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An Eco-Archaeological Study of Late Holocene Indigenous Foodways and Landscape Management Practices at Quiroste Valley Cultural Preserve, San Mateo County, California


Traditional resource and environmental management (TREM) or indigenous landscape management practices in California have been well attested by historical and ethnographic sources. Historians, geographers, ethno-ecologists, and others have conducted research on these data sets since the mid-20th century. However, due to theoretical and methodological limitations, archaeologists in California and elsewhere on the Pacific Coast of North America have only recently and sporadically engaged with TREM research in the period prior to Euro/American colonization. This study is part of a broader multidisciplinary eco-archaeological research project that explores whether (and if so, how) indigenous peoples on the Central California Coast altered coastal landscapes through frequent burning during the Late Holocene (specifically, ca. 1000 C.E. to the time of Spanish colonization). The broader project was initiated by members of the Amah Mutsun Tribal Band, researchers at the University of California, and the California Department of Parks and Recreation to pursue the above and other related research questions of interest to all parties. The primary study location is the Quiroste Valley Cultural Preserve, Año Nuevo State Park, San Mateo County, California. Archaeological data was collected from site CA-SMA-113, a residential site located on the floor of Quiroste Valley with relatively intact cultural deposits dated to ca. 1000-1300 C.E.

Through an integrative historical ecological approach informed by the concepts of niche construction or ecosystem engineering, this study presents and interprets the results of research on four major topics related to indigenous burning management. First, historical and ethnographic evidence on vegetation structure and composition, foodways practices, and indigenous burning in the traditional territory of Ohlone peoples is presented. This study focuses primarily on accounts recorded by the earliest Spanish explorers who passed through the region, responses to the 1812 Interrogatorio by local mission priests, and ethnobotanical information from Rumsen and Mutsun speakers recorded by John P. Harrington in the early 20th century.

Second, characteristics of the fire ecology of common vegetation types and of particular taxa in the local region are reviewed and synthesized to build hypotheses about vegetation conditions under lightning-ignited fire regimes and anthropogenic burning management fire regimes in the research area. Because a) rates of lightning ignition are very low in the local coastal region and b) fire-susceptible woody vegetation types invade grasslands in the absence of disturbance, it is expected that woody vegetation types would dominate the landscape under a lightning-ignited fire regime. Conversely, grasslands would be greatly expanded and maintained by frequent anthropogenic landscape burning. These expectations were verified in the Quiroste Valley research area through repeat aerial photography analysis that indicated major expansion of woody vegetation types over 30 years of vegetation non-disturbance.

Third, results of silica phytolith analysis of paleoecological contexts (Quiroste Valley floor soils) and archaeological contexts (CA-SMA-113 deposits) are presented and evaluated in relation to long-term vegetation conditions and uses of phytolith-producing plants by Late Holocene inhabitants of the valley. Phytolith content in Quiroste Valley floor soils indicates the presence of grasslands in the valley over the long term, estimated to represent at least ca. 500-1000 years of grass-dominated vegetation. Phytolith content in archaeological deposits from site CA-SMA-113 indicated that phytolith producing plants were regularly incorporated into archaeological deposits and that site inhabitants may have sometimes disposed of relatively large quantities of phytolith-producing vegetation through burning.

Fourth, general archaeological characteristics and results of analysis of archaeobiological data sets (particularly archaeobotanical data) are presented and evaluated to explore whether the types of ethnobotanical resources used by site inhabitants and the ways in which these resources were used are consistent with expectations for resource availability and use under either a lightning-ignited fire regime or anthropogenic burning management fire regimes. The macrobotanical assemblage at site CA-SMA-113 was large and rich, making it appropriate for parametric statistical analysis. Intra-assemblage analysis indicates that a suite of grassland and wetland seed foods were commonly consumed by site inhabitants. Comparative analysis between CA-SMA-113 and other sites in interior Central California suggests that the consistently high density of seed foods recovered (and their abundance relative to other plant foods) at the site reflects their prominent contribution to the botanical foodways of site inhabitants. The macrobotanical assemblage contained a greater than expected abundance of fire-follower, fire-enhanced, or potentially fire-enhanced taxa than would be expected based on contemporary vegetation composition, and the assemblage lacked evidence for the types of woody vegetation that dominate the landscape today. Analysis of archaeological charcoal also indicates an absence of these dominant yet fire-susceptible woody taxa. Instead, inhabitants of CA-SMA-113 primarily used woods compatible with frequent, low-intensity landscape fires for fuel, including redwood and California lilac.

The four major lines of evidence described above were evaluated with respect to fourteen research questions that explore these lines of evidence individually and synthetically. In addition, analytical results of the current study were assessed in relation to published results reported by other members of the broader eco-archaeological research team. The major finding of the current study was that all lines of evidence considered here are consistent with expectations for landscape conditions and cultural resource use under an anthropogenic burning management fire regime characterized by frequent (ca. 1-5 year to subdecadal) fire return intervals. I interpret the these data as strongly indicating the persistence of high frequency anthropogenic landscape burning in the research area since ca. 1000-1300 C.E. Results of the broader eco-archaeological research project are in agreement with this finding, although some data sets are relatively ambiguous or still undergoing analysis.

Because theoretical and methodological approaches to indigenous burning management are still developing, many of the expectations and interpretations presented here are subject to varying degrees of uncertainty. Improving these approaches to reduce sources of uncertainty will be an ongoing goal in future research. Because of these issues, the results presented here cannot be said to conclusively prove the persistence of indigenous landscape management through burning since ca. 1000 C.E. Although I argue that indigenous landscape management is the most parsimonious interpretation for the data presented here, multiple alternative interpretations of these results should be pursued through future research.

Archaeological research on TREM practices has the potential to enhance archaeological practice by fostering collaboration with members of indigenous descendant communities; encouraging the pursuit of novel research questions and perspectives through multidisciplinary research; and increasing the relevance and impact of archaeological research for pressing social issues such as ecological restoration and conservation, environmental justice (e.g., access to biotic resources for descendant communities), and public lands management policy guidance. Through an integrative historical ecological approach that considers the development of human and environmental relations as a total system, archaeologists and others can employ TREM research to better understand consequences of these relations over short and long time scales, in small and large scale societies, for groups with varied subsistence economies, and for ecosystem biota and resources that were enhanced or diminished by human practices.

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