Sustainable yield
Encyclopedia
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.
In forestry terms it is the largest amount of harvest activity that can occur without degrading the productivity of the stock.
For example 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. 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.
In the case of groundwater
there is a safe yield of water extraction per unit time, beyond which the aquifer
risks the state of overdrafting
or even depletion.
Natural capital
Natural capital is the extension of the economic notion of capital to goods and services relating to the natural environment. Natural capital is thus the stock of natural ecosystems that yields a flow of valuable ecosystem goods or services into the future...
is the ecological yield
Ecological 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....
that can be extracted without reducing the base of capital itself, i.e. the surplus
Economic surplus
In mainstream economics, economic surplus refers to two related quantities. Consumer surplus or consumers' surplus is the monetary gain obtained by consumers because they are able to purchase a product for a price that is less than the highest price that they would be willing to pay...
required to maintain ecosystem services
Ecosystem services
Humankind benefits from a multitude of resources and processes that are supplied by natural ecosystems. Collectively, these benefits are known as ecosystem services and include products like clean drinking water and processes such as the decomposition of wastes...
at the same or increasing level over time. This yield usually varies over time with the needs of the ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
to maintain itself, e.g. a forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
that has recently suffered a blight
Blight
Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism. It is simply a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this...
or flooding or fire
Fire
Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
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.
In forestry terms it is the largest amount of harvest activity that can occur without degrading the productivity of the stock.
For example 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. 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.
In the case of groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
there is a safe yield of water extraction per unit time, beyond which the aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
risks the state of overdrafting
Overdrafting
Overdrafting is the process of extracting groundwater beyond the safe yield or equilibrium yield of the aquifer.Since every groundwater basin recharges at a different rate depending upon precipitation, vegetative cover and soil conservation practises, the quantity of groundwater that can be safely...
or even depletion.