Subsampling of palynological sequences: Techniques and implications

In an earlier study, detailed analysis (sample interval 15–20 cm) of the Hula LO7 core, northern Israel, resulted in the recognition of 15 late Quaternary palynological zones representing oxygen isotope stages 5 to 3. In order to determine the minimum sampling intervals required, exponential smoothing was applied to the original data set of arboreal pollen proportions and to subsamples of it. In the lower part of the core, subsamples of every fourth, or even every fifth sample adequately reproduced the trends of the original and smoothed data. In the upper part of the core, subsamples representing every third sample seem reasonable. Because compaction seems to act as a natural smoother, more widely spaced samples can be used with increasing depth. It is recommended that one should first sample the core, study in detail a few sequences from various depths, smooth their graphs, evaluate the desirable amounts of subsampling, and only then proceed with the analysis of the other, remaining sequences, each with its appropriate subsampling strategy.