The discussions in the past few threads in which the value of addressing non-native species was raised seem to confuse two items: (1) what are the functions of a wetland or species within a wetland and (2) what are the values that either I, you or we as a society ascribe to a those functions. In 1995, The National Research Council summarized the distinction between these two items as follows:

“Wetland functions are the physical, chemical and biological processes that characterize wetland ecosystems, such as flooding, denitrification, provision of habitat for organisms, and support of aquatic life....Objective measurement of wetland functions falls within the realm of the natural sciences, and barring changes in the ecosystem being measured, is repeatable over time...

The value of a wetland function is a measure of its importance to society. Wetland functions are valued to various degrees by society, but there is no precise, general relationships between functions and the values of wetlands to society, and values can be difficult to determine objectively.”

Getting away from any individual species for a moment, I see a tendency for people to equate their personal values with how they perceive a function by a species or a system. I see this as a major problem in communication among people with different values as too often the values people place on functions obscure any discussion of the functions themselves. I also suggest that people have 2 sets of values: economic and personal. These are different in that economic values are attached to a $ sign , but that personal values (although they may include some economic considerations) tend to be based on other lifestyle factors.

To illustrate, I will use an example remote from wetlands: House siding. When building a house you can choose a variety of siding, stucco, cement wall, wood, brick, and many, many others. Each siding type performs a function: keep your house dry and warm; others also perform differently in cold, wet, dry or fire-prone climates. The degree to which the function can be performed varies by material. These functions can be measured. However, there is a cost to the function that is expressed in terms of $/unit installed. Now in a perfect world, one might say, okay I want to buy X$ of siding function. Except, even such a simple item of siding doesn’t work that way as it is not a linear relationship between cost and function. On top of that, let’s add “personal values”. Do you want to fit in with the neighborhood style? do you want your own style? have you always wanted a house of XXX? Do you want to build a house out of XXX just because? These are your values about a function. So what do you choose for siding–it is just a measurable function after all, or is it a mix of functionality and value attached to that function?

I suggest that in order to address wetland and individual species, we all need to try and separate functions and our own personal interpretations of the value of these functions in our discussions.