How do airborne and deposition pollen samplers reflect the atmospheric dispersal of different pollen types? An example from northern Finland.

We compared two >20 year long data sets of airborne and deposited pollen from northern Finnish Lapland (Kevo) and the middle boreal forest zone (Oulu) in terms of the plant taxa represented and their annual pollen quantities. Tree pollen (Betula spp., Pinus sylvestris) made up 92.8% of the total annual pollen in the air samples at Kevo, while in the ground-level deposition samples the tree pollen fraction was 61.5%; the remaining 38.5% comprising pollen of ground and field level plants (Ericaceae, Cyperaceae and others). In Oulu, the proportion of tree pollen in the air and deposition samples was 90.6% and 89.0%, respectively. The annual fluctuations in the quantity of total pollen and tree pollen in both sampling systems were correlated, but no such correlation was detected for the low growing plants, except in the case of Urticaceae at Kevo. This suggests that pollen of these low-growing plants mainly reflects the vegetation of the sampling site. Because tree pollen rises well into the atmosphere, it reflects pollen production from a larger area. Long-range transported Betula spp. pollen recorded in the atmosphere prior to local flowering comprised a considerable part of the Betula spp. pollen at Kevo and was collected by both sampling systems. [ABSTRACT FROM AUTHOR]