Hi HB,

Thanks to the efficiency of Amey Bailey, we can report how our phenology predictions for 2019 compared to her standardized measurements of leaf expansion.

Predicted budburst on Main bird plot (490 m asl): 19 May

Observed budburst near the Main bird plot:           18 May

Our current model is designed to predict the average date of budburst for Sugar maple, Beech, and Yellow birch. From Amey’s measurements, observed budburst for the three tree species in 2019 were:

14 May, 19 May, and 20 May for Sugar maple, Beech, and Yellow birch, respectively.

During the next year, we will develop separate models for the three tree species. Sugar maple leaves commonly come out some days earlier than the other two tree species, and probably has somewhat physiological controls on leafout phenology. Beech and birch are usually very close to each other.

We have defined “budburst” as the date when leaves reach stage 2 in Amey’s phenology data: “small leaves or flowers visible initial stages of leaf expansion leaves about 1 cm long”. The event date is estimated by interpolation between observation dates, which have usually been weekly. To pair with the Main bird plot, we have used three of Amey’s sites:

1B	bottom of WS1
4B	bottom of WS4, oldest strips
5B	bottom of WS5

Here is the history of model predictions for this spring.

Date of prediction Predicted date of budburst

24 April                                            11 May

4 May                                              16 May

11 May                                            18 May

18 May                                            19 May

21 June                                            19 May

Matt