Evaluation of the potential of surface pollen spectra from caves in SW China for vegetation reconstruction

摘要

Pollen analysis is rarely applied to cave sediments because of the complex range of processes influencing the origin, transport and taphonomy of pollen grains in caves. In order to evaluate the potential of pollen spectra from within caves for vegetation reconstruction, we compared the modern pollen from the interior and exterior of four caves in Guangxi and Guizhou, in southwestern China. The results show that the pollen spectra from within the sack-shaped caves, and from the front and middle of a long, narrow caves, were similar to those outside the caves, and therefore that the pollen spectra from these caves can reliably be used for palaeovegetation reconstruction. Wind is the major transport medium for the pollen entering caves, but animals may be additional transport medium. In addition, cave geometry is likely to be responsible for the observed spatial distribution of pollen concentrations in caves. In long, narrow caves, the entrance is the optimum sampling location for pollen analysis; however, in sack-shaped caves an optimum sampling location cannot be specified due to the gradient in pollen concentration between the entrance and the rear, together with its irregular distribution.