© 1998 Heron Publishing—Victoria, Canada
Effects of dormancy and environmental factors on timing of bud burst in Betula pendula
Risto Häkkinen (1), Tapio Linkosalo (1) and Pertti Hari (2)
1. The Finnish Forest Research Institute, Unioninkatu 40 A, FIN-00170 Helsinki, Finland / 2. Department of Forest Ecology, University of Helsinki, Unioninkatu 40 B, FIN-00170 Helsinki, Finland / Received April 30, 1997
Summary
We tested three theories predicting the timing of bud burst in mature birch (Betula pendula Roth) trees utilizing a 60-year phenological time series together with meteorological temperature observations. Predictions
of the timing of bud burst based on light conditions in addition to temperature were more accurate than predictions based
on dormancy development and temperature (prediction standard error of 2.4 days versus 4.3 days). The signal from light conditions,
represented by fixed calendar date, determined the start of bud ontogenesis rather than dormancy release. We suggest that
models developed to predict the timing of bud burst be utilized in the analysis of plant responses to climate change and of
climate change itself.
Keywords:
annual cycle of development, birch, bud ontogenesis, phenology, photoperiod.
