Micro‐scale patterns of modern pollen deposition within three alpine plant communities*

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Abstract
Summary: Few studies have examined patterns of pollen deposition or the relationship between vegetation and pollen assemblages at the small scale. This paper examines the representation of both individual taxa and whole plant communities in modern pollen spectra. Micro‐scale variations in modern pollen deposition were studied in three alpine plant communities on Storbreen glacier foreland, southern Norway: a pioneer community; a Salix‐shrub community; and an ericaceous heath community. The relationships between vegetation and modern pollen deposition and the variability of these relationships at the local scale were investigated within 16 × 1 m2‐quadrats. The data were classified using two‐way indicator‐species analysis (TWINSPAN) and ordinated using detrended‐correspondence analysis (DCA). In addition, the pollen and vegetation data were ordinated simultaneously, using canonical correspondence analysis (CCA). The effect of removing arboreal pollen from the pollen sum was examined. The three plant communities were distinguished successfully by multivariate statistical techniques, using; both pollen data and vegetation data. However, within the communities there was high variability in pollen deposition, which was most pronounced in the Salix‐shrub community. The abundance of individual taxa in the vegetation was compared with their representation in the pollen spectra. The strongest relationships were shown by Salix Ericales, Empetrum and Lycopodium. Certain taxa showed consistent, reproducible patterns of behaviour. These patterns provided valuable evidence for separating contrasting plant communities. Comparison of modern pollen‐vegetation relationships of this kind with pollen data from Holocene and Pleistocene sites is important to improve the reconstruction of past plant communities. Statistical analyses showed that for the majority of taxa a moss polster consisting of 20 subsamples was necessary to reduce the effect of microscale variability in this environment to acceptable levels.