Tree pollen spectra in the stockholm region (sweden), 1973–1980

By means of a Burkard Seven Day Recording Volumetric Spore Trap located in central Stockhom, about 20 m above ground level, pollen was sampled between March and August for eight consecutive years (1973–1980). The pollen spectra with special reference to trees, in particular Betula and Pinus, were compared as to amount and distribution of taxa. No co-variation between the two latter genera was noted. Betula showed a ± distinct biennial periodicity. The main pollen season is defined. Betula and Pinus showed slightly different patterns regarding beginning and duration of the pollen season; mean intensity is compared.