IN THE LAND OF THE BARRIER OF SPEARS

The Drakensberg Mountains of South Africa and Lesotho

John and Hilary Birks

The Barrier of SpearsIntroduction

Names Location Geology and topographyClimate Land-use and fire Vegetation

Botanical Features

State of knowledge Richness Endemics

Altitudinal ZonationMontane belt Subalpine belt Alpine belt

The Big Taxonomic Headache – Helichrysum!

Why so Rich?

Conservation and the Future

INTRODUCTIONNames

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

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.

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).

Cathkin Peak

The Sentinel

The Sentinel The Amphitheatre

Location

28º30' – 31º20'S, 27º00' – 29º40'E

About 40 000 km2

1800 – 3482 m

Drakensberg Alpine Centre or Region

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.

1. North Drakensberg from near Rhodes

2. North Drakensberg and Amphitheatre

3. Clarens Sandstone, Royal Natal National Park

4. North Drakensberg and Devil's Tooth

5. Maletsunyre Waterfall, Lesotho

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.

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.

6. Sani Top Flats, 2900 m

7. Black Mountain, 3100 m

Climate

Main feature is summer rainfall

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.

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.

3050 m altitude

(1)Precipitation exceeds temperature: climate is 'humid'

(2)Winter has low rainfall and low temperatures

Temperature chart for 3050 m altitude

Mean annual temperature = 5.7ºC; 183 days with frost

Land-use and Fire

Fire is dominant ecological factor

1. 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.

2. 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.

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.

8. Maletsunyre Gorge and Fields, 2400 m

9. Lesotho Huts, Semonkang, 2100m

10. Lesotho Horsemen

11. Lesotho Horsemen and pack ponies

12. Basuto Village

13. Village chiefs

14. Hilary and (other!) chiefs

15. Musicians

16. Semonkong 'hotel' hut

Vegetation

Biomes of southern Africa – all in 'grassland' biome

In Afromontane and Afroalpine phytogeographical region

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

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!

Extent of alpine belt above 2750 m

BOTANICAL FEATURESState of Knowledge, Richness, and Endemics

About 2200 species, 4 endemic genera, 400 endemic species (ca. 18%)

Largest families

1. Asteraceae 5. Cyperaceae

2. Scrophulariaceae 6. Orchidaceae

3. Poaceae 7. Ericaceae

4. Iridaceae

Helichrysum (85) Argyrolobium (18) (Fabaceae)

Senecio (76) Moraea (16) (Iridaceae)

Erica (25) Thesium (15)

Disa (24) (Orchidaceae)

Hypoxis (15) (Hypoxidaceae)

Selago (19) (Scrophulariaceae)

Kniphofia (15) (Liliaceae)

Crassula (19)

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

September 2003

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.

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).

ALTITUDINAL ZONATION

Montane Belt

1280 – 1830 m (lowest visited 1750 m)

Podocarpus latifolius forest

Protea savannah

Grassland – C4 grasses (? result of fire)

Cliffs and rock outcrops

17. Royal Natal National Park Podocarpus forest, 1750 m

18. Thamocalamus tesselatus bamboo

19. Peperomia retusa Piperaceae

20. Zantedeschia albomaculata Arum lily Araceae

21. Carex zulensis 16 species

22. Begonia sutherlandii

23. Impatiens hochstetteri – Old World Tropics

24. Steptocarpus gardenii Gesneriaceae 200 or 1 spp

25. Stenoglottis fimbriata Orchidaceae

26. Pteris cretica

27. Gleichenia umbraculifer S. Hemisphere

28. Adiantum poiretii

29. Elaphoglossum drakensbergensis – tropical America, 400 spp

30. Harveya speciosa Parasitic Scrophulariaceae Africa

31. Golden Gate and scrub, 1895 m

32. Protea roupelliae

33. Cyathea dregei

34. Agapanthus campanulatus Liliaceae 10 spp. S. Africa

35. Agapanthus campanulatus

36. Gladiolus crassifolia

37. Berkheya rapontica 75 spp. S. Africa

38. Leonotis leonuris Labiatae 40 spp. Africa

39. Phygelius capensis 2 spp.

40. Zaluzianskya microsiphon 40 spp. Africa

41. Sopubia cana 50 spp. Africa, Himalaya, Formosa, Vietnam

42. Striga bilobata Hemiparasite, 40 spp. Africa, Asia, Australia

43. Scilla nervosa 40 spp.

44. Ophioglossum polyphyllum

45. Drosera natalensis 125 spp. 18 in SA, mainly NZ or Australia

46. Brunsvigia radulosa Africa, 20 spp. Amaryllidaceae

47. Waterfall, Royal Natal National Park, 18450 m

48. Gladiolus microcarpus 150 spp. 100 in S. Africa

49. Hilary and Galtonia regalis 4 spp. Liliaceae

50. Galtonia viridflora

51. Royal Natal National Park sandstone cliffs, 1800 m

52. Asplenium aethiopicum

53. Cheilanthes multifida

54. Crassula umbraticola 300 spp. 280 in S. Africa

55. Crassula pellucida ssp. brachypetala

Subalpine Belt

1830 – 2750 m

Protea savannah

Grassland – C4 grasses (? result of fire)

Mires, flushes. and 'sponge' bogs

Cliffs and rock outcrops

56. Oxbow, Lesotho 2500 m

57. Protea roupelliae 115 spp. 80 in S. Africa, W Cape

58. Protea dracomontana

59. Protea subvestita

60. Dioscorea sylvatica Dioscoreaveae 600 spp. semi-tropical, 20 in SA

61. Crassula sarocaulis

62. Bowkeria verticillata Shrub Scrophulariaceae

63. Erica drakensbergensis 650 spp. 600 in SA (Cape)

64. Dierama dracomontanum 75 spp. Africa Iridaceae

65. Dieranam robustum

66. Naude's Nek 2400 m

67. Moraea alticola 90 spp. 75 in S. Africa

68. Moraea alpina

69. Sandersonia aurantiaca Liliaceae Christmas Bells

70. Gladiolus longicollis

71. Hesperantha grandiflora 60 spp. Iridaceae

72. Watsonia densiflora 70 spp. S Africa Iridaceae

73. Watsonia pillandsi

74. Androcymbium striatum 30 spp. 3 in Mediterranean

75. Croscosmia pearsii Iridaceae Endemic 9 spp.

76. Dianthus basuticus

77. Naude's Nek Cliffs 2550 m

78. Nerine bowdenii 22 spp. S Africa only Amaryllidaceae

79. Ranunculus baurii

80. Kniphofia ritualis 70 spp. 45 in S Africa Liliaceae

81. Kniphofia triangularis

82. Craterocapsa congesta 4 spp. S Africa

83. Wahlenbergia cuspidata 200 spp. mainly S Africa

84. Chironia perglerae Gentianaceae 30 spp. Africa

85. Cephalaria oblongifolia Dipsaceae Mediterranean, Asia, Cape

86. Harpachloa falix Caterpillar Grass Monotypic

87. Hypoxis rigidula Hypoxidaceae 100 spp. 50 in S Africa

88. Xerophyta viscida Velloziaceae Africa, Arabia 28 spp.

89. Geranium multisectum

90. Monsonia brevirostrata Geraniaceae 25 spp. Africa

91. Pelargonium alchemilloides 250 spp. S Africa

92. Lotononis sericophylla 100 spp. Africa, India

93. Lotononis pulchra

94. Sutherlandia montana 6 spp. S Africa

95. Pachycaprus dealbatus Ascelepiadaceae 50 spp. 24 in S Africa

96. Pachycarpus campanulatus 50 spp. 24 in S Africa

97. Selago cf. flanaganii 150 spp. S Africa

98. Jamesbrittenia pristisepala 83 spp. 74 S Africa

99. Diascia vigilis 30 spp. S Africa

100. Cycnium racemosum 40 spp. Africa Hemi-parasite

101. Alectra capensis Hemi-parasite 40 spp. S America, Asia, 10 in SA

102. Harveya leucopharynx Parasite 40 spp. 25 in S Africa

103. Rhodes – Naude's Nek 2400 m

104. Berkheya cirsiifolia

105. Berkheya purpurea

106. Haplocarpha scaposa 8 spp. Africa

107. Inulanthera calva 10 spp. Africa

108. Senecio macrospermus 2000 spp. 350 in S Africa 80 in area

109. Senecio isatidens

110. Senecio gramineus

111. Senecio macrocephalus

112. Senecio polyodon

113. Naude's Nek grassland 2800 m

114. Hirpicum armerioides 12 spp. Africa

115. Gazania krebsiana 16 spp. S Africa

116. Pterygodium magnum 14 spp.

117. Corycium nigrescens 15 spp.

118. Satyrium neglectum 100 spp.

119. Schizochilus flexuosus 10 spp.

120. Holothrix scopularia 35 spp.

121. Disa nervosa 130 spp. Africa

122. Disa stachyoides

123. Disa crassicornis

124. Disa thodei

125. Disa fragrans

126. Disa versicolor

127. Eucomis autumnalis 10 spp. Africa Liliaceae

128. Eucomis bicolor

129. Eucomis bicolor

130. Eucomis schiffii

131. Bulbine capitata 35 spp. mainly Cape

132. Meadow near Semonkong 2200 m

133. Pharcocapnos pruinosus Fumariaceae 3 spp. Africa

134. Argemone ochroleuca Papaveraceae

135. Papaver aculeatum 100 spp. 1 in Africa

136. Kniphofia caulescens Liliaceae

137. Kniphofia caulescens

138. Kniphofia caulescens sun-birds

139. Carex cognata

140. Cyperus spaerocephalus 600 spp. 50 in Africa

141. Sponge bogs, Black Mountain 2800 m

142. Eriocaulon dregei var. sonderiana 400 spp. 12 in Africa

143. Anagallis huttonii 30 spp. 2 in S Africa

144. Utricularia livida 30 spp. 15 in S Africa

145. Crassula papillosa

146. Limosella major 18 spp. 6 in S Africa

147. Gunnera perpensa Gunneraceae 50 spp. 1 in S Africa

148. Sani Cliffs 1900 m

149. Cotyledon orbiculata var. oblongata Crassulacea 40 spp. Africa

150. Aloe aristata Liliaceae 300 spp. 145 in S Africa

151. Aloe polyphylla

152. Aloe polyphylla

153. Euphorbia clavarioides 2000 spp. 200 in A Africa

154. Erica reenensis

155. Steptocarpus pusillus

156. Holothrix incurva Orchidaceae

157. Hemanthus humilis ssp. hirsutus Amaryllidaceae 21 spp. SA

158. Cyrtanthus epiphyticus Amaryllidaceae 50 spp. Africa

159. Sebaea natalensis 100 spp. 45 in S Africa Gentianaceae

160. Polystichum monticola

161. Ceterach cordatum

162. Cheilanthes hirta

163. Dryopteris athamantica

164. Mohria hirsuta Schizaeaceae

Alpine Belt

2750 – 3484 m

Alpine heath 'tundra'

Alpine grassland and summit areas

Mires and flushes

Aquatic and stream-side communities

Cliffs

165. Ben MacDhui 3001 m

166. Black Mountain, Lesotho 3220 m

167. Macowania sororis 11 spp. 9 in Eastern S Africa

168. Euryops montanus 98 spp. S Africa

169. Euryops tysonii

170. Chrysocoma tenuifolia 18 spp. 12 in S Africa

171. Erica frigida

172. Helichrysum marginatum

173. Helichrysum milfordiae

174. Sentinel Plateau 3010 m

175. Albuca humilis 75 spp. mainly S Africa

176. Crassula natalensis

177. Massonia cf. echinata Liliaceae

178. Lotononis galpinii

179. Jamesbrittenia jurassica

180. Selago galpinii

181. Sutera breviflora 130 spp. Africa 1 in Canary Isles

182. Diascia fetcaninesis

183. Luzula africana 80 spp. 1 in S Africa

184. Cerastium capense 60 spp. 5 in S Africa

185. Polygala gracilenta 600 spp. 100 in S Africa

186. Alchemilla natalensis 250 spp. 20 in S Africa

187. Hesperantha radiata Iridaceae 60 spp Africa

188. Asclepias humilis

189. Aster eruciformis 250 spp. few in S Africa

190. Felicia rosulata 80 spp. mainly S Africa

191. Delosperma congesta Mesembryanthemaceae 140 spp.

192. Delosperma lineare

193. Romulea thodei Iridaceae 90 spp. 70 in S Africa

194. Manulea parviflora Scophulariacea 60 spp. S Africa

195. Sentinel Summit 3010 m

196. Kniphofia fluviatilis

197. Sentinel Summit pools 3000 m

198. Juncus dregeanus 300 spp. 25 in S Africa

199. Cotula lineariloba 90 spp. 40 in s Africa

200. Alepidea woodii Umbelliferae 25 spp. all S Africa

201. Wurmbea elatior Liliaceae 25 spp. Africa and Australia

202. Lobelia erinus Campanulaceae 300 spp. 70 in S Africa

203. Rhodohypoxis baurii var. baurii Hypoxidaceae 6 spp. SA only

204. Rhodohypoxis baurii var. confecta

205. Crassula drakensbergensis

206. Isolepis fluitans 40 spp. 30 in S Africa

207. Aponogeton junceum Aponogetonaceae 25 spp. Africa, Asia, Australia 5 in S Afric

208. Lagarosiphon muscoides Hydrocharitaceae 16 spp. 5 in S Africa

209. Sani Top 3100 m

210. Ben MacDhui 3001 m

212. Devil's Tooth, Sentinel

213. Teguela Falls

214. Steel ladders, Sentinel Escarpment

215. Gladiolus flanaganii

216. Euryops evansii

217. Woodsia montevidensis 40 spp. 1 in S Africa

218. Diascia cordata

219. Diascia stricta

220. Nemesia rupicola 70 spp Africa

221. Crassula setulosa var. curta

222. Glumicalyx goseloides 6 spp. Drakensberg only

223. Tiffendall Ski Resort 2873 m

224. Sani Pass Transport

225. Sani Chalet 2900 m

THE BIG TAXONOMIC HEADACHE – HELICHRYSUM!

Mainly African genus, some in Mediterranean Europe, SW Asia, S India, Sri Lanka, Australia

600 species, 245 in South Africa, 85 in Drakensberg, found 60

Herbs, climbers, low shrubs

Grasslands, woodland, scrub, cliffs, screes, wind-blasted open grassland, rock outcrops, mesic areas

226. Helichrysum montanum

227. H. marginatum

228. H. milfordiae

229. H. pagophilum

230. H. vernum

231. H. bellidiastrum

232. H. tenuifolium

233. H. witbergense

234. H. trilineatum

235. H. ecklonis

236. H. confertiflium

237. H. aureoniteus

238. H. aureum

239. H. albo-aureum

240. H. herbaceum

241. H. flanaganii

242. H. panduratum

243. H. acutatum

244. H. krokii

245. H. hypoleucum – climber

246. H. drakensbergense

247. Hilary and H. montanum

WHY SO RICH?

Drakensberg is an international 'hot-spot' of plant biodiversity, not only of vascular plants (2200 species) but also of bryophytes (over 1000 species).

Nothing known about vegetational history.

Endemics (18%) are mixture of palaeo-endemics and neo-endemics.

Some major disjunctions (e.g. Macowania – Drakensberg, Ethiopia, Yemen; Thamnocalamus – Drakensberg, east Asia).

Small area ca. 40 000 km2 ( Belgium)

Possible contributory factors for high diversity

1. Centuries of low-intensity ('intermediate') disturbance from Bush-people.

2. Soils are infertile but not strongly acid and high in Al.

3. Mixture of floristic elements (Cape, Afromontane, etc.)

4. Altitudinal range of over 2000 m.

5. Climatic gradients within 1500 m from alpine periglacial features to lush Podocarpus forest with Streptocarpus.

6. Topographical diversification into distinct valleys and watersheds, favouring isolation of species.

7. Fine-scale topographical variation with springs, flushes, soaks, mires, etc. within well-drained grassland.

CONSERVATION AND THE FUTURE

3% in Lesotho and 97% in Natal Drakensberg are protected as Nature Reserves, National Parks, and Wilderness Areas.

Major threats by overstocking and soil erosion in Lesotho.

Also threats from invasive exotic plants and clearance for crops in an area very poorly suited to arable agriculture in Lesotho.

At present alpine areas (nearly all in Lesotho) are unprotected.

Urgent need for whole areas as Biosphere Reserve or World Heritage Site.

But conservation is not the major problem facing southern Africa……

Besides problems of overstocking, soil erosion, and hydroelectric development in Lesotho, major threat is from 'global warming'.

McDonald et al. (2002) defined climate envelopes for 16 alpine species today, to define the modern 'alpine' climate.

Predicted the extent of the 'alpine' climate under future scenario of IPCC for 2150.

See major reduction in 'alpine' climate, confined to the few highest areas. Would become very fragmented. Major loss of species.

Much reduced snow cover, loss of available water. Major ecological and economic effects.

248.David MacDonald and John Grimshaw

249.Amphitheatre, Witsishoek 04:30 hours

Thanks

John Grimshaw Bill Burtt

David McDonald Olive Hilliard

Else Pooley Cathy Jenks