Hi Hubbard Brook,

Our phenology model predicts that average budburst of canopy beech and maple on the Main bird plot was last Thursday. As of today, the forecast is for trees to rocket through leaf expansion and reach 90% of full leaf expansion by this Friday. It has been reliably true that late cool springs at HB are associated with particularly warm temperatures during the period leaf expansion. One of our working hypotheses for fluctuations of caterpillar abundance at HB is that years such as this are good for moth populations because the many species with life histories to feed on the nutritious expanding leaves grow faster as caterpillars when it is warm during this period and therefore experience fewer days of high predation risk from birds. Perhaps we will get some more information from this year to evaluate the hypothesis. Enclosed and below is todays view from the phenocam at Headquarters (thank you Andrew Richardson!). The image seems consistent with an extrapolated prediction from our model that leaf expansion should be about complete by now at that elevation (234 m asl).

https://phenocam.sr.unh.edu/webcam/sites/hubbardbrook/

Matt

From: Matthew P. Ayres
Sent: Tuesday, May 19, 2020 20:18
To: Hubbardbrook@lists.sr.unh.edu
Subject: Updated leaf-out forecast for Hubbard Brook

Hi Hubbard Brook,

The last week’s temperatures have been pretty close to the forecasts – just a tad cooler. The updated model forecasts this Friday to be the day of budburst on the Main bird plot (Weir 6, 475 m asl). For context, below is a photo from Weir 6 two days ago. Further details, and the sequence of predictions for this year, are in the enclosure.

Matt