This article needs additional citations for verification .(April 2008) |
Sustainable yield is the amount of a resource that humans can harvest without over-harvesting or damaging a potentially renewable resource. [1]
In more formal terms, the sustainable yield of natural capital is the ecological yield that can be extracted without reducing the base of capital itself, i.e. the surplus required to maintain ecosystem services at the same or increasing level over time. [2] The term only refers to resources that are renewable in nature as extracting non-renewable resources will always diminish the natural capital. [3] The sustainable yield of a given resource will generally vary over time with the ecosystem's needs to maintain itself. For instance, a forest that has suffered from a natural disaster will require more of its own ecological yield to sustain itself and re-establish a mature forest. This results in a decrease of the forest's sustainable yield. The definition of sustainable yield has changed throughout history and the term itself has been described as anthropocentric due to limitations in applying ecological complexity. [4] The term sustainable yield is most commonly used in forestry, fisheries, and groundwater applications.
A sustainable yield is calculated by dividing carrying capacity by 2. [5] At half of the carrying capacity, the population is considered harvestable and capable of regrowth. [6] Errors in calculating the maximum sustainable yield can lead to over or under harvesting a resource. [6]
Understanding sustainable yield is essential because it indicates how much a population can produce and what humans can glean from it without causing irreversible damage to the species population growth. [7] It is possible that policies implementing maximum sustainable yield in ecosystems can cause the extinction of several species, especially if the population is harvested above its maximum sustainable yield. [8] Improving the application of sustainable yield in ecosystems without damaging them is valuable to research.
Sustainable yield is an important component of sustainable forest management. In the forestry context it is the largest amount of harvest activity that can occur without degrading the productivity of the stock. [9] The idea of sustainable yield forestry has shifted focus from only output, to include maintaining production capacity and maintaining the natural renewal capacity of forest vegetation. [10]
In America, the O & C Act of 1937 was one of the first written federal laws to warrant future generations having sufficient wood supply and regulations on wood harvest rate. The Act helped maintain a viable, sustainable yield, by ensuring land management, reforestation, watershed protection, a permanent timber source, and revenue distributed to local counties. [11]
Sweden and Russia are examples of countries that implement sustainable yield forestry. Sweden's market economy strives for maximum yield forestry which is obtained through intense forest management. Russia uses a mid-term horizon to distinguish natural growth from accessible timber. Their take on sustainable yield forestry uses natural regeneration and silviculture. [12] Sustainable yield forestry is widely criticized for its singular focus on wood management. This results in a changed natural landscape with a loss in biodiversity of that ecosystem as well as key ecological processes. [13]
The issue of over-fishing in the mid-1850s led to a new reference point for fishery management known as the maximum sustainable yield. [14] Sustainable yield in fishery management is defined as the number of fish that can be extracted without reducing the base of fish stock, and the maximum sustainable yield is defined as the number of fish that can be extracted under given environmental conditions. [14] In fisheries, the basic natural capital or virgin population, must decrease with extraction. At the same time productivity increases. Hence, sustainable yield would be within the range in which the natural capital together with its production are able to provide satisfactory yield. [15] It may be very difficult to quantify sustainable yield, because every dynamic ecological conditions and other factors not related to harvesting induce changes and fluctuations in both, the natural capital and its productivity. [16]
Groundwater is essential for ecosystems and humans to sustain themselves as it is the largest store of distributed fresh water. [17] In the case of groundwater there is a safe yield of water extraction per unit time, beyond which the aquifer risks the state of over drafting or even depletion. [18] Depletion of an aquifer, or a decline in groundwater levels has the potential to cause land subsidence which can cause sinkholes. [19] In order to calculate a safe yield of water extraction in the area, many factors need to be taken into account. The first is the water budget, figuring out and understanding where water is used by humans, getting recharged, and being lost due to possible maintenance issues and natural phenomena. Another consideration is changing technology. Technology allows for possible gains in supply, for example, desalination technology, turning saltwater into drinking water. [20] The other considerations include temporal, spatial, and monetary aspects, which all cause changes in the water system that change the amount of usable water. [21]
Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests and woodlands for associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. The science of forestry has elements that belong to the biological, physical, social, political and managerial sciences. Forest management plays an essential role in the creation and modification of habitats and affects ecosystem services provisioning.
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars. In forestry, the term logging is sometimes used narrowly to describe the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard. In common usage, however, the term may cover a range of forestry or silviculture activities.
Resource depletion is the consumption of a resource faster than it can be replenished. Natural resources are commonly divided between renewable resources and non-renewable resources. The use of either of these forms of resources beyond their rate of replacement is considered to be resource depletion. The value of a resource is a direct result of its availability in nature and the cost of extracting the resource. The more a resource is depleted the more the value of the resource increases. There are several types of resource depletion, including but not limited to: mining for fossil fuels and minerals, deforestation, pollution or contamination of resources, wetland and ecosystem degradation, soil erosion, overconsumption, aquifer depletion, and the excessive or unnecessary use of resources. Resource depletion is most commonly used in reference to farming, fishing, mining, water usage, and the consumption of fossil fuels. Depletion of wildlife populations is called defaunation.
Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem services. There are many methods to increase the sustainability of agriculture. When developing agriculture within sustainable food systems, it is important to develop flexible business processes and farming practices. Agriculture has an enormous environmental footprint, playing a significant role in causing climate change, water scarcity, water pollution, land degradation, deforestation and other processes; it is simultaneously causing environmental changes and being impacted by these changes. Sustainable agriculture consists of environment friendly methods of farming that allow the production of crops or livestock without causing damage to human or natural systems. It involves preventing adverse effects on soil, water, biodiversity, and surrounding or downstream resources, as well as to those working or living on the farm or in neighboring areas. Elements of sustainable agriculture can include permaculture, agroforestry, mixed farming, multiple cropping, and crop rotation.
Habitat conservation is a management practice that seeks to conserve, protect and restore habitats and prevent species extinction, fragmentation or reduction in range. It is a priority of many groups that cannot be easily characterized in terms of any one ideology.
In population ecology and economics, maximum sustainable yield (MSY) is theoretically, the largest yield that can be taken from a species' stock over an indefinite period. Fundamental to the notion of sustainable harvest, the concept of MSY aims to maintain the population size at the point of maximum growth rate by harvesting the individuals that would normally be added to the population, allowing the population to continue to be productive indefinitely. Under the assumption of logistic growth, resource limitation does not constrain individuals' reproductive rates when populations are small, but because there are few individuals, the overall yield is small. At intermediate population densities, also represented by half the carrying capacity, individuals are able to breed to their maximum rate. At this point, called the maximum sustainable yield, there is a surplus of individuals that can be harvested because growth of the population is at its maximum point due to the large number of reproducing individuals. Above this point, density dependent factors increasingly limit breeding until the population reaches carrying capacity. At this point, there are no surplus individuals to be harvested and yield drops to zero. The maximum sustainable yield is usually higher than the optimum sustainable yield and maximum economic yield.
Ecological yield is the harvestable population growth of an ecosystem. It is most commonly measured in forestry: sustainable forestry is defined as that which does not harvest more wood in a year than has grown in that year, within a given patch of forest.
A conventional idea of a sustainable fishery is that it is one that is harvested at a sustainable rate, where the fish population does not decline over time because of fishing practices. Sustainability in fisheries combines theoretical disciplines, such as the population dynamics of fisheries, with practical strategies, such as avoiding overfishing through techniques such as individual fishing quotas, curtailing destructive and illegal fishing practices by lobbying for appropriate law and policy, setting up protected areas, restoring collapsed fisheries, incorporating all externalities involved in harvesting marine ecosystems into fishery economics, educating stakeholders and the wider public, and developing independent certification programs.
The goal of fisheries management is to produce sustainable biological, environmental and socioeconomic benefits from renewable aquatic resources. Wild fisheries are classified as renewable when the organisms of interest produce an annual biological surplus that with judicious management can be harvested without reducing future productivity. Fishery management employs activities that protect fishery resources so sustainable exploitation is possible, drawing on fisheries science and possibly including the precautionary principle.
Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration.
Ecosystem services are the various benefits that humans derive from healthy ecosystems. These ecosystems, when functioning well, offer such things as provision of food, natural pollination of crops, clean air and water, decomposition of wastes, or flood control. Ecosystem services are grouped into four broad categories of services. There are provisioning services, such as the production of food and water. Regulating services, such as the control of climate and disease. Supporting services, such as nutrient cycles and oxygen production. And finally there are cultural services, such as spiritual and recreational benefits. Evaluations of ecosystem services may include assigning an economic value to them.
Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, protection, and forest regulation. This includes management for timber, aesthetics, recreation, urban values, water, wildlife, inland and nearshore fisheries, wood products, plant genetic resources, and other forest resource values. Management objectives can be for conservation, utilisation, or a mixture of the two. Techniques include timber extraction, planting and replanting of different species, building and maintenance of roads and pathways through forests, and preventing fire.
In ecology, resilience is the capacity of an ecosystem to respond to a perturbation or disturbance by resisting damage and subsequently recovering. Such perturbations and disturbances can include stochastic events such as fires, flooding, windstorms, insect population explosions, and human activities such as deforestation, fracking of the ground for oil extraction, pesticide sprayed in soil, and the introduction of exotic plant or animal species. Disturbances of sufficient magnitude or duration can profoundly affect an ecosystem and may force an ecosystem to reach a threshold beyond which a different regime of processes and structures predominates. When such thresholds are associated with a critical or bifurcation point, these regime shifts may also be referred to as critical transitions.
The sustainable yield of natural capital is the ecological yield that can be extracted without reducing the base of capital itself, i.e. the surplus required to maintain ecosystem services at the same or increasing level over time. This yield usually varies over time with the needs of the ecosystem to maintain itself, e.g. a forest that has recently suffered a blight or flooding or fire will require more of its own ecological yield to sustain and re-establish a mature forest. While doing so, the sustainable yield may be much less.
A fishery is an area with an associated fish or aquatic population which is harvested for its commercial or recreational value. Fisheries can be wild or farmed. Population dynamics describes the ways in which a given population grows and shrinks over time, as controlled by birth, death, and migration. It is the basis for understanding changing fishery patterns and issues such as habitat destruction, predation and optimal harvesting rates. The population dynamics of fisheries is used by fisheries scientists to determine sustainable yields.
Ecosystem management is an approach to natural resource management that aims to ensure the long-term sustainability and persistence of an ecosystem's function and services while meeting socioeconomic, political, and cultural needs. Although indigenous communities have employed sustainable ecosystem management approaches implicitly for millennia, ecosystem management emerged explicitly as a formal concept in the 1990s from a growing appreciation of the complexity of ecosystems and of humans' reliance and influence on natural systems.
Overexploitation, also called overharvesting, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable to replenish. The term applies to natural resources such as water aquifers, grazing pastures and forests, wild medicinal plants, fish stocks and other wildlife.
Deforestation in British Columbia has resulted in a net loss of 1.06 million hectares of tree cover between the years 2000 and 2020. More traditional losses have been exacerbated by increased threats from climate change driven fires, increased human activity, and invasive species. The introduction of sustainable forestry efforts such as the Zero Net Deforestation Act seeks to reduce the rate of forest cover loss. In British Columbia, forests cover over 55 million hectares, which is 57.9% of British Columbia's 95 million hectares of land. The forests are mainly composed of coniferous trees, such as pines, spruces and firs.
The restoration economy is the economic activity associated with regenerative land use, such as ecological restoration activities. It stands in contrast to economic activity premised on sprawl, or on the extraction or depletion of natural resources. The term is meant to convey that activities meant to repair past damage to natural and human communities are often economically beneficial at local, regional, and national scales.
Ann M. Bartuska is an ecologist and biologist. She is a senior advisor at Resources for the Future and a former Deputy Under Secretary for Research, Education, and Economics (REE) at the United States Department of Agriculture and former USDA Chief Scientist.