Thoreau’s observations of fruiting times inform climate change research

By Tara K. Miller
 

“To replenish the possibility of mutual flourishing, for birds and berries and people, we need an economy that shares the gifts of the Earth, following the lead of our oldest teachers, the plants.”

- Robin Wall Kimmerer, The Serviceberry

 
In a recent Annals of Botany article, we compared Thoreau’s fruiting observations from the 1850s in Concord, MA with museum records from the past 150 years across New England to investigate the biological effects of climate change. We found a strong sequence of fruiting, with species such as blueberries fruiting in mid-summer and hollies fruiting later in autumn.   

Digitized museum specimens, such this bluebead lily,
were used to determine the time of fruit ripening.
© Consortium of Northeast Herbaria

 
This is the first use of Thoreau’s fruiting observations in scientific research, and builds on previous studies of Thoreau’s observations of flowering and bird arrival times. The present study was possible because pressed plant specimens – also known as herbarium specimens – have only recently been digitized in large numbers and made available on-line.

Lowbush blueberry plants were observed to fruit early in the year,
based on both Thoreau’s observations and museum specimens. © Jason S. 

 
Both Thoreau’s observations and museum specimens detect similar patterns of plant fruiting times, confirming that they can be combined to create larger and more powerful data sets for climate change and ecological research. However, the museum specimens, collected over a larger area and over more years than Thoreau, show an earlier start to fruiting and later ending than Thoreau’s Concord observations.

This deciduous holly, also known as winterberry, fruits later in the year. © SB Johnny 

Article: Comparing fruiting phenology across two historical datasets: Thoreau’s observations and herbarium specimens