Subsampling of large-volume samples in waterlogged sediments. A time-saving strategy or a source of error?

We found that subsampling of unprocessed waterlogged material in general should only be done if it is indispensable, as it can introduce a bias. We propose methods to adapt sample sizes based on random sampling for unprocessed waterlogged sediment (where random sampling is impossible) so that the proportions or also the diversity of plant species can be estimated with sufficient precision in these sediments. However, it would be best to use an appropriate sieving method first and then subsample the processed residues of the material. We also think that it is important to clearly present the methods used for subsampling in publications and that more detailed tests about subsampling should be performed.