Author: Thomas D. Sisk

Toward a Land Use History of North America: A Context for Understanding Environmental Change (page 2 of 2)

Science and the Historical Perspective

Sediment-laden runoff from Cowpuncher timber sale area enters clear waters of Pine Creek. Dixie National Forest north of Escalante, Utah. Photo © 1998 Ray Wheeler.

While the value of a land-use history to the environmental sciences is clear, scientific inquiry often has been divorced from or in conflict with, historical narrative. One of the world’s most influential ecologists, Robert MacArthur, wrote that "unraveling the history of a phenomenon has always appealed to some people and describing the machinery of the phenomenon to others. In both processes generalizations can be made and tested against new information so both are scientific, but the same person seldom excels at both" (MacArthur 1972, p.). More recently, the escalating severity of environmental problems and the difficulties involved in trying to solve them have led an increasing number of scientists to attempt to do both, often with startling insight. Commonly, the scientific objective of understanding the "machinery" or cause-and-effect relationships that drive environmental issues requires an unraveling of historical factors. For example, concerns over increasing concentrations of carbon dioxide in the atmosphere, and the implications this has for climate change, have led scientists to examine air trapped in rock and ice thousands of years ago. Analyses of the "ancient air" have allowed scientists to reconstruct a record of atmospheric CO₂ concentrations reaching back 160,000 years (reviewed in Vitousek 1994). This history has demonstrated that the build-up of CO₂ and other greenhouse gases since the industrial revolution is unprecedented, at least since the last ice age. For many people, this suggests that the ever-increasing production of greenhouse gasses, with their potential to warm the atmosphere and disrupt climatic patterns, is indeed a serious problem that demands serious attention. Similarly, the reconstruction of fire histories, records of changing climates, and studies of shifts in plant communities give us a deeper perspective on current trends and help us interpret their meaning and environmental importance.

Of course, historical approaches can be misused in scientific inquiry, particularly if we refer to historical information to shore up dubious data, or to "explain away" or downplay controversial scientific observations, or to make observations fit with our previous expectations. Uncritical use of historical arguments has hindered the development of ecological science in the past (Peters 1991), underscoring the need for rigorous, repeatable, and clearly documented approaches to reconstructing the history of land-use and landcover change. Rather than weaving together a historical narrative to "paint a picture" of environmental change, a science-based history of land use will provide a means for placing current conditions and recent trends into a broader temporal context. Compilation of historical trends will allow us to begin to associate cause and effect, exploring the relationship between human activities and environmental change. It also will help us identify the most important questions for future scientific research.

Toward a comprehensive land use history of North America

Compiling a history of land use and land cover is a large undertaking, one already begun by many scholars working in a variety of fields (for examples, see Shepard 1967; Delcourt and Delcourt 1991; Pielou 1991; Turner and Meyer 1994; Loveland and Hutcheson 1995; subsequent chapters in this volume). Nevertheless, the effort to aggregate information from across the continent and to construct a relatively seamless timeline from studies focusing on different time periods and employing a variety of data sources and analytical approaches is a complex endeavor. Clearly, an international effort will be required, not only because different countries occupy the continent, but also because records of early changes, particularly from the time of European settlement, exist in museums and archives throughout the world. Researchers from universities, government agencies, and private institutions have begun this task. Completing it will require a clear set of objectives, a coordinated effort that encourages creative approaches, and substantial new investments. The costs will be repaid many times over through a deeper appreciation of the environment and improved environmental management.

The relationship between human civilization and nature is a complex and changing aspect of all ecosystems, and our understanding of that relationship is itself dynamic (see, for example, Cronon 1995). Recognition of the role of the human within the ecosystem, obvious and inescapable when most people hunted and gathered food or tilled the earth, has been largely lost in the developed world, where links to nature are distant and abstracted for the great majority of the human population. We often see ourselves as being a step or more removed from nature, harvesting resources, recreating, monitoring impacts, interpreting conditions from the sidelines and administering first aid to resuscitate an infirm world, when necessary. Worster (1993) suggests that the way we use the land reflects our understanding of nature and our perceptions of ourselves. If widespread environmental degradation is an indication that our understanding of nature is narrow, it also suggests that so too is our perception of our own role in the functioning of natural systems.

An appreciation of history can widen and deepen this understanding. In 1906, American philosopher George Santayana warned that those who cannot remember the past are condemned to repeat it. But unlike the people who have faced social and political crises throughout the comparatively short history of civilization, those who ignore environmental history will not be blessed with the opportunity to repeat it. Instead, they will likely suffer through an increasingly difficult future, facing complex problems without the opportunity to consult the record of environmental change that stretches back, beyond the limits of human memory. Compiling this history and developing the tools to analyze, interpret, and share it broadly are important and inspiring missions as we enter the next millennium.

Acknowledgements:

I thank H.R. Pulliam, former Director of the National Biological Service, for many stimulating discussions during the formative period of the Land Use History of North America project, and for his unwavering support of this effort throughout his tenure with the U.S. Department of the Interior. Participants in the 1995 Patuxent workshop contributed ideas that have deepened my appreciation of historical data and the relationship between human land-use and landcover change. I also thank the LUHNA investigators who contributed their time and vision, as well as the chapters that appear in this volume, and I am grateful to C. Allen, T. Crews, J. Grahame, N. Haddad, and H. Sparrow for their helpful comments on a previous version of this manuscript.

Thomas D. Sisk
CP LUHNA co-Principle Investigator
Center for Environmental Sciences and Education
Northern Arizona University
Flagstaff, Arizona 86011

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