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The SSI Population and Environment Series

Human Population and Forests

The accelerating loss of the world's forests presents one of the major environmental challenges of the next century. The growth of the human population—from a few million people in prehistory to 6 billion today—looms large among the factors contributing to this loss. Yet many analyses of forest loss despair that population growth is an inevitable force that must be reckoned with but cannot be influenced. This report challenges that view. Its purpose is not only to examine population's role in forest loss, but also to highlight the value of population policies that simultaneously improve human well-being and brighten the prospects for conserving the world's remaining forests.

WHY WE NEED FORESTS

Forests are a vital resource for many of the world's people. They provide societies with a wide array of goods and services, sustain millions of plant and animal species, maintain air and water quality on which human life and health depend, and are important regulators of the planet's climate (Fig.1).

Figure 1

Trees fuel the global economy. Wood is essential to housing and furniture, and remains the principal material used by humans for construction worldwide. Tree products are vital to the flow of information, even in today's electronic age, which shows no signs of producing a paperless society. On the contrary, economic activity has moved more and more from factories into offices, and paper is now a critical component in those offices throughout the world.

For those who lack access to conventional energy sources, trees provide an essential source of fuel. Four-fifths of wood harvested in developing countries is consumed as fuel. For nearly 3 billion people, wood is the main energy source for household heating and cooking. Nearly all this wood must be gathered by hand, and the greatest burden of this work falls on women and their children.

Forest scarcity also impacts on the prospects for improving education and disseminating culture. Eight of every 10 human beings have yet to achieve the level of paper use considered necessary to meet basic needs for literacy and communication (Radka 1994). Things which students and teachers in rich nations take for granted—textbooks, loose-leaf notebooks, pencils and manila folders—are scarce commodities in many schools in developing countries. Bridging this paper gap is essential to improving the effectiveness of education programs.

Beyond material goods, forests also provide a range of other benefits. These "ecosystem services" are not bought and sold in the market, but they nevertheless are vital to human welfare, and indeed to our survival.

For example, forests shelter at least half of the world's known plant and animal species, a genetic library of unknown dimensions that could be the basis for advances in medicine, food production and materials development for generations to come. Most of the world's biodiversity is found in forests, especially tropical forests, and these immense storehouses of knowledge are practically uncatalogued. Estimates of the numbers of tropical forest species not yet described by science range up to 10 times or more the number known today (May 1990).

It has long been understood that forests help protect and enrich soils, sustain the quality and quantity of water resources and reduce the severity of floods, landslides and other natural disasters. Without forest cover, rainfall quickly drains away, carrying vital topsoil with it in immense quantities. Thus deforestation leads to more severe flooding followed later by drought, because the water-storage capacity of the ecosystem has been diminished.

Trees absorb heat-trapping carbon dioxide from the atmosphere and store the carbon as a key constituent of wood and forest soils. The photosynthesis carried out by forests, which takes the greenhouse gas carbon dioxide out of the atmosphere, thus reverses the effects of burning fossil fuels. Expanding the world's forested land would therefore counteract the greenhouse effect, and could help slow human-induced climate change.

It's important to realize that these different goods and services are supplied by very different kinds of forests. Plantations, for example, can produce large amounts of wood or paper, but their biodiversity is usually very low and they're often unavailable to those who need fuelwood. In fact, much of the fuelwood collected in developing countries doesn't come from forests at all, but rather from living fenceposts, savanna trees, orchards and other sources. Thus, the world needs to have different kinds of forests for different uses.

Both the tangible goods and the ecosystem services provided by forests are priceless to individual and planetary well-being. As forests and wildlife both succumb to the spread of farms and settlements, those that remain become increasingly valuable—and irreplaceable—resources, for ourselves and for the generations yet to come.

UNDERSTANDING FOREST LOSS

Spread across six continents, forests cover 27 percent of the world's land area—roughly 35 million square kilometers. The world's developing regions contain 57 percent of global forest cover, with the remaining 43 percent found in developed countries. Just four countries—Russia, Brazil, Canada, and the United States—contain half of the world's current forests (FAO 1997).

Half of the world's original forests have disappeared since the end of the last Ice Age. More forest was cleared from 1850 to the present than in all previous history, and the rates of deforestation have been highest in the last few decades. The ratio of forested land to human beings has dropped steadily as population has grown and the world's forests have retreated (See Figure 2). The amount of forest cover available to each person, a key measure of forest resource pressure, has declined globally by 50 percent since 1960 to 0.6 hectares (1.5 acres) per person.

Figure 2

As a result, more than 1.7 billion people live in 40 nations considered to have low forest cover (less than 0.1 hectares per person) and therefore a scarcity of forest resources. Of these, nearly 250 million live in 20 countries experiencing a scarcity of both forest and freshwater resources. Based on the UN medium population scenario, Population Action International projects that by 2025 nearly 800 million people living in 26 countries will face acute shortages of these two critical natural resources.

What has caused this deforestation? Human beings use wood and products made of wood, and clearly rates of consumption have much to do with why forested land is retreating. Historically, increases in economic growth and population have been the main forces fueling the demand for wood (Brooks 1997). World consumption of wood—including woodfuel and industrial wood—has grown by 60 percent since 1960, to over 3.3 billion cubic meters in 1995. During that same period, world population has grown by 90 percent and the global economy has more than tripled in size (See Figure 3) (FAO 1997).

Figure 3

Per capita wood consumption has declined slightly on a global basis (Solberg 1996), but this average obscures sharp increases in consumption of certain types of wood products. Disparities in wood consumption levels, however, make the wood appetites of industrialized countries a suspect in fueling forest loss. Each American, for example, consumes 15 times as much industrial roundwood (wood used for building materials, paper, packaging and other commercial wood products) as the average person living in a developing country.

While developed countries are the greatest consumers of industrial wood products, they are also the largest producers. In fact, developing country forests on the whole supply only a modest portion of many the world's industrial wood products, although this portion is increasing. And the bulk of this production comes from a few forest-rich countries.

Rising exports of tropical wood also attract attention as potential evidence of the developed world's role in deforestation. However, wood from tropical forests represents only 15 percent of world industrial roundwood production and less than one-quarter of all wood exports come from tropical forests. Nonetheless, the timber trade does contribute to the loss of forests in some countries. Indonesia, for example, produces roughly 20 percent of the world's plywood, nearly all of which it exports (FAO 1998). And in Myanmar, home to 70 percent of the world's remaining teak forests, massive, illegal timber exports go unrecorded in government trade statistics (Brunner et al 1998).

The ecological effects of deforestation and reforestation depend a great deal on what sorts of forest we're talking about. Replacing an native old-growth forest with a pulp-and-paper plantation, for example, can be disastrous for biodiversity even if the forest-covered area remains the same and wood productivity increases. Similarly, even large-scale planting of fast-growing introduced species may do little to provide wildlife habitat.

The fastest increases in consumption are now occurring within the developing world. This increase is linked to the demographic and economic growth experienced by those countries in recent decades. Since 1980, for example, consumption of industrial roundwood grew fastest in South America, while paper use rose most rapidly in Asia and fuelwood use in Africa (FAO 1997). The fact that population growth rates in these regions are now decreasing is among the most positive trends for the long-term conservation of forests.

POPULATION AND FORESTS: THE LITERATURE ON THE LINKAGE

Scholars have cited four main forces—often summarized as "people, poverty, plunder, and policy"—as the underlying or indirect causes of forest loss (Brown and Pearce 1994). Collectively, these represent the systemic conditions rooted within a society that drive individual decisions to cut and clear forests. Of these, population has been the most controversial.

Studies published in the past 20 years that have examined the role of population dynamics in forest loss vary widely in their conclusions. A compilation of research on the causes of tropical deforestation published in 1994 contained studies finding highly significant correlations between population and deforestation, while others found the connection statistically insignificant or even non-existent (Brown and Pearce 1994). Such disparities between these studies' results are due partly to the complex dynamics of land use, differences in how population is defined (e.g., population growth versus population density versus migration rates), and the different conditions of the forest regions being studied (Saxena et al 1998). Population never operates as an independent factor in forest loss (or any other form of environmental degradation) but always within the context of other underlying factors.

Analyses that consider these broad interconnections of factors over long time periods tend to reveal a major role for population dynamics. A comprehensive study published in 1998 examined historical changes in forest cover and population in 111 countries to determine the cumulative effect of what the authors called "human drivers" of forest loss. The study was conducted as part of the Land Use and Land Cover Change project, an international research consortium aimed at better understanding the causes of land cover change and their effect on the global environment. The study concluded that about half of the deforestation over the span of human history could be explained by changes in population (Mather et al 1998).

Another recent study published by the FAO measured the impact of human activity on tropical forest depletion in Asia and Africa. The researchers found that the combined effect of human activities such as subsistence farming, fuelwood overharvesting, and logging had reduced the amount of forest biomass by 50 percent in Asia and 35 percent in Africa. The study concluded that Asia's forests were more depleted than Africa's primarily because population densities in Asia were higher (Brown 1997).

However, the literature also shows that deforestation is not simply the result of too many people on too little land, but more an end product of too many people with too few alternatives to the unclaimed and unregulated opportunities forests offer. Unequal land distribution, inadequate access to agricultural technology, corruption, market forces, and government policies all interact with population dynamics to limit people's capacity to seek better opportunities. Some policies that have resulted in massive deforestation, such as government-sponsored resettlement programs in Indonesia and Brazil, are themselves responses to population pressures.

Thus, although most analysts agree that population dynamics play a role in forest loss, the exact nature of that role remains unclear. Few if any analysts claim that these two processes are unrelated—that, for example, the world's forests would fare the same whether human population levels off early in the next century or triples in size. Population strategies based on the Cairo Programme of Action work simultaneously to improve the lives of women and their families and to bring closer the day population growth comes to an end. The research on the population-forest linkage affirms the benefits in such policies for human beings and for the forests on which they depend.

THE FOREST TRANSITION

A long-term viewpoint is useful in understanding past and likely future trends in deforestation. While forests are disappearing rapidly in much of the developing world, those in most industrialized countries have stabilized or even begun expanding. This shift from shrinking to expanding forests is often referred to as the forest transition (Mather 1992), and the way it has proceeded in developed countries may shed some light on the likely direction of forest area change in less developed ones.

In the developed world population growth has been an influential factor in the forest transition. For example, the ancient forests of Europe once covered most of the continent. But they were thinned out and eventually disappeared over the last millenium as the success of agriculture fueled population growth and the growing demand for timber, fuelwood and cleared land for crops and grazing animals. Centuries of degradation from soil erosion and over-harvesting transformed huge areas of forest into rangelands dotted by shrubs and bushes. By the late 17th century, less than 10 percent of England remained forested (Morin et al 1996). The United States followed a similar pattern, with cropland expanding in line with population growth well into the 20th century (See Figure 4).

Figure 4

These sustained and often steep declines in forest cover were followed by a period of stabilization and then a gradual increase in forest size. Biologists and conservationists accurately point out that the new forests differ from the ancient ecosystems they replace, even though in some respects—from economic value to protection of soils and watersheds—the new secondary forests play similar roles to the original primary ones. In England, the switch to coal as the Industrial Revolution's fuel of choice greatly reduced the demand for wood, though by that time most of the country's forest cover had already been cleared. In the United States, improvements in agricultural technology enabled farmers to grow more food on less land, reducing the need for additional forest clearing.

The transition can also relate to the kinds of forests being used. Over time, Europe and North America have shifted from cutting down their old-growth forests to supplying more and more of their wood needs from plantations, while reserving the remaining natural forests for conservation. The traditional "cut-and-run" or "mining" approach to forests has begun to shift to an emphasis on sustainability and on ecosystem services, not just commodities. These kinds of qualitative changes in forest management can be critical to the success of the transition in ecological terms.

The forest transition occurred at different times and to differing degrees in England and the United States, but they shared common factors: dramatic slowing of once-rapid population growth, revolutions in agricultural technology, and falling demand for forest products, notably woodfuel. Today's developing countries are experiencing the pattern of rising populations and shrinking forests characteristic of the early phase of the forest transition.

However, the populations of these countries at the end of the 20th century are much larger than those of Europe and North America when those transitions occurred decades ago. It is still early to be confident that developing countries will be able to complete this transition while escaping permanent ecosystem damage at the local and possibly global levels. Ongoing declines in fertility rates in these countries could hasten the transition, reducing the risk of ecological disruption and increasing the possibility that the forests of the tropics will some day begin to expand.

POPULATION CHANGE: A WORLD OF OPPORTUNITY

The global trend towards smaller families represents one of the most hopeful signs for the preservation of the world's remaining forests. Declining birthrates—the product of changing ideals about family size and improved access to family planning services—are slowing population growth faster than demographers expected only a few years ago. If governments take action today to make reproductive health care more widely available and to improve educational and economic opportunities for girls and women, world population may peak before the middle of the 21st century and then decrease modestly (See Figure 5). Such a trend would be among the most positive forces affecting the transition to truly sustainable development.

Figure 5

Although the United Nations has revised downward its projections of future population growth, an actual decline in world population is unlikely any time soon for several reasons. First, rather than being at the end of the historic rise in human numbers often referred to as the "population explosion," we are actually just past the halfway point to projected population stabilization. The global decline in fertility from roughly six to less than three births per woman still leaves fertility above the two-child replacement fertility level required for population to eventually reach relative stability in the absence of migration.

In addition, the high fertility levels of the recent past have produced the largest generation in history of women about to enter their childbearing years (Bongaarts 1998). Moreover, death rates overall remain at historic lows. As a result, births will exceed deaths for the foreseeable future even if couples have only two children, causing population to grow well into the next century. This phenomenon is the result of population momentum, the tendency of a population to continue past growth trends for some time after fertility changes occur, simply because today's reproducing generation is the product of fertility rates of several decades ago. The UN Population Fund estimates that raising the age at which mothers have their first child from 18 to 23 would reduce by over 40 percent the impact of population momentum on future population growth (UNFPA 1998).

Lower rates of population growth will improve the future per capita availability of forest resources at the national and global levels. The trend towards below-replacement fertility in many developed countries, where consumption levels are highest, could reduce the amount of industrial logging as the demand for wood declines. In developing regions, increases in girls' education and family planning services can hasten the transition from natural resource-based economies to those based on human capital. These types of social investments reduce pressure on natural resources not only by directly improving human welfare and productivity, but also by slowing population growth as women postpone and limit childbearing to pursue economic opportunities. Strengthening international support for these programs and policies can help transform the demographic bulge in developing countries into a demographic bonus that will greatly enhance the prospects of current and future generations.

By understanding that sound population policy is founded on social investments and human rights, we can consider how population and forestry policy can work together to stabilize or even increase the availability of trees and forests for each human being. With the emerging possibility that world population will peak before the middle of the next century, the future of the world's forests appears at least a bit brighter than before.

MESSAGES FOR POLICYMAKERS AND THE MEDIA

• The world's forests provide a wide array of economically important goods, such as housing materials, furniture and paper. Furthermore, the "ecosystem services" they perform—for free—sustain millions of plants and animal species, maintain air and water quality on which human life and health depend, help regulate climate, and counter global warming.
  
  
• The loss and degradation of forests is most severe in developing countries, where more than 95 percent of the world's annual population growth of about 78 million people occurs.
  
  
• In less than four decades, the forest-to-people-ratio—that is, the area of forest available to each person to supply the broad array of goods and services that forests provide—has fallen by more than 50 percent, from a global average of 1.2 hectares in 1960 to 0.6 hectares in 1995. More than 1.7 billion people live in 40 nations with a scarcity of forest resources.
  
  
• Different kinds of forests satisfy different needs. Plantations can produce large amounts of wood or paper, but they cannot substitute for natural forests in protecting biodiversity.
  
  
• Population-related pressure on forests is greatest in countries where the existing area of forest cover per capita is low. Increasing rural populations in developing countries rely heavily on forests for their daily subsistence needs in the form of fuel, fodder, timber, and farmland.
  
  
• Each American consumes 15 times as much industrial roundwood as the average person living in a developing country.
  
  
• Lasting solutions to the loss of the world's forests must address both population and consumption levels. The global trend towards smaller families represents one of the most hopeful signs for the preservation of the world's remaining forests.
  
  
• Lower rates of population growth will improve the future per capita availability of forest resources at the national and global levels.
  
  
• By understanding that sound population policy is founded on social investments and human rights, we can consider how population and forestry policy can work together to stabilize or even increase the availability of trees and forests for each human being.
  
  
• The United States made a commitment at the United Nations Population Conference in Cairo in 1994 to support international family planning efforts. The United States should re-establish a leadership role in family planning funding and set an example for both donor and recipient countries.

SOURCES

Bongaarts, John, "Demographic Consequences of Declining Fertility," Science (16 October 1998): 419-420.

Brooks, David, "Demand for Wood and Forest Products: Macroeconomic and Management Issues," in Proceedings of the XI World Forestry Congress (Antalys, Turkey: Food and Agriculture Organization of the United Nations, 1997).

Brown, Sandra, Estimating Biomass and Biomass Change of Tropical Forests: A Primer, FAO Forestry Paper 134 (Rome: Food and Agriculture Organization of the United Nations, 1997).

Brown, Katrina and David Pearce, ed., The Causes of Tropical Deforestation: The Economic and Statistical Analysis of Factors Giving Rise to the Loss of Tropical Forests (Vancouver, UBC Press, 1994).

Brunner, Jake, Kirk Talbott, and Chantal Elkin, Logging Burma's Frontier Forests: Resources and the Regime (Washington, DC: World Resources Institute, 1998).

Food and Agriculture Organization of the United Nations, FAOSTAT Statistics Database on CD-ROM (Rome: Food and Agriculture Organization, 1998).

Food and Agriculture Organization of the United Nations, State of the World's Forests, 1997 (Rome: Food and Agriculture Organization, 1997).

Mather, Alexander, "The Forest Transition," Area 24, no. 4 (1992): 367-379.

Mather, Alexander, J. Fairbairn, and C. L. Needle, "The Human Drivers of Global Land Cover Change: The Case of Forests," Hydrological Processes 12, no. 13-14 (1998).

May, Robert M, "How many species?" Philosophical Transactions of the Royal Society of London, Series B, 330 (1990): 293-204.

Morin, G.-A. et al, Long-Term Historical Changes in the Forest Resource, Geneva Timber and Forest Study Papers, no. 10 (Geneva: United Nations Economic Commission for Europe, 1996).

Radka, Mark, Policy and Institutional Aspects of the Sustainable Paper Cycle: An Asian Perspective (United Nations Environment Programme, Regional Office for Asia and the Pacific, 1994).

Saxena, Ashok, Jagdish Nautiyal, and David Foot, "Understanding the Role of Population in Deforestation," Journal of Sustainable Forestry 7, no. 1-2 (1998): 57-107.

Solberg, Birger, ed., "Long-Term Trends and Prospects," in World Supply and Demand for Wood and Implications for Sustainable Forest Management, European Forest Institute Research Report 6 (Joensuu, Finland: European Forest Institute, 1996).

United Nations Population Fund (UNFPA), The State of World Population 1998: The New Generations (New York: The United Nations, 1998).

ADDITIONAL SUGGESTED READING

• Costanza, Robert et al., "The Value of the World's Ecosystem Services and Natural Capital," Nature, May 15, 1997, 253-260.
  
  
• Vandermeer, John and Ivette Perfecto, Breakfast of Biodiversity: The Truth About Rain Forest Destruction. (Food First Books, 1995).
  
  
• Westoby, Jack, Introduction to World Forestry: People and Their Trees. (Blackwell Publishers, 1989).

February, 2000

This report may not be reprinted or posted to electronic networks without permission and acknowledgement.