Original paper

Take-off in anemochorus dispersal units of Carpinus betulus and Clematis vitalba: Observation in wind tunnel experiments and measurement of the basic force

Fonger, Patrick Pütz


Preliminary experiments on dispersal units of Carpinus betulus and Clematis vitalba were aimed at quantitative measurement of the basic forces involved in take-off. The measurements were completed using the spring scale principle. In Carpinus betulus, the take-off force measurements demonstrate that the basic force of take-off correlates to ripeness of dispersal unit. The values for basic force measured were shown to decrease over time, until a minimum take-off force of 0.2 N was finally reached. The force of dispersal unit take-off for Clematis vitalba was also found to be comparable. Several wind tunnel experiments were also carried out with this species. The parameters for take-off were turbulent wind flow and a wind velocity of 17 m/s. Moreover, C. vitalba shows individual adaptation under these conditions, with oscillating movements of the branches, and a complete 'shake off' of the dispersal units. It would appear that these take-off strategies, examples of which are described here, are important in the discussion of dispersal distances.