A Critique of Silviculture: Managing for Complexityby Klaus J. Puettmann
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The discipline of silviculture is at a crossroads. Silviculturists are under increasing pressure to develop practices that sustain the full function and dynamics of forested ecosystems and maintain ecosystem diversity and resilience while still providing needed wood products. A Critique of Silviculture offers a penetrating look at the current state of the field and provides suggestions for its future development.
The book includes an overview of the historical developments of silvicultural techniques and describes how these developments are best understood in their contemporary philosophical, social, and ecological contexts. It also explains how the traditional strengths of silviculture are becoming limitations as society demands a varied set of benefits from forests and as we learn more about the importance of diversity on ecosystem functions and processes.
The authors go on to explain how other fields, specifically ecology and complexity science, have developed in attempts to understand the diversity of nature and the variability and heterogeneity of ecosystems. The authors suggest that ideas and approaches from these fields could offer a road map to a new philosophical and practical approach that endorses managing forests as complex adaptive systems.
A Critique of Silviculture bridges a gap between silviculture and ecology that has long hindered the adoption of new ideas. It breaks the mold of disciplinary thinking by directly linking new ideas and findings in ecology and complexity science to the field of silviculture. This is a critically important book that is essential reading for anyone involved with forest ecology, forestry, silviculture, or the management of forested ecosystems.
"...the authors conduct an excellent review of ecological concepts and the value of those concepts in application to management."
"In this concise work Puettmann, Coates, and Messier address the issue of complexity in forest management by walking readers through a historical accounting of silviculture as a discipline."
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A Critique of Silviculture
Managing for Complexity
By Klaus J. Puettmann, K. David Coates, Christian Messier
ISLAND PRESSCopyright © 2009 Island Press
All rights reserved.
Historical Context of Silviculture
Scientific exploration and natural resource management occur in direct response to human need. Forest science and management are no exception. In this chapter, we review the history of human interaction with forests. In examining how social, economic, and ecological circumstances influence silviculture, we offer numerous examples in support of Cotta's observation: "There would be ... no forest science without deficiency in wood supplies. This science is only a child of necessity or need" (Cotta 1816, 27). We show how the development and application of silvicultural concepts and practices involving the manipulation of forest vegetation to accomplish a specified set of objectives has been closely tied to natural resource issues pertinent to specific localities at specific points in time. Our focus is central Europe, where silviculture first developed (du Monceau 1766; Hartig 1791), and North America, which has adopted many European practices (Hawley 1921), because we are most familiar with these regions and their silvicultural literature. Despite the historic, cultural, and linguistic differences that influence specific silvicultural practices, our main arguments also apply to other regions.
Management approaches and silvicultural practices must be viewed within the context of contemporaneous economic, societal, and cultural developments (Weetman 1996). The general history of human relationships with forests has been extensively reviewed (Smith 1972; Mustian 1976; Thirgood 1981; Hausrath 1982; Mantel 1990; Kimmins 1992; Schama 1995; Weetman 1996; Botkin 2002). The variety of silvicultural practices is attributed to practices developing independently in multiple regions (Mayr 1984; Mantel 1990), indicating that small-scale, local conditions are important in understanding the historical context of silviculture. Just like any scientific development, the rate of change in silviculture has been neither linear, constant, nor even continuous (Kuhn 1962; Hausrath 1982; Mantel 1990; Bengtsson et al. 2000; Tomsons 2001). Instead, the progress of silviculture directly followed trends in societal developments. During periods of fairly constant social and environmental conditions, such as during the 1950s through the 1970s, forest management changed little. On the other hand, times of societal upheaval or transformation quickly resulted in fairly drastic changes in forest practices. Our definition of "societal development" includes changes in basic demands for commodities from the forest, improvements in scientific understanding of forest ecosystems, and changes in philosophical, cultural, and spiritual attitudes toward forests.
This chapter provides an overview of the history of forest management and silviculture because it is important to understand how silviculturists arrived at their current set of practices. Possibly even more important is the need to understand how the historical development of silviculture has affected the cultural attitudes of silviculturists and the way they think and address problems. It is the combination of historical convention and current scientific understanding that provides the basis for choices that so profoundly affect the management of forests. A basic understanding of silvicultural history provides useful and necessary context to the contemporary debate about the future role of silviculture in managing forests. We present a brief history of the external factors that were most influential on forestry and describe how human needs and external conditions led to the development of silvicultural practices and the subsequent combining of individual practices into silvicultural systems to meet management objectives. We highlight the importance of context, especially the need to consider time and place when evaluating practices, and discuss issues associated with "adoption without adaptation" by presenting examples of where silvicultural practices successful in one region were transplanted to other conditions or regions.
Major External Factors Influencing Development of Forestry and Silviculture
External factors are factors outside forestry that had a large influence on the field of forestry and the discipline of silviculture and originated from a variety of economic and social conditions. The main factors discussed in this chapter include population pressures, shifts in economic philosophy, development of industries, and scientific and technical advancements. The most important factor driving changes in forest management in central Europe during the last 2,000 years is the ever-increasing pressure of human populations on the natural resources. This pressure is determined through a combination of human population levels (fig. 1.1) and changes in the standard of living with an associated increase in the demand for forest products. For a brief perspective, during Roman times, the human population in central Europe was estimated to be less than 34 million. Settlements were separated by large tracts of forest, although they were not necessarily culturally or economically isolated (Schama 1995). Major trade routes existed, but larger population movements were quite limited, resulting in fairly stable population levels (McEvedy and Jones 1978).
For the last 2,000 years, the human population has increased at an ever-faster rate, with notable exceptions. Several famines (e.g., Great Famine of 1315–1317), disease pandemics (e.g., typhoid in 1309–1317, bubonic plague in 1348), and periods of intense warfare (e.g., Thirty Years' War of 1618–1648) not only slowed rates of population growth in Europe, but also were responsible for major population declines in many regions. Other societal developments, such as the emergence of new farming techniques, the appearance of potatoes as a human and animal food source, and improved medical knowledge, increased the rate of population growth. Emigration, especially the emigration wave to the Americas during the nineteenth century, slowed population growth in Europe. More recently, the population in central Europe is decreasing (mainly due to low birth rates) but the impact of the declining population on the forest resource may be offset by an increased standard of living.
Major shifts in the economy of Europe in the late seventeenth and early eighteenth century strongly influenced the philosophical and cultural factors in the development of silviculture (fig. 1.1). During that time, economies in many parts of central Europe shifted from an agricultural base to an industrial base. The development of iron, salt, and glass industries in the sixteenth century caused a rapid increase in the demand for wood (Mantel 1990). The demand for energy wood, however, decreased somewhat in the eighteenth century as coal and oil replaced wood as an energy source in many factories. Other uses, such as the use of wood to support mine shafts and in the building of large shipping fleets, took its place.
Other influences of industrialization had a longer-lasting impact on the human relationship to forests and forest uses; some of these influences continue today. For example, hand in hand with industrialization came new ideas about economics from philosophers, such as Adam Smith (1723–1790). Especially the development and popularization of economic liberalism and a free-market economy was novel to the forestry sector. While wood products have been traded for a long time, the appearance of wood in a marketing context is first documented in the fifteenth century (Lorey 1888). However, until the seventeenth century, forest products were either used locally or sold in markets that were regulated strictly by local principalities (Mantel 1990). The shift in economic thinking in the eighteenth century and the adoption of free- market ideas and concepts of management efficiencies by silviculturists (see chap. 2) had a long-lasting impact, and still influence our understanding of forest management and the development and application of silviculture today.
Forestry was rather slow to adopt economic liberalism, compared to other industries. But when it did, the view of the role of economics in the ownership of forests changed dramatically. The forest had previously been viewed primarily as a stable component of a regional economy and employment base. Management decisions were applied in this context (Ruppert 2004). With the adoption of economic liberalism in the nineteenth century came the notion that the purpose of forests was to maximize profit for landowners (Ruppert 2004). This was a substantial shift in thinking, and its influence on forestry research and management activities cannot be underestimated. To apply the notion of profit maximization in forestry required new concepts and decision-making tools (Mantel 1990). In response to this demand, silviculturists started to inventory forests and document their growth and utilization (Hundeshagen 1826). The most notable advances in this context were the development of the normal forest concept (Normalwaldkonzept; Hundeshagen 1826; Speidel 1984) and the Faustmann formula (Faustmann 1849), both of which are still central ideas in forestry today (Speidel 1984; Edwards and Kirby 1998; Brazee 2001; Davis et al. 2001; Salo and Tahvonen 2002).
Under economic liberalism, all forest management activities were viewed as investments and therefore subject to economic evaluations. The calculation of interest rates for management activities and forest properties (Cotta 1817) was especially prevalent in the Bodenreinertragslehre (Speidel 1984). Under this popular economic school, maximizing interest rates was the dominant consideration in the decision-making process. Viewing forests through this fiscal lens profoundly changed the foundation for silvicultural decision making. Previously, silvicultural decision criteria were based on the structure of forests as defined by volume or area of harvestable, fully stocked stands. These criteria were now replaced by productivity criteria, for example, current and expected tree and stand growth as reflected in profits. In practice, under this economic philosophy rotation lengths were fairly short, mainly due to the impact of interest compounding. For the same reason, fast-growing species were usually favored in regeneration efforts and management activities were implemented only if they either were cheap or resulted in quicker recovery of investments due to faster growth of the managed trees
As with any trend, these new economic approaches were not accepted by all silviculturists, and alternative views developed. Especially, some silviculturists questioned whether using the internal rate of return as a dominant driver of forest management decisions was appropriate for an industry with long-term investments, such as forestry. Other ideas, most prominently the Waldreinertragslehre (Speidel 1984), became recognized as viable alternatives (Ruppert 2004). The management goal under the Waldreinertrag focused on maximizing annual returns rather than the internal rate of return. Since returns were calculated as the difference between investments and revenues on an annual basis, interest rates were not considered when evaluating the profitability of management activities.
Compared to the Bodenreinertragslehre, the Waldreinertragslehre encouraged implementation of more intensive forest management practices with little concern for the delay between when investment costs were incurred and recovered. One of the best examples of this philosophy is the management of high-value oak (Quercus robur or Q. pubescens) stands in central Europe, specifically in Spessart, Germany. Because of the extremely high value of quality oak logs, just about any investment can be justified under the Waldreinertragslehre. Typical practices in these stands include very expensive reforestation activities, such as dense planting, intensive vegetation control, and multiple pre-commercial thinnings, underplanting of European beech (Fagus sylvatica) or other trainer species, or artificial pruning (Burschel and Huss 1997). Moreover, without the compound interest penalty, longer rotations and associated management goals such as large, high-quality timber became more common. Typical rotations for oak in these regions vary between 150 and 240 years, a length that could never be justified under the Bodenreinertragslehre economic philosophy.
These two economic approaches became a widespread basis for forest management decisions, partially reflecting the different values that societies place on private property and social responsibilities. In Europe most emphasis was on the Waldreinertragslehre, while North American forest economists tended to favor the Bodenreinertragslehre (Speidel 1984; Davis et al. 2001). Over the years the two approaches were refined and modified, but their basic fundamental principles are still the dominant basis for forest management decisions on many ownerships today (Davis et al. 2001).
The influences of economic liberalism were so entrenched in the forestry profession and were so widely accepted that they carried across ownerships with different management objectives. In many regions, ownership patterns were not easy to detect just by examining forest conditions in the landscape (Ohmann et al. 2007; Spies et al. 2007). Public, small private, and industrial owners obviously had different management constraints and goals. These differences, however, were smothered by the common economically driven approach to forest management. The fairly homogenous landscape (in terms of stand sizes, rotation lengths, and harvesting patterns) partially reflects an educational system that did not directly distinguish between training silviculturists for different ownerships. Also in some regions, specifically in Germany, the line between public and private forestry was blurred; a typical job description of state forestry employees included not only management of state land, but also consultations with small, private woodlands. All of these aspects allowed a single dominant philosophical approach—that is, economic liberalism—to express itself by homogenizing the forested landscape.
This homogenization of forests of different ownerships did not change significantly until the 1990s, when the emphasis of management on public land shifted away from a focus on timber production. In many regions, especially in North America, public owners have moved from economically driven management approaches toward some form of ecosystem management with a focus on late-successional habitat and therefore longer rotations and partial harvests (Kohm and Franklin 1997). Industrial forestlands remain driven by economic incentives with fairly short rotations. Small private landowners appear to fall somewhere in between those two extremes, often focusing less on economic values and more on recreational and ecological values (Uliczka et al. 2004).
Another major factor that influenced the human relationship with forests was the progress in scientific understanding of forest ecosystems. During early human history, forest management efforts were limited to gathering wood products and tending the forest for agricultural use, such as animal grazing (Hasel 1985; Mantel 1990). However, during Roman times humans developed an understanding about regeneration requirements, specifically for sprouting and growth rates of different tree species (Hausrath 1982). During the next 1,800 years, much of the new scientific knowledge was locally developed and applied by foresters, whose main tasks were focused not on silvicultural applications, but on hunting and police functions. With few exceptions, most information was carried forward through oral tradition. In Europe, the first comprehensive documents demonstrating a scientific understanding of ecological and silvicultural issues were prepared by Hartig (1791) and Cotta (1817).
These publications can be viewed as the initiation of silviculture as a scientific undertaking. Shortly thereafter, the science of ecology became established (chap. 3) and investigations into ecosystem structure and function began, but they had little impact on silviculture for a long time (chap. 4). The establishment of research institutions in government agencies and forest faculties at universities (e.g., 1792 at Freiburg, Germany; 1805 at Koselev, Russia; 1811 at Tharandt, Germany; 1824 at Nancy, France; 1828 at Stockholm, Sweden; 1862 at Evo, Finland; 1870 at London, Great Britain; 1898 at Biltmore and Cornell, United States; and 1900 at Yale University, United States) is a clear sign that forestry, and thus silviculture, had become a recognized scientific discipline.
Excerpted from A Critique of Silviculture by Klaus J. Puettmann, K. David Coates, Christian Messier. Copyright © 2009 Island Press. Excerpted by permission of ISLAND PRESS.
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Meet the Author
Klaus J. Puettmann is professor of silviculture and forest ecology in the Department of Forest Science at Oregon State University in Corvallis. K. David Coates is a senior research silviculturist with the Northern Interior Forest Region of the Ministry of Forests and Range in Smithers, British Columbia. Christian Messier is professor of forest ecology and director of the Center for Forest Studies in the Department of Biological Sciences at the University of Quebec at Montreal.
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