Scientists tell us that climate change is upon us and the physical world is changing quickly with important implications for biodiversity and human well-being. Forests cover vast regions of the globe and serve as a first line of defense against the worst effects of climate change, but only if we keep them healthy and resilient.
Forests in Our Changing World tells us how to do that. Authors Joe Landsberg and Richard Waring present an overview of forests around the globe, describing basic precepts of forest ecology and physiology and how forests will change as earth’s climate warms. Drawing on years of research and teaching, they discuss the values and uses of both natural and plantation-based forests. In easy-to-understand terms, they describe the ecosystem services forests provide, such as clean water and wildlife habitat, present economic concepts important to the management and policy decisions that affect forests, and introduce the use of growth-and-yield models and remote-sensing technology that provide the data behind those decisions.
This book is a useful guide for undergraduates as well as managers, administrators, and policy makers in environmental organizations and government agencies looking for a clear overview of basic forest processes and pragmatic suggestions for protecting the health of forests.
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About the Author
Joe Landsberg is a forest scientist, consultant, and past chief of the CSIRO Division of Forest Research in Australia. Richard Waring is emeritus Distinguished Professor of Forest Science at Oregon State University in Corvallis.
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Forests in Our Changing World
New Principles for Conservation and Management
By Joe Landsberg, Richard Waring
ISLAND PRESSCopyright © 2014 Joseph Landsberg and Richard Waring
All rights reserved.
Introduction: Looking Back and Into the Future
Our objective in this book is to describe and discuss forests and their significance in our world. Human societies need the products of forests—not just wood and wood products but all the ecological goods and services that forests provide: biodiversity and its essential benefits, carbon sequestration and storage, stable water supplies, land protection, recreation. But relatively few people are aware of these services and benefits, so we hope to contribute to raising awareness of these values and the importance of forests, and to providing the science-based information needed to guide political action and decisions about them. Toward achieving these objectives we consider how forests grow and why different types occur in different parts of the earth; what constrains their growth, why they are important to us and how they should be managed.
Most people like trees. We plant and nurture them in our parks and gardens—in fact the very idea of a suburb suggests leafy, tree-lined streets—but there are big differences between trees in the suburbs or scattered around farmhouses or in small woodlots, and those in forests. Forests are embedded in our psyche: they have been important to us throughout our history, but most people, nowadays, know too little about their importance to the planet and to our lives and economies.
People of different cultures and backgrounds view forests in different ways: some see them as rather mysterious wilderness, others simply as blocks of land with commercial potential. Forests are basic to the folklore of people who have lived in and with them for generations. Scandinavian and German myths and legends tend to involve dark and sometimes forbidding forests. In some countries, access to the forests to camp, collect berries and mushrooms, hunt, or simply to walk in and enjoy them is a right entrenched in law.
In the modern world virtually all forests are exploited by humans in various ways, mostly, of course, for wood production for industrial purposes or for fuel. Some natural forests are protected and well managed but economic pressures are bringing about the destruction of many others. Tropical forests provide a living to—sadly, remnant—native peoples in Indonesia, Papua New Guinea, and the Amazon, but those forests are being destroyed at frightening rates by illegal logging or to establish oil palm plantations or cleared for crop production. Forests have been and, indeed, remain among the dominant vegetation types across the earth, but one of the most important processes by which humans have transformed the earth is through deforestation. In the following paragraphs we provide an outline of the history of human interaction with forests and a short synopsis of the history of deforestation around the world. In later chapters we consider some of the consequences and implications of destroying forests.
Forests in Human History
It's now generally accepted by anthropologists and archeologists that our species evolved in the forests of central Africa somewhere around 3.5 million years ago—less than 1 percent of the total age of our earth. Why those early ape-like creatures started to walk upright on two limbs instead of just going on the way they were, presumably swinging through the trees, is a matter of speculation. It seems inarguable that our very early ancestors moved from living in the central African forests to the savannah; the species called Homo sapiens emerged about half a million years ago and became essentially identical to modern humans about 50,000 years ago.
Much of the early development of human societies was in the area covered by modern Israel, Lebanon, Syria, Iraq, and eastern Iran, none of which was heavily forested. From there, early humans radiated west along the north coast of the Mediterranean Sea and east, within the warm subtropical latitudes. There is also archeological evidence of Homo erectus (not yet H. sapiens) activity in China more than a million years ago.
It's estimated that the human population of the earth has increased from a few hundred thousand at the time of the retreat of the glaciers, around 10,000 years ago, to about 200 million at the beginning of what we in the Western world call the Christian era. Of that 200 million, a significant proportion was in China. Morris (2010) says there is evidence that rice and millet were cultivated in the Yangtze valley between 8,000 and 9,000 years ago, and that 6,000 years ago the Yangtze and Yellow River valleys were mostly subtropical forest. Forests were cleared as the steady growth of human populations led to the expansion of cropland around more and more villages.
As the glaciers and ice sheets of the Ice Age retreated, forests expanded into huge areas where tree growth had previously been impossible. Human populations also increased as the ice retreated and people moved north into regions of Europe that had been uninhabitable. Human disturbance of forests in Europe seems to have become significant around 6,000 years ago—approximately the same time as in China—and increased from then on. There are written accounts from the ancient Mediterranean civilizations, notably Greece and Rome, of extensive forest clearing for wood for fuel, building, and shipbuilding, leading to denudation of the countryside. The damage was exacerbated by widespread overgrazing and browsing, particularly by goats. This led to soil loss by erosion and reduced agricultural productivity, which may well have been a significant contributor to the decline of those civilizations.
The Roman Empire at its peak, near the beginning of the Christian era, included about sixty million people; Rome itself reached about one million, a massive city population for the time. Wood was the most important building material and, throughout the empire, trees were cut for housing and the great shipbuilding program of the Romans, as well as to provide fuel for domestic heating, iron-working, and ceramics manufacture. The expansion of agriculture also resulted in increasing land clearance, so the Roman period saw considerable changes in forest cover, particularly in southern Europe. Clearance in Europe was checked by declining populations associated with the disintegration of the Roman Empire, the invasions by Huns and Goths from the east, constant war, the spread of various lethal diseases, and famine. Populations recovered and increased between the fourth and seventh centuries, with accelerated land clearance; by the end of the fourteenth century "farmers had plowed up vast tracts of what had once been forest, felling perhaps half the trees in western Europe" (Morris 2010, 367). The plagues known as the "black death" caused human populations to crash in the fourteenth century, and large areas of forests recovered by natural regeneration during that period.
Morris (380) also describes how, in the Chinese city of Kaifeng on the Yellow River, iron output increased sixfold between AD 800 and 1100: "Foundries burned day and night, sucking in trees to smelt ores into iron; so many trees, in fact, that ironmasters bought up and clearcut entire mountains.... There was simply not enough wood in northern China to feed and warm its million (human) bodies and keep foundries turning out thousands of tons of iron." This demand triggered the increased utilization of a new fuel source—coal. Morris does not concern himself with environmental impacts, although he does comment that "Kaifeng was apparently entering an ecological bottleneck," by which he means, presumably, that it was reaching a tipping point, where the surrounding ecosystems would collapse. In the modern era, forests in China were devastated during Mao Zedong's Great Leap Forward when, to reduce China's need to import steel and machinery, people were encouraged to set up backyard steel furnaces to turn scrap metal (including their own pots, pans, and farm implements) into steel. This resulted in very little, if any, usable steel, while entire forests were cut down to fuel the smelters, leaving the land vulnerable to erosion and contributing to massive environmental damage.
Discussing the impact of humans on the land in the immediate preindustrial period, Morris (2010) tells us, "One scholar complained in the 1660s that four-fifths of Japanese mountains had been deforested." The same thing happened in Britain. The forests of Britain had been cleared for farmland well before the arrival of the Romans1 and later were heavily exploited for timber; only 10 percent of England and Scotland were still wooded around 1550, and by the 1750s most of those trees were gone too. The demand for timber, and consequently much of the deforestation in England between the sixteenth and eighteenth centuries, was caused by shipbuilding: Britannia, as it was happy to tell the world, ruled the waves, and to do that it needed ships. The British navy was the means by which the island kingdom protected itself and projected its power; thousands of wooden ships were built through the seventeenth, eighteenth, and nineteenth centuries. The toll on the forests was enormous. English demand for access to American forests and wood supplies was one of the sources of tension between England and its American colonies in the eighteenth century. Ireland, by contrast, was still 12 percent forest in 1600, but colonists eliminated more than 80 percent of those trees by 1700.
In Europe the need for timber drove exploitation of the forests, but the need to manage them in a systematic way that would ensure their survival and long-term productivity (today we would use the word sustainability) was recognized early, particularly in Germany, where formal forest management dates back to the fourteenth century. Germany was not a single country at that time, so management practices and control of the forests varied between states. Some of the mixed temperate forests in Germany are regrowth; they were at one time completely destroyed, as in the northeastern United States (see our comment a little later, about the recovery of those forests).
In his fascinating and salutary book Collapse, Jared Diamond (2005) examines the reasons various human societies of the past have collapsed. They are as varied as the societies he considers, but a common thread is environmental destruction and deforestation, leading to degeneration of the ecosystems on which every society relies, and ultimately the collapse of the societies. Deforestation was seldom the only problem, although in the case of Easter Island, where trees provided the rollers to move stone statues, it was the primary cause of soil erosion, loss of soil fertility and productivity, and the loss of material to make canoes for fishing and trading. Eventually deforestation brought about the total disintegration of the Easter Island society. In the highly successful Mayan civilization on the Yucatan peninsula, which lasted from about AD 250 to 900, high population growth outstripped the availability of resources. The process was accelerated by deforestation of the hillsides, leading to soil erosion and the accumulation of infertile sediment in the valley bottoms and loss of agricultural production. In modern times the island of Haiti, in the Caribbean, is a failed state with unstable government and frequent breakdowns of law and order. Heavily overpopulated and desperately poor, it has been almost completely deforested with disastrous effects on water supplies and agricultural production. Things are very different in the Dominican Republic, which occupies the other section (two-thirds) of the island. Forest cover there is good and the ecology seems to be healthy. Perhaps not coincidentally, the Dominican Republic is economically healthy and politically stable.
A point we need to make with respect to all this historical deforestation is that it was rarely deliberate, at least not by native inhabitants. People needed wood and fuel and they needed to clear land for agriculture and living space. The forests, in many cases, seemed huge and a few people with axes would not have felt they were doing significant damage. Each generation was comfortable with its actions and did not consciously set out to destroy the forests. In most cases each generation had increasing appreciation for a declining resource. Even in Australia, where permanent land settlement only started in the nineteenth century, the forests seemed endless and men with axes and cross-cut saws, wielded with immense labor, could not imagine that they would end up destroying a large proportion of them. Things are different now. With our communication systems, satellite coverage of the earth, and methods of disseminating knowledge, we have no excuse for not knowing what's going on. We know how much forest there is, how fast it grows, and how fast we are harvesting or destroying it. We understand the importance of forests and what their loss entails. In this book we discuss what we need to know to use forests sensibly, so we can benefit from them—as humans always have—without destroying them.
But across the world, as we write, the destructive trend continues. Amazonian rainforests are being destroyed to make way for commercial production of soybeans, mainly for export to the United States. Indonesian and Malaysian rainforests are cleared to free land for agro-industrial purposes, such as oil palm cultivation. The rainforests of Papua New Guinea, the Solomon Islands, Vanuatu, and other Pacific islands are being destroyed to satisfy voracious Korean, Japanese, Taiwanese, and Chinese commercial interests. Poor decisions, such as those based on superficial economic analyses, without taking account of the long-term implications, can lead to irreversible loss of options in the future. For example, a recent analysis of the effects of climate change on forest production in California notes that pulp yields (for paper production) will decrease, but the land values for urban development will increase. Therefore, in conventional economic terms, additional urban development (sprawl) is considered justifiable: the gain in land values is deemed to compensate for the loss in forests and forest productivity, although the environmental costs are likely to be high. We discuss the values of forests and the economics of using them in chapters 5 and 6.
The forest cover of Australia has been estimated at 33 percent at the time of European settlement. It is now 19 percent. The country has a remarkably cavalier attitude about its forest resources: clear-felling (clearcutting) and logging of old-growth forests continue to this day, although this activity has now been greatly reduced, largely because of pressure brought by an increasingly concerned public. But much of Australia's agricultural land—land that was covered by forests, or at least woodlands—now has serious salinity problems, because the deep-rooted trees that were once present, transpiring water all the year round and keeping the water tables down, are largely gone.
There are some bright spots in all this. A forest is not necessarily destroyed when all the trees are cut down. It is destroyed when the land is no longer allowed to support trees, but is converted to crops, pastures, or urban development. If once-forested lands are left alone after clear-felling, the forests will, in most cases, regenerate and reestablish themselves, sometimes with astonishing rapidity. The trees may not initially be the same species but under a stable climate will evolve to once more resemble a natural forest. We will discuss the processes involved in more detail later.
The United States provides examples. It was colonized from east to west by Europeans, who in the seventeenth and eighteenth centuries cleared the forest from large areas of New England for agriculture. As the colonists moved west and the more productive and easily farmed lands of Ohio, Indiana, Illinois, and Iowa came into agricultural production, and transport improved, it became uneconomical to farm in New England and New Hampshire, so the cleared lands were abandoned. These areas are now thriving hardwood and mixed forests. Similarly, large areas in the southern United States were cleared of forests to grow cotton. These too were abandoned and forests reestablished themselves across millions of hectares. Large areas of denuded cotton lands have also been planted to conifer plantations, which, with appropriate management to deal with the results of soil degradation by the exploitive cotton culture, are highly productive. They are not always native trees, but plantations are part of the "family" of forests. We will discuss them in some detail later. In Russia, large areas of cooperative farmland have been abandoned since the fall of the Soviet Union in 1989, and abundant regrowth of forests is now evident.
Excerpted from Forests in Our Changing World by Joe Landsberg, Richard Waring. Copyright © 2014 Joseph Landsberg and Richard Waring. Excerpted by permission of ISLAND PRESS.
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Table of Contents
Chapter 1. Introduction: Looking Back and Into the Future
-Forests in Human History
-Outline of the Rest of the Book
-A Look into the Future
Chapter 2. Forest Types around the World
-The Main Forest Types
-On Being Evergreen or Deciduous
-Plantations and Managed Forests
Chapter 3. Weather and Climate Determine Forest Growth and Type
-How Trees Grow
-Weather Factors: Temperature
-Weather Factors: Solar Radiation
-Weather Factors: Air Humidity
-Weather Factors: Precipitation and Hydrology
-Implications of Forest Clearance for Hydrology and Climate
Chapter 4. The Causes and Consequences of Rapid Climate Change
-The Causes of Global Warming
-Fossil Fuel Burning and Land Use Change
-How Fast Is the Earth Warming?
-A Word about Denialists
-On Variation and Uncertainty
-Extreme Weather Events
-TheImpacts and Implications of Climate Change
Chapter 5. How We Value and Use Forests
-Ecosystem Services and Universal Values of Forests
-The Uses of Forests
-Abuses of Forests
Chapter 6. The Economics and Practices of Forest Management
-An Outline of Relevant Economic Theory
-Microeconomics: Commercial Operations on State Land
-Microeconomics: Commercial Operations on Private Land
-Forest Growth and Yield Estimates
-Fire and Its Management
Chapter 7. The Future for Forests
-Conserve the Forests
-Management for the Future: Natural Forests
-Management for the Future: Plantations