Limited Species Rucker Indices   Edward Frank
  Nov 22, 2004 19:35 PST 


One concern with the Rucker Index we need to figure out, and we touched on
it when discussing some of the western forests - is that in some of the
harsher environments there aren't ten species of trees from which to create
a standard Rucker index. Some examples would be at the extreme northern
edge of the taiga forests. Basically the only species present in these
areas is spruce. They may be old growth untouched by man, but the 10 tree
rucker index is not usable. I think some of the desert communities in the
arid and semi-arid west would also have a limited diversity.

Another case would be a site is so dominated by one or two species, that
even if there are occasional representatives of other species, whatever
their height, a false picture of the site would be formed by including the
full ten species depth. An example would be some of the redwood forests in
the west. Bob Van Pelt wrote: "The low diversity of trees in some Western
forests quickly reduces the Index to below 200. Humboldt Redwoods SP, for
example, has the world's tallest tree, and 86 trees over 350'. Due to the
overwhelming dominance by redwood, the Index drops below 200 after only six
species are included!" Oct 29, 2002

These are not likely a problem for the area you are reporting, but I could
see a lack of diversity in perfectly untouched old growth on some of the
knobs - the dwarf forests I have been thinking about lately - in both the
Catskills, in Mass, and other areas of New England with similar topography.

Ed Frank

RE: Kaaterskill Falls-Catskills-NY   Robert Leverett
  Nov 23, 2004 10:46 PST 

Ed, Howard, Will, Dale, Lee, John, Don, et al:

   In preparation for next year's Black Hills excursion, I've been
toying with the idea of the Rucker Index tied to a different number of
species. We might have a RI5, where 5 represents the number of included
species. I had thought about suggesting something of this sort once
before, but at the time, it sounded like over-kill. Then WNTS was born.
Don Bertolette needs to have the primary say-so on the approach used to
compute Rucker indexes for sites in the Rocky Mountain West, an approach
based on the number of available species seems natural.     

RE: Rucker index   Lee E. Frelich
  Nov 23, 2004 11:38 PST 

Bob et al.:

Yes, you can do a Rucker3, R5, R10 or any number of species you want. You
can always pare down the number of species in a diverse forest so that it
can be compared to a less diverse one. I have already been using it in
lectures at the University of MN.

Re: Kaaterskill Falls-Catskills-NY   Don Bertolette
  Nov 23, 2004 13:20 PST 

Ed's right, relative to the NE, the forests of the NW and SW are often
depauperate species-sise. I can think of exceptions to the rule (I've shown
you some classic mixed conifer old-growth with 6 or 7 species that could put
up some big numbers.
My guess is that we're going to find that East is East and West is West and
only the Treeti shall meet at the Uintahs shall they meet...
(quoting from a document some months past...
"this summer's past trip that included the Black Hills, I realize that there
is a story to be told and modified Rucker indices to be calculated (forget
about a 10-species index). I'll likely spend a good deal of time in the Utah
Wasatch and Uintahs also.")
Re: Kaaterskill Falls-Catskills-NY
  Nov 23, 2004 13:52 PST 

Even for the Northeast, 10 species sounds like quite a lot. Also, if we are
truly interested in growth potential, once you past the first 4-5 species,
it would seem that there might be a number of tracts where the remaining 5-6
trees would be hangers on and less adapted to the particular microsite?
Maybe a RI10 and RI4 should be kept for everything (where possible), along
with the HRI. (And while I'm at it, just to make a complete complicated
mess of everything, fat diameters trees are also very impressive and seem
to me as important as purely tall ones, perhaps a fatness index should be
kept along with the Rucker height index, restricted to count only in forest
(no field) grown trees having single trunks to say 20' or greater above
ground, and just to add even more, something like the American forest great
trees list, except with the restriction that the trees be tall, columnar,
forest grown types, and that crown spread counts for nothing, front yard and
field trees can be very nice, but there are much different breed than
forest grown trees, which I think should have there own list.) An
Appalachian mixed mesophyetic forest might easily have 10 solid species,
but otherwise, it seems perhaps a stretch. I can think of some fabulous
old-growth tracts in the Adirondacks that are so sugar maple dominated,
that beyond some scattered white ash and yellow birch I don't recall seeing
all that much else, and yet the tract was tall and impressive, clearly OG,
but I'm not sure if it could qualify for the 10 species rucker, perhaps
there are 10 species there, but I have my doubts, and even if so, it would
surely have its index unfairly cut down quite drastically. Then again my
tree identification skills are weak, and I haven't really paid enough
attention, perhaps. Even my backyard tract back in NJ, which has some nice
trees, quite well grown back and significant pit and mound topography, I
can think of sugar maple, two oaks, white ash, tulip, ironwood, hemlock (1
single tree), beech and maybe one other. That's 9. I'm not sure if there is
a 10th species in the tract, and yet its quite a nice tract, although the
older part is quite small in acreage, which is the only part I was
counting, it would go beyond 10 species if I extended it to encompass the
extensive surrounding woods (some parts of which are also quite mature), so
perhaps it is simply too small a tract to make a fair test out of, although
the additional species would be picked up from areas with different growing
RE: Rucker index   Edward Frank
  Nov 23, 2004 18:50 PST 


I tried to address the terminology of using something other than 10 species
to create an index variant. The post was dated April 25, 2004.

Certainly it is easy to create a shortened version of the index for
comparison between areas with less species diversity to those with a higher
diversity. Lee using this format in his lectures is excellent. One reason
that I like the ten species requirement for a standard index is that it
requires a certain depth of measurement. A site is examined in more detail
in the attempt to find tall specimens of all ten species, rather than
concentrating on just those few species you expect to produce the tallest
trees. In the acre or so of land my home sits on, I can list over a dozen
different species that could be measured for an index of "My Backyard." I
think if these additional species are present, it is important to measure
them to adequately represent the diversity of the site. I have argued in
the past that if possible, I would like to see an RI20 including twenty
species if that many are present.

In some cases as have been cited by others and myself there simply is not a
great enough diversity to include 10 species, or possible inclusion of a
full ten species would provide a false impression of the site. In these
cases a RI of less than ten is appropriate. I have also been considering
how we can use our height measurements to look at forest composition and
structure from the uppermost canopy to the herbaceous layer on the forest
floor. I will address this in another post in a few days.

Ed Frank