Modern Pollen-Representation Factors for Woods in South-East England

Abstract

(1) An analysis of the relationship between pollen frequency and plant numbers in a given area is an essential step if pollen diagrams are to be used as records of past tree populations. This relationship was studied by comparing the pollen content of moss samples with the vegetation within 20-m radius of each sample site, at seventy-eight sites in the New Forest, Hampshire, The Mens and the Cut, Sussex, and Bradfield Woods, Suffolk. (2) Linear regression analysis was used to analyse the relationship between the intensity of pollen deposition and tree basal area, and between pollen percentages and percentages of total basal area per plot for the major tree species. (3) The rank-order of taxa for number of pollen grains deposited per unit of tree basal area for all sites was Betula > Pinus > Taxus > Alnus > Quercus > Fraxinus - Fagus Salix. The correlations between pollen and basal-area data were significant for all tree taxa except Fraxinus, Fagus and Salix; the correlations for these taxa were higher when the data were expressed as percentages. There was a wide range of pollen representation for different shrub and herb taxa. (4) With the exception of Quercus, a consistent order of pollen representation for the major forest trees of northern Europe can be recognized. Senescent Quercus populations are a contributory factor to the low pollen representation of this taxon in south-east England. (5) The regression coefficients derived in this study can be used to convert fossil pollen counts into estimates of tree basal area for areas of 20-m radius around very small sedimentary basins. An example is given for a small woodland pond in Suffolk.