Christiane Runyan and Jeff Stehm
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Environmental Science. Please check back later for the full article.
Eight thousand years ago, forests covered an estimated 47% of Earth’s land surface. In 2015, forests covered roughly 30% of the Earth’s land surface, a cumulative loss over the last 8,000 years of approximately 2.2 billion hectares (ha). Between 1990 and 2015, forest losses occurred at the rate of about 0.13% annually, but this rate appears to be slowing. These losses mostly occur in tropical forests (58%), followed by boreal (27%) and temperate forests (8%). Deforestation is driven by a number of direct and indirect factors and processes that vary across regions and interact in complex ways. The primary driver of deforestation is agricultural expansion (both commercial and subsistence), followed by mining, infrastructure extension, and urban expansion. Indirectly, population and economic growth increase the demand for agricultural and timber products. Global food demand will increase 70% by 2050, requiring a net increase of 70 million ha of arable land under cultivation, with approximately 80% of this expansion occurring in the tropics. Deforestation is affected by other indirect 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. Environmentally, forests provide an expansive range of 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 indirectly, by taking up atmospheric CO2 during photosynthesis), biogeochemical benefits (e.g., enhancing nutrient availability and reducing nutrient losses), and by supporting greater biodiversity as well as ecosystem stability and resiliency, to name a few. The loss of forest vegetation may negatively affect important ecosystem processes and services, and may induce bistable ecosystem dynamics. The existence of bistable ecosystem dynamics in some forest ecosystems suggests that these forests are prone to abrupt and irreversible shifts to a stable and often degraded state with no trees. In addition to environmental impacts, the long-term loss of forest resources negatively affects societies. About 8% (450 million) of the world’s population live in forest ecosystems, with an estimated 350 million people entirely dependent on forest ecosystems for their livelihoods. The forest sector, in 2011, contributed an estimated total amount of USD 600 billion to global GDP, or about 0.9% of global GDP. Understanding how to best manage forest resources to preserve their unique qualities is a challenge that will require an integrated and concentrated effort from scientists and policymakers alike. In particular, improving forest management will require being able to more accurately measure and monitor forest resources, identifying the trade-offs between competing objectives, valuing forest goods and services, and equitably balancing costs and benefits. On the policy front, approaches to strengthen land tenure and property rights, reduce corruption, improve the capacity of public agencies, and develop more inclusive governance arrangements are needed. Underlying these management and policy goals is the need to better understand the environmental processes occurring in forests—to improve their management, minimize adverse impacts, and strengthen our models of these systems, because the long-term loss of forest resources affects not only the functioning of ecosystems but also the societies whose health and livelihoods depend upon them.
Brent M. Haddad
Watersheds are physical regions from which all arriving water flows to a single exit point. The shared hydrology means that other biophysical systems are linked, typically with upper-gradient regions influencing lower-gradient ones. This situation frames the challenge of managing economic and other uses of watersheds both in terms of individual activities and their influence on other connected processes and activities. Economics provides concepts and methods that help managers with decision making in the complex physical, biological, and institutional environment of a watershed. Among the important concepts and methods that help characterize watershed processes are externalities, impacts of economic activity that fall upon individuals not party to the activity, and third parties, individuals impacted without consent. Public goods and common pool resources describe categories of things or processes that by their nature are not amenable to regular market transactions. Their regulation requires special consideration and alternative approaches to markets. Benefit-cost analysis and valuation are related methods that provide a means to compare alternative uses of the same system. Each is based on the normative argument that the best use provides the greatest net benefits to society. And intergenerational equity is a value orientation that argues for preservation of watershed processes for the benefit of future generations. The need for effective watershed management methods pushed 20th-century economists to adapt their discipline to the complexity of watersheds, from which emerged subdisciplines of natural resource economics, environmental economics, and ecological economics. The field is still evolving with a growing interest in data gathering through land-based low-cost data collection systems and remote sensing, and in emerging data analysis techniques to improve management decisions.
Boreal countries are rich in forest resources, and for their area, they produce a disproportionally large share of the lumber, pulp, and paper bound for the global market. These countries have long-standing strong traditions in forestry education and institutions, as well as in timber-oriented forest management. However, global change, together with evolving societal values and demands, are challenging traditional forest management approaches. In particular, plantation-type management, where wood is harvested with short cutting cycles relative to the natural time span of stand development, has been criticized. Such management practices create landscapes composed of mosaics of young, even-aged, and structurally homogeneous stands, with scarcity of old trees and deadwood. In contrast, natural forest landscapes are characterized by the presence of old large trees, uneven-aged stand structures, abundant deadwood, and high overall structural diversity. The differences between managed and unmanaged forests result from the fundamental differences in the disturbance regimes of managed versus unmanaged forests. Declines in managed forest biodiversity and structural complexity, combined with rapidly changing climatic conditions, pose a risk to forest health, and hence, to the long-term maintenance of biodiversity and provisioning of important ecosystem goods and services. The application of ecosystem management in boreal forestry calls for a transition from plantation-type forestry toward more diversified management inspired by natural forest structure and dynamics.
Scott M. Moore
It has long been accepted that non-renewable natural resources like oil and gas are often the subject of conflict between both nation-states and social groups. But since the end of the Cold War, the idea that renewable resources like water and timber might also be a cause of conflict has steadily gained credence. This is particularly true in the case of water: in the early 1990s, a senior World Bank official famously predicted that “the wars of the next century will be fought over water,” while two years ago Indian strategist Brahma Chellaney made a splash in North America by claiming that water would be “Asia’s New Battleground.” But it has not quite turned out that way. The world has, so far, avoided inter-state conflict over water in the 21st century, but it has witnessed many localized conflicts, some involving considerable violence. As population growth, economic development, and climate change place growing strains on the world’s fresh water supplies, the relationship between resource scarcity, institutions, and conflict has become a topic of vocal debate among social and environmental scientists.
The idea that water scarcity leads to conflict is rooted in three common assertions. The first of these arguments is that, around the world, once-plentiful renewable resources like fresh water, timber, and even soils are under increasing pressure, and are therefore likely to stoke conflict among increasing numbers of people who seek to utilize dwindling supplies. A second, and often corollary, argument holds that water’s unique value to human life and well-being—namely that there are no substitutes for water, as there are for most other critical natural resources—makes it uniquely conductive to conflict. Finally, a third presumption behind the water wars hypothesis stems from the fact that many water bodies, and nearly all large river basins, are shared between multiple countries. When an upstream country can harm its downstream neighbor by diverting or controlling flows of water, the argument goes, conflict is likely to ensue.
But each of these assertions depends on making assumptions about how people react to water scarcity, the means they have at their disposal to adapt to it, and the circumstances under which they are apt to cooperate rather than to engage in conflict. Untangling these complex relationships promises a more refined understanding of whether and how water scarcity might lead to conflict in the 21st century—and how cooperation can be encouraged instead.
James B. London
Coastal zone management (CZM) has evolved since the enactment of the U.S. Coastal Zone Management Act of 1972, which was the first comprehensive program of its type. The newer iteration of Integrated Coastal Zone Management (ICZM), as applied to the European Union (2000, 2002), establishes priorities and a comprehensive strategy framework. While coastal management was established in large part to address issues of both development and resource protection in the coastal zone, conditions have changed. Accelerated rates of sea level rise (SLR) as well as continued rapid development along the coasts have increased vulnerability. The article examines changing conditions over time and the role of CZM and ICZM in addressing increased climate related vulnerabilities along the coast.
The article argues that effective adaptation strategies will require a sound information base and an institutional framework that appropriately addresses the risk of development in the coastal zone. The information base has improved through recent advances in technology and geospatial data quality. Critical for decision-makers will be sound information to identify vulnerabilities, formulate options, and assess the viability of a set of adaptation alternatives. The institutional framework must include the political will to act decisively and send the right signals to encourage responsible development patterns. At the same time, as communities are likely to bear higher costs for adaptation, it is important that they are given appropriate tools to effectively weigh alternatives, including the cost avoidance associated with corrective action. Adaptation strategies must be pro-active and anticipatory. Failure to act strategically will be fiscally irresponsible.