A first-of-its-kind study by SFU finds that Indigenous forest gardens filled with fruit and nut trees are still thriving, at least 150 years later
Along Canada’s northwest coast, ancient Indigenous forest gardens — untended for more than 150 years — continue to thrive. Ts’msyen and Coast Salish peoples once planted and cared for plots of native fruit and nut trees, shrubs, and medicinal plants and roots along the north and south Pacific coast, a new Simon Fraser University study finds.
Forest gardening is a common method of food cultivation and agroforestry in Indigenous communities around the world, especially in tropical regions. But the findings published in Ecology and Society mark the first time these lush, open, orchard-like plots have been studied in North America.
In coastal forest gardens, crabapple, hazelnut, wild cherry and plum trees provide a canopy, shielding plants such as cranberry, elderberry and hawthorn, wild ginger and wild rice root. Containing more species diversity than the surrounding conifer forests, according to the research, the intentionally planted patches continue to provide a significant habitat for birds, bears and pollinators.
“These plants never grow together in the wild. It seemed obvious that people put them there to grow all in one spot — like a garden,” says SFU ethnobiologist and archaeologist Chelsey Geralda Armstrong, lead author of the study, in a statement.
In their management of these ancient forest gardens, the researchers write, Indigenous peoples practiced controlled burning, coppicing (encouraging growth by cutting back trees or shrubs to ground level), fertilizing, long-distance transplanting, pruning and weeding.
Despite being unmanaged for more than a century, evidence of these historical practices can still be seen at remote archaeological villages. This resilience is the most surprising aspect of the research, Armstrong told Popular Science. “On the Northwest coast, conifer forests are stubborn. They will reestablish themselves 20 to 30 years after a disturbance.”
With such a varied mix of species occupying different niches, the researchers said, there’s less room for new species to take root. Their effective use of space — “there’s a canopy, a sub-canopy, a bush-shrub layer, a vine layer going up and around, and then a herbaceous layer” — is likely central to their longevity.
For their study, the researchers selected four archaeological sites that had been occupied for more than 2,000 years: two Ts’msyen village complexes in northwestern B.C. and two Coast Salish complexes in the southwest. (A village complex consists of two or more nearby villages, each containing five to 20 houses.) Indigenous peoples tended forest gardens on these sites until they were displaced in the late 1800s.
“Elders and knowledge holders talk about perennial management all the time,” says Armstrong. “It’s no surprise these forest gardens continue to grow at archeological village sites that haven’t yet been too severely disrupted by settler-colonial land-use.”
Sampling species growing in the vicinity of the archaeological sites showed more biological and functional diversity (offering insight into traits such as drought tolerance) in forest gardens than in the dominant evergreen woodlands.
“It’s striking to see how different forest gardens were from the surrounding forest, even after more than a century,” Jesse Miller, study co-author, ecologist and lecturer at Stanford University, told Science.
A neighbouring swath of conifer forest, which had been logged decades ago and allowed to regenerate naturally, contained only a fraction of the number of species: “The forest gardens bucked the trend,” Armstrong said.
Originally planted with a rich array of edible and medicinal flora for people to use, forest gardens are now a source of food for animals and pollinators. While human activities, such as industrial land management, are often seen as being harmful to biodiversity, their study shows how Indigenous practices have benefited the health and resilience of forest ecosystems in the long-term, the researchers say.
“A lot of functional diversity studies have a ‘humans are bad for the environment’ approach,” Armstrong told Science. “This shows humans have the ability to not just allow biodiversity to flourish, but to be a part of it.”
by Laura Brehaut