An International Network of Trees, published in Silva

Posted by Amanda Gallinat

"Nothing makes the earth seem so spacious as to have friends at a distance; they make the latitudes and longitudes" -Thoreau in a letter, May 22, 1832

For the last five years, the Primack Lab has been part of a collaborative effort to monitor leaf-out, leaf senescence, and fruiting times at a network of seven international botanical gardens. We recently published an overview of this collaborative work in the Arnold Arboretum's magazine, Silva. 

Richard Primack carefully monitors leaf senescence at the Arnold Arboretum

In the article, we describe how the living collections of botanical gardens have allowed us to monitor the phenology of an enormous range of species; with our colleagues, we have monitored >1600 species for leaf-out, 1360 species for leaf senescence, and several hundred species for fruiting. Our lab conducts our observations right here in Boston, MA, at the Arnold Arboretum.

Young leaves of Acer japonicum observed on April 24th at the Arnold Arboretum

The group's observations across botanical gardens and years have demonstrated that species leaf-out and fruit in a consistent order from year to year and place to place (and related species have similar timing), while the order in which species change color and drop their leaves is not consistent across space and time.

I record fruiting times for plants in the vast Viburnum collection at the Arnold Arboretum

Uncovering these and other patterns in the spring and autumn phenology of many species has given us new insight into the rich natural history present at the Arnold Arboretum (our home site) and other botanical gardens, and helps us understand how plant schedules will respond to climate change.