History of Western Landscapes

Evaluating the Purpose, Extent, and Ecological Restoration Applications of Indigenous Burning Practices in Southwestern Washington

Linda Storm and Daniela Shebitz. 2006. Evaluating the Purpose, Extent, and Ecological Restoration Applications of Indigenous Burning Practices in Southwestern Washington. Ecological Restoration, Vol. 24, No. 4, 2006.

Selected excerpts:

Abstract

Understanding the historic fire regime is essential before restoring fire to an ecosystem. Historical ecology provides a means to use both quantitative and qualitative data from different disciplines to address questions about how the traditional ecological management (TEM) practices of indigenous peoples influenced prairie and savanna ecosystems in the past. In this article, we evaluated paleoecological, archaeological, ethnographic, and ethnobotanical information about the Upper Chehalis River basin prairies of southwestern Washington to better understand the extent to which TEM influenced prairie distribution, composition, and availability of wild plant food resources. We also surveyed areas that had been burned at differing frequencies to test whether frequent fires increase camas (Camassia quamash) productivity. Preliminary results support the hypothesis that camas productivity increases with fire-return intervals of one to two years.

Introduction

A number of anthropologists, ethnobotanists, and ecologists now believe that indigenous peoples contributed to the long-term maintenance and distribution of prairie and savanna ecosystems in pre-European western Washington through traditional management techniques, such as burning (Norton 1979a, 1979b; Kruckeberg 1991; Agee 1993; Dunn and Ewing 1997; Boyd 1999a; Leopold and Boyd 1999; Wray and Anderson 2003). Following the decline of indigenous cultures and the subsequent absence of low-intensity, high-frequency fires, areas in western Washington that were once prairies and savannas have naturally succeeded to conifer-dominated forests (Lang 1961).

Today, there are efforts underway to restore the fire-dependent prairies and savannas of western Washington and the many now rare, threatened, and endangered species that continue to exist in those degraded ecosystems (Dunn and Ewing 1997, Chappell and others 2001, Peter and Shebitz 2006).

In this paper, we use a historical ecology methodology to evaluate both the reasons why indigenous peoples in the Upper Chehalis River basin managed prairie and savanna ecosystems and the extent of those practices through time and space. …

Background: Ecological and Cultural History of the Pacific Northwest

The climatic history of the Pacific Northwest can be reconstructed by using pollen data (Tsukada and others 1981, Barnoski 1985, Brubaker 1991), glacial geology (Porter and Swanson 1998), dendrochronology (Agee 1993), global climate model predictions (Hebda and Whitlock 1997), and charcoal evidence (Clark and Royall 1995, Hallett and Walker 2000, Pellatt and others 2001).

From these sources, scientists have confirmed that the Pacific Northwest experienced an “early post-glacial” period between 16,000-11,300 years ago. They describe this period as cool and moist with a characteristic vegetation of grasses and sedges along with some boreal conifers (Picea spp. and Pinus spp.). A warmer and drier period, from 11,200-9,500 years ago, led to an open forest with an increase in spruce and pine pollen and the first occurrence of Douglas fir (Psuedostuga menseizii). The maximum warming period from 10,000-6,000 years ago, which is estimated to have been about 3.6°F (2°C) warmer than modern climate conditions, produced a vegetation complex of Douglas fir, Garry oak (Quercus garryana), and alder (Alnus rubra). Spruce, pine, and boreal species declined in this period and fire, as indicated by increases in charcoal remains, became more prevalent (Brubaker 1982). From 6,000-5,000 years ago, western hemlock (Tsuga heterophylla), western red cedar (Thuja plicata) and Pacific yew (Taxus brevifolia) increased (Tsukada and Sugita 1982, Hebda and Mathewes 1984), and charcoal inputs decreased (Brubaker 1991), reflecting a transition to a wetter, cooler time period. However, scientists also confirm that prairie and savanna ecosystems persisted in southwestern Washington from the maximum warming period until the time of European contact and that they coincide with evidence of a short fire-return interval (Leopold and Boyd 1999).

The human history of western Washington extends back at least 10,000 years (Ames and Maschner 1999) with sedentary village life beginning after 3,800 years ago. Human populations increased as plank house village sites were established, salmon harvest intensified, and winter storage developed in some locales after this period. Some researchers postulate that during this period inland, up-river groups of indigenous peoples in southwestern Washington began using fire to maintain prairie and savanna habitats and subsequently increased their production and storage of important plant food resources (Ames 2005, Storm dissertation in progress).

Native American Burning in the Pre-European Pacific Northwest and Western Washington

Historic fire return intervals in pre-European Pacific Northwest were a function of both natural and anthropogenic fires (Boyd 1999a). Prescribed burning enabled the management of large landscapes and promoted greater abundance of useful species and habitats. For example, fire was used to create forest openings and maintain expansive prairies, keeping plant communities in early to mid-seral stages, and enhancing the diversity and yield of useful plants and game (Norton 1979a, 1979b; Connelly and others 1997, Leopold and Boyd 1999; Connelly 2000; Storm 2002, 2004). Beyond those purposes, indigenous burning reduced insect pests, improved basketry materials, helped clear areas for home sites and safe travel corridors, reduced the risk of wildfire, and improved grazing for game and (later) horses (Lewis 1993, Anderson 1996, Boyd 1999a). Robin Kimmerer and Frank Lake (2001:38) contend that for indigenous peoples “[m]aintaining a diversity of habitats buffers the impact of natural fluctuation in a single food species and increases overall productivity.”

By using fire for millenia, indigenous people developed a set of TEM practices that were grounded in an understanding of how fire travels across a landscape or slope, how to use fire to maintain trails that in turn serve as firebreaks, how to set backfires, and how to wet conifer boughs to control fires (Turner 1999). They used seasonal cues—plant phenologies (Lantz and Turner 2003), local climate, weather conditions, moisture levels of soils and fuels—to determine the time to burn.

Patterns of burning by indigenous peoples varied both between and within a given region, the effects of which would differ depending on soil type, moisture regime, and plant assemblages present. The effects of such practices have been well described for other western grassland and oak woodland savannas (Blackburn and Anderson 1993), but have only been partially described for western Washington (White 1975; Norton 1979a, 1979b; Leopold and Boyd 1999; Norton and others 1999). …

Findings and Recommendations: Implications of Reconstructing Indigenous Fire Regimes for Pacific Northwest Ecological Restorationists

“If land managers, ecologists, and archaeologists understand the intricacies and mechanics of how and why native people shaped ecosystems, this will enrich their inventory of management methods, and they will be in a better position to make informed, historically based decisions.” (Anderson and Barbour 2003:276)

A question that ecological restorationists must contemplate is whether to consider indigenous fire frequency as “natural” or seek to mimic historic fire regimes by understanding and incorporating indigenous TEM practices. Anderson (2005:335) argues that restoring landscapes and ecosystems to a condition that is self-sustaining may be impossible if that “natural” condition has not existed in the last ten to twelve thousand years. Therefore, understanding the practices, patterns and effects of indigenous fire management is critical to restoring historic fire regimes. To do so requires an interdisciplinary and integrative approach that addresses issues of scale (in time and space) and acknowledges the important role of indigenous peoples’ TEM (Anderson and Barbour 2003, Anderson 2005). …

We recommend a framework (Table 5) for developing restoration projects in landscapes that were formerly managed by indigenous burning. In this framework, reconstructing historic fire regimes that reflect indigenous peoples’ management practices and their reasons to burn is an essential first step to restoring traditionally managed prairies to pre-European settlement conditions. Site selection and exploratory experiments to simulate indigenous management techniques are other key steps. Our framework builds upon recommendations for restoring endangered species habitats and for applying indigenous management practices to restoration projects (Schultz 2001, Anderson 2005).

For both sets of objectives, it is important to understand what the distribution, geographical extent, and species composition of historic prairies and savannas were in the past. Understanding how indigenous management practices shaped the ecology of these habitats includes learning what the historic species assemblages were, the ways indigenous people used fire and other management techniques, including how ethnobotanical plants were harvested (Anderson 2005:339-340). Whether focal species are culturally significant or at risk of endangerment, returning frequent, low-intensity fires and implementing follow-up monitoring are essential restoration project elements. …