FIRE ECOLOGY AND NATIVE AMERICAN CULTURAL USE OF BEARGRASS (XEROPHYLLUM TENAX MELANTHIACEAE) IN THE PACIFIC NORTHWEST, U.S.A.

Abstract

Investigating biological and cultural conservation together provides the opportunity to characterize complex linkages between humans and nature. Understanding these human-nature interconnections within social-ecological systems is often essential in addressing environmental problems. Major goals of social-ecological research include describing the attributes of resilient systems and transitioning our globe towards them. The social-ecological systems of local and Indigenous Peoples can guide the development of resilience theory because these communities have persisted over hundreds of years to millennia and have in many cases survived the cataclysmic trauma of European colonization. Further, the traditional resource management systems of local and Indigenous Peoples often increase the abundance, diversity, reliability and/or quality of plant and animal resources. Here I explore possibilities to support both biological and cultural conservation under changing global conditions through a case study of an understory herb called beargrass (Xerophyllum tenax Melanthiaceae). Beargrass is well-suited to a social-ecological study as it has ecological, cultural and economic value. Beargrass has been traditionally managed through fire by Native Americans for millennia and is likely sensitive to fire suppression and other major drivers of change in the Pacific Northwest. To understand management needs and adaptive practices of Native American communities and to gather recommendations for biocultural revitalization of beargrass traditions, I interviewed beargrass weavers and cultural practitioners in Northern California, Oregon and southern Washington. To understand how plants may be responding to changes in management overtime, I conducted a plant demographic study. I collected field data over three years which was used to build mixed-effects regression models to understand the relationship of fire, leaf harvest and abiotic factors to beargrass survival, growth and reproduction. I then combined these regression models into integral projection models (IPMs) to understand how individual-level effects scaled up to the population level. I next used these IPMs to simulate stochastic beargrass population growth rates under different conditions. From the ethnographic study, I found that increasing access to beargrass leaves of appropriate quality for weaving and connecting Native American basket weavers with native youth were key opportunities for maintaining beargrass traditions, and that adaptive practices such as management substitutions in the absence of fire have helped maintain traditions over time. In the ecological study I found that beargrass growth and reproduction increased in response to fire, and that low intensity leaf harvest for cultural use reduced survival but increased vegetative reproduction. The fire scenario simulations revealed that re-introduction of traditional fire regimes (low severity fire every 1-20 years) led to population growth, while business as usual (high and low severity fire occurring every 180 years) and no fire both led to population decline. Leaf harvest slightly increased population growth in the traditional fire scenario due to increased vegetative reproduction. These results point to the key opportunities to support biocultural conservation through re-introduction of fire and cultural leaf harvest, restrictions on commercial harvest that reduce access, and education of the broader public on tribal sovereignty. Resilience of beargrass traditions appears tied to the deep spiritual and cultural importance of beargrass, its irreplaceability, the cultural values of respect and reciprocity embedded in beargrass traditions, and the ability to innovate management techniques in the absence of fire.