XVI International Botanical Congess

Phenological models constructed from observations of one species are often extrapolated to predict the phenology of other species. In this study, time series of the flowering and bud burst of several boreal zone trees were collected. The observation series were regressed in pairs in order to test mutual variation. Two models of phenology, one based on dormancy, the other assuming the ontogenetic development starting from a signal from light climate, were fitted to the phenological time series. The average residual error of the regression models forecasting one observation series from another was 5.1 days. It seems that different plant species react to climate variables in a similar manner, thus the use of the same models for different species is justified. The light climate model, albeit being more simple, gave estimates that were better than those of the regression models, while the average residuals of the estimates from the dormancy model were 50% larger. The dormancy component seems redundant for the accuracy of prediction in the spring phenology models of boreal trees.