Our native forests are full of food. The understories are packed with blueberries and huckleberries and for thousands of years, local overstories have been full of nut trees: hickories and chestnuts and walnuts and oaks. Marc Abrams, a fire ecologist who visited Cape Cod from Pennsylvania and walked our forests with me, says this isn’t an accident:
"Most plant ecologists and forest ecologists believe that Indigenous People did a significant amount of burning for many, many reasons, basically to clear forests and to promote certain desirable species that were important to their diet," he explained.
"So they were burning routinely in the upland forests and basically maintaining oak and pine forests through this periodic burning."
This burning has historically promoted what’s called mast species — trees that produce abundant nuts — because many of these trees are adapted to fire.
"Look at an oak tree over here, and you can see that thick, furrowed bark. And you can imagine that a normal low to moderate intensity surface fire would not harm this tree. But hickory is also a thick bark species along with the pine, you can see it pitch pine there that has a nice thick bark on it."
Thick bark is part of a suite of adaptations that help fire-adapted species thrive with periodic, low-intensity fires. These are what ecologists call prescribed burns and what many Indigenous People call cultural fires — in other words, fires that we humans set intentionally.
"There was actually a lot of burning going on through the 1800s and early 1900s," Marc explained. "But then we got into the Smokey the Bear era in the 1930s, where basically fire went from very, very high to almost negligible. And that's when these forests really started to change dramatically and moved from oak and pine to later successional species such as red maple and beech."
The forests Marc is talking about are the eastern woodlands in general — not just Cape Cod forests, but a huge swath of the northeast. And the ecological process he’s talking about, succession, refers to an ecosystem moving from bare earth to old-growth forest, and all the stages that come along the way.
In most eastern woodlands, without human intervention, succession proceeds from bare earth to meadow to shrubland to early successional forests dominated by nut trees and finally to later successional forests with mostly shade-tolerant species like beeches and red maples and hemlocks and birches. And this is what’s happening in a lot of places where these nut trees have been dominant for the past 9,000 years — now that human fire has been suppressed, over the decades the oaks and hickories are starting to disappear and are being replaced by shade tolerant species like red maple and birch. And many ecologists, Marc included, believe this is a big food loss in our ecosystems.
"We don't use acorns to the extent that Indigenous People did. You just can't eat a raw acorn because of the really high tannins in it. You have to kind of, you know, chop it up, mash it up, and then rinse it with water multiple times to get the tannin chemicals out of it. But it's so interesting to think what an important food source acorns used to be for the Indigenous People that we are not using. And if we lose our oak type, we're losing all of that acorn production. Hickory is within that mix, also a big mast nut species. We've already lost the chestnut, but luckily the oak and hickory kind of filled in for the chestnut. But if we lose that mast type, if you will, then we're going to be losing wildlife populations like crazy."
Some areas of Cape Cod are exceptions to the changes Marc’s describing across the northeast. Our soil can be so nutrient-poor and sandy that forests don’t necessarily require fire here to keep succession in the oak and pine and hickory dominant phase. But our landscape has still evolved with fire — and in many places can still benefit from regular burning, whether it's to reduce fuels and the chances of catastrophic wildfires or to produce an abundance of nuts and berries for us humans and the countless other species we share this place with.
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Here's a link to learn more about prescribed fire in Massachusetts.
Here's a link to learn more about Marc Abrams' recent research.
And here's a link to learn more about Elspeth's book.
