Timing of spring phenological phases of bird cherry and silver birch under climate change in 21st century in latvia

Phenology is a study of timing of event taking place in nature. In a functional ecosystem phenological phases for mutually dependent are synchronized. In a rapidly changing climate there is a risk of decoupling, that is spring development of interdependent could species proceed at different peace. We are investigating the likely timing of spring phenological phases during the last and upcoming centuries for two tree species common in northern and central Europe: bird cherry (Prunus padus known also as Padus racemosa or Padus avium) and silver birch (Betula pendula). The study is based on long term voluntary – citizens-scientist – phenological observations since 1927. A thermal-time phenological model is used to describe the timing of the spring phenological phases of bird cherry and silver birch. The phenological model was parametrized using the observations from national meteorological stations. The shifts of the timing of phenological phases due to climate change are analysed using simulated meteorological data from bias-corrected ENSEMBLES data set. It is found that the phases onset, modelled with ENSEMBLES data, in comparison to observations at some stations are biased by few days earlier, but the trends for modelled and observed phase timing are overlapping. During the last 50 years the average timing for flowering of the bird cherry have sifted by a week earlier, while the leaf unfolding, and flowering of the silver birch has shifted even more. Modelling results suggest that the trend will continue in future as well. The warm winters in future with sudden could spells in early spring rises risks that the prematurely unfolded leaves may suffer from frost damage.