Physiology-based phenology models for forest tree species in Germany

Area of Science:

• Ecology
• Plant Physiology
• Climate Change Science

Background:

• Phenology models are crucial for projecting climate change impacts on ecosystems and public health.
• Existing models have limitations in accurately predicting deciduous tree bud burst across diverse species and regions.

Purpose of the Study:

• To develop and parameterize a novel phenology model for deciduous tree bud burst.
• To improve the accuracy of spring phenology predictions under changing climatic conditions.
• To investigate the species-specific roles of photoperiod and temperature in bud burst timing.

Main Methods:

• Developed a new phenology model based on interactions between inhibitory and promotory agents controlling plant development.
• Formulated and tested several alternative model structures representing different physiological processes.
• Determined model parameters for a wide geographical range in Germany and multiple forest tree species.

Main Results:

• The new models demonstrated improved fit to observational data compared to classical models.
• The developed model reduced, but did not eliminate, the bias observed in older models.
• Species-specific analyses revealed that photoperiod is more dominant in late spring bud burst (e.g., Fagus sylvatica, Quercus robur) than early spring bud burst (e.g., Betula pendula, Aesculus hippocastanum).
• Chilling played a subordinate role compared to preceding temperatures for spring bud burst.

Conclusions:

• The new modeling approach allows for species-specific weighting of dominant phenological processes.
• Results support the significant role of day length in late spring bud burst.
• The model offers enhanced capabilities for projecting climate change effects on forest phenology.