I stumbled on a discussion list which seems to be based at the University of Toronto School of Landscape Architecture, containing a 'TREE VALUE' thread circa 1997. I haven't quite figured out there organizational theme, seems like the ISA site (not easy to follow like Knothole!).

I've provided a URL to one particularly interesting post (you'll have to navigate up and down the thread from there). It suggestes that there are no "objectively" right or wrong values, that value is a human construct to guide conduct or decisions. It is very well said.

This is a message I've been trying to get across here. Appraisal is a guide to decision makers. It must be employed with a clear and specific understanding of the Purpose and Use of the appraisal (what question is the decision maker asking?). Appraisal is not a measurement exercise. Value is not a physical property and is not directly measurable. The longer we tinker with techniques that purport to provide THE accurate or "reasonable" or universal value, the longer those opinions will be open to attack.

Reply to post by Scott Cullen, on August 11, 1999 at 07:31:54:

First, if you want to view the list of messages in the archive, just drop the page label- the part after the last "/"


This will display the whole list, with hot links.

AS to the message, I agree... to a point. At the risk of sounding like the self-banished one, I believe that there are other values beyond the human ones. Call it intrinsic if you want. The distinction must be made though that those non-human oriented values remain mostly unknown and totally unmeasureable to us. A beech has value to the deer that eats the mast. But I'll be darned if I can figure out how to quantify that value. It must be left to the deer, I suppose. The beech may also have negative value to the young oak struggling to grow in its shade. The oak can't tell me what that value is, but that doesn't mean it isn't there in some sense.

When we speak of the value of a tree or any object, we must by reason confine that definition to human terms, as you pointed out. And that means defining the purpose and use, so everyone understands the point of view used to derive the value.

Reply to post by Russ Carlson, on August 11, 1999 at 07:31:54:

Good observation Russ. I think the writer's point was that "value" is a peculiarly human construct, a perception, a abstraction perhaps. Not necessariliy rational, since it's often emotional, but an element of human thought nonetheless.

Biota... and I suppose the non-biotic environment... have certain biological, chemical and physical "functions" which inter-relate ecologically and which might be described as intrinsic (at least a given moment in evolutionary and geologic time). The various entities have certain obligate, non-obligate and maybe even preferential relationships. Will the deer "feel" hunger if food is insufficient? I guess so. Will the doe "grieve" for the fawn which starves? Maybe. Does the deer "value" habitat? I think not in the sense that humans quantify monetary value.

As appraisers we deal with monetary value. As environmental professionals we certainly recognize all those ecological functions and relationships. As educators we may ultimately influence how people at large "value" them. We may even point out certain sets of potential or unappreciated "values." But in an appraisal role we MUST stop short of becoming advocates.

BTY, I was able to move from message to list in the archive, but no matter how I sorted the thread was not continuous as it is in KnotHole. The "previous message" or "probably in response to" keys were not reliable. (Pat yourself on the back now Russ, good software selection.)