In search of finiteness: the limits of fine-resolution palynology of Sphagnum peat

High-resolution analysis of ombrogenous peats often reveals pollen frequencies that change markedly from one sample to the next, indicating limited postdepositional mixing. This raises the question whether — with sufficiently thin samples — seasonal differences in pollen deposition can be observed. Seasonal resolution in peat would provide a dating technique with an accuracy similar to that of other, annually banded archives. To study the limits of temporal resolution, contiguous 0.5 mm thick slices of slightly humified Sphagnum section Cuspidata peat were palynologically analysed. No seasonal patterns in the pollen stratigraphy could be observed. This is ascribed to the mixing of pollen grains as a result of small-scaled vertical water movements and to the horizontal mode of shoot layering in the Sphagnum species. The latter process may also be the cause of a smoothed annual signal. Because of the absence of seasonal differentiation, the palynological distinction of annual peat layers is not feasible.