Wind conditions and pollen deposition in a mixed deciduous forest: I. Wind conditions and pollen dispersal

Abstract

Pollen deposition in a mixed deciduous forest in South Jutland, Denmark, was studied by means of pollen analyses (Andersen, 1970) and pollen collectors. In this connection it was important to know the wind conditions outside and inside the forest. Wind velocities and wind directions in the flowering seasons were measured at 2 stations in a 3-year period. High wind velocities prevail above the forest in spring and summer. At such wind velocities the difference in loss of large and small pollen grains by filtration in the tree tops is reduced. The winds inside the forest tend to turn into the direction of easiest flow. The velocities are about 20% of the outside wind before and 12-15% after the leafing. Single pollen grains released from the trees will be carried wide distances before deposition in the spring, and it is suggested that the tree pollen falls to the ground rather in aggregates or included in rain-drops. © 1974 Taylor & Francis Group, LLC.