Present-day landscape patterns are the outcome of a number of ecological, geological, climatological, and cultural processes occurring over prehistoric and historic time frames (Delcourt and Delcourt, 1991, 2004; Delcourt, 2002). The interactions of these processes change through time and are mediated by changing natural and anthropogenic disturbance regimes (Wiens et al., 1985; Delcourt and Delcourt, 1988; Turner, 1989; Russell, 1997; Foster et al., 1998a). The legacy of long-term landscape history is a lasting overprint upon both natural and cultural landscapes, as the effects of past processes leave a mark on present landscapes that may endure long into the future. This legacy has been understood for a long time in Great Britain (Rackham, 1986) and Europe (Delcourt, 1987; Birks et al., 1988) and it is now increasingly recognized in North America (Abrams, 1992; Russell, 1997; Delcourt et al., 1998; Delcourt and Delcourt, 1998, Foster et al., 1998a, 1998b).

How we view the relevant processes involved in the development of landscape patterning is conditioned by the temporal and spatial window through which we view landscape change as well as by the techniques we use to measure landscape response to physical and biological interactions (Fig. 16.1). Physical constraints on landscape development may be depicted as a nested hierarchy of controlling factors (Urban et al., 1987; Delcourt and Delcourt, 1988). For example, on a timescale of thousands of years, large and predictable changes occur in global and regional climate.

OVERVIEW

In Chapter 9 we summarize the implications of viewing Holocene human ecosystems as adaptive and panarchical in nature. In the United States, land management plans have been predicated on the premise that prehistoric humans had no lasting influence on native ecosystems. Well-documented paleoecological and archaeological studies clearly indicate that this assumption is not warranted. Since their arrival on the North American continent, Native Americans were part of an evolving set of human ecosystems. Through time, increasing complexity of the human–ecosystem panarchy arose from both cultural and ecological interactions. These interactions were effective at all levels of biological organization, from genetic, to population, community, landscape, and regional levels (Figure 3.4). No single arbitrary time line is appropriate as a focus for land management, since ecosystems have been evolving continuously in response to late-Quaternary environmental change and human activities. Scientific studies combining paleoecological and archaeological techniques provide a context for the trajectory of change on a local, regional, and continent-wide basis. Understanding this context is essential for guiding future efforts to manage biological diversity.

PALEOINDIANS, MEGAFAUNAL EXTINCTIONS, AND PANARCHY REORGANIZATION

During the late Pleistocene, humans interacted with their environment on a regional scale during a time of major climate change and ecosystem reorganization. Human predation, climate change, plant–animal interactions, and disease each may have played a role in the collapse and reorganization of regional ecosystems at the end of the Pleistocene (Figure 3.4). Regional-level influences of Paleoindians followed from success in immigration, establishment, and increase in human populations to a threshold at which they began to play a discernible role as agents of ecological change in the New World. Adaptations for hunting and foraging (Figure 3.5) would have influenced not only the regional dispersal pattern of human populations across the Americas at the end of the Pleistocene, but also would have determined the extent to which Paleoindians would have been active participants as keystone predators in the extinction of megafauna (adult mammals >44 kg).

DYNAMICS OF LATE-PLEISTOCENE ENVIRONMENTAL CHANGE

During the late Quaternary, mean global temperature warmed by 5 °C from peak glacial cold 18 000 BP to peak interglacial warmth 6000 BP Climate warming was accompanied by changes in hemispheric patterns of atmospheric circulation and shifts in regional storm tracks (Wright, 1989; Lowe et al., 1994). Seasonal temperature contrast at middle and high latitudes heightened after 17 000 BP and peaked between 12 000 and 9000 BP (Figure 8.1) as systematic changes in incoming solar radiation forced the changeover from cool, equable ice-age climate to the highly seasonal late-glacial and early-interglacial pattern of very cold winters offset by very warm summers (Kutzbach and Guetter, 1986).

OVERVIEW

Complex ecological feedbacks between humans and their environment have taken place on many different spatial and temporal scales (Figure 3.4). To look at cycles of adaptation, organization, destabilization, and reorganization in their appropriate contexts (Figure 3.1) requires being able to slide back and forth in time and place, as relevant to the panarchical level of interest. In Part II, we summarize examples of prehistoric Native American ecosystem dynamics based on level of biological interaction, from genetic and population level to community, landscape, and regional level.

In Chapter 4, Gene-level interactions, we explore the ecological implications of the transition from foragers to farmers that occurred beginning in the Archaic cultural period. This transition in lifeways resulted in the addition of a panarchical level (Figure 3.5), and was characterized by a number of facilitative interactions among plants, their pollinators, their seed dispersers, and their harvesters. Incipient domestication of native plant species began by 4500 BP. In the process of becoming farmers, Archaic Native Americans developed mutualistic relationships with individual plant domesticates as they selected phenotypes of edible plants that showed the greatest robustness of seeds and fruits. With first domestication, genetic diversity was enhanced locally for squash, sunflower, maygrass, little barley, goosefoot, and marsh elder.

Chapter 5, Population-level interactions, explores the relationship between Archaic and Woodland people and their plant domesticates, as well as their animal prey.

PANARCHY THEORY

The term “panarchy” was coined as a combination of “pan,” the ancient Greek god of nature, and “hierarchy” (Holling, 2001). Panarchy theory is an extension of ecosystem theory, which rests upon the assumption that a hierarchically nested series of adaptive cycles result in self-organizing, evolving, complex natural systems that assemble across all scales in space and time. Holling (1995) defined four ecosystem functions that are interconnected by a series of flows of nutrients and energy (Figure 2.1). Ecosystem development begins with an exploitation phase during which opportunistic, pioneer species (r-strategists) dominate. During successional development, the ecosystem enters a conservation stage in which nutrients are garnered and biomass is gained, with early-successional pioneer species gradually replaced by late-successional species (K-strategists). The exploitation stage proceeds slowly to the conservation stage. Once attaining the conservation stage, ecosystems are vulnerable to more rapid changes that may be triggered by stochastic events such as fire, windstorm, or pathogen outbreaks, resulting in release of energy and nutrients (omega phase) and necessitating a major reorganization (alpha phase) during which the system can either recycle along the same loop or flip to an alternate state. This view of ecosystem development is consistent with results from long-term ecological research studies such as Hubbard Brook Watershed (Bormann and Likens, 1979). It forms an adaptive cycle that continually moves through the four phases of ecosystem growth, accumulation, restructuring, and renewal, but also is subject to evolutionary change (Holling, 2001).

OVERVIEW

Whether or not prehistoric Native Americans were a significant ecological factor has been the subject of intense debate among generations of ecologists. During the latter half of the twentieth century, the pendulum of opinion has swung from the belief that American Indians had no influence on the composition and structure of plant and animal communities to the assertion that they were responsible for destruction of native habitats through over-exploitation of natural resources and widespread use of fire.

Quaternary paleoecology and archaeology are inherently multidisciplinary fields, drawing upon proxy information from data sets representing past states of climate, soils and geomorphology, biota, and material culture to make interpretations of changes in natural and cultural landscapes over millennial time scales. Time series of paleoecological and archaeological data yield chronologies of changes in both ecosystems and social systems. Before 1980, however, relatively few studies combined archaeological and paleoecological methods to determine objectively the kinds, extent, and duration of ecological influences by prehistoric Native Americans. Although a number of exemplary studies have been conducted since that time, the challenge remains to integrate available information effectively from paleoecology and archaeology in order to understand the linkages and dynamic feedbacks of processes underlying the documented patterns of change in prehistoric human ecosystems.

Panarchy theory has been developed recently by C.S. Holling and colleagues (Gunderson and Holling, 2001; Holling 2001) as an extension of hierarchy theory that includes cycles of adaptation in ecological and cultural processes.

THE MYTH OF THE PRISTINE FOREST

The explicitly stated choice of targets for ecological land management efforts in the United States mandates a “return to the presettlement equilibrium,” defined as a preColumbian baseline (Peacock, 1998; Kimmerer, 2000; Kloor, 2000). Since the inception of academic ecology in the United States at the turn of the twentieth century, scientific investigations have been predicated on the assumption that the North American continent has been relatively undisturbed by human activities, giving investigators a series of “natural experiments” from which fundamental relationships of plants and animals to their environment can be ascertained (Wright, 1977; McIntosh, 1985; Risser et al., 1984). During much of the twentieth century, ecologists also viewed the original vegetation and fauna of North America as being in a steady state, in equilibrium with climate and other environmental factors (McIntosh, 1985; Golley, 1984).

Both the assumption that ecosystems existing prior to the time of European American settlement were untouched by Native American activities and that they were in a state of equilibrium have been questioned, based upon a number of lines of reasoning, as well as historical and prehistoric information (Denevan, 1992; Kay, 1995; Hamel and Buckner, 1998; Peacock, 1998; Krech, 1999; Redman, 1999; Kimmerer, 2000; Minnis and Elisens, 2000).

“The forests the settlers saw”

Ecological methods have been developed to assess the distribution and composition of vegetation existing at the time of the westward expansion of European American settlement, using records from the General Land Office Surveys, under the assumption that “the forests the settlers saw” were representative of pristine “presettlement” wilderness (Bourdo, 1956, 1983; Marschner, 1959, 1974; Williams, 1989).

THE MYTH OF THE NATURAL MAN

The concept of the Native American as “noble savage,” living in harmony with nature, stems largely from the writings of the French philosopher, Rousseau, who lived from AD 1712 to 1778. Rousseau contrasted the “natural man,” who lived in the unspoiled wilderness, with the “civilized man,” who lived in society and sought to conquer the wilderness (Dolph, 1993). The concept of the noble savage was used in describing Native Americans by European American colonists of the eighteenth and nineteenth centuries, and those early descriptions became the basis for subsequent interpretations of the “presettlement” North American landscape by environmental historians and historical ecologists (Cronon, 1983; Crosby, 1986; Russell, 1997; Krech, 1999). The prevailing viewpoint of early twentieth-century ecologists was that human interference with natural succession began with European American settlement, and that in prehistoric times the vegetation was in equilibrium with climate and other environmental factors, including aboriginal human presence (Clements, 1936).

The debate among ecologists

Day (1953) was among the first academic ecologists to question this assumption. He argued that at the time of first European contact, the landscape of Eastern North America was not an unbroken virgin forest that had not been disturbed significantly by activities of Native Americans. Rather, settlers often described large tracts of open forest with little understory. Day cited ethnographic accounts (e.g., Densmore, 1927) to infer that prehistoric and historic Indians of New England drew upon the forest for a large variety of products.