Authors
Ernesto Medina, Juan F Silva
Publication date
1990/7/1
Journal
Journal of Biogeography
Pages
403-413
Publisher
Blackwell Scientific Publications
Description
Savannas in northern South America (the Orinoco Llanos) are found on a variety of highly leached substrates, from tertiary sediments to alluvial soils, with markedly seasonal rainfall, 800-2500 mm/year. Physiognomic types range from tree-less grasslands to woodland type communities. Dominant tree species are evergreeen and sclerophyllous being favoured by low soil fertility and fire against deciduous, mesopyllous trees. Water appears not to be a limiting factor for established trees since leaf flushing and flowering take place in the dry season. Tree/grass ratios increase with soil water availability during the dry season. Areas with high water table, or in which a large fraction of the previous rainfall is accessible to tree roots, have higher tree densities than savannas with soils of low water retention capacity and/or deep water tables. Tree recruitment is dependent on their capability to withstand grass-root …
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