Introduction
The prime aim of Quaternary palaeoecologists is to reconstruct past vegetation communities as accurately and in as much detail as possible and through this reconstruction deduce other environmental variables such as climate, edaphic conditions, the extent of anthropogenic interference, disturbance, etc. Frequently pollen analysis is the central technique for such a reconstruction and so it is important that the interpretation of pollen data should be constantly refined in both temporal and spatial dimensions. It is no longer sufficient to determine the broad regional trends in vegetational development, many of today's questions can only be solved by examining changes at the more local level, the behaviour of an individual species or an ecologically significant group of species over a given period of time, or through correlating vegetation communities from region to region for a narrowly defined time period.
In these instances it is often imperative to know whether a species, whose pollen is recorded in a sediment, was present in the immediate vicinity of the sampling site or only at a distance of some kilometres. Because pollen production and pollen dispersal vary so widely from species to species, and because pollen diagrams are usually constructed on the basis of percentage presence in the total pollen assemblage, the representation of a pollen type is only very rarely in a 1:1 relationship with the abundance of that species in the local vegetation. For a forested area, a 10% presence of Pinus pollen by no means indicates that pine was present locally whereas a 10% presence of either Picea or Ulmus pollen almost certainly indicates that those species were growing within a few hundred metres of the sampling site.
Although pollen analysts have learnt to make such interpretations intuitively it would be better to have a more objective basis for these deductions. This can be achieved by using POLLEN INFLUX values (number of grains of a pollen type(s) deposited on a unit surface area in a given time, commonly grains cm-2 year-1) rather than percentage values as demonstrated by Davis 1976, Davis et al., 1980. The pollen influx of a species to a sediment is very closely related to the distance of that species from the site. Because of the differential factors of pollen production and dispersal, however, the actual influx value varies from species to species. For example, the presence/absence threshold in Fennoscandian forests for Pinus, seems to be a pollen influx of around 500 pollen cm-2 year-1 while that for Picea is closer to 100 pollen cm-2 year-1 (Hyvärinen, 1976, Hicks, 1994 ).
Trapping experience gained within the major forest belts of northern Finland (Hicks, 1993, 1994 ), a discrete forest area in Denmark (Andersen, 1974 ) and the small scale mosaic of forest types both in the spruce dominated forest areas of Kuusamo (Hicks, 1985, 1986 ) and on the island of Hailuoto, Finland (Hicks, 1992a ) has shown that the regional vegetation is expressed almost exclusively by the arboreal pollen and is relatively constant throughout the regional unit so that one trap per unit gives reliable results, while the ground-level local vegetation is expressed by the non-arboreal pollen and can vary over quite short distances (Hicks, 1991, 1992b ). In unforested areas, where the regional vegetation is expressed by the non-arboreal elements and the arboreal pollen is all of long-distance origin, the arboreal pollen values can also vary dramatically. It is axiomatic that in these situations, percentage values based on the total pollen assemblage give a very misleading picture of the local vegetation (those based on total arboreal pollen even more so!!). In these situations the recognition that the total pollen influx is distinctly lower than in a forested region is crucial.
Obviously, if a body of data could be built up about the influx values of 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. This was amply demonstrated many years ago with respect to the Late Glacial (Davis, 1969, Pennington and Bonny, 1970 ).
A comparable situation is found at the forest limit, both altitudinally and latitudinally, it is found in terms of species migration and refugia, and potentially also in forest clearance related to anthropogenic activity. Two prerequisites for using pollen influx to better interpret fossil pollen diagrams exist:
  1. That there should be some reliable means of measuring pollen influx of individual species under known conditions, i.e. at the present time.
  2. That the pollen diagrams to be interpreted should also be presentable in pollen influx terms i.e. that both the pollen concentration and the rate of sediment accumulation should be known.
The project outlined here aims at providing the data for point 1). Point 2) is already achievable. The addition of a known quantity of an exotic (e.g. Stockmarr's Lycopodium tablets) to the pollen sample at the commencement of sample preparation makes the calculation of pollen concentration a relatively easy matter and a series of independent dates for the profile (14C, tephra, known historical events etc.) enables a calculation of the sediment accumulation rate.
There is always the situation, of course, in which a fossil pollen assemblage has no modern analogue. In such a case that section of a pollen diagram can not be interpreted with reference to modern pollen influx. However, the verification of such a situation is, in itself, a significant piece of knowledge. The fact that such situations exist is not considered sufficiently significant to invalidate the planned project.
The EUROPEAN POLLEN MONITORING PROGRAMME was launched at a meeting held in Oulanka, Kuusamo and Marjaniemi, Hailuoto, Finland 4 - 8.7.96 with the support of INQUA (International Quaternary Association), NorFA (Nordisk Forskerutdanningsakademi) and the Academy of Finland. The meeting was attended by representatives from 15 countries. The following guidelines are a concensus of opinion of this 25-strong founder group (see list in Appendix I).
It should be emphasized that the guidelines set out here refer to the monitoring of the passive deposition of pollen on a land surface. They do not consider the active sampling of the pollen composition of the air nor the incorporation of pollen in the surface sediment of lakes and other water bodies. Because it is terrestrial deposition which is in question, the results obtained are primarily relevant to the interpretation of pollen spectra from peat and soil profiles.