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The Summit Vegetation of Cerro Autana

1974; Wiley; Volume: 6; Issue: 1 Linguagem: Inglês

10.2307/2989692

1744-7429

Julián A. Steyermark,

Plant Diversity and Evolution

Cerro Autana is one of the smallest of all the sandstone table mountains of the Guayana Highland. It appears to represent a fragmented portion of the nearby Cerro Sipapo (Paraque) in Territorio Federal Amazonas, Venezuela. One hundred and thirty-two species of plants are now known from the summit, of which seven are new to science, four new to Venezuela, one new to the flora of the Guayana Highland, and sixteen newly recorded for the flora of Territorio Federal Amazonas. The majority of the species found on the sumit prove to be either generally distributed ones common to other mountains of the Guayana Highland or to certain mountains of the Territorio Federal Amazonas or Estado Bolivar. An obvious relationship is shown with the nearby Cerro Sipapo. Of significance is the fair proportion of species represented on the summit of Cerro Autana and elsewhere found commonly in lowland portions of the Venezuelan Guayana, indicating a former geological connection allowing for past migrations and interchange of floras between lowland and summit. It is postulated that this migration of floras has proceeded from top to bottom. CERRO AUTANA, located in Territorio Federal Amazonas of southwestern Venezuela, at Lat. 40 52' N., Long. 670 27' W., about 100 kilometers south-southeast of Puerto Ayacucho, may be likened to a giant tower (fig. 1) rising abruptly from a lowland green rain forest to a height of approximately 1300 meters. It is completely isolated. The upper part of this mountain is completely walled by precipitous salmon-pink and buff-white sandstone cliffs up to 900 meters high. It is one of the smallest of all the sandstone table mountains of the Guayana Highland with its summit about one kilometer long and 200350 meters wide. Near the middle portion of the summit is a boulder-strewn hump about 55 meters higher than the nearly level ends. The large Cerro Sipapo (Paraque) lies 18 kilometers to the south-