In the 1930s, an archeologist from the Smithsonian wrote a short paper remarking on the exquisite vegetation around First Nation villages in Alaska. The surroundings were filled with nuts, stone fruit, berries, and herbs—several non-native to the area and many that would never grow together naturally. Apart from this brief mention, however, the significance of these forest gardens went largely overlooked and unrecognized by modern archeology for the next 50-plus years.

In the last decades, archeologists have learned that perennial forest management—the creation and care of long-lived food-bearing shrubs and plants next to forests—was common among the Indigenous societies of North America’s northwestern coast. These forest gardens played a central role in the diet and stability of these cultures in the past, and now a new publication shows that they offer an example of a far more sustainable and biodiverse alternative to conventional agriculture.

In a collaboration with the Tsm’syen and Coast Salish First Nations, this research shows that these gardens have become lasting hotspots of biodiversity, even 150 years after colonists forcibly removed the inhabitants from their villages. In a project combining archeology, botany, and ecology, this work is the first to systematically study the long-term ecological effects of Indigenous peoples’ land use in this region. Beyond the impressive longevity of these gardens, they offer ideas for farming practices that might restore, rather than deplete, local resources to create healthier, more resilient ecosystems.

Cultivated over millennia

Indigenous forest gardens in the tropics and subtropics have been increasingly appreciated as valuable models for more sustainable agriculture. These practices have been somewhat easier for researchers to identify because some are still in use today, and they also more closely resemble Eurocentric notions of agriculture—such as annual cycles of planting and harvesting.

In contrast, the forest gardens of the Pacific Northwest are cleared spots nestled alongside the native coniferous forests. The gardens contain collections of perennial plants and shrubs like Pacific crabapple, wild cherry and plum, soapberry, wild ginger, rice roots, and medicinal herbs. Rather than annual cycles of planting, the Indigenous people collected, transplanted, and carefully tended these plants over many years—pruning, fertilizing, coppicing, and using controlled burns to promote productivity.

These lasting effects are seen elsewhere in North America, including the semiarid Bears Ears region in Colorado. The archeological sites in both regions have a diversity of plant species that cannot be explained by natural causes alone, suggesting the potential transplantation of these species over significant distances.

One of the cornerstone species of the Pacific Northwest gardens—hazelnut—was even transplanted from 700 km away. “Hazelnut is a big piece of our understanding of forest gardens because it was one of the first species recognized as having no business being there—but it’s in this nice pocket where we see a cultural explosion about 5000 years ago,” says Chelsey Armstrong, first author of the study. “As I studied, it was increasingly clear that it wasn’t just hazelnut—these were entire ecosystems. And it wasn’t just gathering—this was a completely different food system, where there was clearly active management and investment in the landscape.”

Sustainable and biodiverse

For their latest research, Armstrong and her collaborators selected villages that had been continuously inhabited for more than 2,000 years before the residents were forced to leave. The team surveyed the variety of plant species as well as an ecological metric called functional diversity. The researchers measured the range of traits represented, such as seed mass, shade tolerance, and the method of pollination and seed distribution.

By comparing the gardens to the neighboring forests, their results clearly showed that the gardens had a much higher species and functional diversity. In addition, the gardens frequently showed a carefully overlapped structure, with a canopy of fruit and nut trees, a midlayer of berries, and roots and herbs in the undergrowth. Thanks to the increased availability of fruit, nuts, and other edible plants, these places also supported local wildlife, such as moose, bears, and deer.

“There’s a kind of false dichotomy debate going on right now that biodiversity is at odds with food production, and what we see here is very clearly that it’s not,” says Armstrong. “Forest gardens are one of the examples of how you can get multiple species occupying multiple niche spaces—there are all sorts of ecological lessons there.”

Restoring a legacy

Although the First Nation people aren’t using the gardens as much as when the villages were inhabited, many have been returning to them over the past decades to preserve these places and the knowledge about them. Despite being confined to reservations and penalized for practicing their culture in the past, there’s been a strong movement to restore as much of the traditional knowledge as possible.

“There’s a conscious effort to revive traditional use of the land—it’s taught now in our schools, and it’s being shared more openly amongst all age groups,” says Willie Charlie, former chief and current employee of the Sts’ailes Nation of the Coast Salish people, who has helped form a working group to maintain and manage access to the gardens. “More and more people are going back to these traditional places to harvest the plants, herbs, medicine, and food.”

Dozens of tribes live in the region, each with different practices and different relationships to their ancestral lands, but land-based foods are a staple for many. Armstrong is collaborating with these communities and designing her research to aid the preservation and restoration of the gardens—and to provide additional evidence to counter local logging interests as well.

“Our people’s belief is that we don’t own the land—we are the land,” says Charlie. “Sharing our continued use of the land is a way of bringing awareness, which brings protection.”

K.E.D. Coan is a freelance journalist covering climate and environment stories at Ars Technica. She has a Ph.D. in Chemistry and Chemical Biology.

https://arstechnica.com/?p=1765746