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IN THE LAND OF THE BARRIER OF SPEARS

IN THE LAND OF THE BARRIER OF SPEARS. The Drakensberg Mountains of South Africa and Lesotho John and Hilary Birks. The Barrier of Spears. Introduction Names Location Geology and topography Climate Land-use and fire Vegetation Botanical Features State of knowledge Richness Endemics

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IN THE LAND OF THE BARRIER OF SPEARS

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  1. IN THE LAND OF THE BARRIER OF SPEARS The Drakensberg Mountains of South Africa and Lesotho John and Hilary Birks

  2. The Barrier of Spears Introduction Names Location Geology and topography Climate Land-use and fire Vegetation Botanical Features State of knowledge Richness Endemics Altitudinal Zonation Montane belt Subalpine belt Alpine belt The Big Taxonomic Headache – Helichrysum! Why so Rich? Conservation and the Future

  3. INTRODUCTIONNames Barrier of Spears or 'a row of spears pointing upwards' – Zulu name (Quathlamba or uKhahlamba) for the jagged spires of the Drakensberg Mountains

  4. Highest mountain of the 'Great Escarpment' in southern Africa rising to 3000 m, with the highest peak at Thabana Ntlenyma at 3482 m, the highest mountain in Africa south of Kilimanjaro (Tanzania). 'Great Escarpment' lies parallel to the south-eastern coast of South Africa from the Eastern Cape extending into Zimbabwe. Separates southern Africa from the interior plateau. Great Escarpment initiated during the break-up of Gondwanaland.

  5. Called Drakensberg ('dragon mountain') by early Dutch settlers (Voortrekkers) because of its resemblance to the ridges of a dragon's back. Steep ridges of its dragon-like back are formed by headwater erosion of rivers that separate the Highveld Plateau from the coastal lowlands of southern Africa. Less likely, the name may be derived from an insignificant peak called Drakensberg or Dragon's Rock. Part of KwaZulu-Natal of South Africa and Lesotho (= Mountain Kingdom, Basutoland).

  6. Cathkin Peak The Sentinel

  7. The Sentinel The Amphitheatre

  8. Location

  9. 28º30' – 31º20'S, 27º00' – 29º40'E About 40 000 km2 1800 – 3482 m Drakensberg Alpine Centre or Region

  10. Geology and topography Much of the area lies on the high plateau above 3000 m of Lesotho bounded by the Drakensberg escarpment to the east, north, and south extending into South Africa. Mostly formed of basalt lavas, up to 1400 m thick and forming sheer cliffs up to 460 m high. Underlain by Clarens sandstone (up to 2500 m), often undercut with caves with many Bushman paintings.

  11. North Drakensberg from near Rhodes • North Drakensberg and Amphitheatre • Clarens Sandstone, Royal Natal National Park • North Drakensberg and Devil's Tooth • Maletsunyre Waterfall, Lesotho

  12. Thought to be some of the oldest mountains in the world. In centre of continent rather than at edges of continents. At edge of the interior plateau of southern Africa. With break-up of Gondwanaland about 200 million years ago, lavas flowed through fissures and capped the sedimentary sandstones for about 50 million years from early Jurassic to the Cretaceous.

  13. Soils are thin on the basalt plateau; almost non-existent on the escarpment; deep on the Clarens sandstone. Soil pH about 5.5 – 6.0, very deficient in N and P, high levels of exchangeable Al. Summit soils become wet and water-logged in summer. In winter subject to freezing at night and thawing by day. Ice-heaved stones, stone polygons, solifluction terraces, frost hummocks (thurfur) on the high plateau.

  14. Sani Top Flats, 2900 m • Black Mountain, 3100 m

  15. Climate Main feature is summer rainfall

  16. Temperate climate with summer rainfall. Mean temperature of warmest month at 3050 m ca. 10.9ºC. Mean annual rainfall 635 mm in west to 2000 mm on main plateau. Diminishes in the east due to the rain-shadow effect. Alpine belt (above 2750 m) is severe with a mean annual temperature of 5.7ºC. Highest recorded is 31ºC (January 1972), coldest -20.4ºC (June 1967). Half year, minimum temperatures are below 0ºC.

  17. Snow cover – four months or longer in protected gullies or south-facing slopes. Frost daily in winter. Mist common throughout year. Summit winds important. Very high winds in spring and summer, especially in afternoons and evenings. Summer heavy thunderstorms characteristic.

  18. 3050 m altitude • Precipitation exceeds temperature: climate is 'humid' • Winter has low rainfall and low temperatures

  19. Temperature chart for 3050 m altitude Mean annual temperature = 5.7ºC; 183 days with frost

  20. Land-use and Fire • Fire is dominant ecological factor • Natural caused by lightning usually in spring or when boulders roll down and collide with other boulders to produce sparks that ignite dry grass swards. • Bushmen burning to produce new grass growth that would attract game for hunting. • Bantu and European farmers burnt grasslands to provide winter grazing for sheep and cattle. • Natural lightning ground-flash density of 12 - 14 flashes per km2 per year.

  21. Alpine areas burnt by Lesotho people on fairly regular annual basis. Summer grazing by cattle, horses, sheep, and goats. Extreme overstocking of grazing animals in Lesotho (300% overstocking). Severe soil erosion and inwashing of silt. Large areas in Lesotho flooded to provide Lesotho Highlands Water Project for South Africa. Value about $38 million per year by 2030. Natal Drakensberg produces water worth about $929 million per year for South Africa.

  22. Maletsunyre Gorge and Fields, 2400 m • Lesotho Huts, Semonkang, 2100m • Lesotho Horsemen • Lesotho Horsemen and pack ponies • Basuto Village • Village chiefs • Hilary and (other!) chiefs • Musicians • Semonkong 'hotel' hut

  23. Vegetation Biomes of southern Africa – all in 'grassland' biome

  24. In Afromontane and Afroalpine phytogeographical region

  25. Montane belt 1280 – 1830 m Podocarpus latifolius forest Subalpine belt 1830 – 2750 m Fynbos (= species-rich heath); now mainly grassland Alpine belt 2750 – 3484 m Erica – Helichrysum 'tundra' heath and grasslands

  26. Debate about what is the 'alpine belt'. Defined climatically rather than floristically at 2750 – 2865 m elevation. Called Afroalpine region, whereas lower levels above 1800 m are Afromontane region. No real change, gradual floristic changes, but there is the big escarpment in the way!

  27. Extent of alpine belt above 2750 m

  28. BOTANICAL FEATURESState of Knowledge, Richness, and Endemics About 2200 species, 4 endemic genera, 400 endemic species (ca. 18%) Largest families • Asteraceae 5. Cyperaceae • Scrophulariaceae 6. Orchidaceae • Poaceae 7. Ericaceae • Iridaceae

  29. Life-study of Olive Hilliard and Bill Burtt, now retired but still very active at Royal Botanic Gardens Edinburgh.

  30. September 2003

  31. Visited Drakensberg with Alpine Garden Society 5 – 20 January 2002 with David McDonald and John Grimshaw. Saw about 700 species – richest area we have visited! Great show of colourful bulbous plants, orchids, and composites.

  32. Has strong affinities with the Cape Floristic Region as well as the Afromontane Region. Weak links with the Afroalpine Region of East Africa. 88 genera in Drakensberg have their centres of diversity in the Cape Floristic Region (e.g. Erica, Protea, Helichrysum).

  33. ALTITUDINAL ZONATION

  34. Montane Belt 1280 – 1830 m (lowest visited 1750 m) Podocarpus latifolius forest Protea savannah Grassland – C4 grasses (? result of fire) Cliffs and rock outcrops

  35. Royal Natal National Park Podocarpus forest, 1750 m • Thamocalamus tesselatus bamboo • Peperomia retusa Piperaceae • Zantedeschia albomaculata Arum lily Araceae • Carex zulensis 16 species • Begonia sutherlandii • Impatiens hochstetteri – Old World Tropics • Steptocarpus gardenii Gesneriaceae 200 or 1 spp • Stenoglottis fimbriata Orchidaceae • Pteris cretica • Gleichenia umbraculifer S. Hemisphere • Adiantum poiretii • Elaphoglossum drakensbergensis – tropical America, 400 spp • Harveya speciosa Parasitic Scrophulariaceae Africa

  36. Golden Gate and scrub, 1895 m • Protea roupelliae • Cyathea dregei • Agapanthus campanulatus Liliaceae 10 spp. S. Africa • Agapanthus campanulatus • Gladiolus crassifolia • Berkheya rapontica 75 spp. S. Africa • Leonotis leonuris Labiatae 40 spp. Africa • Phygelius capensis 2 spp. • Zaluzianskya microsiphon 40 spp. Africa • Sopubia cana 50 spp. Africa, Himalaya, Formosa, Vietnam • Striga bilobata Hemiparasite, 40 spp. Africa, Asia, Australia • Scilla nervosa 40 spp.

  37. Ophioglossum polyphyllum • Drosera natalensis 125 spp. 18 in SA, mainly NZ or Australia • Brunsvigia radulosa Africa, 20 spp. Amaryllidaceae • Waterfall, Royal Natal National Park, 18450 m • Gladiolus microcarpus 150 spp. 100 in S. Africa • Hilary and Galtonia regalis 4 spp. Liliaceae • Galtonia viridflora • Royal Natal National Park sandstone cliffs, 1800 m • Asplenium aethiopicum • Cheilanthes multifida • Crassula umbraticola 300 spp. 280 in S. Africa • Crassulapellucida ssp. brachypetala

  38. Subalpine Belt 1830 – 2750 m Protea savannah Grassland – C4 grasses (? result of fire) Mires, flushes. and 'sponge' bogs Cliffs and rock outcrops

  39. Oxbow, Lesotho 2500 m • Protea roupelliae 115 spp. 80 in S. Africa, W Cape • Protea dracomontana • Protea subvestita • Dioscorea sylvatica Dioscoreaveae 600 spp. semi-tropical, 20 in SA • Crassula sarocaulis • Bowkeria verticillata Shrub Scrophulariaceae • Erica drakensbergensis 650 spp. 600 in SA (Cape) • Dierama dracomontanum 75 spp. Africa Iridaceae • Dieranam robustum • Naude's Nek 2400 m • Moraea alticola 90 spp. 75 in S. Africa • Moraea alpina • Sandersonia aurantiaca Liliaceae Christmas Bells • Gladiolus longicollis

  40. Hesperantha grandiflora 60 spp. Iridaceae • Watsonia densiflora 70 spp. S Africa Iridaceae • Watsonia pillandsi • Androcymbium striatum 30 spp. 3 in Mediterranean • Croscosmia pearsii Iridaceae Endemic 9 spp. • Dianthus basuticus • Naude's Nek Cliffs 2550 m • Nerine bowdenii 22 spp. S Africa only Amaryllidaceae • Ranunculus baurii • Kniphofia ritualis 70 spp. 45 in S Africa Liliaceae • Kniphofia triangularis • Craterocapsa congesta 4 spp. S Africa • Wahlenbergiacuspidata 200 spp. mainly S Africa • Chironiaperglerae Gentianaceae 30 spp. Africa • Cephalaria oblongifolia Dipsaceae Mediterranean, Asia, Cape • Harpachloa falix Caterpillar Grass Monotypic

  41. Hypoxis rigidula Hypoxidaceae 100 spp. 50 in S Africa • Xerophyta viscida Velloziaceae Africa, Arabia 28 spp. • Geranium multisectum • Monsonia brevirostrata Geraniaceae 25 spp. Africa • Pelargonium alchemilloides 250 spp. S Africa • Lotononis sericophylla 100 spp. Africa, India • Lotononis pulchra • Sutherlandia montana 6 spp. S Africa • Pachycaprus dealbatus Ascelepiadaceae 50 spp. 24 in S Africa • Pachycarpus campanulatus 50 spp. 24 in S Africa • Selago cf. flanaganii 150 spp. S Africa • Jamesbrittenia pristisepala 83 spp. 74 S Africa • Diascia vigilis 30 spp. S Africa • Cycnium racemosum 40 spp. Africa Hemi-parasite • Alectra capensis Hemi-parasite 40 spp. S America, Asia, 10 in SA

  42. Harveya leucopharynx Parasite 40 spp. 25 in S Africa • Rhodes – Naude's Nek 2400 m • Berkheya cirsiifolia • Berkheya purpurea • Haplocarpha scaposa 8 spp. Africa • Inulanthera calva 10 spp. Africa • Senecio macrospermus 2000 spp. 350 in S Africa 80 in area • Senecio isatidens • Senecio gramineus • Senecio macrocephalus • Senecio polyodon • Naude's Nek grassland 2800 m • Hirpicum armerioides 12 spp. Africa • Gazania krebsiana 16 spp. S Africa • Pterygodium magnum 14 spp.

  43. Corycium nigrescens 15 spp. • Satyrium neglectum 100 spp. • Schizochilus flexuosus 10 spp. • Holothrix scopularia 35 spp. • Disa nervosa 130 spp. Africa • Disa stachyoides • Disa crassicornis • Disa thodei • Disa fragrans • Disa versicolor • Eucomis autumnalis 10 spp. Africa Liliaceae • Eucomis bicolor • Eucomis bicolor • Eucomis schiffii • Bulbine capitata 35 spp. mainly Cape • Meadow near Semonkong 2200 m

  44. Pharcocapnos pruinosus Fumariaceae 3 spp. Africa • Argemone ochroleuca Papaveraceae • Papaver aculeatum 100 spp. 1 in Africa • Kniphofia caulescens Liliaceae • Kniphofia caulescens • Kniphofia caulescens sun-birds • Carex cognata • Cyperus spaerocephalus 600 spp. 50 in Africa • Sponge bogs, Black Mountain 2800 m • Eriocaulon dregei var. sonderiana 400 spp. 12 in Africa • Anagallis huttonii 30 spp. 2 in S Africa • Utricularia livida 30 spp. 15 in S Africa • Crassula papillosa • Limosella major 18 spp. 6 in S Africa • Gunnera perpensa Gunneraceae 50 spp. 1 in S Africa • Sani Cliffs 1900 m

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