Defined by Webster to be the quality of a thing according to which it is
thought of as being more or less desirable, useful, estimable or important.
Using this definition the value of an ecosystem might be defined in terms of
its beauty, its uniqueness, its irreplacability, its contribution to life
support functions or commercial or recreational opportunities, or its role in
supporting wildlife or reducing environmental or human health risks, or
providing many other services that benefit humans.
Source: Ecosystem Valuation
The economic concept of value is that value is human driven (i.e., it is
anthropocentric), meaning that goods and services are not considered to have
value unless humans place value on them [willingness to pay].
From a strict economic perspective, there is no such thing as
intrinsic or natural value. Of course, this
focus on human-based value leads economists to measure market and nonmarket values using monetary instruments such as dollars.
Source: Agricultural Economics & Agribusiness department of the Louisiana
How is economic value measured
Intrinsic value - Non-market value
To read about this term in context:
GreenFacts Summary on Ecosystem Change: