus, the journal of the Emirates Natural History Group, Abu Dhabi, is available online at: http://www.enhg.org/trib/1
Gary R. Feulner
Chadbourne & Parke
P.O. Box 23927
Dubai, United Arab Emirates
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|Author:||Feulner, Gary R.|
|Date:||Jan 1, 2014|
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