© 2000 Heron Publishing—Victoria, Canada
Predicting spring phenology and frost damage risk of Betula spp. under climatic warming: a comparison of two models
Tapio Linkosalo (1), Timothy R. Carter (2), Risto Häkkinen (3) and Pertti Hari (1)
1. Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 Helsinki, Finland / 2. Finnish Environment Institute, Box 140 (Kesäkatu 6), FIN-00251 Helsinki, Finland / 3. The Finnish Forest Research Institute, Unioninkatu 40 A, FIN-00170 Helsinki, Finland / Received October 20, 1999
Summary
Timing of bud burst and frost damage risk for leaves of Betula spp. in response to climatic warming in Finland was examined with two models. In the first model, ontogenetic development
in spring was triggered by an accumulation of chilling temperatures. The second model assumed an additional signal from the
light climate. The two models gave radically different estimates of frost damage risk in response to climate warming.
The chilling-triggered model forecast a significant and increasing risk with increased warming, whereas the light-climate-triggered
model predicted little or no risk. The chilling-triggered model is widely applied in phenological research; however, there
is increasing experimental evidence that light conditions play a role in the timing of spring phenology. Although it is not
clear if the light response mechanisms are appropriately represented in our model, the results imply that reliance on a light
signal for spring development would afford a degree of protection against possible frost damage under climate warming that
would not be present if chilling were the sole determinant. Further experimental tests are required to ascertain the light-related
mechanisms controlling phenological timing, so that credible model extrapolations can be undertaken.
Keywords:
boreal forest, bud burst, climate change, light response.
