Hummel, S.

Lake, F. K.

Watts, A.

How silviculture 

can benefit 

from ecological 

knowledge systems 

about beargrass 

harvesting sites

How silviculture 

can benefit 

from ecological 

knowledge systems 

about beargrass 

harvesting sites

Hummel, S.

Lake, F.K.

Watts, A.

Forest 

Service

General Technical Report

PNW-GTR-912

Pacific Northwest 

Research Station

June 

2015

United States Department of Agriculture

Using Forest

Knowledge
1

Managing National Forests a Role for Silviculture 

Sustaining the health, diversity, and productivity of national forests and 

grasslands is the mission of the U.S. Department of Agriculture (USDA) 

Forest Service. Yet managing these lands is challenging because people 

hold different expectations for them. Public uses can include: 

•	 Recreation (scenery, trails, bicycle and snowmobile routes) 

•	 Timber (structural, decorative, manufactured wood products) and 

wood-based energy (biomass) 

•	 Nontimber forest products (foods, fibers, medicines)

•	 Sustaining or restoring natural processes (water, nutrient cycles) 

•	 Preserving cultural and natural history (archaeological or other sites)

In mixed-conifer forests of the three Pacific coast states, some public

uses may benefit from changes to the existing structure of living and

dead trees arrayed on a site or in an area. 

Silviculture—a practice derived from the Latin word for forest—

focuses on how to distribute the growing space for trees within an area. 

It is one method federal and other foresters use to manage land for 

desired beneficial uses.

One way of deciding among silvicultural options for a specific place

is by identifying forest conditions consistent with several management 

objectives. An accepted practice is using general structural and compositional knowledge of a given forest type and then supplementing or 

refining it with site-specific information. Scientific research generates

knowledge that can be generalized and applied across similar conditions 

while site-specific information often comes from observations of a given

place. In particular, the relationship people have to a place can offer 

insights into how it changes over a range of growing seasons and conditions. Such a two-tiered approach provides forest managers with flexibility within local ecological “sideboards.” By tailoring silviculture to a 

specific place, multiple objectives can be achieved over the long term.

This booklet describes how knowledge gained from a tri-state study of 

good harvesting sites of a popular forest understory plant can contribute to 

Cover photo: Beargrass flowering in Glacier National Park, David Restivo, National Park local silvicultural decisions about tree density and levels of down wood.

Service, 2008.
2 3

The Significance of Beargrass

Beargrass (Xerophyllum tenax) (cover photo) is an ecologically, economically, and culturally important plant. It is a long-lived perennial 

that reproduces by flowering or by sprouting, and grows in habitats from

coastal to montane mixed-conifer forests, meadows, and clearings and 

on various soil types. Beargrass provides: 

•	 Food for insects and mammals 

•	 Protective habitat for invertebrate species

•	 Nutrient-rich pollen for bees, beetles, and flies

The majority of beargrass harvested from federal lands in California, 

Oregon, and Washington is for the multi-million-dollar floral greens

industry. American Indians also harvest beargrass for use in basketry 

and regalia, and for medicinal and decorative purposes (fig. 1). While

the industry mainly exports the plant for use as decoration, for many 

American Indian tribes, beargrass is a key fiber in traditional weaving.

Beargrass leaves are particularly valued for adding design and structure 

to twined and coiled baskets. 

The U.S. government has a trust responsibility to American Indians 

and, for the USDA Forest Service, this means sustaining natural and 

cultural resources like beargrass on ancestral lands now under federal 

jurisdiction and management. 

Understanding Beargrass in the National Forests

Researchers with the USDA Forest Service Pacific Northwest and

Southwest Research Stations sought to learn what forest conditions 

relate to harvest site quality for tribal basketry. Their study blended 

traditional ecological knowledge (TEK) with quantitative and 

qualitative methods for generating scientific ecological knowledge

(SEK). Results, therefore, reflect blended ecological knowledge

systems and experiences.

Six expert weavers, members of the Grand Ronde, Karuk, Siletz,

and Yakama Tribes, volunteered to cooperate, and they visited study 

sites in California, Oregon, and Washington with a Forest Service 

researcher (Karuk descendant) and assistant (Penobscot). The sites 

covered a range of potential harvest conditions, some sites had a 

history of beargrass harvesting, and other considerations included 

accessibility to a road, terrain, and location on tribal ancestral lands. 

The weavers classified the sites at the time of this study as good,

marginal, or poor according to their personal observations and 

harvesting experience. 

On 72 sample plots at each classified site, Forest Service staff measured variables that they thought might affect beargrass leaf quality. 

Variables included:

•	 Number and diameter of all trees

•	 Amount and size of dead, down wood

•	 Color of beargrass leaves

Analysis of the field data revealed statistically significant

differences in good harvest sites and poor harvest sites across the three 

states and the two weaving styles represented by the tribal weavers. 

Figure 1— The basal leaves of beargrass are harvested for traditional weaving.

B. Gervais
4 5

How Studying Beargrass Can Guide Silviculture 

Silviculture is considered both an art and a science because it involves 

incorporating knowledge from various sources into written prescriptions 

that can include different treatments. What the beargrass study showed 

is that a combination of TEK and SEK yielded general knowledge about 

good harvest-site conditions. Silviculturists can draw upon this information to write site-specific prescriptions when local objectives include

sustaining culturally important plant populations and forest resilience to 

disturbance. On average, “good” beargrass harvesting sites had

•	 Total surface wood and litter averaging 14 tons/acre

•	 Down wood (>3 inches) averaging 12 tons/acre

•	 An average of 127 trees per acre

•	 A basal area of 197 square feet/acre

This general knowledge may be incorporated in several ways 

depending upon management objectives and forest type (table 1). For

example, the study found that higher levels of down wood 

(particularly large logs with limbs) diminished the quality of the site 

for harvesting (fig. 2). When walking is difficult, harvest efficiency

drops. This was one tribal criterion the study revealed. In contrast, 

Figure 2—This study plot illustrates higher levels of down surface wood, more trees with 

smaller diameters, and lower densities of beargrass plants associated with poor harvesting 

sites for traditional weaving. 

B. Gervais

Figure 3—This study plot shows lower levels of down surface wood, fewer trees with larger 

diameters, and higher densities of beargrass plants associated with good harvesting sites for 

traditional weaving. 

B. Gervais

Table 1—Scaled knowledge systems

Management 

targets 

(variables)

Field measurements 

(metrics)

Tribal concerns 

(criteria)

Silvicultural 

treatments 

(options)

Fuel loads Surface wood and litter 

(volume and size) 

Ladder fuels (ground 

to crown ratio)

Site mobility 

(ease of walking)

Fuels reduction 

(mechanical or 

manual, including 

wildland fire)

Stand density Trees per acre 

Basal area per acre 

Canopy closure or 

canopy bulk density

Site mobility

Number of 

beargrass plants 

Color of 

beargrass leaves 

Density reduction 

(tree harvest); 

tree/slash removal;

wildland fire

Tree size Height 

Diameter

Understory light

Harvester mobility

Thinning to manage 

tree number and 

growth

Beargrass 

quality and 

quantity

Plant density 

(number per area) 

Density of whorls (new 

growth)

Leaf color 

and abundance 

Density 

management, 

(thinning, 

wildland fire)

Note: Geographic scale and knowledge system affect terminology but share treatment options.
6 7

Figure 4—Average trees per acre and basal area (ft2/acre) by quality of harvesting site. The

knowledge used by weavers to classify harvesting sites as good, marginal, or poor was 

matched by statistically significant differences in trees per acre between good and poor

harvesting sites.

other research shows that some surface wood (mostly large logs, 

without protruding limbs) contributes positively to habitat for 

mammals, amphibians, and invertebrates, and for cycling water and 

nutrients. A range of 0 to 12 tons/acre of down wood was found on

good beargrass harvesting sites (figs. 3 and 4). In stands where there

are known or potential harvesting areas, silviculturists could prescribe 

lower levels of down wood to allow for easier mobility while still 

meeting habitat or other objectives.

Sites with basal area distributed on fewer, larger trees (fig. 5) were

considered good for harvesting, because the beargrass leaves were 

of the desired color and quality for weaving. A range of 0 to 127

trees per acre was associated with these good harvesting sites. 

Prescriptions that reduce tree density within this range, whether to 

alter fire behavior or reduce competitive stress, would also be

consistent with good beargrass harvesting sites for weaving. In 

contrast, other research suggests that shadier sites produce 

commercial-quality beargrass leaves. Because beargrass harvesting 

sites are associated with a range of tree stocking densities, 

silviculturists can adjust prescriptions accordingly depending on 

harvester preference. Dry sites, for example, could be candidates for 

lower numbers of trees per acre where an objective is to sustain 

beargrass for tribal weaving. 

Road access adjacent to gathering sites was another tribal harvesting 

criterion. Study sites were chosen to be accessible from roads owing 

to preferences expressed by participant tribal weavers. However, if a 

management goal is to sustain good beargrass harvesting sites wherever 

the plant grows, attention to less-accessible sites may benefit youthful

and future generations of traditional weavers. 

0

50

100

150

200

250

0

50

100

150

200

250

Basal area (ft2/acre)

Avg. trees per acre

Quality of harvesting site

0

5

10

15

20

25

0

5

10

15

20

25

Avg. down wood >3 inches (tons/acre) 

Quality of harvesting site

Avg. total (tons/acre)

Figure 5—Average down wood (tons/acre) by quality of harvesting site. Down wood was

significantly different between good and poor harvesting sites. The combination of traditional

ecological knowledge and scientific ecological knowledge provided general knowledge and

interpretations of data useful for land managers.
8 9

Future Management Considerations Beyond Beargrass

Silviculture is one management tool for sustaining good beargrass 

harvesting sites because it can affect leaf properties and weaver mobility. Another tool for sustaining weaving traditions is accessibility to 

good harvesting sites. During the study, Forest Service staff heard about 

access difficulties, whether because of closed gates or perceived requirements for obtaining permits. These issues were not universal across the 

study area, however. In California, federal and state agencies collaborated on standardized guidelines to help tribal weavers access sites with 

minimal difficulty and cost. A similar protocol for Oregon and Washington will require cooperation between agency staff and tribal members. 

Mutual respect and listening are essential. 

“It is important for tribal weavers to communicate with people who 

have decision-making authority over our lands.” 

~ Bud Lane, president 

Northwest Native American Basketry Association, 2014

The Food, Conservation and Energy Act (2008 Farm Bill) provides 

guidance to federal managers about authorizing access and use of forest resources for traditional cultural purposes by federally recognized 

American Indians.

References

Food, Conservation, and Energy Act of 2008; Public Law 110-234,

Cultural and Heritage Cooperation Authority, SEC. 8105.

Hummel, S.; Foltz-Jordan, S.; Polasky, S. 2012. Natural and cultural 

history of beargrass (Xerophylum tenax). Gen. Tech. Rep. PNWGTR-864. Portland, OR: U.S. Department of Agriculture, Forest

Service, Pacific Northwest Research Station. 80 p. DOI: http://www.

fs.fed.us/pnw/pubs/pnw_gtr864.pdf.

Hummel, S.; Lake, F.K. 2015. Forest site classification for cultural plant

harvest by tribal weavers can inform management. Journal of Forestry. 

113(1): 30–39. DOI: dx.doi.org/10.5849/jof.13-082
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