Tuesday, October 11, 2016

Richard Primack on Fall

Richard Primack is professor of biology and plant ecology at Boston University, and famous among us for his study of effects of climate change, making use of  Henry David Thoreau's meticulous seasonal notes to study long-term seasonal change in Concord's woods.   In a recent interview he walks with WBUR's Meghna Chakrabarti in Webster Woods.  (The audio recording lasts eight minutes.)

The two discuss:
1. drought-induced early leaf color and fall (and even fall of green leaves)
2. governing of timing of fall color by temperature, day length, moisture, & frost events
3. fallen green oak twigs cut by squirrels, a sign of a shortage of food (here mainly insects, and perhaps hickory nuts, since acorns are about as abundant as last year).  Primack says squirrels are eating the inner bark on branchlets and dropping the twigs. 
4. Missing insects and early bird migration
5. I the Massachusetts drought linked to climate change?  No--climate change predicts wetter conditions here, on average.

Some surprises for me here: the big one is that gray squirrels are short of food: many of the trees losing twigs were heavy with acorns.  And some scepticism: the fallen twigs are the result of their eating bark, but there is no bark missing on the fallen parts and the twigs are cut off sharp. 

I have my doubts about the food shortage hypothesis:
this twig was cut with high-quality acorns still in place. 

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