Helping Forests to Walk

By R. Gary Raham

Speaking about human beings and the ebb and flow of glaciers over the past million years, writer Loren Eiseley said, “We are things forgotten when the ice withdrew, and meant to perish really, but the ice forgot, and somehow from the ice-streams we survived—a tough, ill-mannered beast, outthinking all the rest.” Ironically, human thoughts and actions are now doing their best to erase ice from the world entirely, by turning our former ice world into a hothouse world in record time. And as ill-mannered as we may be, the challenges of surviving changing climate did give us the big brains that could still help us survive the warming world we are creating. 

One way to do that is helping forests to walk.

Helping forests to walk is a Native American phrase used by biologist Robin Wall Kimmerer in her book, Braiding Sweetgrass. Later, the evolutionary biologist/writer Connie Barlow picked up the term as a more poetic way to say human beings can help forests migrate out of their current ranges into places that will better fulfill their needs a few decades into the future. And those forests bring with them entire suites of organisms big and small that tie ecological systems together.

Barlow pointed out severed ecological relationships caused by climate changes as glaciers retreated from our most recent ice age in her 2000 book, The Ghosts of Evolution, inspired by the work of Paleoecologist Paul S. Martin. Martin and other scientists recognized the fact that animals like pronghorn run so fast (60 miles per hour) because they are still haunted by cheetahs that could have caught them in an ice age North America. Similarly, gourd-producing plants miss their mammoth seed distributors and prickly pear cactus in the southwest grow tall to avoid camels that found them tasty for countless generations.

These anachronistic ecological relationships have had nearly 12,000 years to heal since the last ice age. Human beings are wreaking havoc by forcing ecosystems to adapt within mere decades to global warming. Barlow was an early advocate for Forest Assisted Migration (FAM) before it had that name by advocating the planting of the endangered Florida Torreya toxifolia (a kind of yew) far north of its current range. Initially, she caught flack from other scientists who thought her methods would lead to more invasive species problems than they would solve.

Today, however, forestry practices recognize the importance of having “deep time eyes”—eyes that see visions of a future world warming far more quickly than ever seen in the geological past.

One of the leaders in the field is Colorado State University, which belongs to an Adaptive Silviculture for Climate Change network (ASCC) exploring ways to help forests walk successfully. Three sites in Colorado are involved: Colorado State Forest (high elevation spruce-fir), Taylor Park (high elevation lodgepole pine), and San Juan National Forest (warm, dry mixed conifer). You can see more about the work in Colorado at adaptivesilviculture.org.

If trees only need help moving within their current range, the forestry practice is called assisted population migration. Assisted range expansion involves moving just beyond a forest’s current range. Assisted species migration means helping trees to walk far beyond their current habitat. Barlow’s work with yews involved the latter, more scientifically controversial, scenario. 

There’s the problem of trees being unwelcome immigrants to wherever they move, of course. But moving a forest also involves insuring that all the floral, faunal, and fungal networks that keep forests healthy make the transition successfully as well. 

Dr. Linda Nagel is co-founder and leader of the ASCC network. She, along with many colleagues recently published “Ten years of adaptive silviculture for climate change: an applied co-produced experimental framework” in the prestigious journal BioScience in 2026. (See https://doi.org/10.1093/biosci/biaf170) Rylee McMillan, an undergraduate student in forest and land management at CSU does a nice interview with Dr. Nagel on the adaptivesilviculture.org website.

Kimmerer, the Native American author of Braiding Sweetgrass, thinks that the arrogance of the English language almost forces us to deny the animacy of other living things. When a tree becomes an it and not a who “we put a barrier between us, absolving ourselves of moral responsibility and opening the door to exploitation. Saying it makes a living land into ‘natural resources.’” The phrase helping forests to walk gives us more permission to see forests as living companions on parallel journeys.

Hopefully, we ill-mannered humans can use our ice age inflated brains to imagine viable paths into a warmer future that includes most of the creatures with whom we share the Earth.  Nature provides more than necessary services. Her landscapes help make us whole. Her parts are distant kin and we need to treat them like part of our family in need.

Raham will delve into some of the topics in this article in more detail in a presentation called “Ghostly Echoes From the Last Ice Age” at Soapstone Prairie Natural Area north of Fort Collings on September 5 from 10 to 11 am. Registration opens for the event 30 days prior at fcgov.com/register or call 970-416-2815. Raham is a biologist/author/illustrator based in Wellington, Colorado. Visit rgaryraham.com.