Resumen

MONTES, RUBÉN ANTONIO; SAN-JOSE, JOSÉ  y  AYMARD, GERARDO ANTONIO. Characteristics of the Flora and vegetation of the Mesa high plain and the eolic plain at the Aguaro-Guariquito National Park, Guárico State, Venezuela. Caldasia [online]. 2013, vol.35, n.2, pp.219-240. ISSN 0366-5232.

We studied the relationships between vegetation and topography in two topo-sequences corresponding to the National Park Aguaro-Guariquito, Guárico State, Venezuela. The first is a high plain or Mesa landscape covered by a well-drained Savanna (site 1). In the dissected areas of this plateau geofractures occur with permanently saturated soils where the palm Mauritia flexuosa (morichals) grows (site 2). The other topo-sequence corresponds to an eolic plain with soils consisting of materials originating from the Mesa plateau and covered by wet savanna (site 3), which remains waterlogged for three months (June-August) with a water level of 0.25 ± 0.10 m. The most deprived areas in this topo-sequence feature temporary conditions of extreme flooding in which a community dominated by Acosmium nitens (congrial) occurs (site 4), and a vegetation characterized by the presence of Caraipa llanorum (saladillal) (Site 5). The congrial remains flooded for seven months(June-December), with a high water level of 1.02 ± 0.10 m. In contrast, the saladillal remains flooded for six months (June-November) and the water level reaches a height of 0.80 ± 0.10 m. Flooded communities (sites 2-5) are on more acidic soils (4.0 - 4.6 units) than those characteristic of the well-drained savanna (site 1; 5.0 units). The pH was associated with the aluminum concentration. The organic matter content was higher in flooded (8.59%) than in seasonally flooded and well-drained sites (0.7- 1.0 %). The flooded habitat restricts biodiversity. The congrial, saladillal, wet savanna and morichal featured 52, 52, 56 and 74 species, respectively. In contrast, well-drained Savanna has 114 species. The similarity between the saladillal and congrial was 56%. For other communities, similarity was less than 38%. The results indicate that life-forms of Teroculmi and Teroherbae (i.e., annual species of grasses, sedges and herbs) account for 43% of the average of the spectrum of biological forms.

Palabras clave : Central Venezuelan savannas; Caraipa llanorum; Acosmium nitens; topo-sequences.

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