Colombian vegetation at the Last Glacial Maximum: a comparison of model‐ and pollen‐based biome reconstructions

Abstract

Van der Hammen, T. and Wille, M. 2004. Colombian vegetation at the Last Glacial Maximum: a comparison of model-and pollen-based biome reconstructions.ABSTRACT: Colombian vegetation, at the ecological level of the biome, is reconstructed at the Last Glacial Maximum (LGM) using two methods. A reconstruction of modern biomes shows that, for the majority of the sites, the pollen data accurately reflect the potential vegetation, even though much of the original vegetation has been transformed by agricultural practices. At 18 000 14 C yr BP a generally cool and dry environment is reflected in biome assignments of cold mixed forests, cool evergreen forests and cool grassland/shrub, the latter extending to lower altitudes than presently recorded. Differential responses of the vegetation to climatic shifts are related to changes in moisture sources and the importance of edaphic control on the vegetation. Secondly, biomes at the LGM are also investigated by applying a vegetation model (BIOME-3) set to operate at CO 2 levels of 200 ppmV and with climatic data from 12 meteorological stations that encompass a range of environments within Colombia. At lower altitudes it is apparent that moisture is the dominant control on driving vegetation change whereas temperature becomes more important at higher altitudes. The combined reconstruction of biome-scale vegetation dynamics in Colombia allows an understanding of the environmental controls on these to be developed that demonstrates the need to invoke different factors to explain the vegetation change rather than a uniform reduction in temperature or moisture.

Did Humans Cause the Late Pleistocene-Early Holocene Mammalian Extinctions in South America in a Context of Shrinking Open Areas?

“…In Colombia, pollen indicates that at 18,000 BP a generally cool and dry environment is refl ected in biome assignments of cold mixed forests, cool evergreen forests and cool grassland/ shrub, the latter extending to lower altitudes than presently recorded (Marchant et al, 2004). From 11,150 to 9,100 cal bp, grass savanna dominated the landscape while gallery forest along the drainage system was poorly developed.…”

Biomization and quantitative climate reconstruction techniques in northwestern Mexico—With an application to four Holocene pollen sequences

“…We based on the classification proposed for Europe (Prentice et al, 1996), modified by Thompson and Anderson (2000) for the SW United States. Moreover, we took into account the classification of Marchant et al (2001Marchant et al ( , 2004 for South and Central America, and the work done for the Sonoran Desert by Ortiz-Acosta (2003). Finally, to obtain a better representation of the modern vegetation of NW Mexico, we modified the pollen-FPT assignation based on the information of vegetation distribution and environmental adaptations at the NW SMO given in the literature.…”

Predictive modelling of tree species distributions on the Iberian Peninsula during the Last Glacial Maximum and Mid-Holocene

“…in the deciduous and evergreen oak (Quercus ) pollen type groups or between some species of the genus Pinus . Another group of modelling strategies attempts to predict past plant distributions using plant functional types (Marchant et al 2004, Crucifix and Hewitt 2005, Ni et al 2006. In recent years, phylogeographic studies have provide much information on the past refuge locations and postglacial recolonization routes of European tree species (Taberlet et al 1998, Hewitt 1999, Petit et al 2002, Chedaddi et al 2006.…”