T27 Late Quaternary Climate Change in Tropical America (Posters)

POLLEN-BASED BIOME RECONSTRUCTIONS FOR LATIN AMERICA: APPLICATIONS AT A RANGE OF SPATIAL AND TEMPORAL SCALES

Paper number: T27-13
Program: Technical Sessions
Time: 1:30 PM – 4:30 PM

Authors

Abstract

The biomisation method is used to reconstruct vegetation from fossil pollen data across Latin American at 6000 and 18000 radiocarbon years before present (yr BP), we then focus in on Colombia at a higher temporal resolution. Tests using modern pollen from core top, surface samples, pollen traps and moss polsters were able to broadly reproduce vegetation distribution as reflected in a map of potential natural vegetation. The calibration between the pollen-based reconstruction and the potential vegetation makes it possible to reconstruct vegetation at past periods, and determine patterns of change relative to the present. Mismatches between the pollen-based vegetation reconstruction and the potential vegetation results from forcing factors such as human impact, methodological artefacts and mechanisms of pollen transport and representivity of the parent vegetation. At a Latin American scale, the main differences between the modern and the 6000 yr BP reconstruction is a transition to biomes characteristic of a slightly drier climate. At 18,000 yr BP the pattern of vegetation change is more pronounced and is characterised by a range of biomes where tropical dry forest, tropical seasonal forest and cool grass / shrub are common, these describing a generally cool and dry environment.

By focusing our analysis on Colombia, which is prominent in Latin America due to the high quality and quantify of pollen-based environmental records stemming form some 50 years of palaeoecological study, it is possible to increase the temporal and spatial resolution, while retaining more information from the analysis that has to be discarded at the broader scale. Results are presented from the Holocene where the increasing importance attributed to human activity is documented initially in the lowlands and then at higher altitudes. This spatial and temporal zoom allows a discussion about differential response of the vegetation to Late Quaternary environmental change and a greater understanding on the forcing factors behind changing vegetation patterns than attainable at a continental scale.

This abstract is coauthored with Latin American Pollen Database members, Latin American Pollen Database, http://www.ngdc.noaa.gov/paleo/lapd.html.