Height records per site   Jess Riddle
  Oct 08, 2006 11:47 PDT 

Ents,

A few months ago, Ed Frank challenged us to improve upon or come up
with alternatives to the Rucker Index to quantify a site. I pondered
the question for a while, but never discovered any useful measure.
However, I still think questioning the Rucker Index is useful since
the index is often reported at the end of site description to sum up
the site. But it doesn't sum up the whole site; shorter species make
no impact at all. One alternative that would take them into account
would be to simply list the number of state height records known to
occur at the site. Again, this measure would be imperfect since a
site could offer excellent growing conditions to many species, but
lose credit to other sites where just a few species are stellar
performers. However, combining state height records with the Rucker
Index would give a somewhat more complete view of a site in an easily
accessible manner. To test out this approach, I've looked at species
in Georgia and South Carolina that ENTS has many measurements from,
seen what site the height records grow at, and also listed the Rucker
Indexes from those sites.

Georgia
Site                        # Ht Records Rucker Index (rank)
Panther Creek         11                  137.8' (1)
Ocmulgee Flats      10                  133.3' (5)
Cliff Creek               7                   135.8' (2)
Rock Creek             7                   129.9' (8)
Kelly Ridge RA        6                   135.4' (3)
Pigeon Mountain      6                   NA
Brasstown Bald       5                    NA
Cohutta Wilderness 3                    132.0' (7)
Cohutta WMA         2                    132.2' (6)
Camp Creek            0                   133.6 (4)


South Carolina
Congaree NP         23+                  151.0' (1)
Wadakoe Mtn        10                    144.2' (3)
Brevard Fault Zone 8                     150.6' (2)
East Fork Chattooga 6                     NA
Coon Branch NA     5                     NA
Mountain Bridge     4                      124.3' (8)
Paris Mountain SP 4                       NA
Long Cane Creek   3                       128.3' (6)
Opossum Creek     2                      132.2 (4)
Turkey Creek         1                       129.4 (5)

In both states, sites with the highest Rucker Indexes had large
numbers of state height records. However, some site with several
height records have not even had a rucker index calculated. Those
sites typically have shorter statured forests featuring some unusual
species, like Pigeon Mountain with the only population of smoketree in
GA and one of only three populations of blue ash, or have tall trees
but relatively low diversity, like the East Fork of the Chattooga
River. Some sites with high Rucker Indexes had few height records due
to other dominate sites with similar species mixes having the records.
The height records help to show how exceptional Congaree National
Park is; of all true bottomland species measured by ENTS in South
Carolina, only cottonwood has state height record outside of the
Congaree.

Jess Riddle
Re: Height records per site   Edward Frank
  Oct 08, 2006 15:32 PDT 
Jess, ENTS,

This certainly seems a worthwhile idea to pursue. It is interesting how the rankings of state records differ from the basic Rucker Height Index.   Perhaps as an option the rankings could be listed, as in the case of Panther Creek, GA, as 11/57 meaning there are a 11 out of 57 state records at the site. This would tell someone both how many records were at the site as well as how many height records have been accurately documented in the state (or study area). I am also wondering if there are listings by the various state forestry departments or universities or such of how many different trees or trees/woody shrubs are know to inhabit the state? This would give some indication of how big of a chunk of potential records have been measured by ENTS methodology.

Other ideas I have thought about myself would be some type of diversity index keyed to the acreage of the site. I am very impressed by documents such as Colby Rucker's Belt Woods: Tree Heights and Forest Structure in the South Woods, MD with detailed species listings/habitat notes and tree profile data for all of the species found on the site. This is certainly a model to strive for - not on every site - but for our most measured sites such as MTSF and Cook Forest.

Ed Frank
RE: Height records per site   Robert Leverett
  Oct 17, 2006 09:24 PDT 

Jess, Ed, Will, John, et al.:

   In terms of state or regional height champions along with a high RHI,
MTSF ranks #1 and #1 respectively in New England. As you know, MTSF's
RHI is 136.1 and it boasts no less than 19 state or regional height
champions that included 2 non-native species. However, as we widen and
deepen our search of other New England properties, Mohawks share of
champions is sure to go down, but MTSF will likely retain 14 or 15
champions. Even if the count drops to as low as 12, Mohawk will still
far exceed any other property in New England.

Thinking beyond the concept of listing the RHI along with the number
of state or regional height champions (NHC), the next step might be to
include a RCI and a listing of the number of circumference champions at
a site (NCC). The young, tall tree sites would then be seen in proper
perspective to older sites with large, but not especially tall trees.

Taking this approach to its extreme, a second round of the
(RHI,NHC),(RCI,NCC) combination would be to apply the concept to
understory species. That would give us 8 indices per site. We would
always be working toward building these indices for our best sites. The
marginal site would probably not receive much attention. There are only
so many hours we can devote to the process.

    One troublesome aspect to all this analysis is how to best treat the
site with tall trees of a few species, but an overall low species
diversity. Those sites may be eye-poping gorgeous, but show up way down
on our lists. Alas, our job will never be truly finished.

     BTW, John Eichholz e-mailed me yesterday that while his field time
has been minimal over these past several months, he did get back to Ash
Flats and bagged a 107-foot white birch. This puts the count of white
birches in Mohawk confirmed to over 100 feet to 4. John has accounted
for 3 of the 4. There are many white birches between 85 and 95 in MTSF.
But white birch has been greatly under-sampled at all New England sites.


Bob     
Re: Height records per site   Jess Riddle
  Oct 18, 2006 14:42 PDT 
Bob,

Mohawk's dominance in terms of height champions comes as no surprise
to me. Given the diversity of the forests at MTSF, the high Rucker
Index, and you're documentation of the huge gap between the white
pines their and at other sites in Massachusetts, it makes since that
MTSF would have at least a few other height records.

I agree, adding a Rucker Circumference Index to out descriptions makes
a lot of sense. Since trees with conspicuously large circumferences
usually catch our attention, we could probably put together reasonably
complete lists of circumference records. I just need to refocus a
little when I'm in the woods to start collecting the data for a RCI.

I having more trouble following your point about the eight indexes for
a sight. Do we have a method in place for calculating some version of
a Rucker index for understory species. If we just use the same
mathematical process applied to the set of understory species, how do
we define understory species and what is our justification for
applying the process to understory species. I originally proposed
listing the number of height champions at a site as a way to
compensate for the lack of understory species in the traditional
Rucker Index; I included all species, overstory or understory, when I
listed the number of height champions. Thus, again I don't see how or
why the number of height records would be listed for just understory
species. On a more general level, I don't see that partitioning a
site into overstory and understory components is the best way to
develop an overall measure of a site. However, when I hear more about
your ideas or other ways of evaluating sites are proposed, I may
change my mind.

Jess
Re: Height records per site   Edward Frank
  Oct 18, 2006 15:10 PDT 

Jess and Bob,

I also do not see how the understory species could be effectively separated
from the canopy species, nor why you would want to do this. It would
require an arbitrary determination of what was a canopy species and what was
an understory species, even though most of the canopy species would also be
present in the understory.

As for circumference indexes - I am all for their inclusion, but would
prefer they be called Girth Indexes as the RGI is a set of initials less
subject to confusion (At some point their may be a canopy index and C should
be reserved for that usage, especially as I can't think of a better way to
phrase it.) Also I think circumference brings to mind a circle, where trees
are not perfectly round. This is not a strict definition just the
impression that is given by the word.

NHC = National Height Champion
N = National
R = Regional - I would like something other than R which can be confused
      with Rucker
S = State

Ed Frank
Re: Tsuga Report   Jess Riddle
  Oct 18, 2006 19:59 PDT 

Ed,

We are defining shrubs as having perennial stems over 1cm basal
diameter and less than 10cm dbh. Off the top of my head, beech,
hemlock, sugar maple, silverbell, witch hazel, black birch, yellow
birch and buckeye have occurred in the plots as both trees and
shrubs/saplings.

Jess

On 10/18/06, Edward Frank wrote:
 
Jess and Will,

I have been reading your last Tsuga progress report with respect to the
Rhododendrons. You indicated that 841 shrub stems of 1211 shrub stems were
rhododendron. Then it goes on to say that 35 stems were counted as trees.
What cut-off did you use between trees and shrubs in the report? I don't
see where it is specified. Are other species present as both shrubs and
trees?

Ed Frank
RE: Height records per site   Robert Leverett
  Oct 19, 2006 04:57 PDT 

Jess,

   I think my emphasis on understory as a separate index stems from some
of us seeing understory species as a special category of plants, filling
a niche. Shrubs would like wise be a third category. If you ask me to
partition the woody plants into canopy, understory, and shrub, I'd
struggle a bit, but could probably make a good case for the division and
what belongs where for MTSF. Applying my partitions to other forests
might not work.

   If we go with just a separate champion listing for understory
species, a site with otherwise tall understory species (just no champs)
could be completely invisible through our system. I'm probably grasping
at straws. Let's continue the discussion.

Bob
RE: Height records per site   Robert Leverett
  Oct 19, 2006 05:01 PDT 

Ed,

   I'm not fixated on a separate listing for understory, and canopy
dominate species like red oak do spend their time in the understory, but
I'm pretty clear on which species in Massachusetts never play a
consistent role as a canopy species - although there are places where a
past fire or blowdown occurred where striped maple is the canopy
dominate for a brief period of time. I wonder what others think on this
topic.

Bob