Was Henry David Thoreau a good naturalist?

 By Richard B. Primack

“It is not enough that we are truthful; we must cherish and carry out higher purposes to be truthful about.”  Henry David Thoreau in Early Essays and Miscellanies. 

For much of the past century-and-a-half Henry David Thoreau has been regarded as one of America’s greatest environmental philosophers. Meanwhile, his extensive observations of the natural world were largely ignored or criticized for their inaccuracy. 

An example of Thoreau’s records of plant flowering times. Primack notes are in blue.

Were Thoreau’s observations good enough for scientific use? Or were his early critics right?

In a recent article published in the journal BioScience, we present a framework for evaluating the scientific observations of historical figures using the criteria of rigor, accuracy, and utility. We apply this framework to Thoreau’s observations of flowering, leafing out, fruiting, and bird arrival times in Concord, Massachusetts. 

Not surprisingly, we find Thoreau was a good naturalist. His observations are rigorous—based on frequent and repeatable sampling. They are accurate—based on a comprehensive knowledge of species and places. And they have utility in modern ecological studies of climate change. 

The sequence of flowering of spring wildflowers that Thoreau observed is almost identical to current observations of flowering times.

This study adds to our confidence in what Thoreau has to tell us about how to observe the nature world and how we can use his observations to understand how climate change affects our world today.  

Publication: Richard Primack, Abraham Miller-Rushing, Tara K. Miller  (2022). Was Henry David Thoreau a good naturalist? An approach for assessing data from historical natural history records. BioScience.  https://doi.org/10.1093/biosci/biac063 

Plant Traits Affect Phenology

By Richard Primack 

 

“You may know what a thing costs or is worth to you; you can never know what it costs or is worth to me.” Henry David Thoreau in his Journal. 

 

The timing of events in the life of wildflowers remains under-studied despite their importance in the species richness of temperate ecosystems. To provide this information, a recent paper in the New Phytologist reports on the results of a study of 212 wildflower species at 5 botanical gardens in Germany.   

Trout lily is an early spring woodland wildflower. 

Data was collected on timing of leaf out and initial growth, flowering, fruiting, and leaf senescence.  Functional traits were also measured, including plant height, absolute and specific leaf area, leaf dry matter content, leaf carbon and nitrogen content and seed mass.  

 

Rose mallow flowers late July and August in river margins and flood plains.

Taller plants showed later timing of initial growth, and flowered, fruited and underwent leaf senescence later. Large-leaved species had shorter flowering and fruiting durations.  

Figure. Taller plants have later fruiting; blue indicates positive relationships, and red indicates negative relationships.

 

Figure. Plants with larger leaves have a shorter flowering duration.

 

There were also major differences in phenology among the five gardens, highlighting the importance of local growing conditions in affecting plant phenology.  

 

The study was published as: Sporbert, M. et al. 2022. Functional traits influence patterns in vegetative and reproductive plant phenology – a multi-botanical garden study. New Phytologist 235: 2199–2210 doi: 10.1111/nph.18345