Hi Wayne,
Thanks for the interesting account of your work, and yes, perhaps I
confused the issue a bit by mentioning "flat" indices and the Wisconsin
index in quick succession.
About the Wisconsin index, probably one should look at the original
evaluation to get a full understanding of how this was implemented,
rather than this report which was written by a lawyer and two policy
analysts whose level of scientific training is unclear. The report
contains a few statements that suggest a superficial understanding of
science. For example, in one rather flippant footnote on p. 12, a list
of "famous approaches that were once widely held and later rejected"
includes Newtonian physics -- which still forms the main basis for most
practical mechanical engineering calculations, up to and including much
of what counts as "rocket science." But I digress ...
For the Wisconsin controversy, the reference in this report points to a
1997 Minnesota Law Review article which doesn't seem to be freely
available on the web. So we're left with at best a third-hand
description of the methodology. I think the reference is to the
management plans for the Nicolet and Chequamegon National Forests that
were challenged in the 7th District Court case Sierra Club v. Marita
(1995), but I haven't been able to confirm that so far.
The concept of a "flat" diversity index (giving equal weight to all
species) versus other possible measures of biodiversity is a separate
topic, so my apologies for mixing up the two.
I agree with your point that a "flat" index certainly is simpler to
explain, but it's not necessarily more objective than alternatives.
There's an implicit value judgment that regionally common species have
equal value to regionally rare or uncommon species. If you use a flat
index to measure avian biodiversity, and design management strategies to
maximize this measure on the local scale, you could well end up with
lower diversity on the regional scale.
Certainly if you highlight regionally rare or habitat-specialist species
in reporting (as you did in your VA/SC surveys), that provides another
measure that can be used for management decisions. But these things can
get lost as they travel up the management and decision-making chain.
In the popularized versions (such as coverage of John Marzluff's book,
"Welcome to Subirdia,") the importance of these other measures gets lost
as the results get boiled down to a few sound bites. For example this
radio blurb:
http://www.scienceupdate.com/2014/12/suburban-birds/
This essay by Kenn Kaufman gives a more thoughtful perspective:
http://www.audubon.org/news/do-birds-prefer-suburbia
Kaufman's point #6 is basically what I was driving at -- shouldn't we be
using avian biodiversity indices that represent this kind of thinking,
as part of conservation and management decisions?
Again, the botanists have come up with the idea of a "Floristic Quality
Index" which has seen widespread application for prioritizing sites for
conservation, for example:
http://pubs.usgs.gov/fs/2011/3044/pdf/FS11-3044.pdf
My main suggestion here is that we could use something like this for
birds, to help guide conservation decisions. As you can guess, even
though I used old-growth-affiliated birds as an example, this issue also
comes up for grassland bird conservation.
Joel
