. The Conservation Atlas of Tropical Forests: the Americas. The History of the Forests and Climate of Tropical South America PRESENT 20,000-14,000 yr BP 5000 4000 3000 2000 1000 â ra 0. warm tropical loresl ⢠high plain ol Bogota * Magdalena River /^/ xerophytic vegetation -â¢- upper forest line Figure Schematic presentation of the zonation of the main vegetation behs in the Colombian Andes during present-day conditions (interglacial) and during ice age (glacial) conditions about years ago. ArierVandcrHammen. I974i although most of these genera are not restricted in their
. The Conservation Atlas of Tropical Forests: the Americas. The History of the Forests and Climate of Tropical South America PRESENT 20,000-14,000 yr BP 5000 4000 3000 2000 1000 â ra 0. warm tropical loresl ⢠high plain ol Bogota * Magdalena River /^/ xerophytic vegetation -â¢- upper forest line Figure Schematic presentation of the zonation of the main vegetation behs in the Colombian Andes during present-day conditions (interglacial) and during ice age (glacial) conditions about years ago. ArierVandcrHammen. I974i although most of these genera are not restricted in their distribu- tion to this belt. The next vegetation zone, extending from approximately 3200 to 3500 m elevation, is the irregular belt of high Andean dwarf forest and shrub formations, and the sub-paramo. The for- est trees of the genera Weinmannia and Querciis are absent and the most common woody taxa belong to the Compositae, Ericaceae. Aragoa, EscaUonia, Hypericum and Polylepis. Above this, the paramo extends from about 3500 m up to 4000- 4200 m elevation. Apart from grasses, the most characteristic elements of the paramo are stem-rosette plants of the genus Espelelia. and a number of herbs, such as Bartsia, Gentiana. Geranium. Halenia. Paepalanthus. Plataaf^o. Ranunculus and Valeriana. The super-paramo belt extends upwards from 4000- 4200 m to the snow-covered zone. In order to make the pollen diagrams more easily understood, they are presented here as cumulative diagrams. They show the variation with time of the percentages of the major ecological groups of pollen: subandean forest elements, Andean forest ele- ments, subparamo elements and paramo elements. It will be clear that for correct interpretations one must take into account the relationships between vegetation and pollen rain, and the altitudinal ranges and ecologies of the individual taxa present. The Andes have been subjected to great geological uplift over the last few million years. This uplift has created ne
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