Good conditions identified by tribal weavers for harvesting beargrass can inform forest management

Background/Question/Methods

We blended methods from scientific and traditional ecological knowledge to describe forest conditions on sites considered good (G), marginal (M), or poor (P) for harvesting the leaves of beargrass (X. tenax) used in tribal basket weaving. We relied on voluntary participation of six expert tribal weavers, a stratified, randomized field sample, and discriminant analysis (DI).  We accepted each weavers qualitative classification of a forested site (G, M, or P) for beargrass harvest and then sampled site and plant attributes on two plots in each site class (n=36).  Variables included: basal area (BA), fuel loading, canopy cover, beargrass abundance, and leaf color.  We used DI resubstitution to identify the combination of variables that maximized the number of correctly classified good sites.

Results/Conclusions

We found trends in BA, coarse wood, and leaf color on good sites versus marginal or poor ones across all tribal weaving styles and forest types. On our sites in Washington, Oregon, and California, the average tree BA was between 180-200 ft2/ac.  On sites considered by tribal weavers as good for beargrass harvest, however, the BA was distributed on fewer trees than it was on sites they identified as marginal or poor for harvest.  Similarly, the average amount of coarse wood (>3”) was lowest on good sites and increased inversely as the suitability of sites for beargrass harvest declined.  Taken together, the forest conditions identified by tribal weavers as good for harvesting beargrass had, on average, fewer, larger diameter trees and less coarse wood than did less desirable sites.  These results imply that structural elements associated with managing fire behavior and severity in western forests are consistent with the site conditions preferred by tribal weavers for beargrass harvest.