Scales of plant stewardship in the precontact Pacific Northwest, USA

Numerous oral histories and substantial ethnographic evidence illustrate how plant species, communities, and even landscapes were extensively managed and cared for by ancestral communities in the Pacific Northwest. Camas (Camassia spp.) is one such cultural keystone plant, common from the Pacific Ocean to the Rocky Mountains, with numerous records describing its role as a staple food for many Northwest peoples. Supporting deep time archeological evidence for such management or stewardship practices, however, has remained elusive. In this paper we analyze archived collections of archeological camas bulbs from 11 sites across the Willamette Valley, Oregon to demonstrate people began preparing camas within earth ovens by approximately 8000 calendar years before present and deliberately harvesting sexually mature camas plants circa 3500 calendar years before present. We compare these findings with climatological, palynological, and fire history reconstructions to discuss stewardship strategies for camas and associated plant communities through time at the population, community, and landscape levels. These findings confirm and expand upon Indigenous knowledges as well as offer time-tested methods for cultural keystone conservationists seeking to revitalize traditional plant stewardship practices throughout this region and beyond. This "camas case study" also offers another example of a human-plant symbiotic relationship, expanding our knowledge of plant food pathways, processes, and mutualisms.