The use of pollen traps enables the calculation of pollen accumulation rates
, (not just pollen percentages), which provides a more objective basis for interpreting the local vegetation.
With an accumulated database of influx values for the major tree species and the ecologically significant shrub and herb species of Europe, the interpretation of pollen diagrams could be much more precise, particularly for those periods or situations where there is a change from unforested to forested conditions or vice versa.
Guidelines for vegetation mapping
can be found here.