Changes at the Core

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Science  01 Feb 2013:
Vol. 339, Issue 6119, pp. 490
DOI: 10.1126/science.339.6119.490-a

Airborne pollen grains deposited in sediments—particularly in undisturbed lake beds—are a crucial element in understanding how vegetation and its constituent species respond to changing climates. Research on the high-altitude lake sediments from the Bogotá basin in the Colombian Andes has produced a rich record of climate and vegetation over the Quaternary period. In particular, two deep sediment cores obtained in the late 1980s have provided detailed information on climatic fluctuations and vegetation change. However, interpretation of the record has been hampered by uncertainties. Torres et al. now present a new analysis of these cores, in which many of the technical challenges concerning the chronology have been addressed. The development of the Andean forest and high-altitude páramo vegetation—the uniquely Andean biome that occurs above the treeline and has evolved de novo with the uplift of the Andes—was shown to be a dynamic process, with ephemeral associations of plant species continually fluctuating over the past 2 million years as temperatures rose and fell with glacial cycles. This unbroken record provides further evidence that plant communities at any given point in time often have no analog, in terms of species composition, with past or future associations of species.

Quat. Sci. Rev. 63, 59 (2013).

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