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 Montane Forest

Ranging at altitudes from about 500 - 3000 m these forests occur on a variety of mountain systems from the conspicuous high tepuis to extensive granitic ranges and low massifs. In the Gran Sahana uplands, which include the spectacular highlands of the eastern tepui chain (Roraima - Ilú), there is a fascinating sequence of altitudinal forests types, but even forests at given altitudes can vary from place to place. On many of the slopes surrounding the tepuis there is often a high frequency of orographic mist creating conditions for cloud forest formation from about 1400 m upwards. Here the typical trees include endemic species like Endlicheria nilssonii (Lauraceae), Moronobea ptaritepuiana (Clusiaceae), Platycarpum rugosum (Rubiaceae) and Sterigmapetalum guianense (Rhizophoraceae). On peat at slightly higher elevations, roughly between 1600-2000 m up to where the slopes reach the vertical cliffs of the tepuis, the near endemic Bonnetia (Theaceae) becomes the main cloud forest genus with endemic species such as Bonnetia steyermarkii and B. tepuiensis predominating, although at the base other species, such as the endemic Stenopadus chimantensis (Asteraceae), become more prolific. Other important trees include the endemic Magnolia ptaritepuiana (Magnoliaceae). At the highest altitudes the trees become stunted producing elfin forest, and typical of cloud forests all of the tree trunks and branches are covered in lichens, bryophytes, ferns and other epiphytes. The under story is less typical, however, being dominated in places by giant endemic rosette herbs such as Brocchinia tatei (Bromeliaceae), Didymiandrum stellatum (Cyperaceae) and Orectanthe ptaritepuiana (Xyridaceae).  On the upper slopes of Cerro Duida tepui the main trees are again mainly endemic taxa such as Neotatea longifolia (Clusiaceae), Tyleria floribunda and T. spathulata (Ochnaceae). The ground flora here includes many large endemic herbs like Saxofridericia duidae, Stegolepis grandis (Rapateaceae) and species of the near endemic genus Everardia (Cyperaceae). Along the rivers and creeks the vegetation is typified by the endemic Archytaea multiflora (Theaceae) and Gleasonia duidana (Rubiaceae). A few scattered bits of forest can also be found in depressions on the summit of this tepui. The dominant trees unsurprisingly include various endemics such as Daphnopsis steyermarkii (Thymelaeaceae), Podocarpus roraimae (Podocarpaceae) and Psychotria jauaensis (Rubiaceae).

References

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