Langeberg Mountains

icon

General Information

Status:

Global IBA (A1, A2, A3)

Province:

Western Cape

Protection:

Partially Protected

Size:

116 450 ha

Number:

SA113

Additional Info

  • Site description

    One of several mountain ranges that trend east–west in the Western Cape, the Langeberg stretches c. 170 km from the Gourits River in the east to the town of Montagu in the west. It consists of sediments of the Table Mountain Sandstone group and occasionally the Malmesbury group. South of the range, the Agulhas Plain and Overberg wheat-belt stretch towards the coast. To the north lie the open plains of the Little Karoo.

    The area can be divided into three distinct sectors: Marloth Nature Reserve; the Boosmansbos Wilderness Area; and the Bergfontein–Rooiwaterspruit–Phesantefontein area, which includes Garcia State Forest. Marloth Nature Reserve is situated in the west of the mountain catchment area, above the town of Swellendam. The south-facing slopes above Swellendam are steep and rise rapidly to form the 'clock' peaks, although in places the steepness is interrupted by expanses of flat plateau. On the northern slopes, the Boskloof Valley and Hermitage Kloof rise steeply to form Hermitage Peak (1 154 m a.s.l.) and Goedgeloof Peak (1 710 m a.s.l.), the latter being the highest point in the Langeberg range. To the east, Goedgeloof Ridge lies adjacent to the Little Karoo. The topography towards the Nooitgedacht River is dominated by a series of peaks: Kruispad (1 365 m a.s.l.), Leeurivierberg (1 628 m a.s.l.), Middelrivierberg (1 405 m a.s.l.) and Klipspringerkop (1 127 m a.s.l.). Numerous streams drain these mountains, flowing into many of the Western Cape's primary river systems and supplying the Agulhas Plain and Overberg wheat-belt with water. The plateau-like southern slopes at the foot of the Langeberg are deeply incised by various rivers.

    Boosmansbos Wilderness Area, near Heidelberg, is more or less centrally situated in the southern Langeberg. Grootberg (1 627 m a.s.l.) is its highest peak. There are fault valleys at higher elevations, and to the north a series of sandstone ridges interspersed with shallow valleys gives way to a mesa-like plateau of gravel and sandstone conglomerates. The south-facing slopes above Bergfontein are not as steep as those further west. A prominent, isolated low ridge known as the Koksposberg runs along the front of the mountain. This hill and others similar to it range in altitude from 457 to 727 m a.s.l. There are no deeply incised inter-montane valleys and the topography is relatively flat in comparison to that of the western Langeberg.

    In Garcia Forest Reserve, west of Garcia's Pass, the Peninsula Formation Sandstone forms some impressive peaks. Sleeping Beauty (1 343 m a.s.l.), Korinteberg (1 330 m a.s.l.), Stinkhoutbos (1 341 m a.s.l.) and Phesanteberg (1 330 m a.s.l.) are the tallest peaks in this region. Numerous watercourses dissect the sandstone slopes. To the north of the Langeberg, the mesic sandstone ridge gives way to arid sandstone slopes, which in turn make contact with the Bokkeveld Shale of the Little Karoo.

    The Langeberg falls in the transition zone between year-round and winter-rainfall areas. In summer, the mountains trap onshore, moisture-laden, south-easterly winds and orographic rain falls. In winter, the prevailing north-westerly and south-westerly winds bring rain associated with sub-Antarctic cold fronts. Although micro-climates significantly affect local rainfall, in general the lower slopes receive about 600 mm and the upper slopes and high peaks receive c. 1 400 mm of rain p.a., falling mostly in spring and autumn. Snow and mist occur annually. Temperatures are moderate and range between 2.9 °C in winter and 30 °C in summer.

    The mesic mountain fynbos is dominated by a multitude of communities, the primary constituents of which are plants of the Proteaceae, Ericaceae and Restionaceae families. Patches of Afro-temperate forest occur in deep, secluded valleys on the southern slopes of the range, while the northern slopes host karroid scrub.

    Birds

    Langeberg Mountains A FronemanThe Langeberg and surrounding plains hold a remarkable number of avian habitats that support many restricted-range and biome-restricted assemblage species. A total of 206 bird species has been recorded for this IBA during SABAP2. All the Cape Fynbos EBA restricted-range and biome-restricted assemblage species may be found in the mountains, while several South African Forest restricted-range species occur in the patches of forest. Where the northern foothills grade into Little Karoo plains, a number of Namib-Karoo biome-restricted assemblage species are found.

    In the fynbos, Orange-breasted Sunbird Anthobaphes violacea is widespread in ericas, whereas Cape Sugarbird Promerops cafer is mostly restricted to the proteoid elements. Cape Spurfowl Pternistis capensis, Cape Bulbul Pycnonotus capensis and Cape Siskin Crithagra totta are widespread, while Victorin's Warbler Cryptillas victorini is localised and restricted to moist seeps in hilly areas. Cape Rockjumper Chaetops frenatus and Ground Woodpecker Geocolaptes olivaceus are common on most rocky slopes above 1 000 m a.s.l. In low fynbos scrub both Hottentot Buttonquail Turnix hottentottus and Striped Flufftail Sarothrura affinis are found. Red-necked Spurfowl Pternistis afer also occurs in the east of this IBA. The mountain peaks and associated cliffs hold Black Stork Ciconia nigra, Booted Eagle Hieraaetus pennatus, Verreauxs' Eagle Aquila verreauxii, Cape Eagle-Owl Bubo capensis and Peregrine Falcon Falco peregrinus. Martial Eagle Polemaetus bellicosus is a rare, yet widespread resident in the Langeberg.

    The isolated forest patches in the range hold several forest endemics, including Forest Buzzard Buteo trizonatus, Knysna Woodpecker Campethera notata, Knysna Warbler Bradypterus sylvaticus and Forest Canary Crithagra scotops. Other forest species, some of which are at the western limit of their distribution, include Olive Bush-Shrike Chlorophoneus olivaceus, Narina Trogon Apaloderma narina and Crowned Eagle Stephanoaetus coronatus.

    The Little Karoo plains and the foothills of the north-facing Langeberg hold Karoo Korhaan Eupodotis vigorsii, Karoo Lark Calendulauda albescens, Sickle-winged Chat Cercomela sinuata, Karoo Chat C. schlegelii and Rufous-eared Warbler Malcorus pectoralis. Black-headed Canary Serinus alario occurs when seeding grass and water are available. The northern slopes also support Layard's Tit-Babbler Sylvia layardi and Grey Tit Parus afer. African Rock Pipit Anthus crenatus, Pale-winged Starling Onychognathus nabouroup and the secretive and localised Cinnamon-breasted Warbler Euryptila subcinnamomea occur in rocky gorges and kloofs. Other arid-zone species occurring in the Little Karoo portion of the IBA include Pale Chanting Goshawk Melierax canorus, Pririt Batis Batis pririt, Fairy Flycatcher Stenostira scita and White-throated Canary Crithagra albogularis.

    The agricultural wheat-growing belt to the south, which nestles up against the Langeberg slopes, holds populations of Blue Crane Anthropoides paradiseus, Denham's Bustard Neotis denhami, Southern Black Korhaan Afrotis afra, Black Harrier Circus maurus, Secretarybird Sagittarius serpentarius and White Stork Ciconia ciconia. All these species regularly forage in the modified agricultural matrix of the Langeberg.

    IBA trigger species

    Globally threatened species are Blue Crane, Denham's Bustard, Martial Eagle, Black Harrier, Hottentot Buttonquail, Knysna Woodpecker and Knysna Warbler. Regionally threatened species are Verreauxs' Eagle, Karoo Korhaan, African Marsh Harrier Circus ranivorus, Lanner Falcon Falco biarmicus, Black Stork, Cape Rockjumper and Striped Flufftail.

    Restricted-range and biome-restricted species that are common in specific habitats include Cape Spurfowl, Cape Sugarbird, Cape Bulbul, Orange-breasted Sunbird, Cape Siskin, Victorin's Warbler, Forest Buzzard, Forest Canary, Olive Bush-Shrike, Swee Waxbill Coccopygia melanotis, Knysna Woodpecker, Knysna Warbler, Grey Cuckooshrike Coracina caesia and Yellow-throated Woodland Warbler Phylloscopus ruficapilla. Uncommon species in this category include Cape Rockjumper, Striped Flufftail, Hottentot Buttonquail, Protea Seedeater Crithagra leucoptera, Karoo Chat, Karoo Lark, Namaqua Warbler Phragmacia substriata, Pale-winged Starling, Black-headed Canary and Layard's Tit-Babbler.

    Other biodiversity

    Of the 1 228 plant species recorded in the southern Langeberg, 160 (13%) are restricted to the range. Many more endemics probably await discovery during more comprehensive botanical surveys. As it is impractical to give a full list of all the threatened and endemic species, only unique or spectacular plants are mentioned. The monotypic family Geissolomataceae is endemic to the range, as is the monotypic genus Langebergia (Asteraceae). There are 48 endemic ericas and 17 endemic restios in the southern Langeberg.

    This area is also home to several special vertebrate species, including strawberry rain frog Breviceps acutirostris, which is virtually endemic to the Langeberg. The slender redfin Barbus tenuis is globally restricted to the tributaries of the Keurbooms and Gourits rivers; the latter forms the eastern border of the IBA and may hold a small population of this threatened and highly localised fish species. A Biodiversity Management Plan for the Tradouw redfin Pseudobarbus burchelli is being drafted as this species is now separated from P. burchelli forms from the Breede, Goukou and Heuningnes rivers. The spectacular Cape ghost frog Heleophryne purcelli, a Western Cape endemic, is restricted to perennial streams in forested, boulder-strewn gorges in montane areas. Other localised amphibians found in the Langeberg include the plain rain frog Breviceps fuscus and banded stream frog Strongylopus bonaspei, which are restricted to the Cape Floral Kingdom. The Tradouw toadlet Capensibufo tradouwi breeds in moist depressions, vleis and springs, and is found in the Langeberg and in the Cederberg–Koue Bokkeveld Complex IBA.

    Some South African endemic reptiles occurring here are Cape mountain lizard Tropidosaura gularis, graceful crag lizard Pseudocordylus capensis and spotted thick-toed gecko Pachydactylus maculatus. Southern African endemics of more general occurrence include parrot-beaked tortoise Homopus areolatus, angulate tortoise Chersina angulata, black thread snake Leptotyphlops nigricans, spotted harlequin snake Homoroselaps lacteus, Sundevall's shovel-snout Prosymna sundevallii, cross-marked grass snake Psammophis crucifer, Cape cobra Naja nivea, many-spotted snake Amplorhinus multimaculatus, berg adder Bitis atropos, Cape legless skink Acontias meleagris, red-sided skink Mabuya homalocephala, spotted sand lizard Pedioplanis lineoocellata, common mountain lizard Tropidosaura montana, Cape girdled lizard Cordylus cordylus, Cape crag lizard Pseudocordylus microlepidotus, southern rock agama Agama atra, ocellated thick-toed gecko Pachydactylus geitje and Cape grysbok Raphicerus melanotis. Threatened mammals include leopard Panthera pardus and the endemic subspecies Boosmansbos long-tailed forest shrew Myosorex longicaudatus boosmani.

    Conservation issues

    Threats

    The land ownership of this IBA is mixed, comprising large CapeNature provincial nature reserves (Marloth and Grootvadersbosch and Boosmansbos Wilderness Area) and privately owned mountain catchment land. Historically the largest areas conserved in the Cape Floral Kingdom were placed under the jurisdiction of the DWAF in order to protect water catchment areas. When it was shown in the early 1960s that the annual run-off from mature forest plantations was 50–100% less than that of neighbouring natural fynbos vegetation, land was acquired rapidly during that decade and afforestation was strictly controlled under the Mountain Catchment Areas Act of 1970 to protect South Africa's dwindling water supply. Within this region, the Langeberg West (77 096 ha) and Langeberg East (71 300 ha) Mountain Catchment Areas were declared.

    The major threats to this IBA are associated with the forestry plantations and comprise invasive alien vegetation (especially Pinus pinaster), increased fire risk and habitat transformation. Alien vegetation burns more frequently than fynbos and at higher temperatures, so fires on alien-infested land burn more often and more intensely, and potentially in the incorrect season. Alterations to the fire regime are one of the most significant threats to this IBA, as they can lead to a loss of certain plant species from the IBA's vegetation. It is difficult to quantify the impact of changes in the composition and quality of habitats resulting from fire, but they do reduce food availability and overall habitat quality for some trigger species. Invasive alien species include pine trees Pinus pinaster, which were and still are planted for timber, and Eucalyptus and Hakea species, as well as Port Jackson Acacia saligna, black wattle A. mearnsii and Australian blackwood A. melanoxylon. Bugweed Solanum mauritianum, which is dispersed widely by African Olive Pigeon Columba arquatrix, and American bramble Rubus cuneiforme are emerging as additional invasive species. Alien vegetation can invade and transform indigenous fynbos habitat, leading to a reduction in its extent and/or quality. The importance of these mountains for both water management and biodiversity conservation cannot be over-emphasised. The Langeberg is the source of many of the freshwater systems in the southern Cape, including those of the Gourits and Duiwenhoks rivers, and forms the major part of the Vetrivier, Kruisrivier, Goukou and Breërivier catchments. It would be desirable to link the three formally protected areas within the IBA via corridors.

    Agricultural land is expanding up the slopes of the mountain ranges; as temperatures increase and space for planting diminishes, some crops, such as honeybush tea, are planted higher up slopes, transforming the natural habitat. There are minor development pressures on the mountain land, such as ecotourism, 4x4 routes or adventure sports courses, but they are not of a large enough scale to transform habitat. They do, however, reduce the extent of pristine habitat in the buffer zones and at the margins of the IBA. An additional issue is the lack of accurate data on the numbers of certain trigger bird species. This is the case for all the Cape Fold Mountains IBAs and it is suggested that a monitoring programme could be instituted with CapeNature to bridge this information gap.

    Conservation action

    In 1928 the 129-ha Marloth Nature Reserve was set aside behind Swellendam for the local residents. In 1981, in accordance with the policy of the former DFEC to extend reserves for more effective management, the reserve was enlarged to more than 11 000 ha. Further east, Boosmansbos Wilderness Area (14 200 ha), which forms part of the Grootvadersbosch State Forest, was proclaimed in 1978. Similarly, Garcia State Forest (12 000 ha) is managed principally to protect the water catchment area. These areas are now under the ownership and management of CapeNature and are declared provincial nature reserves, mountain catchment areas (private and State-owned) and old State forest reserves.

    The provincial CapeNature reserves (Marloth Nature Reserve, Grootvadersbosch Nature Reserve and Boosmansbos Wilderness Area) have complex management plans and the resources to implement them, so the conservation actions at these sites are comprehensive. However, the responsibility for the mountain catchment and State forest areas is uncertain and thus little or no direct management occurs. The conservation actions on the private land vary widely from landowner to landowner, depending on their attitude towards nature conservation and to what extent they need the land to provide income.

    The CapeNature management plans cover all aspects of the management of the nature reserves, and even buffer areas around certain sites. However these reserves do not constitute the entire IBA and a lack of management planning and implementation at sites adjacent to the reserves is a threat to the future of this IBA. CapeNature management plans are currently being revised and processed in accordance with NEM:PAA and will ultimately be signed off by the relevant ministers. The plans detail the implementation of a number of different activities, including the eradication and control of alien vegetation, fire-fighting and fire prevention protocols, the prevention of soil erosion, the maintenance of trails and other infrastructure, law enforcement and biodiversity monitoring.

    Related webpages

    http://www.capenature.co.za/reserves/grootvadersbosch-nature-reserve/

    http://www.capenature.co.za/reserves/boosmansbos-wilderness-area/

    http://www.capenature.co.za/reserves/marloth-nature-reserve/

    Contact

    If you have any information about the IBA, such as a new threat that could impact on it, please send an e-mail to iba@birdlife.org.za or call BirdLife South Africa +27 (11) 789 1122.

    Page last updated

    Wednesday, 04 February 2015

    Further Reading

    Armstrong AJ, Van Hensbergen HJ. 1995. Effects of afforestation and clearfelling on birds and small mammals at Grootvadersbosch, South Africa. South African Forestry Journal 174(1): 17–21.

    Cowling RM. (ed). 1992. The ecology of fynbos: nutrients, fire and diversity. Cape Town: Oxford University Press.

    McDonnald DJ. 1993a. The vegetation of the southern Langeberg, Cape Province. 1. The plant communities of the Boosmansbos Wilderness Area. Bothalia 23(1): 129–151.

    McDonnald DJ. 1993b. The vegetation of the southern Langeberg, Cape Province. 2. The plant communities of the Marloth Nature Reserve. Bothalia 23(1): 153–174.

    McDonnald DJ. 1993c. The vegetation of the southern Langeberg, Cape Province. 3. The plant communities of the Bergfontein, Rooiwaterspruit and Phesantefontein areas. Bothalia 23(1): 239–263.

    McDonnald DJ. 1995. Phytogeography, endemism and diversity of the fynbos of the southern Langeberg. PhD thesis, University of Cape Town, South Africa.

    Richardson DM, Macdonald IAW, Holmes PM, Cowling RM. 1992. Plant and animal invasions. In: Cowling RM (ed.), The ecology of fynbos: nutrients, fire and diversity. Cape Town: Oxford University Press. pp 271–309.

    Van Wilgen BW, Bond WJ, Richardson DM. 1992. Ecosystem management. In: Cowling RM (ed.), The ecology of fynbos: nutrients, fire and diversity. Cape Town: Oxford University Press. pp 345–372.

Read 13140 times Last modified on Thursday, 26 November 2015 08:02
blog