Three clues for reading the forest

Tom Wessels discusses how trees offer clues to the past—if you know where to look. Photo by Steele Hays.

By Steele Hays

Maine forests are loaded with clues that enable you to see into the past–if you know where to look and how to spot the clues.  

Unraveling mysteries about the past and “reading the forest” was the focus of an Oct. 2 walking tour at Ellsworth’s Woodlawn Estate led by forest ecologist Tom Wessels of Blue Hill, a nationally-recognized expert and author of multiple books on the subject.  

Here are three of the insights Wessels shared that can potentially enrich your next forest walk and let you impress your friends and family.  

Pay attention to the forest floor.

Is it relatively smooth and level or bumpy, with many pits and mounds? Maine forests are shaped by weather events like wind, snow and ice storms. When the trees topple over, their roots pull up soil, rocks and other material, which decay into mounds and leave pits where the roots were. That’s the typical surface of a Maine forest—so if you see a smooth, level forest floor, it means that land was probably crop land or pasture land in the past that has since regrown into forest.  

Look closely at individual trees, especially white pines.

White pines are often excellent indicators of the past, Wessels said. If a large white pine has many large branches along the lower parts of its trunk, there is a strong likelihood it grew up in an open field in its early life, with a lot of lateral exposure to sunlight. Or, if a white pine has especially large branches up and down its trunk along only one side, it was probably “a border tree” on the edge of a field.  

Study the terminal branch or “leader” of pines and other evergreens, for clues about the past.

Weevils, a native pest, prefer fast-growing, young trees in sunny areas with a thick, fat terminal leader–the top of the tree–which provides the maximum amount of food for the weevil larva. Young pines in mature forests receive less sunlight and have thinner, less tempting leaders, so they are usually not attacked by the weevils. When a weevil-hit leader dies, the pine tree responds by generating multiple new leaders, creating a new structure and shape that remains evident for the rest of the tree’s life. So the presence of weevil-hit trees in the forest is a strong indicator that those trees began life when the forest was transitioning from open crop land or pasture to forest, or perhaps when a forest was regenerating after a clear cut or fire. 

Clearly, 2025 will be remembered as a drought year in Maine, but it is also a “mast year,” according to Wessels, when white pine trees are generating an unusually high volume of cones and seeds. Mast years occur periodically and irregularly, not on any fixed cycle, and these mast years illustrate how “a lot of the living things out here are a lot smarter than we thought,” Wessels said, referring to the capacity of trees and other plants to adapt to threats and change their behavior. By producing a much higher-than-average volume of seeds in selected mast years, tree species ensure that more seeds can avoid being consumed by predators and can sprout and grow to maturity.  

“The natural world is a lot more intelligent than we know,” Wessels said. 

Wessels is a retired professor of ecology at Antioch University New England, who now lives in Blue Hill.  He is the author or co-author of five books, including “Reading the Forested Landscape: A Natural History of New England.”