Prior to the European colonization of the Americas, indigenous peoples used fire to modify the landscape. This influence over the fire regime was part of the environmental cycles and maintenance of wildlife habitats that sustained the cultures and economies of the Indigenous peoples of the Americas. What was initially perceived by colonists as "untouched, pristine" wilderness in North America was the cumulative result of the indigenous cultural burning, creating a mosaic of grasslands and forests across North America, sustained and managed by the peoples indigenous to the landscape.
Radical disruption of indigenous burning practices occurred with European colonization and the forced relocation of those who had historically maintained the landscape. Some colonists understood the traditional use and benefits of low-intensity broadcast burns ("Indian-type" fires), but others feared and suppressed them. By the 1880s, the impacts of colonization had devastated indigenous populations, and fire exclusion had become more widespread. By the early 20th century, fire suppression had become the official US federal policy.
Understanding pre-colonization land management and the traditional knowledge held by the indigenous peoples who practice it provides an important basis for current re-engagement with the landscape and is critical for the correct interpretation of the ecological basis for vegetation distribution.
Human-shaped landscape
Prior to the arrival of Europeans, Native Americans played a major role in determining the diversity of their ecosystems.
The most significant type of environmental change brought about by Pre-Columbian human activity was the modification of vegetation. [...] Vegetation was primarily altered by the clearing of forest and by intentional burning. Natural fires certainly occurred but varied in frequency and strength in different habitats. Anthropogenic fires, for which there is ample documentation, tended to be more frequent but weaker, with a different seasonality than natural fires, and thus had a different type of influence on vegetation. The result of clearing and burning was, in many regions, the conversion of forest to grassland, savanna, scrub, open woodland, and forest with grassy openings. (William M. Denevan)
The benefits of forest management have been seen throughout history, and natives knew the dangers of letting forests become overly dense. Fire was used to keep large areas of forest and mountains free of undergrowth for hunting or travel. It also was a tool to help manage natural resources such as food. Fire was used in warfare for the protection of settlements
Authors such as William Henry Hudson, Henry Wadsworth Longfellow, Francis Parkman, and Henry David Thoreau contributed to the widespread myth that pre-Columbian North America was a pristine, natural wilderness, "a world of barely perceptible human disturbance." At the time of these writings, however, enormous tracts of land had already been allowed to succeed to climax due to the reduction in anthropogenic fires after the depopulation of native peoples from epidemics of diseases introduced by Europeans in the 16th century, forced relocation, and warfare.
Grasslands and savannas
When first encountered by Europeans, many ecosystems were the result of repeated fires every one to three years, resulting in the replacement of forests with grassland or savanna, or opening up the forest by removing undergrowth. Terra preta soils, created by slow burning, are found mainly in the Amazon basin, where estimates of the area covered range from 0.1 to 0.3%, or 6,300 to 18,900 km2 of low forested Amazonia to 1.0% or more. "Discovery and awareness of anthropogenic amazonian dark earths (terra preta)", by William M. Denevan, University of Wisconsin–Madison, and William I. Woods, Southern Illinois University, Edwardsville. "Classification of Amazonian Dark Earths and other Ancient Anthropic Soils" in "Amazonian Dark Earths: origin, properties, and management" by J. Lehmann, N. Kaampf, W.I. Woods, W. Sombroek, D.C. Kern, T.J.F. Cunha et al., Chapter 5, 2003. (eds J. Lehmann, D. Kern, B. Glaser & W. Woods); cited in Lehmann et al.., 2003, pp. 77–102
In the Klamath Valley region of northern California, the frequent and low-intensity fire of cultural burns are key to keeping grasslands open that otherwise would be invaded by conifers, which are less fire tolerant than the native oak. In the Pacific Northwest, the implementation of cultural burning led by tribal practitioners has been found to facilitate the growth of culturally important plants such as camas, yampa, and tarweed. Camas, yampa, and tarweed are all plants that have been part to several tribes' diets. The Blackfoot, Cree, and Nez Perce tribes would eat the bulbs of the Common Camas (Camassia quamash), which could be steamed or dried to make flour. Yampa, part of the genus Perideridia and also known as wild carrots, are harvested by the Yokut tribe of the San Joaquin Valley, California. The seeds of tarweed are also edible, described as "rich as butter." Burning to keep grasslands open can provide space for diverse flora that grow in very few places, found in the diversity of prairies, like the western lily and Howell's triteleia.
There is some argument about the effect of human-caused burning when compared to lightning in western North America. Eyewitness accounts of extensive pre-settlement prairie in the 1600s, and the rapid conversion of extensive prairie areas to woodland on settlement, combined with accounts of the efforts made to make indigenous prairie burning practices illegal in Canada and the US, all point to widespread pre-settlement control of fire with the intent to maintain and expand prairie areas.
As Emily Russell (1983) has pointed out, "There is no strong evidence that Indians purposely burned large areas....The presence of Indians did, however, undoubtedly increase the frequency of fires above the low numbers caused by lightning." As might be expected, Indian fire use had its greatest impact "in local areas near Indian habitations." John E. Keeley (2002) theorized Native American burning in the coastal ranges of central and southern California subsidized natural lightning ignitions to the extent that landscape patterns of grassland and open shrub land were significantly increased. "Intact shrub lands provided limited resources for native Americans and thus there was ample motivation for using fire to degrade this vegetation to an open mosaic of shrub lands/grassland
Reasons for and benefits of burning Reasons given for intentional burns in pre-contact ecosystems are numerous. They include: Facilitating agriculture by rapidly recycling mineral-rich ash and biomass. Increasing nut production in wild/wildcrafted orchards by darkening the soil layer with carbonized leaf litter, decreasing localized albedo, and increasing the average temperature in spring, when nut flowers and buds would be sensitive to late frosts. Promoting the regrowth of fire-adapted food and utility plants by initiating seed germination or coppicingshrub species like osier, willow, hazel, Rubus, and others have their lifespan extended and productivity increased through controlled cutting (burning) of branch stems. Facilitating hunting by clearing underbrush and fallen limbs, allowing for more silent passage and stalking through the forest, as well as increasing visibility of game and clear avenues for projectiles. Burning helps to create an environmental context within which more localized burning could then be conducted for specific cultural purposes. Facilitating travel by reducing impassible brambles, underbrush and thickets. Assisting in pollination by several species, such as hummingbirds, bees, butterflies benefit from burned soil and charred wood which can serve as spots to nest. The California Tortoiseshell butterfly (Nymphalis californica) and the Ceanothus silk moth (Hyalophora euryalus) are two specific examples of pollinators that can help for some culturally significant plants thrive in intentionally burned land. Increasing the local biodiversity in the understory of forest. Burning has been found to be beneficial in increasing the biodiversity found in the grasslands created beneath the understory of oak tree groves, bringing a greater presence of reptiles, amphibians and small mammals, and the density of blueberry bushes has been found to be benefit from prescribed burning as well. Reinforcing an ecosystem's ability to withstand encroachment of invasive species, which can push out native species. Decreasing the risk of larger scale, catastrophic fires which consume decades of built-up fuel. Increasing population of game animals by creating habitat in grasslands or increasing understory habitat of fire-adapted grass forage (in other words, wildcrafted pasturage) for deer, lagomorphs, bison, extinct grazing megafauna like mammoths, rhinoceros, camelids and others, the nearly extinct prairie chicken; and the populations of nut-consuming species like rodents, turkey and bear and notably the passenger pigeon through increased nut production (above); as well as the populations of their predators, i.e. mountain lions, lynx, bobcats, wolves, etc. Increasing the frequency of regrowth of beneficial food and medicine plants, like clearing-adapted species like cherry, plum, and others. Beargrass is a culturally significant member of the Liliaceae family, and the leaves that are produced from a year to three years after being treated with fire are the high quality that are useful to the Karuk people Northern California for traditional basketry. Decreasing tick and biting insect populations by destroying overwintering instars and eggs. In chaparrals, burning was used as a way to control pests and pathogens that affected the culturally significant plants found there. Increasing streamflow due to reduction of evapotranspiration by plants. Rivers cooled by smoke density alert salmon that they may begin upstream migration. Religious practices - setting fire to attract fair weather, to bring rain, to "call" salmon back from the ocean Seed supporting areas were burned to facilitate harvesting, stimulate seed production, protect the perennial stock, replenish the annual stock, recycle nutrients, and remove detritus to allow for new growth.
Impacts of European settlement
By the time that European explorers first arrived in North America, millions of acres of "natural" landscapes were already manipulated and maintained for human use. Fires indicated the presence of humans to many European explorers and settlers arriving on ship. In San Pedro Bay in 1542, chaparral fires provided that signal to Juan Rodríguez Cabrillo, and later to others across all of what would be named California. In the American west, it is estimated that burned annually pre-settlement in what is now Oregon and Washington.
By the 17th century, native populations were greatly affected by the genocidal structure of settler colonialism. Many colonists often either deliberately set wildfires and/or allowed out of control fires to "run free." Also, sheep and cattle owners, as well as shepherds and cowboys, often set the alpine meadows and prairies on fire at the end of the grazing season to burn the dried grasses, reduce brush, and kill young trees, as well as encourage the growth of new grasses for the following summer and fall grazing season. Native people were forced off their traditional landbases or killed, and traditional land management practices were eventually made illegal by settler governance.