61-80 of 328 Results

Article

The Cultivation and Environmental Impact of Mushrooms  

Shu Ting Chang and Solomon P. Wasser

The word mushroom may mean different things to different people in different countries. Specialist studies on the value of mushrooms and their products should have a clear definition of the term mushroom. In a broad sense, “Mushroom is a distinctive fruiting body of a macrofungus, which produce spores that can be either epigeous or hypogeous and large enough to be seen with the naked eye and to be picked by hand.” Thus, mushrooms need not be members of the group Basidiomycetes, as commonly associated, nor aerial, nor fleshy, nor edible. This definition is not perfect, but it has been accepted as a workable term to estimate the number of mushrooms on Earth (approximately 16,000 species according to the rules of International Code of Nomenclature). The most cultivated mushrooms are saprophytes and are heterotrophic for carbon compounds. Even though their cells have walls, they are devoid of chlorophyll and cannot perform photosynthesis. They are also devoid of vascular xylem and phloem. Furthermore, their cell walls contain chitin, which also occurs in the exoskeleton of insects and other arthropods. They absorb O2 and release CO2. In fact, they may be functionally more closely related to animal cells than plants. However, they are sufficiently distinct both from plants and animals and belong to a separate group in the Fungi Kingdom. They rise up from lignocellulosic wastes: yet, they become bountiful and nourishing. Mushrooms can greatly benefit environmental conditions. They biosynthesize their own food from agricultural crop residues, which, like solar energy, are readily available; otherwise, their byproducts and wastes would cause health hazards. The spent compost/substrate could be used to grow other species of mushrooms, as fodder for livestock, as a soil conditioner and fertilizer, and in environmental bioremediation. The cultivation of mushrooms dates back many centuries; Auricularia auricula-judae, Lentinula edodes, and Agaricus bisporus have, for example, been cultivated since 600 ad, 1100 ad, and 1650 ad, respectively. During the last three decades, there has been a dramatic increase in the interest, popularity, and production of mushrooms through farming worldwide. The cultivation methods can involve a relatively simple farming activity, as with Volvariella volvacea and Pleurotus pulmonarius var. stechangii (=P. sajor-caju), or a high-technology industry, as with Agaricus bisporus, Flammulina velutipes, and Hypsizygus marmoreus. In each case, however, continuous production of successful crops requires both practical experience and scientific knowledge. Mushrooms can be used as food, tonics, medicines, cosmeceuticals, and as natural biocontrol agents in plant protection with insecticidal, fungicidal, bactericidal, herbicidal, nematocidal, and antiphytoviral activities. The multidimensional nature of the global mushroom cultivation industry, its role in addressing critical issues faced by humankind, and its positive contributions are presented. Furthermore, mushrooms can serve as agents for promoting equitable economic growth in society. Since the lignocellulose wastes are available in every corner of the world, they can be properly used in the cultivation of mushrooms, and therefore could pilot a so-called white agricultural revolution in less developed countries and in the world at large. Mushrooms demonstrate a great impact on agriculture and the environment, and they have great potential for generating a great socio-economic impact in human welfare on local, national, and global levels.

Article

Environmental Footprints of Modernization Trends in Rice Production Systems of Southeast Asia  

Reiner Wassmann

Assessing the environmental footprints of modern agriculture requires a balanced approach that sets the obviously negative effects (e.g., incidents with excessive use of inputs) against benefits stemming from increased resource use efficiencies. In the case of rice production, the regular flooding of fields comprises a distinctive feature, as compared to other crops, which directly or indirectly affects diverse impacts on the environment. In the regional context of Southeast Asia, rice production is characterized by dynamic changes in terms of crop management practices, so that environmental footprints can only be assessed from time-dependent developments rather than from a static view. The key for the Green Revolution in rice was the introduction of high-yielding varieties in combination with a sufficient water and nutrient supply as well as pest management. More recently, mechanization has evolved as a major trend in modern rice production. Mechanization has diverse environmental impacts and may also be instrumental in tackling the most drastic pollution source from rice production, namely, open field burning of straw. As modernization of rice production is imperative for future food supplies, there is scope for developing sustainable and high-yielding rice production systems by capitalizing on the positive aspects of modernization from a local to a global scale.

Article

Cultivation and Impact of Wheat  

Peter Shewry

Wheat is the most widely grown food crop in the world and the dominant staple crop in temperate countries where it contributes between about 20% and 50% of the total energy intake. About 95% of the wheat grown is hexaploid bread wheat, with tetraploid durum wheat being grown in the hot dry Mediterranean climate and very small volumes of ancient species. About 80% of the dry weight of the mature grain is starchy endosperm. This is the major grain storage tissue, which is separated by milling to give white flour, the outer layers and germ together forming the bran. However, white flour and bran differ significantly in their compositions, with white flour being rich in starch (about 80% dry wt) and protein (about 10% dry wt) and the bran rich in fiber, minerals, vitamins, and phytochemicals. Most of the wheat consumed by humankind is in the form of bread, noodles, pasta, and other processed foods, and the quality for processing is determined by two major characteristics: the grain texture (hardness) and the viscoelastic properties conferred to dough by the gluten proteins. In addition to being a source of energy, wheat also contributes protein and a range of other essential and beneficial components, particularly dietary fiber. However, because most of these components are concentrated in the bran, it is important to increase the consumption of whole grain products or to improve the composition of white flour. Although there is concern among consumers about possible adverse effects of consuming wheat products on health, these are unlikely to affect more than a small proportion of the population, and wheat should form part of a healthy balanced diet for the vast majority.

Article

Cultivation, Improvement, and Environmental Impacts of Tea  

Mainaak Mukhopadhyay and Tapan Kumar Mondal

Tea, the globally admired, non-alcoholic, caffeine-containing beverage, is manufactured from the tender leaves of the tea [Camellia sinensis (L.)] plant. It is basically a woody, perennial crop with a lifespan of more than 100 years. Cultivated tea plants are natural hybrids of the three major taxa or species, China, Assam (Indian), or Cambod (southern) hybrids based on the morphological characters (principally leaf size). Planting materials are either seedlings (10–18 months old) developed from either hybrid, polyclonal, or biclonal seeds, or clonal cuttings developed from single-leaf nodal cuttings of elite genotypes. Plants are forced to remain in the vegetative stage as bushes by following cultural practices like centering, pruning, and plucking, and they are harvested generally from the second year onward at regular intervals of 7–10 days in the tropics and subtropics, with up to 60 years as the economic lifespan. Originally, the Chinese were the first to use tea as a medicinal beverage, around 2000 years ago, and today, around half of the world’s population drink tea. It is primarily consumed as black tea (fermented tea), although green tea (non-fermented) and oolong tea (semifermented) are also consumed in many countries. Tea is also used as vegetables such as “leppet tea” in Burma and “meing tea” in Thailand. Green tea has extraordinary antioxidant properties, and black tea plays a positive role in treating cardiovascular ailments. Tea in general has considerable therapeutic value and can cure many diseases. Global tea production (black, green, and instant) has increased significantly during the past few years. China, as the world’s largest tea producer, accounts for more than 38% of the total global production of made tea [i.e. ready to drink tea] annually, while production in India, the second-largest producer. India recorded total production of 1233.14 million kg made tea during 2015–2016, which is the highest ever production so far. Since it is an intensive monoculture, tea cultivation has environmental impacts. Application of weedicides, pesticides, and inorganic fertilizers creates environmental hazards. Meanwhile, insecticides often eliminate the fauna of a vast tract of land. Soil degradation is an additional concern because the incessant use of fertilizers and herbicides compound soil erosion. Apart from those issues, chemical runoff into bodies of water can also create problems. Finally, during tea manufacturing, fossil fuel is used to dry the processed leaves, which also increases environmental pollution.

Article

Dairy, Science, Society, and the Environment  

Christopher Lu

Dairy has intertwined with human society since the beginning of civilization. It evolves from art in ancient society to science in the modern world. Its roles in nutrition and health are underscored by the continuous increase in global consumption. Milk production increased by almost 50% in just the past quarter century alone. Population growth, income rise, nutritional awareness, and science and technology advancement contributed to a continuous trend of increased milk production and consumption globally. With a fourfold increase in milk production per cow since the 1940s, the contemporary dairy industry produces more milk with fewer cows, and consumes less feed and water per liter of milk produced. The dairy sector is diversified, as people from a wider geographical distribution are consuming milk, from cattle to species such as buffalo, goat, sheep, and camel. The dairy industry continues to experience structural changes that impact society, economy, and environment. Organic dairy emerged in the 1990s as consumers increasingly began viewing it as an appropriate way of both farming and rural living. Animal welfare, environmental preservation, product safety, and health benefit are important considerations in consuming and producing organic dairy products. Large dairy operations have encountered many environmental issues related to elevated greenhouse gas emissions. Dairy cattle are second only to beef cattle as the largest livestock contributors in methane emission. Disparity in greenhouse gas emissions per dairy animal among geographical regions can be attributed to production efficiency. Although a number of scientific advancements have implications in the inhibition of methanogenesis, improvements in production efficiency through feeding, nutrition, genetic selection, and management remain promising for the mitigation of greenhouse gas emissions from dairy animals. This article describes the trends in milk production and consumption, the debates over the role of milk in human nutrition, the global outlook of organic dairy, the abatement of greenhouse gas emissions from dairy animals, as well as scientific and technological developments in nutrition, genetics, reproduction, and management in the dairy sector.

Article

Data Infrastructures in Ecology: An Infrastructure Studies Perspective  

Florence Millerand and Karen S. Baker

The development of information infrastructures that make ecological research data available has increased in recent years, contributing to fundamental changes in ecological research. Science and Technology Studies (STS) and the subfield of Infrastructure Studies, which aims at informing infrastructures’ design, use, and maintenance from a social science point of view, provide conceptual tools for understanding data infrastructures in ecology. This perspective moves away from the language of engineering, with its discourse on physical structures and systems, to use a lexicon more “social” than “technical” to understand data infrastructures in their informational, sociological, and historical dimensions. It takes a holistic approach that addresses not only the needs of ecological research but also the diversity and dynamics of data, data work, and data management. STS research, having focused for some time on studying scientific practices, digital devices, and information systems, is expanding to investigate new kinds of data infrastructures and their interdependencies across the data landscape. In ecology, data sharing and data infrastructures create new responsibilities that require scientists to engage in opportunities to plan, experiment, learn, and reshape data arrangements. STS and Infrastructure Studies scholars are suggesting that ecologists as well as data specialists and social scientists would benefit from active partnerships to ensure the growth of data infrastructures that effectively support scientific investigative processes in the digital era.

Article

Decision-Making in a Water Crisis: Lessons From the Cape Town Drought for Urban Water Policy  

Johanna Brühl, Leonard le Roux, Martine Visser, and Gunnar Köhlin

The water crisis that gripped Cape Town over the 2016–2018 period gained global attention. For a brief period of time in early 2018, it looked as if the legislative capital of South Africa would become the first major city in the world to run out of water. The case of Cape Town has broad implications for how we think about water management in a rapidly urbanizing world. Cities in the global South, especially, where often under-capacitated urban utilities need to cope with rapid demographic changes, climate change, and numerous competing demands on their tight budgets, can learn from Cape Town’s experience. The case of Cape Town draws attention to the types of decisions policymakers and water utilities face in times of crisis. It illustrates how these decisions, while being unavoidable in the short term, are often sub-optimal in the long run. The Cape Town drought highlights the importance of infrastructure diversification, better groundwater management, and communication and information transparency to build trust with the public. It also shows what governance and institutional changes need to be made to ensure long-term water security and efficient water management. The implementation of all of these policies needs to address the increased variability of water supplies due to increasingly erratic rainfall and rapidly growing urban populations in many countries. This necessitates a long-term planning horizon.

Article

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.

Article

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.

Article

Deliberative Monetary Valuation  

Bartosz Bartkowski and Nele Lienhoop

While economic values of nonmarket ecosystem goods and services are in high demand to inform decision-making processes, economic valuation has also attracted significant criticism. Particularly, its implicit rationality assumptions and value monism gave rise to alternative approaches to economic nonmarket valuation. Deliberative monetary valuation (DMV) originated in the early 2000s and gained particular prominence after 2010, especially in the context of the United Kingdom National Ecosystem Assessment (UK NEA). It constitutes a major methodological development to overcome the limitations of conventional nonmarket valuation methods by incorporating deliberative group elements (information provision, discussion, time to reflect in a group setting) in the valuation process. DMV approaches range from those that focus on facilitating individual preference formation for complex and unfamiliar environmental changes and stay close to neoclassical economic theory to those that try to go beyond methodological individualism and monetary valuation to include a plurality of different values. The theoretical foundation of DMV comprises a mix of economic welfare theory, on the one hand, and various strands of deliberative democratic theory and discourse ethics, on the other. DMV formats are mostly inspired by deliberative institutions such as citizens’ juries and combine those with stated preference methods such as choice experiments. While the diversity of approaches within this field is large, it has been demonstrated that deliberation can lead to more well-informed and stable preferences as well as facilitate the inclusion of considerations going beyond self-interest. Future research challenges surrounding DMV include the exploration of intergroup power relations and group dynamics as well as the theoretical status and the validity of DMV results.

Article

Desalination Technology and Advancement  

P.S. Goh, A.F. Ismail, and N. Hilal

Water scarcity as an outcome of global population expansion, climate change, and industrialization calls for new and innovative technologies to provide sustainable solutions to address this alarming issue. Seawater and brackish water are abundantly available on earth for drinking water and industrial use, and desalination is a promising approach to resolving this global challenge. Recently, the considerable reduction in the cost of desalination has contributed to the growing capacity for global desalination. The desalination technologies that have been deployed worldwide for clean water production can be categorized into two main types: membrane-based and thermal-based. Technological advancement in this field has focused on the reduction of capital and operating cost, particularly the energy consumption of the systems. Seawater and brackish desalination technologies are promising solutions for water shortages.

Article

The Early Anthropogenic Hypothesis  

William Ruddiman

Throughout the 1900s, the warmth of the current interglaciation was viewed as completely natural in origin (prior to greenhouse-gas emissions during the industrial era). In the view of physical scientists, orbital variations had ended the previous glaciation and caused a warmer climate but had not yet brought it to an end. Most historians focused on urban and elite societies, with much less attention to how farmers were altering the land. Historical studies were also constrained by the fact that written records extended back a few hundred to at most 3,500 years. The first years of the new millennium saw a major challenge to the ruling paradigm. Evidence from deep ice drilling in Antarctica showed that the early stages of the three interglaciations prior to the current one were marked by decreases in concentrations of carbon dioxide (CO2) and methane (CH4) that must have been natural in origin. During the earliest part of the current (Holocene) interglaciation, gas concentrations initially showed similar decreases, but then rose during the last 7,000–5,000 years. These anomalous (“wrong-way”) trends are interpreted by many scientists as anthropogenic, with support from scattered evidence of deforestation (which increases atmospheric CO2) by the first farmers and early, irrigated rice agriculture (which emits CH4). During a subsequent interval of scientific give-and-take, several papers have criticized this new hypothesis. The most common objection has been that there were too few people living millennia ago to have had large effects on greenhouse gases and climate. Several land-use simulations estimate that CO2 emissions from pre-industrial forest clearance amounted to just a few parts per million (ppm), far less than the 40 ppm estimate in the early anthropogenic hypothesis. Other critics have suggested that, during the best orbital analog to the current interglaciation, about 400,000 years ago, interglacial warmth persisted for 26,000 years, compared to the 10,000-year duration of the current interglaciation (implying more warmth yet to come). A geochemical index of the isotopic composition of CO2 molecules indicates that terrestrial emissions of 12C-rich CO2 were very small prior to the industrial era. Subsequently, new evidence has once again favored the early anthropogenic hypothesis, albeit with some modifications. Examination of cores reaching deeper into Antarctic ice reconfirm that the upward gas trends in this interglaciation differ from the average downward trends in seven previous ones. Historical data from Europe and China show that early farmers used more land per capita and emitted much more carbon than suggested by the first land-use simulations. Examination of pollen trends in hundreds of European lakes and peat bogs has shown that most forests had been cut well before the industrial era. Mapping of the spread of irrigated rice by archaeobotanists indicates that emissions from rice paddies can explain much of the anomalous CH4 rise in pre-industrial time. The early anthropogenic hypothesis is now broadly supported by converging evidence from a range of disciplines.

Article

Early History of Animal Domestication in Southwest Asia  

Benjamin S. Arbuckle

The domestication of livestock animals has long been recognized as one of the most important and influential events in human prehistory and has been the subject of scholarly inquiry for centuries. Modern understandings of this important transition place it within the context of the origins of food production in the so-called Neolithic Revolution, where it is particularly well documented in southwest Asia. Here, a combination of archaeofaunal, isotopic, and DNA evidence suggests that sheep, goat, cattle, and pigs were first domesticated over a period of several millennia within sedentary communities practicing intensive cultivation beginning at the Pleistocene–Holocene transition. Resulting from more than a century of data collection, our understanding of the chronological and geographic features of the transition from hunting to herding indicate that the 9th millennium bce and the region of the northern Levant played crucial roles in livestock domestication. However, many questions remain concerning the nature of the earliest predomestic animal management strategies, the role of multiple regional traditions of animal management in the emergence of livestock, and the motivations behind the slow spread of integrated livestock husbandry systems, including all four domestic livestock species that become widespread throughout southwest Asia only at the end of the Neolithic period.

Article

Ecological Effects of Environmental Stressors  

Bill Freedman

Regimes of environmental stress are exceedingly complex. Particular stressors exist within continua of intensity of environmental factors. Those factors interact with each other, and their detrimental effects on organisms are manifest only at relatively high or low strengths of exposure—in fact, many of them are beneficial at intermediate levels of intensity. Although a diversity of environmental factors is manifest at any time and place, only one or a few of them tend to be dominant as stressors. It is useful to distinguish between stressors that occur as severe events (disturbances) and those that are chronic in their exposure, and to aggregate the kinds of stressors into categories (while noting some degree of overlap among them). Climatic stressors are associated with extremes of temperature, solar radiation, wind, moisture, and combinations of these factors. They act as stressors if their condition is either insufficient or excessive, in comparison with the needs and comfort zones of organisms or ecosystem processes. Chemical stressors involve environments in which the availability of certain substances is too low to satisfy biological needs, or high enough to cause toxicity or another physiological detriment to organisms or to higher-level attributes of ecosystems. Wildfire is a disturbance that involves the combustion of much of the biomass of an ecosystem, affecting organisms by heat, physical damage, and toxic substances. Physical stress is a disturbance in which an exposure to kinetic energy is intense enough to damage organisms and ecosystems (such as a volcanic blast, seismic sea wave, ice scouring, or anthropogenic explosion or trampling). Biological stressors are associated with interactions occurring among organisms. They may be directly caused by such trophic interactions as herbivory, predation, and parasitism. They may also indirectly affect the intensity of physical or chemical stressors, as when competition affects the availability of nutrients, moisture, or space. Extreme environments are characterized by severe regimes of stressors, which result in relatively impoverished ecosystem development. This may be a consequence of either natural or anthropogenic stressors. If a regime of environmental stress intensifies, the resulting responses include a degradation of the structure and function of affected ecosystems and of ecological integrity more generally. In contrast, a relaxation of environmental stress allows some degree of ecosystem recovery.

Article

Ecology in American Literature  

Hubert Zapf and Timo Müller

The ecological dimension of literature has found proper attention only in the late 20th century, with the rise of ecocriticism as a new direction of literary studies. Ecocriticism emerged from a revalorization of nature writing in the United States and initially understood itself as a countermovement to the linguistic turn in literary and cultural studies. Since the early 21st century, the scope of ecocritical studies has widened to include literary texts and genres across different periods and cultures. Against the background of the global environmental crisis, it has made a strong case for the contribution of literature, art, and the aesthetic to the critique of anthropocentric master narratives as well as to the imaginative exploration of sustainable alternatives to the historically deranged human–nature relationship. Ecocritical scholars have examined the ecological potential of texts in various periods and literary cultures that make up American literature. They have given particular attention to the Indigenous poetic and storytelling modes of Native Americans, the Romantic and transcendentalist movements of the mid-19th century, the aesthetic practices of modernism and postmodernism, the ethnic diversification of American literature since the late 20th century, and, most obviously, contemporary writing that explicitly defines itself as a critical and creative response to the Anthropocene. Thus, an ecological awareness in American literature emerged in different forms and stages that correspond to major periods, styles, and cultures of literary writing. While it is impossible to do justice to all relevant developments, the rich archive of ecological thought and perception in American literature can be productively brought into the transdisciplinary dialogue of the environmental sciences and humanities. The value of literary texts in relation to other forms of environmental knowledge lies not just in the topics they address but in distinctive aesthetic features, such as embodied multiperspectivity, empathetic imagination, reconnection of cultural to natural ecosystems, polysemic openness, and participatory inclusion of the reader in the transformative experience offered by the texts.

Article

Economic Causes and Consequences of Desertification  

Luca Salvati

Land degradation and desertification are composite processes that reflect how components of land capital have worsened over time, both quantitatively and qualitatively. Land degradation is intended as a truly socioeconomic issue because the idea and practice of use (and misuse) of land are socially constructed. In this perspective, soil productivity and land capacity, water consumption and landscape fragmentation, agriculture and sustainable development all reflect the vast ensemble of human-nature interactions. The intrinsic heterogeneity of land degradation processes at the global scale limits the development of mitigation actions. Comprehension of the socioeconomic processes underlying land degradation can benefit from a multidisciplinary approach that considers the intricate feedback between biophysical and economic dimensions. The mutual relationship between economic growth, social inequality, political action, and land degradation provides examples of the interplay among proximate causes and factors underlying desertification.

Article

Economic Development and Groundwater Sustainability  

Cecilia Tortajada and Francisco González-Gómez

An analysis is made of the relationship between economic development and water sustainability in Campo de Dalías, in southeastern Spain. What used to be a poor, deserted region based on traditional agriculture has become one of the most prosperous regions in Spain. Economic development has been based on highly productive greenhouse agriculture, but this has resulted in the overexploitation of the aquifer that supplies water to different users in the region. Contradictions are considered between economic development and water sustainability in the area, as well as the plans and policies that have been put in place to improve the status of the aquifer but that have had limited success so far.

Article

Economic Instruments to Control Greenhouse Gas Emissions: REDD+  

Rawshan Ara Begum

Deforestation causes up to 10% of global anthropogenic carbon emissions. Reducing emissions from deforestation and degradation and enhancing forest carbon stocks can contribute to controlling greenhouse gas (GHG) emissions and limit global warming and climate change. However, global warming cannot be limited without decreasing the use of fossil fuel or emission-intensive energy sources. The forestry sector could contribute 7%–25% of global emissions reduction by 2020. Apart from emissions reduction and sink (mitigation), forests also provide cobenefits such as ecosystem services (providing food, timber, and medicinal herbs); biodiversity conservation; poverty reduction; and water quality, soil protection, and climate regulation. In 2005, the UNFCCC introduced a cost-effective mitigation strategy to reduce emissions from deforestation (RED) in developing countries. The UN’s initiative to reduce emissions from deforestation and forest degradation (REDD+) aims to transform forest management in developing countries, where the majority of tropical forests are located, using finances from developed countries. REDD+ seeks to reward actors for maintaining or restoring forests, acting as an economic instrument by putting a monetary value on every tonne of CO2 that is prevented from entering the atmosphere. Implementation of REDD+ requires economic and policy instruments that can help to control GHG emissions by enhancing carbon sinks, reducing deforestation and forest degradation, and managing sustainable forests. Payment for environmental services offers opportunities for either cofinancing or economic valuation in regard to REDD+ implementation. The challenge is to identify the most appropriate and cost-effective instrument. REDD+ fulfills the current needs for economic instruments and incentives that can be implemented with existing land use and forestry policies to control global GHG emissions. However, REDD+ requires forest governance, law enforcement, clarification of land and resource rights, and forest monitoring to work in the long term. REDD+ payments can be made for results-based actions, and the UNFCCC has identified potential ways to pay for them, but challenges remain, such as clarifying financing or funding sources, distribution of funding and sharing of benefits or incentives, carbon rights, and so on. Different aspects pf the implementation, effectiveness, and scale of REDD+ and their interactions with economic, social, and environmental benefits are important for successful REDD+ implementation.

Article

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.

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Economics, Agriculture, and Famines  

Noel Russell

There are continuing developments in the analysis of hunger and famines, and the results of theoretical and empirical studies of hunger and food insecurity highlight cases where hunger intensifies sufficiently to be identified as famine. The varying ability of those affected to cope with the shocks and stresses imposed on them are central to the development of food insecurity and the emergence of famine conditions and to explaining the complex interrelationships between agriculture, famine, and economics. There are a number of approaches to understanding how famines develop. The Malthusian approach, which sees population growth as the primary source of hunger and famine, can be contrasted with the free market or Smithian approach, which regards freely operating markets as an essential prerequisite for ensuring that famine can be overcome. A major debate has centered on whether famines primarily emerge from a decline in the availability of food or are a result of failure by households to access sufficient food for consumption, seeking to distinguish between famine as a problem related to food production and availability and famine as a problem of declining income and food consumption among certain groups in the population. These declines arise from the interaction between food markets, labor markets and markets for livestock and other productive farm resources when poor people try to cope with reduced food consumption. Further revisions to famine analysis were introduced from the mid-1990s by authors who interpreted the emergence of famines not as a failure in markets and the economic system, but more as a failure in political accountability and humanitarian response. These approaches have the common characteristic that they seek to narrow the focus of investigation to one or a few key characteristics. Yet most of those involved in famine analysis or famine relief would stress the multi-faceted and broad-based nature of the perceived causes of famine and the mechanisms through which they emerge. In contrast to these approaches, the famine systems approach takes a broader view, exploring insights from systems theory to understand how famines develop and especially how this development might be halted, reversed, or prevented. Economists have contributed to and informed different perspectives on famine analysis while acknowledging key contributions from moral philosophy as well as from biological and physical sciences and from political and social sciences. Malthus, Smith, and John Stuart Mill contributed substantially to early thinking on famine causation and appropriate famine interventions. Increased emphasis on famine prevention and a focus on food production and productivity led to the unarguable success of the Green Revolution. An important shift in thinking in the 1980s was motivated by Amartya Sen’s work on food entitlements and on markets for food and agricultural resources. On the other hand, the famine systems approach considers famine as a process governed by complex relationships and seeks to integrate contributions from economists and other scientists while promoting a systems approach to famine analysis.