Study: Climate (Not Humans) Shaped Early Forests of New England

A new study in the journal Nature Sustainability overturns long-held interpretations of the role humans played in shaping the American landscape before European colonization. The findings give new insight into the rationale and approaches for managing some of the most biodiverse landscapes in the eastern U.S.

The study, led by archaeologists, ecologists, and paleoclimatologists at Harvard and elsewhere, focuses on the coast from Long Island to Cape Cod and the nearby islands of Nantucket, Martha’s Vineyard, Block Island, and Naushon —areas that historically supported the greatest densities of Native people in New England and today are home to the highest concentrations of rare habitats in the region, including sandplain grasslands, heathlands, and pitch pine and scrub oak forests. 

“For decades, there’s been a growing popularization of the interpretation that for millennia, Native people actively managed landscapes – clearing and burning forests, for example – to support horticulture, improve habitat for important plant and animal resources, and procure wood resources,” says study co-author David Foster, Director of the Harvard Forest at Harvard University. This active management is said to have created an array of open-land habitats and enhanced regional biodiversity.

But, Foster says, the data reveal a new story. “Our data show a landscape that was dominated by intact, old-growth forests that were shaped largely by regional climate for thousands of years before European arrival.”

Fires were uncommon, the study shows, and Native people foraged, hunted, and fished natural resources without actively clearing much land. “Forest clearance and open grasslands and shrublands only appeared with widespread agriculture during the European colonial period,” says Wyatt Oswald, a professor at Emerson College and lead author of the study, “within the last few hundred years.”

The authors say the findings transform thinking about how landscapes have been shaped in the past – and therefore how they should be managed in the future. “Ancient Native people thrived under changing forest conditions not by intensively managing them but by adapting to them and the changing environment,” notes Elizabeth Chilton, archaeologist, co-author of the study, and Dean of the Harpur College of Arts and Sciences at Binghamton University. 

To reconstruct historical changes to the land, the research team combined archaeological records with more than two dozen intensive studies of vegetation, climate, and fire history spanning ten thousand years. They found that old-growth forests were predominant for millennia but are extremely uncommon today.

“Today New England’s species and habitat biodiversity are globallynique, and this research transforms our thinking and rationale for the best ways to maintain it,” says Oswald. “It also points to the importance of historical research to help us interpret modern landscapes and conserve them effectively into the future.” historical changes to the land, the research team combined archaeological records with more than two dozen intensive studies of vegetation, climate, and fire history spanning ten thousand years. They found that old-growth forests were predominant for millennia but are extremely uncommon today.

The authors also note the unique role that colonial agriculture played in shaping landscapes and habitat. “European agriculture, especially the highly varied activity of sheep and cattle grazing, hay production, and orchard and vegetable cultivation in the 18^th and 19^th centuries, made it possible for open-land wildlife species and habitats that are now rare or endangered – such as the New England cottontail – to thrive,” says Foster. Open-land species have declined dramatically as forests regrow on abandoned farmland, and housing and commercial development of both forests and farms have reduced their habitat.

Foster notes that the unique elements of biodiversity initiated through historical activities can be encouraged through analogous management practices today. “Protected wildland reserves,” he says, “would preserve interior forest species that were abundant before European settlement. Lands managed through the diversified farming and forestry practices that created openlands and young forests during the colonial period would support another important suite of rare plants and animals.”

For successful conservation models that leverage this historical perspective, the authors point to efforts by The Trustees of Reservations, the oldest land trust in the world, which manages more than 25,000 acres in Massachusetts embracing old and young forests, farms, and many cultural resources. The organization uses livestock grazing to keep lands open for birds like bobolinks and meadowlarks, which in turn supports local farmers and produces food for local communities.

• Read the full paper in Nature Sustainability entitled "Conservation implications of limited Native American impacts in pre‐contact New England"
• Read the Boston Globe article entitled "New study: Native Americans didn't change the landscape as much as previously thought" (PDF version)
• Read the companion piece in the Nature Research "Behind the Paper" channel entitled "Retrospective science informs regional conservation and land management"
• Read The Conversation article entitled "Native people did not use fire to shape New England's Landscape"
• Read the Harvard Gazette article entitled "Finding new land management lessons in old ways"
• Read the Harvard Magazine article entitled "New England's Forest Primeval"
• Read the Emerson Today article entitled "Incendiary Study: Climate, Not Humans, Shaped Ancient New England Landscape"
• Read the National Science Foundation article entitled "Climate shaped early forests of New England"
• Read the Vineyard Gazette article entitled "Study Shows Climate, Not Humans, Shaped Early Forestland"
• Read the article in EOS entitled "New England Forests Were Historically Shaped by Climate, Not People"

An excerpt of the 2017 book "A Meeting of Land and Sea: The Nature and Future of Martha's Vineyard" includes an expanded exploration of early human activity on the coast. The book's accompanying website also provides more information on the archaelogical, historical, and paleoecological research behind this paper.

Photos by David Foster and Wyatt Oswald.