Annual variations in pollen deposition and meteorological conditions on the fell Aakenustunturi in northern Finland: Potential for using fossil pollen as a climate proxy

Annual variation in meteorological parameters (7 years) and pollen deposition (6 years) for 4 sites on a transect across an altitudinal timberline on Aakenus, a fell in northern Finland were monitored, in order to see how pollen production, as reflected by pollen deposition (grains cm(-2) year(-1)), is related to climate conditions. Wind direction and wind speed before and after estimated flowering time were determined. These indicated that within the forest and at the physiognomic forest line, pollen deposition is primarily from plants growing within the forested area on the fell and that the contribution of windblown pollen from further south is minimal. Pollen deposition can, therefore, be taken as equivalent to pollen production. Simple linear correlation coefficients between pollen deposition and one-month and two-week mean temperature effective temperature sums and cumulative effective temperature sums for the current and previous summers were calculated. For Pinus sylvestris the quantity of pollen deposited is affected by July mean temperature, July effective temperature sum and total effective temperature sum, for the year previous to pollen emission. Pollen deposition of Betula pubescens and Picea abies is also affected by thermal factors but of different time periods (Betula of early June and Picea of early July), but always of the year previous to flowering. However, the correlation is not as strong as for Pinus. The results suggest that annual fossil Pinus pollen quantities, if calculated from peat and/or lake sediments, are a potential climate proxy. They also demonstrate that it is possible to use temperature parameters of the current year to make forecasts of the intensity of flowering and pollen production in the following year.