Indigenous Forestry

Inner Bark as Food

Walking overland west of the Gates of the Mountains on 19 July 1805, Clark “saw where the natives had pealed the bark off the pine trees about this same season.” This, Lewis reported, “the indian woman with us informs that they do to obtain the sap and soft part of the wood and bark for food.” And on 12 September 1805, the second day of their toilsome journey over the Bitterroot Range from Travelers’ Rest to Weippe Prairie, Clark wrote, “On this road, & particularly on this creek,”—today’s Lolo Creek—”the indians have peeled a number of Pine for the under bark, which they eate at certain Seasons of the year, I am told in the Spring.” The species that was favored was Pinus ponderosa, ponderosa pine. Trees could be peeled early in May, after the bitterroot was judged ready for harvest, and never before. The process was steeped in ceremony; the result was literally the first sweet taste of spring.

It was women’s work. Hard work. They used sharpened juniper sticks or rib bones of elk or bison to pry heavy slabs of thick bark from each tree. Then, with slicing tools made from the horns of mountain sheep, they carefully scraped off the nutritious inner bark and ate it immediately. The treat had a brief shelf-life, because it was unpalatable after it dried out.^[1]Jeff Hart, Montana: Native Plants and Early Peoples (Helena: Montana Historical Society, 1976), 50-51.

It is often said that Indians ate the cambium, but that is not true, for the cambium itself is functionally just one cell thick, and overall its components divide to produce a cambial zone, which is only a few cells thick. Although it is essential to a tree’s life, the cambium has no value as human food.

On its inner surface, the cambial zone generates the water-conducting cells, or xylem (ZY-lem), which, as the tree grows, expand the dead, woody center of the tree’s stem, or trunk. On its other side the cambium merges into the phloem (pronounced FLO-um), or bast. About one-eighth to one quarter of an inch thick in a mature ponderosa pine, the phloem carries food between the tree’s roots and crown. In spring, at the onset of the tree’s new growing season, it is rich in proteins and carbohydrates, and that is why it was once valued as food. As the outer cells of the phloem deteriorate, they become the corky interior surface of the outer bark.^[2]Stephen H. Spurr and Burton V. Barnes, Forest Ecology (3rd ed., New York: John Wiley & Sons, 1980), 89.

Peeled trees also served as trail signs. En route back across the Bitterroot Mountains, on 17 June 1806, over deep snowbanks that hid the ground, Clark noted: “I was in front and Could only pursue the derection of the road by the trees which had been peeled by the nativs for the iner bark of which they Scrape and eate.”

The peeling of ponderosa pine trees was discouraged and finally prohibited as settlers moved onto reservation lands, because it was considered injurious to trees that were valuable to them as sources of lumber for building. But since cuts such as that illustrated in the photo above did not sever the cambial zone around the whole circumference of the tree, they did no harm. In fact, a layer of cambium soon formed within the callus tissues to help heal the wound.

Prescribed Burns

Archaeological evidence indicates that deliberate burning of forests and fields has been occurring on the North American continent for at least the past 10,000 to 20,000 years. Here are a few of the reasons native people used fire as an aid to subsistence:

• Forest Treatment. To kill insect infestations, and to diminish shrubs and grasses through which wildfire might spread, and destroy trees.
• Improve Horse Pasture. To make spring grass more easily available, and to eliminate competing species such as brush and tree seedlings.
• Improve Hunting. To thin out dense underbrush, and stimulate growth of good browse. Also used to surround deer herds to make them more accessible to hunters.
• Encourage Food Plants. To favor or increase the growth of one or more of the 200 species of plants used for food and other purposes.
• Campsite Clearing. To improve visibility and eliminate underbrush and tall grass in which attackers could hide.
• Communication. William Clark, 31 August 1805, as the Corps began the climb up to the Bitterroot Divide, wrote:

• Rituals. William Clark, on 25 June 1806, wrote of the three Nez Perce men who had agreed to guide them over the trail from the Clearwater River to Travelers’ Rest:

Today it is against federal and state laws to deliberately set a forest or range fire without authorization. “Prescribed burns” are carefully designed and monitored by professional foresters. Natural, lightning caused fires sometimes are allowed to burn, but are closely monitored according to a complex set of interrelated factors, including the density of underbrush and dead or fallen trees, and the proximity of sensitive resources such as structures and very young replanted trees.

Content reviewed by: Stephen F. Arno, Intermountain Fire Sciences Laboratory; Mary Horstman, Forest Historian, Bitterroot National Forest; Stan Underwood, Sula Ranger District, Bitterroot National Forest.