Before European settlers arrived in the Americas, Native American groups used fire to shape the land. This practice helped control the environment and keep habitats healthy for plants and animals, which supported their way of life. Early European settlers saw large areas of North America as untouched wilderness, but these lands were actually shaped over time by Native American burning practices, creating a mix of grasslands and forests managed by the people who lived there.

Major changes happened when Europeans colonized the land and forced Native Americans to move. Some settlers recognized the usefulness of controlled, low-intensity fires used by Native peoples, but others feared them and stopped these practices. By the 1880s, Native American populations had been greatly reduced due to colonization, and fire suppression became more common. By the early 1900s, stopping fires became official U.S. government policy.

Learning about how Native peoples managed the land before colonization and the knowledge they used helps today’s scientists and land managers understand how ecosystems developed. This knowledge is important for making informed decisions about land use and understanding how plants and trees are distributed in different areas.

Human-shaped landscape

Before Europeans arrived, Native Americans had a significant influence on the variety of plants and animals in their environments.

Throughout history, managing forests has provided many benefits. Native peoples understood the risks of allowing forests to grow too thick. They used fire to clear undergrowth in forests and mountains, making it easier for hunting, traveling, and managing natural resources like food. Fire was also used in battles to protect homes and communities.

Writers such as William Henry Hudson, Henry Wadsworth Longfellow, Francis Parkman, and Henry David Thoreau helped spread the idea that North America before European contact was a wild, untouched land with little human impact. However, by the time these writers were writing, large areas of land had already reached a final stage of plant growth. This happened because human-caused fires, which Native peoples had used to manage the land, decreased after many Native people died from diseases brought by Europeans in the 16th century, were forced to move, or were involved in wars.

Grasslands and savannas

When Europeans first arrived, many ecosystems had been shaped by fires that happened every one to three years. These fires changed forests into grasslands or savannas, or cleared undergrowth from forests. In the Amazon basin, special soils called terra preta were created by slow burning. These soils are mostly found in the Amazon, and estimates suggest they cover 0.1 to 0.3% of low forested areas in the region, or up to 1.0% or more.

In the Klamath Valley of northern California, frequent, low-intensity fires started by people helped keep grasslands open. Without these fires, conifer trees, which are less able to survive fires, might have taken over the area. In the Pacific Northwest, tribal communities used cultural burning to grow plants important to their traditions, such as camas, yampa, and tarweed. These plants were part of the diets of many tribes. For example, the Blackfoot, Cree, and Nez Perce tribes ate the bulbs of the Common Camas (Camassia quamash), which could be steamed or dried into flour. The Yokut tribe of California harvested yampa, a plant also called wild carrot. Tarweed seeds are also edible and described as "rich as butter." Burning grasslands can create space for rare plants found only in prairies, such as the western lily and Howell's triteleia.

Some people debate whether fires started by humans had a greater impact than lightning-caused fires in western North America. Historical records show that large prairies existed in the 1600s, but after European settlement, these areas quickly turned into woodlands. Accounts also mention that laws were passed in Canada and the United States to stop Indigenous people from burning prairies. Emily Russell (1983) noted that there is no strong evidence that Indigenous people burned large areas intentionally, but their presence likely increased fire frequency beyond what lightning alone caused. She also said that fires were most common near where Indigenous people lived. John E. Keeley (2002) suggested that Native American burning in California’s coastal ranges helped increase the number of fires caused by lightning, leading to more grasslands and open shrublands. He explained that shrublands provided few resources for Indigenous people, so they used fire to change these areas into more usable open spaces.

Reasons for and benefits of burning

Reasons for intentional burns in ecosystems before contact with outside groups are varied. These include:

• Helping farming by quickly returning nutrients from burned plants and soil to the ground.
• Boosting nut production in wild orchards by darkening soil with burned leaves, reducing how much sunlight reflects off the ground, and raising spring temperatures to protect nut flowers from frost.
• Encouraging growth of plants that survive fire by starting seeds to grow or cutting branches to promote new growth. Shrubs like osier, willow, hazel, and Rubus benefit from this process, as it helps them live longer and produce more.
• Making hunting easier by clearing bushes and fallen branches, allowing hunters to move quietly and see animals better. It also creates open paths for throwing tools or weapons.
• Creating conditions that allow for smaller, more targeted burns for cultural or practical purposes.
• Improving travel by removing thick, tangled plants and bushes that block movement.
• Helping pollinators like hummingbirds, bees, and butterflies by providing burned soil and charred wood as nesting spots. Examples include the California Tortoiseshell butterfly (Nymphalis californica) and the Ceanothus silk moth (Hyalophora euryalus), which support plants important to human cultures.
• Increasing the variety of plants and animals in forest undergrowth. Burning helps grasslands grow under oak trees, supporting more reptiles, amphibians, small mammals, and blueberry bushes.
• Strengthening ecosystems to resist invasive plants that harm native species.
• Reducing the chance of large, dangerous fires by removing built-up plant material.
• Increasing numbers of animals like deer, rabbits, bison, and extinct species like mammoths by creating habitats in grasslands or under forest canopies. It also helps animals that eat nuts, such as rodents, turkeys, and bears, and their predators like mountain lions and wolves.
• Encouraging the regrowth of useful plants like cherry and plum trees. Beargrass, a plant important to the Karuk people of Northern California, produces high-quality leaves for basket-making 1 to 3 years after fire.
• Reducing ticks and biting insects by destroying their eggs and young.
• Controlling pests and diseases in chaparral areas that affect culturally important plants.
• Increasing water flow in rivers by reducing water loss from plants.
• Cooling rivers with smoke, which signals salmon to begin moving upstream.
• Religious practices, such as burning to ask for rain, good weather, or to guide salmon back from the ocean.
• Burning areas where seeds grow to help harvest them, encourage seed production, protect long-lived plants, renew yearly plants, return nutrients to the soil, and clear dead material to allow new plants to grow.

Impacts of European settlement

By the time European explorers first reached North America, millions of acres of "natural" landscapes had already been changed and cared for by humans. Fires often showed that people were nearby to European explorers and settlers who arrived by ship. In San Pedro Bay in 1542, fires in the chaparral helped Juan Rodríguez Cabrillo and later others notice human presence across what would become California. In the American West, it is estimated that about 456,500 acres (184,737 hectares) burned each year before settlers arrived in what is now Oregon and Washington.

By the 17th century, Native populations were deeply affected by the violent systems of settler colonialism. Many colonists intentionally started wildfires or let fires spread without control. Sheep and cattle owners, along with shepherds and cowboys, often set fires in alpine meadows and prairies at the end of the grazing season. These fires helped remove dried grasses, reduce brush, and kill young trees, while also encouraging new grasses to grow for future grazing. Native people were forced from their traditional lands or killed, and their traditional land management practices were later banned by settler governments.

By the 19th century, many Indigenous nations were required to sign treaties with the federal government and move to reservations, which were sometimes hundreds of miles away from their ancestral lands. Alongside forced removal, fire suppression became a tool used by colonists to displace and harm Native people. As sociologist Kari Norgaard explained, "Fire suppression was required by the first session of the California Legislature in 1850, during the height of genocide in northern California." For example, the Karuk people of Northern California burned forests to improve the quality of forest food sources like elk, deer, acorns, mushrooms, and lilies, as well as materials used for basketry, such as hazel and willow. They also kept travel routes clear. When these practices were banned through fire suppression, it had major effects on their ways of living, relationships with the environment, food sources, and education. Many scholars argue that fire suppression can be seen as a form of "colonial ecological violence," causing specific harms to Native communities.

By the early 20th century, settlers continued to use fire to clear land of brush and trees to create farmland for crops and pastures for grazing animals—a practice similar to "slash and burn" techniques used elsewhere in North America. Others burned land intentionally to reduce the risk of large fires, a method called "light burning." This technique was also known as "Paiute forestry," a term that unfairly refers to the fire practices of southwestern tribes. The effects of settler-caused fires were very different from those of Native American cultural burning practices. Cultural burning became illegal after the Weeks Act was passed in 1911.

Modern management

When indigenous people were removed from their lands and their burning practices stopped, big changes happened in the environment. These changes included more severe wildfires, especially when combined with climate change. In recent years, people have started to see the value in traditional Native American fire practices. Tribal groups and organizations now use these methods again to care for forests and grasslands near their lands. Many scientists and forest workers have also learned from Native American traditions. They use controlled burns to reduce fire risks, change plant types, and improve the health of forests and open lands.

Fire was an important tool for Native Americans. According to Dave Roos, a writer for the History Channel, Native Americans saw fire as a science. In Yosemite, they used controlled burns to clear brush and create soil rich in nutrients for growing plants. Fire was also seen as a form of medicine by indigenous people, and they believed it was most useful when used at the right time.

Forest management includes controlled burns, thinning trees, and planting new trees. Fire agencies in the United States now use these methods. Some agencies look to Native American stories and traditional knowledge to guide their work. Native Americans in California and Australia understood the dangers of overgrown forests for many years. They used controlled burns to prevent wildfires and help plants grow. Controlled burns reduce the amount of dry plant material that could fuel fires. Native Americans used small fires to clear brush between trees, lowering the chance of large fires.

Selective thinning helps replace old, weak trees with plants that can survive fires. These plants, called pyrophytes, have traits that help them resist fire. Native Americans knew which plants were most likely to burn during fire season. They removed or burned these plants to protect the forest.

Indigenous groups work with other organizations to care for the land using traditional methods, such as cultural burning. For example, in Oregon’s Quamash Prairie Natural Area, the Confederated Tribes of Grand Ronde team up with Oregon Metro to burn the prairie regularly. This helps them grow and harvest camas, a type of plant.

Archaeological studies

Studies by U.C. Berkeley showed that fire has had a major effect on forest plants over the past few decades. A study from 1990 to 2014 looked at some of the most damaging wildfires and found that humans have always been involved in managing forests. Native people played an important role in helping forests survive.

Researchers use several types of evidence to study how humans used fire in the past:

• Charcoal data: Scientists look at how often and how much charcoal is found in layers of soil. They also study the charcoal to find out which plants it came from.
• Pollen data: Pollen from plants is found in soil layers. Even though pollen is tiny, it can last a long time. Scientists compare pollen types and amounts with charcoal to learn about past fires.
• Tree ring data: By studying the rings inside tree trunks, scientists can tell how old trees are and how healthy they are. Burn scars on tree rings can show when fires happened.
• Phytolith data: Scientists measure phytoliths (tiny plant parts) in soil to find out if grasslands existed in an area long ago.

In California, Indigenous groups stopped using fire after Spanish settlers banned the practice and because many Native people were forced to work on missions, ranchos, and pueblos. After this, fires became less common in many areas of the state.

California’s Native population relied on fire to grow plants they used for food and tools. For example, the hazel bush was burned to make straight branches for weaving baskets used to carry newborn babies. Fire also helped grow native foods like acorns and salmon. Many other plants, such as bulbs, leaves, fruits, and seeds, needed fire to grow in open woods, meadows, prairies, or grasslands.

A study by Don L. Hankins showed that burning done by Indigenous people helped protect animals living near rivers. The study found that prescribed burns increased the variety of plant and animal life in these areas. Fall fires were especially helpful for growing more native plants. Spring fires only helped native plants, not non-native ones.

A study of the Quiroste Valley in California used plant remains, charcoal, and ecological data to learn about past fires. Researchers found that the area had few lightning strikes and many plants that grow after fires, suggesting humans caused the fires. However, the study could not confirm past lightning frequency or whether the climate was different in the past.

Paul Delcort’s research at Cliff Palace Pond in Jackson County used pollen and charcoal samples to study fires over time. The study found that between 1000 BCE and 1800 CE, there were many small fires. Pollen from fire-resistant trees like oak and chestnut increased during this time. Pollen from sunflowers and goosefoot plants also grew, suggesting people may have grown food in burned areas. These fires created a mix of plant life that humans could use.

A study of sites in Stockbridge, Massachusetts, found that periods of small fires matched times when people lived there. Fossilized pollen showed more chestnut trees during these times. Though no direct evidence of human-caused fires was found, historical records and the need for nut-producing trees suggest humans may have used fire.

A study of the Jemez Mountains used charcoal and tree ring scars to learn about past fires. It found that more small fires happened when human populations grew, not because of climate changes. Fungal evidence also showed more animals lived in areas with frequent fires. Fires during ancient times were less severe than modern wildfires.

A study of the Cumberland Plateau in Tennessee found that humans used fire regularly from 3,000 years ago until 200 years ago. However, the study found no evidence that these fires changed the types of plants in the area.

A study of the Ohio River Valley in West Virginia showed that humans and ecosystems evolved together over time. People used fire and cleared land, which changed how soil stored carbon and the variety of plants. These practices reduced plant growth but increased the amount of charcoal and made more plants usable for humans.