Taxon turnover in Odonata across a 3000 m altitudinal gradient in southern Africa
Odonatologica , Volume 18 - Issue 3 p. 263- 274
In Natal, South Africa (30°E, 29°S), the land elevation ranges from 0m a.s.l. to 3000 m a.s.l. along an E-W 200 km transect. The area is in Zonobiome 11. It is strongly modified by a montane climate at the higher elevations, and has a subtropical/ tropical climate at sea level. A total of 117 spp. was recorded across this transect. The narrow coastal plain (< 200 m a.s.l.) supported 86 spp. From 200-1400 m elevation there was fairly constant species richness of about 43 spp. dropping to 4 spp. between 2400-3000 m. The Libellulidae accounted for 44% of all spp., and declined from 50% in the 0-200 m belt to 25% at 2800-3000 m. The Coenagrionidae accounted for 24% and remained at this level across the whole 3000 ra range. The Aeshnidae accounted for 9% and remained fairly constant at about that level up to 1600 m, thereafter increasing to reach 35% at 3000 m. The Gomphidae accounted for 8%, remaining at that level from 0-1400 m, declining to zero at 1600 m. The Lestidae remained fairly constant at about 5% from 0-1600 m, above which they disappeared. The Chlorolestidae ranged from 1% at 0 m increasing steadily to 25% above 2400 m. The Chlorocyphidae, Calopterygidae, Protoneuridae and the Corduliidae are consistently rare, low-altitude families, while the Platycnemididae is a rare middle-altitude family. The Lestidae, Libellulidae, Corduliidae and Gomphidae are moderate-climate families, while the Coenagrionidae is equally tolerant of all climatic conditions. -The Aeshnidae tolerate the harsher climate of the high altitudes, and the Gondwana relic family Chlorolestidae is a conspicuous feature of the very high altitudes.
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