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The Forest Transition  

Thomas Rudel

Forest transitions take place when trends over time in forest cover shift from deforestation to reforestation. These transitions are of immense interest to researchers because the shift from deforestation to reforestation brings with it a range of environmental benefits. The most important of these would be an increased volume of sequestered carbon, which if large enough would slow climate change. This anticipated atmospheric effect makes the circumstances surrounding forest transitions of immediate interest to policymakers in the climate change era. This encyclopedia entry outlines these circumstances. It begins by describing the socio-ecological foundations of the first forest transitions in western Europe. Then it discusses the evolution of the idea of a forest transition, from its introduction in 1990 to its latest iteration in 2019. This discussion describes the proliferation of different paths through the forest transition. The focus then shifts to a discussion of the primary driver of the 20th-century forest transitions, economic development, in its urbanizing, industrializing, and globalizing forms. The ecological dimension of the forest transition becomes the next focus of the discussion. It describes the worldwide redistribution of forests toward more upland settings. Climate change since 2000, with its more extreme ecological events in the form of storms and droughts, has obscured some ongoing forest transitions. The final segment of this entry focuses on the role of the state in forest transitions. States have become more proactive in managing forest transitions. This tendency became more marked after 2010 as governments have searched for ways to reduce carbon emissions or to offset emissions through more carbon sequestration. The forest transitions by promoting forest expansion would contribute additional carbon offsets to a nation’s carbon budget. For this reason, the era of climate change could also see an expansion in the number of promoted forest transitions.


Economics of Reforestation and Afforestation  

Daowei Zhang

Reforestation is the natural or intentional restocking of existing forests and woodlands that have been harvested or depleted, and afforestation is the establishing of a forest in an area where there were no trees. For economic and practical purposes, reforestation and afforestation have similar goals and processes and thus can be treated as identical activities. Although reforestation and afforestation have a long history, large-scale reforestation and afforestation activities started with industrialization, which caused scarcity in timber and forest-based ecosystem services. In a unified economic model of reforestation and afforestation, factors influencing investments in reforestation and in afforestation on private and public lands include timber prices, unit reforestation cost, interest rate, the responsiveness of tree growth to silviculture, and the value of nontimber benefits, such as ecosystem services. Market and public policies may facilitate, enhance, or hinder reforestation and afforestation activities, and nontimber benefits are an increasingly important motive for reforestation and, especially, afforestation efforts around the world.


Urban Development and Environmental Degradation  

Wayne C. Zipperer, Robert Northrop, and Michael Andreu

At the beginning of the 21st century more than 50% of the world’s population lived in cities. By 2050, this percentage will exceed 60%, with the majority of growth occurring in Asia and Africa. As of 2020 there are 31 megacities, cities whose population exceeds 10 million, and 987 smaller cities whose populations are greater than 500 thousand but less than 5 million in the world. By 2030 there will be more than 41 megacities and 1290 smaller cities. However, not all cities are growing. In fact, shrinking cities, those whose populations are declining, occur throughout the world. Factors contributing to population decline include changes in the economy, low fertility rates, and catastrophic events. Population growth places extraordinary demand for natural resources and exceptional stress on natural systems. For example, over 13 million hectares of forest land are converted to agriculture, urban land use, and industrial forestry annually. This deforestation significantly affects both hydrologic systems and territorial habitats. Hydrologically, urbanization creates a condition called urban stream syndrome. The increase in storm runoff, caused by urbanization through the addition of impervious surfaces, alters stream flow, morphology, temperature, and water quantity and quality. In addition, leaky sewer lines and septic systems as well as the lack of sanitation systems contribute significant amounts of nutrients and organic contaminants such as pharmaceuticals, caffeine, and detergents. Ecologically, these stressors and contaminants significantly affect aquatic flora and fauna. Habitat loss is the greatest threat to biodiversity. Urbanization not only destroys and fragments habitats but also alters the environment itself. For example, deforestation and fragmentation of forest lands lead to the degradation and loss of forest interior habitat as well as creating forest edge habitat. These changes shift species composition and abundance from urban avoiders to urban dwellers. In addition, roads and other urban features isolate populations causing local extinctions, limit dispersal among populations, increase mortality rates, and aid in the movement of invasive species. Cities often have higher ambient temperatures than rural areas, a phenomenon called the urban heat island effect. The urban heat island effect alters precipitation patterns, increases ozone production (especially during the summer), modifies biogeochemical processes, and causes stresses on humans and native species. The negative effect of the expansion and urbanization itself can be minimized through proper planning and design. Planning with nature is not new but it has only recently been recognized that human survival is predicated on coexisting with biodiversity and native communities. How and if cities apply recommendations for sustainability depends entirely on the people themselves.


Deforestation: Drivers, Implications, and Policy Responses  

Christiane W. Runyan and Jeff Stehm

Over the last 8,000 years, cumulative forest loss amounted to approximately 2.2 billion hectares, reducing forest cover from about 47% of Earth’s land surface to roughly 30% in 2015. These losses mostly occurred in tropical forests (58%), followed by boreal (27%) and temperate forests (8%). The rate of loss has slowed from 7.3 Mha/year between 1990–2000 to 3.3 Mha/year between 2010–2015. Globally since the 1980s, the net loss in the tropics has been outweighed by a net gain in the subtropical, temperate, and boreal climate zones. Deforestation is driven by a number of complex direct and indirect factors. Agricultural expansion (both commercial and subsistence) is the primary driver, followed by mining, infrastructure extension, and urban expansion. In turn, population and economic growth drive the demand for agricultural, mining, and timber products as well as supporting infrastructure. Population growth and changing consumer preferences, for instance, will increase global food demand 50% by 2050, possibly requiring a net increase of approximately 70 million ha of arable land under cultivation. This increase is unlikely to be offset entirely by agricultural intensification due to limits on yield increases and land quality. Deforestation is also affected by other factors such as land tenure uncertainties, poor governance, low capacity of public forestry agencies, and inadequate planning and monitoring. Forest loss has a number of environmental, economic, and social implications. Forests provide an expansive range of environmental benefits across local, regional, and global scales, including: hydrological benefits (e.g., regulating water supply and river discharge), climate benefits (e.g., precipitation recycling, regulating local and global temperature, and carbon sequestration), biogeochemical benefits (e.g., enhancing nutrient availability and reducing nutrient losses), biodiversity benefits, and the support of ecosystem stability and resiliency. The long-term loss of forest resources also negatively affects societies and economies. The forest sector in 2011 contributed roughly 0.9% of global GDP or USD 600 billion. About 850 million people globally live in forest ecosystems, with an estimated 350 million people entirely dependent on forest ecosystems for their livelihoods. Understanding how to best manage remaining forest resources in order to preserve their unique qualities will be a challenge that requires an integrated set of policy responses. Developing and implementing effective policies will require a better understanding of the socio-ecological dynamics of forests, a more accurate and timely ability to measure and monitor forest resources, sound methodologies to assess the effectiveness of policies, and more efficacious methodologies for valuing trade-offs between competing objectives.


Deforestation of the Brazilian Amazon  

Phillip Fearnside

Deforestation in Brazilian Amazonia destroys environmental services that are important for the whole world, and especially for Brazil itself. These services include maintaining biodiversity, avoiding global warming, and recycling water that provides rainfall to Amazonia, to other parts of Brazil, such as São Paulo, and to neighboring countries, such as Argentina. The forest also maintains the human populations and cultures that depend on it. Deforestation rates have gone up and down over the years with major economic cycles. A peak of 27,772 km2/year was reached in 2004, followed by a major decline to 4571 km2/year in 2012, after which the rate trended upward, reaching 7989 km2/year in 2016 (equivalent to about 1.5 hectares per minute). Most (70%) of the decline occurred by 2007, and the slowing in this period is almost entirely explained by declining prices of export commodities such as soy and beef. Government repression measures explain the continued decline from 2008 to 2012, but an important part of the effect of the repression program hinges on a fragile base: a 2008 decision that makes the absence of pending fines a prerequisite for obtaining credit for agriculture and ranching. This could be reversed at the stroke of a pen, and this is a priority for the powerful “ruralist” voting bloc in the National Congress. Massive plans for highways, dams, and other infrastructure in Amazonia, if carried out, will add to forces in the direction of increased deforestation. Deforestation occurs for a wide variety of reasons that vary in different historical periods, in different locations, and in different phases of the process at any given location. Economic cycles, such as recessions and the ups and downs of commodity markets, are one influence. The traditional economic logic, where people deforest to make a profit by producing products from agriculture and ranching, is important but only a part of the story. Ulterior motives also drive deforestation. Land speculation is critical in many circumstances, where the increase in land values (bid up, for example, as a safe haven to protect money from hyperinflation) can yield much higher returns than anything produced by the land. Even without the hyperinflation that came under control in 1994, highway projects can yield speculative fortunes to those who are lucky or shrewd enough to have holdings along the highway route. The practical way to secure land holdings is to deforest for cattle pasture. This is also critical to obtaining and defending legal title to the land. In the past, it has also been the key to large ranches gaining generous fiscal incentives from the government. Money laundering also makes deforestation attractive, allowing funds from drug trafficking, tax evasion, and corruption to be converted to “legal” money. Deforestation receives impulses from logging, mining, and, especially, road construction. Soybeans and cattle ranching are the main replacements for forest, and recently expanded export markets are giving strength to these drivers. Population growth and household dynamics are important for areas dominated by small farmers. Extreme degradation, where tree mortality from logging and successive droughts and forest fires replace forest with open nonforest vegetation, is increasing as a kind of deforestation, and is likely to increase much more in the future. Controlling deforestation requires addressing its multiple causes. Repression through fines and other command-and-control measures is essential to avoid a presumption of impunity, but these controls must be part of a broader program that addresses underlying causes. The many forms of government subsidies for deforestation must be removed or redirected, and the various ulterior motives must be combated. Industry agreements restricting commodity purchases from properties with illegal deforestation (or from areas cleared after a specified cutoff) have a place in efforts to contain forest loss, despite some problems. A “soy moratorium” has been in effect since 2006, and a “cattle agreement” since 2009. Creation and defense of protected areas is an important part of deforestation control, including both indigenous lands and a variety of kinds of “conservation units.” Containing infrastructure projects is essential if deforestation is to be held in check: once roads are built, much of what happens is outside the government’s control. The notion that the 2005–2012 deforestation slowdown means that the process is under control and that infrastructure projects can be built at will is extremely dangerous. One must also abandon myths that divert efforts to contain deforestation; these include “sustainable logging” and the use of “green” funds for expensive programs to reforest degraded lands rather than retain areas of remaining natural forests. Finally, one must provide alternatives to support the rural population of small farmers. Large investors, on the other hand, can fend for themselves. Tapping the value of the environmental services of the forest has been proposed as an alternative basis for sustaining both the rural population and the forest. Despite some progress, a variety of challenges remain. One thing is clear: most of Brazil’s Amazonian deforestation is not “development.” Trading the forest for a vast expanse of extensive cattle pasture does little to secure the well-being of the region’s rural population, is not sustainable, and sacrifices Amazonia’s most valuable resources.


Environmental Impacts of Tropical Soybean and Palm Oil Crops  

Kimberly M. Carlson and Rachael D. Garrett

Oil crops play a critical role in global food and energy systems. Since these crops have high oil content, they provide cooking oils for human consumption, biofuels for energy, feed for animals, and ingredients in beauty products and industrial processes. In 2014, oil crops occupied about 20% of crop harvested area worldwide. While small-scale oil crop production for subsistence or local consumption continues in certain regions, global demand for these versatile crops has led to substantial expansion of oil crop agriculture destined for export or urban markets. This expansion and subsequent cultivation has diverse effects on the environment, including loss of forests, savannas, and grasslands, greenhouse gas emissions, regional climate change, biodiversity decline, fire, and altered water quality and hydrology. Oil palm in Southeast Asia and soybean in South America have been identified as major proximate causes of tropical deforestation and environmental degradation. Stringent conservation policies and yield increases are thought to be critical to reducing rates of soybean and oil palm expansion into natural ecosystems. However, the higher profits that often accompany greater yields may encourage further expansion, while policies that restrict oil crop expansion in one region may generate secondary “spillover” effects on other crops and regions. Due to these complex feedbacks, ensuring a sustainable supply of oil crop products to meet global demand remains a major challenge for agricultural companies, farmers, governments, and civil society.


The Economics of Tropical Rainforest Preservation  

Carlos Eduardo Frickmann Young

Tropical forests are among the most biodiverse areas on Earth. They contribute to ecosystem functions, including regulating water flow and maintaining one of the most important carbon sinks on the planet, and provide resources for important economic activities, such as timber and nontimber products and fish and other food. Rainforests are not empty of human population and are sites of ethnically and culturally diverse cultures that are responsible for many human languages and dialects. They also provide resources for important economic activities, such as timber and nontimber products. However, tropical deforestation caused by the expansion of agricultural activities and unsustainable logging continues at very high levels. The causes of forest loss vary by region. Livestock is the main driver in the Amazon, but commercial plantations (soybeans, sugar cane, and other tradable crops) also have an impact on deforestation, in many cases associated with violent conflicts over land tenure. In Southeast Asia, logging motivated by the tropical timber trade plays an important role, although palm oil plantations are an increasing cause of deforestation. In Africa, large-scale agricultural and industrial activities are less important, and the most critical factor is the expansion of subsistence and small-scale agriculture. However, trade-oriented activities, such as cocoa and coffee plantations in West Africa and logging in Central Africa, are becoming increasingly important. Public policies have a strong influence on these changes in land use, from traditional community-based livelihood practices to for-profit livestock, cultivation, and timber extraction. Investments in infrastructure, tax and credit incentives, and institutional structures to stimulate migration and deforestation represent economic incentives that lead to deforestation. Poor governance and a lack of resources and political will to protect the traditional rights of the population and environmental resources are another cause of the continuous reduction of tropical forests. Consequently, deforestation prevents the expansion of economic activities that could be established without threats to the remnants of native forest. There are also negative social consequences for the local population, which suffers from the degradation of the natural resources on which their production is based, and is hampered by air pollution caused by forest fires. In some situations, a vicious cycle is created between poverty and deforestation, since the expansion of the agricultural frontier reduces the forest areas where traditional communities once operated, but without generating job opportunities. New approaches are required to reverse this paradigm and to lay the foundation for a sustainable economy based on the provision of ecosystem services provided by tropical forests. These include (a) better governance and public management capacity, (b) incentives for economic activities compatible with the preservation of the tropical forest, and (c) large-scale adoption of economic instruments to support biodiversity and ecosystem services. Public policies are necessary to correct market failures and incorporate the values of ecosystem services in the land use decision process. In addition to penalties for predatory actions, incentives are needed for activities that support forest preservation, so the forest is worth retaining rather than clearing. Improving governance capacity, combining advanced science and technology with traditional knowledge, and improving the management of existing activities can also help to ensure sustainable development in tropical forest regions.


Environmental Degradation, Tropical Diseases, and Economic Development  

John Luke Gallup

It’s complicated. Tropical diseases have unusually intricate life cycles because most of them involve not only a human host and a pathogen, but also a vector host. The diseases are predominantly tropical due to their sensitivity to local ecology, usually due to the vector organism. The differences between the tropical diseases mean that they respond to environmental degradation in various ways that depend on local conditions. Urbanization and water pollution tend to limit malaria, but deforestation and dams can exacerbate malaria and schistosomiasis. Global climate change, the largest environmental change, will likely extend the range of tropical climate conditions to higher elevations and near the limits of the tropics, spreading some diseases, but will make other areas too dry or hot for the vectors. Nonetheless, the geographical range of tropical diseases will be primarily determined by public health efforts more than climate. Early predictions that malaria will spread widely because of climate change were flawed, and control efforts will probably cause it to diminish further. The impact of human disease on economic development is hard to pin down with confidence. It may be substantial, or it may be misattributed to other influences. A mechanism by which tropical disease may have large development consequences is its deleterious effects on the cognitive development of infants, which makes them less productive throughout their lives.


Economic Issues Related to Asian Deforestation  

Stefanie Onder, James T. Erbaugh, and Georgia Christina Kosmidou-Bradley

The loss of Asian forests represents one of the most significant changes in contemporary land cover. Between 2000 and 2020 alone, an area twice the size of Malaysia has lost its tree cover as measured by Earth observation data. These trends have significant repercussions for greenhouse gas emissions, carbon storage, the conservation of biodiversity, and the wellbeing of Indigenous Peoples and local communities (IPLCs), making Asian deforestation a phenomenon of global concern. There are many immediate factors that drive deforestation across Asia, but the conversion to commodity agriculture is the leading cause. Most notably, the expansion of oil palm and rubber plantations by both multinational corporations and smallholders has led to dramatic conversion of forests. The production of timber as well as pulp and paper has further contributed to significant deforestation, with the evolution of each sector often driven by government policies, such as logging bans. However, it is the underlying drivers (i.e., distal and proximate causes) that determine where and when commodity production displaces forest cover. They are particularly challenging to tackle in a globalized world, where consumption patterns driven by local population and income growth lead to environmental and social change in distant producer countries, including in Asia. Certification programs and legality requirements have been put in place to address these externalities with varying success. Deforestation in Asia is also facilitated by weak governance and regulatory frameworks, where forest rights are often unclear, and financial, technological, and human resources for forest monitoring are limited. Several contemporary forest governance strategies seek to promote sustainable management of Asian forests. Financial mechanisms such as reducing emissions from deforestation and forest degradation (REDD+) and payments for ecosystem services (PES) schemes seek to provide economic incentives for forest conservation. Pledges and activities to remove deforestation from commodity supply chains seek to respond to consumer demand, promote corporate environmental and social responsibility, and reduce the extent to which commodity supply chains contribute to Asian deforestation. And multiple state-led initiatives across Asia to empower IPLCs aim to align forest management objectives between national governments, subnational administrations, and local people. Assessing the impact of interventions related to financial mechanisms, corporate responsibility, and local forest governance will be critical to shaping the future of Asian forest cover change.


An Image Reconnaissance: Agricultural Patterns and Related Environmental Impacts Viewed From Space  

Richard W. Hazlett and Joshua Peck

Satellite reconnaissance of the Earth’s surface provides critical information about the state of human interaction with the natural environment. The strongest impact is agricultural, reflecting land-use approaches to food production extending back to the dawn of civilization. To variable degrees, depending upon location, regional field patterns result from traditional farming practices, surveying methods, regional histories, policies, political agendas, environmental circumstances, and economic welfare. Satellite imaging in photographic true or false color is an important means of evaluating the nature and implications of agricultural practices and their impacts on the surrounding world. Important platforms with publicly accessible links to satellite image sets include those of the European Space Agency, U.S. National Aeronautics and Space Administration, the Centre D’etudes Spatiales, Airbus, and various other governmental programs. Reprocessing of data worldwide in scope by commercial concerns including Digital Globe, Terrametrics, and GoogleEarth in the 21st century enable ready examination of most of the Earth’s surface in great detail and natural colors. The potential for monitoring and improving understanding of agriculture and its role in the Earth system is considerable thanks to these new ways of viewing the planet. Space reconnaissance starkly reveals the consequences of unique land surveys for the rapid development of agriculture and political control in wilderness areas, including the U.S. Public Land Survey and Tierras Bajas systems. Traditional approaches toward agriculture are clearly shown in ribbon farms, English enclosures and medieval field systems, and terracing in many parts of the world. Irrigation works, some thousands of years old, may be seen in floodplains and dryland areas, notably the Maghreb and the deep Sahara, where center-pivot fields have recently appeared in areas once considered too dry to cultivate. Approaches for controlling erosion, including buffer zones, shelter belts, strip and contour farming, can be easily identified. Also evident are features related to field erosion and soil alteration that have advanced to crisis stage, such as badland development and widespread salinization. Pollution related to farm runoff, and the piecemeal (if not rapid) loss of farmlands due to urbanization can be examined in ways favoring more comprehensive evaluation of human impacts on the planetary surface. Developments in space technologies and observational platforms will continue indefinitely, promising ever-increasing capacity to understand how humans relate to the environment.


Conservation in the Amazon: Evolution and Situation  

Marc Dourojeanni

In 1945 the Amazon biome was almost intact. Marks of ancient cultural developments in Andean and lowland Amazon had cicatrized and the impacts of rubber and more recent resources exploitation were reversible. Very few roads existed, and only on the Amazon’s periphery. However, from the 1950s, but especially in the 1960s, Brazil and some Andean countries launched ambitious road-building and colonization processes. Amazon occupation heavily intensified in the 1970s when forest losses began to raise worldwide concern. More roads continued to be built at a geometrically growing pace in every following decade, multiplying correlated deforestation and forest degradation. A no-return point was reached when interoceanic roads crossed the Brazilian-Andean border in the 2000s, exposing remaining safe havens for indigenous people and nature. It is commonly estimated that today no less than 18% of the forest has been substituted by agriculture and that over 60% of that remaining has been significantly degraded. Theories regarding the importance of biogeochemical cycles have been developed since the 1970s. The confirmation of the role of the Amazon as a carbon sink added some international pressure for its protection. But, in general, the many scientific discoveries regarding the Amazon have not helped to improve its conservation. Instead, a combination of new agricultural technologies, anthropocentric philosophies, and economic changes strongly promoted forest clearing. Since the 1980s and as of today Amazon conservation efforts have been increasingly diversified, covering five theoretically complementary strategies: (a) more, larger, and better-managed protected areas; (b) more and larger indigenous territories; (c) a series of “sustainable-use” options such as “community-based conservation,” sustainable forestry, and agroforestry; (d) financing of conservation through debt swaps and climate change’s related financial mechanisms; and (e) better legislation and monitoring. Only five small protected areas have existed in the Amazon since the early 1960s but, responding to the road-building boom of the 1970s, several larger patches aiming at conserving viable samples of biological diversity were set aside, principally in Brazil and Peru. Today around 22% of the Amazon is protected but almost half of such areas correspond to categories that allow human presence and resources exploitation, and there is no effective management. Another 28% or more pertains to indigenous people who may or may not conserve the forest. Both types of areas together cover over 45% of the Amazon. None of the strategies, either alone or in conjunction, have fully achieved their objectives, while development pressures and threats multiply as roads and deforestation continue relentlessly, with increasing funding by multilateral and national banks and due to the influence of transnational enterprises. The future is likely to see unprecedented agriculture expansion and corresponding intensification of deforestation and forest degradation even in protected areas and indigenous land. Additionally, the upper portion of the Amazon basin will be impacted by new, larger hydraulic works. Mining, formal as well as illegal, will increase and spread. Policymakers of Amazon countries still view the region as an area in which to expand conventional development while the South American population continues to be mostly indifferent to Amazon conservation.