Included here is the Guayana Highlands situated east of the Andes. The area covers much of southern Venezuela and in addition to Guayana it extends marginally into Brazil and Colombia. Of considerable interest are the many spectacular tableaux (tepuis), which were the inspiration behind the legendary 'Lost World' of Sir Arthur Conan Doyle (1912). The indigenous name for these plateaux is tepuis and the biogeographical area comprising all of the tepui is called Pantepui. Many are graced with spectacular waterfalls including Angel Falls - the highest waterfall in the world at 979 m. The highest tepui is Pico da Nebline at 3,014 m. Others include Pico Phelps (2992 m), Roraima-tepui (2810 m) and Cerro Marahuaka (2800 m). They are relicts of a former, ancient sandstone peneplain created between 1.6 and 1 billion years ago, and it is thought that the sand came from the easterly uplands of the ancient Gondwana continent where it was deposited in a shallow sea or large inland lake.

Guayana Highlands Shrublands

In these uplands shrubby growth forms have attained an unparalleled degree of physiognomic and floristic diversity. On the extensive plateaus that surround the Auyan-tepur, for example, there is an impressive mixture of lowland and upland species from about 400 m upwards. Among the dominants are various endemic species such as Blepharandra fimbriata (Malpighiaceae), Bonnetia sessilis (Theaceae), Humiria balsamifera (Humiriaceae), and Platycarpum rhododactylum (Rubiaceae). The phytogeographically interesting endemic Pakaraimaea dipterocarpaceae (Diperocarpaceae) also occurs here as a small solitary shrub, but elsewhere it grows as tall gregarious trees. In the Gran Sabana another type of upland scrub occurs at elevations of between 800 and 1500 m. Its density and height varies according to substrate, but the main species typically include the endemic Bonyunia minor (Loganiaceae), Cyrillopsis micrantha, Ochthocosmus roraimae (Ixonanthaceae), Euphronia guianensis (Euphroniaceae), Gongylolepis benthamiana (Asteraceae) and Notopora schomburgkii (Ericaceae). Moving on to the summit of Cerro Guaiquinima, a tall very diverse shrubland has developed with interesting endemic elements like Bonnetia lanceifolia (Theaceae), Stenopadus colveei and Stomatochaeta cylindrica (Asteraceae). At higher elevations on the summit of Auyán-tepui in the Rio Caroni Basin a relatively homogenous stand of tall scrub up to 3 m occurs at elevations up to 2400 m. Here endemic taxa such as Tepuianthus auyantepuiensis (Tepuianthaceae) and Blepharandra hypoleuca (Malpighiaceae), species of the endemic genera Maguireothamnus and Pagameopsis (Rubiaceae) and the near endemic genus Macairea (Melastomataceae) predominate, but plants with stem rosettes, such as the endemic Achnopogon steyemarkii (Asteraceae) become much less frequent. In the same area, the huge, fragmented Chimantá massif probably supports the greatest variety of shrubby species in the Pantepui Province. One type, a tall, paramoid scrub on peat is dominated by species of the endemic genus Chimantaea (Asteraceae), especially Chimantaea mirabilis. This spectacular shrubland has many similarities with the páramos shrublands of the Andes. The caulirosulata growth form of Chamantaea can also be seen in the Andean genus Espeletia and provides a striking example of convergent evolution. Another scrub type is dominated by the endemic Adenanthe bicarpellata (Ochnaceae), Bonnetia multinervia (Theaceae) and Mallophyton chimantense (Melastomataceae). On the summit plateaus of Jaua Sarisariñama massif dense, species-rich shrublands can be found around the mountain’s large sinkholes (simas).  Here the characteristic endemic species include Bonnetia jauaensis (Theaceae), Celianella montana (Euphorbiaceae) and Tepuianthus sarisarinamensis (Tepuianthaceae). On the nearby, but higher summit of Cerro Jaua the shrublands share many species, but physiognomically they are quite different mainly due to the predominance of Bonnetia jauaensis (Theaceae), and these are considered to be true Pantepui (high-tepui) shrublands. Other codominants include various endemics like Gongylolepis jauaensis, Stenopadus jauaensis (Asteraceae), Maguireothamnus jauaensis (Rubiaceae) and Tyleria breweri (Ochnaceae). On peat, however, dense, almost monospecific stands of the endemic Archytaea multiflora (Theaceae) occur in isolated patches.

Guayana Highlands Upland ‘Meadows’

Meadow is used here as a collective term for any extensive stands of herbaceous vegetation, and can be broadly divided into gramineous meadows, dominated by grasses and/or sedges, and nongramineous meadows, dominated by other herbs or forbs. The former can be further subdivided into savannas (sabanas) and montane grasslands (praderas), while the latter comprises four types: broad-leaved meadows, tubiform meadows, rosette meadows and fruticose meadows. Broad-leaved meadows are mainly dominated by various species of Rapataceae; tubiform meadows are dominated by various tube forming herbs of the Bromeliaceae and Sarreceniaceae; rosette herbs of the Eriocaulaceae and Xyridaceae dominate rosette meadows, and fruticose meadows comprise a mixture of herbs and dwarf shrub and represent types of heathland.  Montane grasslands are rare in this BioProvince and tend to be confined to periodically waterlogged areas. Some of the best examples are found on Auyán-tepui, the Chimantá massif, Cerro Marahuaka and Sierra de maigulida. These tend to be dominated by the endemic tussock grass Cortaderia roraimensis (Poaceae), which has Andean affinity, together with various other gramineous species such as the endemic sedge Rhynchocladium steyermarkii (Cyperaceae). In the upland valleys grass of the genus Axonopus becomes more conspicuous accompanied by the endemic rosette plant Orectanthe sceptrum (Xyridaceae). On the rocky, open, windswept plateaus of Ilú-Tramen, Kukenán, Roraima and Yuruaní tepuis rosette meadows predominated populated by plants of the endemic genera Conellia (Bromeliaceae), especially Conellia angustae, C. caricifolia and C. quelchii, and Rondonanthus (Eriocaulaceae). Down on the lower slopes of Karaurí-tepui and Wadakapiapué-tepui the rosette meadows are dominated by large colonies of the endemic Brocchinia tatei (Bromeliaceae), while other species include the endemic South American pitcher plant Heliamphora heterodoxa (Sarraceniaceae). At lower altitude meadows just two species of Rapateaceae (of the endemic genus Schoenocephalium) form important floristic elements, while in the uplands rapateaceous taxa have attained a much higher degree of differentiation with several endemic genera recognized including Amphyphyllum, Kunhardtia, Marahuacaea, Phelpsiella and Stegolepis. On the spectacular summit of Uei-tepui, the upland vegetation differs markedly from all other eastern tepuis in having stands of broad-leaved meadow, mostly composed of the endemic Stegolepis guianensis (Rapateaceae) interspersed with rich montane grasslands dominated by the Axonopus caulescens and Panicum chnoodes (Poaceae). Extensive broad-leaved meadows are also found on the playeau of Gran Sabana. The dominant plants here include the endemic Stegolepis angustae and S. ptaritepuiensis (Rapateaceae), which form dense colonies up to 1.5 m tall. After the start of the rainy season, their bright yellow flowers provide an eye-catching display. Other associated endemic herbs are Abolboda macrostachya (Xyridaceae), Brocchinia reducta (Bromeliaceae), Lagenocarpus guianensis (Cyperaceae), Nietneria paniculata (Liliaceae) and Trimezia fosteriana (Iridaceae), while some of the more interesting endemic dwarf shrubs include Chalepophyllum guianense (Rubiaceae), Clusia pusilla and Poecilandra pumila (Ochnaceae). An example of a tubiform meadow can be seen on the summit plateau of Cerro Duida where irregular stands dominated by the endemic Brocchinia hechtioides (Bromeliaceae) occur in common association with the giant, endemic pitcher plant Heliamphora tatei (Sarraceniaceae) which can grow to a heights of 1.5 m. Other common endemics here include Amphiphyllum rigidum (Rapateaceae).

References

Anon. 1996. Habitats of South America. Institute of Terrestrial Ecology and Intitut Royal Des Sciences Naturelles De Belgique.

Berry, P. E., Holst, B. K. & Yatskievych, K. 1995. Flora of the Venezuelan Guayana. Missouri Botanical Garden Press.

Doyle, A. C. 1912. The Lost World. Hodder & Stoughton, New York.

Huber, O. 1988. Guayana highlands versus Guayana lowlands, a reappraisal. Taxon, 37: 595-614.

Kelloff, C. L. & Funk, V. A. 2004. Phytogeography of the Kaieteur Falls, Potaro Plateau, Guyana: floral distributions and affinities. Journal of Biogeography, 31: 501-513.

Maguire, B. 1970. On the flora of the Guayana Highlands. Biotropica, 2: 85-100.

Rull, V. 2004a. Biogeography of the ‘Lost World’: a palaeoecological perspective. Scence Direct (online): 125-137.

Rull, V. 2004b. Is the ‘Lost World’ really lost? Palaeoecological insights into the origin of the peculiar flora of the Guayana Highlands. Naturwissenschaften, 91: 139-142.

Rull, V. 2005. Biotic diversifications in the Guayana Highlands: a proposal. Journal of Biogeography, 32: 921-927.

Steege, H. T. Jansen-Jacobs, M. J. & Datadin, V. K. 2000. Can botanical collections assist in a National Protected Area Strategy in Guyana?  Biodiversity and Conservation, 9: 215-240.

Steyermark, J. A. 1979. Plant refuge and dispersal centres in Venezuela: their relict and endemic elements. In: Tropical Botany. Eds. K. Larsen and L. B. Holm-Nielsen. Academic Press.

Steyermark, J. A. 1986. Speciation and endemism in the flora of the Vaneuzuelan tepuis. In: High Altitude Tropical Biogeography. Eds. F. Vuilleumier and M. Monasterio. Oxford University Press and American Museum of Natural History.