2. Primary Value (PV):
This is value of system characteristics upon which all ecosystem functions depend representing prior value of ecosystem and is also known as ‘glue’ value since system holds everything together and in principle, therefore has economic value.
It is called primary value because structured ecosystem produces functions of secondary value. Secondary value will exist as long as ecosystem retains its ‘health’ existence, homeostasis, operation and maintenance.
3. Total Economic Value (TEV):
TEV also called Total Value (TV) or simply Value (V) denotes sum total of all kinds of values attached to biodiversity minus primary value. It is the function of use and non use values “with due consideration of any trade-offs or mutually exclusive uses or functions of resources habitat in question” (UNEP, 1995). Care must be taken to avoid simply adding up resultant values to obtain TEV. TEV underestimate the true value of ecosystem. It has to be considered along with primary value.
4. Use value (UV):
Value arising from an actual use made of a given component of biodiversity (MacArthur, 1997). It is often a function of direct and indirect use values. Pearce and Moran (1994) included option value as a third function of use value. UNEP (1995) included Quasi Option Value under use value.
5. Direct Use Value (DUV):
People directly consume and use species for their benefits which belong to direct use values. Direct use values are associated with values of natural products for developing pharmaceuticals, for developing and maintaining genetic basis for agriculture and for supporting industries based on use, species such as fisheries and timber extraction of although most of such industries are not based directly on species.
MacArthur (1997) defines this as “Actual uses, especially in consumption”. It represents the economic values derived from direct use interaction with a biological resource or resource system (UNEP, 1995).
Bio-resource contributes to human welfare in the form of either enjoyment or satisfaction. DUV can be easily observed and measured, often by assigning market prices. McNeely (1988) considered DUV a function of Consumptive Use Value (CUV) and Productive Use Value (PUV).
Ravi and Pushpangadan (1997) consider DUV as a function of CUV, PUV, and Non-Consumptive Use Value (NUV). Economic value of ecosystem services is enormous. For example, 40 crops in the United States with a total annual market value of US$40 billion are completely dependent on insect pollinators. Biological pest control has a framework for action on health and the environment.
6. Consumptive Use Value (CUV):
Value that is consumed enjoyed directly, without passing through a market (McNeely, 1988) is the CUV. This is “consumption in physical form” including all types of biomass, industrial raw materials (Ravi and Pushpangadan. 1997). CUV seldom appear in countries GNP but are very important. Fuel wood is a consumptive value of great importance in rural areas.
7. Productive Use Value (PUV):
Value given to a component of biodiversity that is commercially harvested or is a source for a commercially harvestable product. Such items pass through a market. Examples include minor forest produces, fruits and seeds, latex, timber, pharmaceuticals, medicines, fibres, gums and resins. Values of such items are usually estimated at production end. PUV is included in national economic statements and budgets.
8. Indirect use value (IUV):
This is defined as ”benefits arising from an ecosystem function”. It represents economic value derived from role of resources and systems in supporting or protecting activities whose outputs have direct value in production or consumption. Indirect contributions of biodiversity like biogeochemical cycles, photosynthesis, climate regulation, pollutant degradation, prevention of soil loss to human welfare possess this value.
9. Non consumptive use value (NUV):
Value possessed by components/ systems of biodiversity in terms of functions or services. Some consider this a subcategory of IUV (McNeely, 1988), while others (Ravi and Pushpangadan, 1997) treat it as a category of DUV.
10. Non-Use Valve:
Define as “value relating to safeguarding the existence of assets, even though not related to their actual use in a foreseeable period” (Mac Arthur, 1997). NV is also referred to as Passive Use Value referring to value of a biodiversity resources in production or consumption to someone/thing other than user. Such value exists “where individuals who do not intend to make use of such resources would nevertheless feel, a “Loss” if they were to disappear” (Randall, 1991).
11. Option Value (OV):
Defined as “willingness to pay to safeguard an asset for option of using it in future” (MacArthur, 1997). UNEP (1995) defined OV as Potential value of resource for future (direct and indirect) use. Wild relatives of cultivated plants that are yet to be exploited may be cited as examples possessing OV.
12. Quasi-Option Value (QOV):
QOV represents “value of future information made available through preservation of a resource” (UNEP, 1995). Distinction between option and quasi- option values is not always maintained.
13. Existence Value (EV):
Defined as “value deriving from existence of a particular asset (MacArthur, 1997).”Value of knowing that a particular species, habitat or ecosystem does and will continue to exist. It is independent of any use that value may make of resource”. EV notes the benefits derived by anyone individual from more knowledge that the bioresource exits.
People who have donated money to a conservation organization without expecting anything in return other than satisfaction of knowing that they have contributed something to cause of biodiversity, may be said to have realized the existence value. Such values generally generate sympathy and concern among people.
14. Bequest Value (BV):
“Value of knowing that others may benefits from existence of an asset in future” (McaArthur, 1997). It is a value defined by willingness to pay to ensure that people’s offspring or future generations inherit a particular environmental asset (UNEP, 1995). This is the value of keeping a resource intact for one’s heirs (Krutilla, 1967). Aldred (1994) views BV as merely one of a number of types of Existence Value and not warranting a separate category.