© 1990 Heron Publishing—Victoria, Canada
Timing of growth cessation in relation to climatic adaptation of northern woody plants
H. Hänninen (1), R. Häkkinen (2), P. Hari (2) and V. Koski (3)
1. Faculty of Forestry, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland / 2. Department of Mathematics, The Finnish Forest Research Institute, Unioninkatu 40 A, SF-00170 Helsinki, Finland / 3. Department of Forest Genetics, The Finnish Forest Research Institute, P.O. Box 18, SF-01301, Vantaa, Finland / Received January 23, 1989
Summary
The efficiency of timing models of cessation of growth of northern woody plants was defined as their ability to allow maximum
utilization of the growing season without autumn frost damage. The efficiencies of three timing models were compared with
the aid of computer simulations, using long-term meteorological data. A model based on night length was the most efficient,
followed by one based on a joint factor of the night length and temperature sum. A model based on temperature sum alone was
the least efficient. The reason for these differences in efficiency was the great year-to-year variation in the annual temperature
sum accumulation. The results were compared with empirical evidence for each of the models. The relevance of the theoretical
approach is discussed, as well as the application of the
simulations.
