Stepwise linear regression for the explanatory variable BBCH 65 (full flowering: > 50% of flowers open/emitting pollen, first petals falling) for silver birch (Betula pendula Roth),
common hazel (Corylus avellana L.) and horse chestnut (Aesculus hippocastanum L.) in Munich in 2010. Significant predictors: T ¼ air temperature (common hazel: mean of
January and February; silver birch and horse chestnut: mean of March and April), O3: long-term exposure of ozone, NOx: long-term exposure of nitrogen dioxide, significance
levels: ***p 0.001, *p 0.05, R2; ¼ goodness of fit.