Defining Historical Baselines for Conservation: Ecological Changes Since European Settlement on Vancouver Island, Canada
Anne D. Bjorkman, Mark Vellend (2010) Defining Historical Baselines for Conservation: Ecological Changes Since European Settlement on Vancouver Island, Canada. Conservation Biology, Volume 24, Issue 6, pages 1559–1568, December 2010
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Abstract
Conservation and restoration goals are often defined by historical baseline conditions that occurred prior to a particular period of human disturbance, such as European settlement in North America. Nevertheless, if ecosystems were heavily influenced by native peoples prior to European settlement, conservation efforts may require active management rather than simple removal of or reductions in recent forms of disturbance. We used pre-European settlement land survey records (1859–1874) and contemporary vegetation surveys to assess changes over the past 150 years in tree species and habitat composition, forest density, and tree size structure on southern Vancouver Island and Saltspring Island, British Columbia, Canada. Several lines of evidence support the hypothesis that frequent historical burning by native peoples, and subsequent fire suppression, have played dominant roles in shaping this landscape. First, the relative frequency of fire-sensitive species (e.g., cedar [Thuja plicata]) has increased, whereas fire-tolerant species (e.g., Douglas-fir [Pseudotsuga menziesii]) have decreased. Tree density has increased 2-fold, and the proportion of the landscape in forest has greatly increased at the expense of open habitats (plains, savannas), which today contain most of the region’s threatened species. Finally, the frequency distribution of tree size has shifted from unimodal to monotonically decreasing, which suggests removal of an important barrier to tree recruitment. In addition, although most of the open habitats are associated with Garry oak (Quercus garryana) at present, most of the open habitats prior to European settlement were associated with Douglas-fir, which suggests that the current focus on Garry oak as a flagship for the many rare species in savannas may be misguided. Overall, our results indicate that the maintenance and restoration of open habitats will require active management and that historical records can provide critical guidance to such efforts.
Introduction
In many parts of the world, conservation and restoration goals are often based on perceptions of ecosystem states prior to intense disturbance by people of European origin (Foster 2000). Although relict patches of relatively undisturbed habitat are often used in studies of the structure and functioning of past ecosytems, such areas may be exceedingly rare and remain only in a highly biased subset of environmental contexts relative to the past (e.g., Vellend et al. 2008) or they may have been influenced in important ways by human activities that are not obvious through observation of their current state (e.g., Dupouey et al. 2002). An alternative is to look directly at historical records, which can provide critical insights into former landscape conditions and processes, and reasons for subsequent changes (Foster 2000; Whitney & DeCant 2005; Rhemtulla et al. 2009).
When using past ecosystem states to define conservation goals in North America, a key debate concerns the degree to which the pre-European settlement (henceforth presettlement) landscape was shaped by natural versus anthropogenic processes (Vale 2002). The pre-1492 landscape is often thought of as a pristine wilderness, where small groups of indigenous people had little ecological impact (Stankey 1989; G´omez-Pompa & Kaus 1992). This view has strongly influenced conservation strategies (Foster 2000; Hobbs & Cramer 2008). Many of these strategies rest on the assumption that removing the human factor will restore pre-European (“natural”) conditions (Foster 2000). Other studies suggest, however, that many areas of North America were “cultural landscapes” and as such were heavily influenced by native peoples through land cultivation or prescribed fire (Denevan 1992; Vale 2002). This implies that conservation strategies may need to consider not only current human disturbances, but also the possibility of reinstating cultural practices that were historically important in maintaining ecosystems (Higgs 1997; Anderson & Barbour 2003). Natural and anthropogenic processes have always been temporally dynamic, and both factors have influenced historical vegetation composition in North America (Vale 2002). The primary issue is the scale of anthropogenic impacts: were they highly localized around areas of intense land use (e.g., settlements) or were entire landscapes fundamentally transformed (Whitlock & Knox 2002). …
The 1859 notes revealed a landscape mosaic of prairie, plains, open woods, and forest. Of the 155 historical points with habitat descriptors, more than two-thirds were described as prairie, plains or open woods, with the remainder as forest, swamp, or bottom land (Table 1). … [T]he majority of 2007 points (79%) were classified as forest and only 3% as prairies or plains (Table 1). … Even if all undescribed areas were forests, however, the proportion of the landscape in forest still roughly doubled over the past 150 years, whereas the proportion of prairies or plains declined precipitously. …
Finally, although frequent fires do not necessarily imply an anthropogenic cause, our results do indicate that the fire regime was influenced by native peoples. The observed patterns are characteristic of landscapes prone to more frequent fires than expected by lightning strikes. Experiments suggest that the unimodal tree size distribution observed on Saltspring Island occurs at a fire interval of <5 years (Fule & Covington 1994; Peterson & Reich 2001). In contrast, a study in the Douglas-fir forests of Vancouver Island estimated a fire cycle of 5700 years, on the basis of the frequency of lightning strikes between 1950 and 1992 (Pew & Larsen 2001). A more localized study of charcoal in lake sediments (Cowichan Valley), which would not have detected low-intensity grassland fires, estimated a fire-return interval of 27–41 years, although it was difficult to detect distinct fire events relative to the background level of charcoal (McCoy 2006; Pellatt et al. 2007). These results suggest fires were more frequent than expected given the natural fire-return interval and were therefore likely related to anthropogenic activity (Turner 1999; MacDougall et al. 2004). …
Conclusions
Our results have important implications for the development of a perspective on historical human impacts in the New World that is more balanced than the simple dichotomy of landscapes as either humanized or pristine (Vale 2002). Ambiguities concerning the intensity, spatial extent, and timing of anthropogenic impacts were identified by Vale (2002) as being in great need of clarification in order to reconcile opposing viewpoints. Most of our study region appears to represent an intermediate level of intensity of historical landscape modification—less intense than within the confines of a densely populated village, but of sufficient intensity to have modified vegetation structure relative to what one would expect in the absence of humans.
In terms of space, the presence of both forested and open habitats historically suggests considerable spatial variability in the magnitude of human impacts, with prescribed fire likely to have maintained at least half of the landscape as open habitat (Table 1). In terms of time, the duration of impacts has likely varied across the landscape, with sites on relatively deep soils filling in rapidly with forest and sites on shallower soils remaining as open habitats to the present day (Vellend et al. 2008). Our results support the viewpoint that for the conservation implications of historical human impacts to be fully appreciated, conservation professionals need to abandon the simple yes–no dichotomy and embrace the reality of continuous variation in the intensity, spatial extent, and duration of such impacts.
Restoration efforts are often prone to uncertainty about target conditions (Higgs 1997; Hobbs & Cramer 2008), especially in areas with no appropriate reference sites to help define historical conditions. Land managers often follow a do-nothing approach and allow land to return to its “natural” state (Hobbs & Cramer 2008). Nevertheless, our study indicates that the open nature of the endangered savannas on Vancouver Island was likely maintained by fires purposefully set by native peoples.
Thus, restoration of these habitats to their pre-European state cannot be accomplished simply by removing human influences. Achieving the goal of maintaining open savannas would almost certainly need to involve active removal of encroaching trees and shrubs, either through burning or alternative strategies (e.g., mowing, tree removal) (MacDougall et al. 2004; Gedalof et al. 2006). Ideally such measures should be implemented in controlled experiments (i.e., through adaptive management; Walters 1986). Furthermore, the tree species currently most closely associated with savannas (Garry oak) does not appear—in a historical context—to be an appropriate flagship for savannas in general or their rich diversity of associated species. This highlights the necessity of understanding
and preserving ecosystem processes, rather than patterns only, and emphasizes the need for active management to achieve conservation and restoration goals in many ecosystems.
Indigenous wetland burning: conserving natural and cultural heritage in Australia’s World Heritage-listed Kakadu National Park
Sandra McGregor, Violet Lawson, Peter Christophersen, Rod Kennett, James Boyden, Peter Bayliss, Adam Liedloff, Barbie McKaige, Alan N. Andersen (2010). Indigenous wetland burning: conserving natural and cultural heritage in Australia’s World Heritage-listed Kakadu National Park. Human Ecol (2010) 38:721-729
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Introduction
Growing worldwide interest in, and appreciation of, traditional ecological knowledge (TEK) is creating a new approach to contemporary land and sea management (Redford and Mansour 1996; Berkes et al. 2000; Huntington 2000; Schmidt and Peterson 2009). Driven by concerns about the failure of western science and management to address ecosystem degradation and species loss, people are looking to the deep ecological understandings and management practices that have guided indigenous use of natural resources for millennia for alternative ways of sustainably managing the earth’s natural resources (De Walt 1993; Bart 2006; Berkes and Davidson-Hunt 2006). Equitable partnerships between indigenous and non-indigenous researchers and managers are revealing a way of looking after the world that emphasizes human obligations to natural resource management and promotes holistic thinking about the role and impact of humans in the environment (Ross et al. 2009). This new recognition of traditional knowledge, coupled with greater control by indigenous peoples over their land and sea estates, holds great promise for better management of the world’s natural resources.
Aboriginal people have occupied northern Australia for at least 40,000 years, and over this period have developed a rich culture of law, ceremony, oral history and detailed ecological knowledge. Despite nearly two centuries of European colonization, large areas of northern Australia remain in Aboriginal ownership or have recently been returned to indigenous management and control (Ross et al. 2009). A high priority for Aboriginal people is to record and revitalize their indigenous knowledge and practices to meet stewardship obligations and to ensure they are available for younger generations of Aboriginal land and sea managers. In recent years there has also been increasing recognition by non-indigenous peoples of the value of applying such traditional ecological knowledge and practice to contemporary land management (Burbidge et al. 1988; Horstman and Wightman 2001; Walsh and Mitchell 2002).
This is particularly the case for fire management in the savanna landscapes of northern Australia, where in many areas fire management remains an integral part of Aboriginal life and traditional fire knowledge is still strong (Haynes 1985; Whitehead et al. 2003; Hill et al. 2004; Fig. 1).
The general principles behind Aboriginal burning in Australia have been well documented (Jones 1969; Nicholson 1981; Bowman 1998), and there are emerging examples in northern Australia where Aboriginal burning practices are being adopted on non-Aboriginal lands to improve environmental management (Russell-Smith et al. 2009). However there are few case studies written and informed from an Aboriginal perspective that describe in detail the specific aims and practices of Aboriginal fire management. Effective documentation is important for validating traditional ecological knowledge (Davis and Ruddle 2010), and for enabling Western land managers to appreciate both the depth of ecological understanding held by indigenous people and the complexity and effectiveness of traditional land management practices.
In this paper we provide such a case study, describing Aboriginal fire management of wetlands in the World Heritage-listed Kakadu National Park. In Kakadu, traditional ecological knowledge is being used in powerful combination with Western science to manage and monitor vital cultural and natural resources, leading to a dramatic enhancement of biodiversity and cultural values, and to a deeply enriched tourist experience. We hope this paper will contribute to a greater appreciation of the importance of fire management to Aboriginal people, and a greater understanding of the complexities of managing land with fire. …
The burning of wetlands, with the seasonally shifting land and water interfaces, is a more complex procedure than burning the surrounding savanna woodlands, and the timing and extent of traditional wetland burning continue to be the focus of scientific and community debate. This scientific debate can constrain contemporary Aboriginal burning by raising doubts in the minds of Aboriginal people over whether or not they are doing the “right thing.” The knowledge we draw on and present here has been passed down from Minnie and Yorky Billy Alderson, parents to Violet Lawson, and grandparents to Sandra McGregor. Like their ancestors before them, Minnie and Yorky lived all their lives on the country, and had traditional obligations to manage it and to pass on their knowledge to the next generations. …
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A Qualitative Study with the Eastern Band of Cherokee and Southern Appalachian Community Members
Nicolette Cooley. 2004. Understanding Traditional Knowledge for Ecological Restoration: A Qualitative Study with the Eastern Band of Cherokee and Southern Appalachian Community Members. Masters Thesis, NAU School of Forestry.
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Abstract
The primary objective of the research project, Understanding Traditional Knowledge for Ecological Restoration: A Qualitative Interview Study with Cherokee and Southern Appalachian Community Members, in North Carolina was to gather data concerning historical land management practices exemplified by traditional ecological knowledge and practices of the Cherokee Nation, specifically burning. This particular research project was established due to a collaborative effort between the Ecological Restoration Institute (ERI) at Northern Arizona University (NAU) and Coweeta Hydrological Laboratory in Otto, North Carolina. The study was designed to collect information about the fire history of the Southeast focusing on the region historically and currently occupied by the Eastern Band of Cherokee Indians (E.B.C.I) within a two year time frame.
Introduction
The use of traditional ecological knowledge (TEK) of fire has been debated since the mid sixteenth century (Goodwin 1977) when non-Native American people viewed Indians as not being civilized enough to know the uses and effects of fire. This view brought about the belief that the Indians could not have had any significant influence on the environment (Kretch III 1999). The arrival of European explorers and settlers brought on a number of changes for the Indians and the land they occupied. Indians have brought on a number of changes for the Indians and the land they occupied. Indians have used fire to clear land for agriculture, improve visibility for hunting and traveling, and reduce the accumulation of fuels to prevent catastrophic wildfires (Noss 1983). Particularly in the Southern Appalachians Native Americans have been burning for agricultural and hunting purposes for 10,000 years (Keel 1976 in Van Lear and Waldrop 1989). Instead of acting as a destructive force, the Indians were acting as a functioning component of the ecosystem (Goodwin 1977). As a functioning component in the ecosystem, Native Americans were intentionally burning and cutting trees down because they knew burning and cutting created specific effects. For example, Goodwin describes how Indians burned forests to prevent uncontrolled fires, to clear heavy fuel loads, and undesirable weeds for cultivation. He goes on to discuss how Indians burned longleaf pine (Pinus palustrus) forests to eliminate brown-spot needle disease and competitive vegetation. Goodwin describes the importance of longleaf pine to build shelter, build canoes, and for firewood.
