Fixed Area Plots/ Rucker Index Analysis   John Eichholz
  Nov 14, 2006 09:57 PST 


If we are going to produce further improvements in the
data, we ought to structure it to allow analysis like Lee Frelich is

As our corps of tree measurers are aware, tree heights are maximized in
a very localized pattern. Overall, a forest can have many primo sites,
and in the vicinity of any tall tree are often several others of the
same species and sometimes of different species. Move away from that
tree a couple hundred meters and everything changes. In some cases, you
can move a few hundred meters more, into another high growth area, and
the pattern repeats. We gain a sense for where this will happen, but
not only are we sometimes wrong, but we don't know enough about what
makes a site support high tree growth.

One idea I am working with is to consider the local site conditions at
each area that contributes a tree to the Rucker index. In order to
support this research, I am delimiting the topo map for MTSF into
even-sized sections, using the UTM grids on the map. Those are 1km by
1km, there are 15 to 20 of them in the forest, and they could usefully
be further divided into 250m by 250m quadrants. On a first pass, most
of our contiguous high growth areas would each fit into one or two
quadrants. Many quadrants have high growth areas, but fewer quadrants
have Rucker iteration members in them. An initial project would be to
map as many trees from the top 25 iterations onto the grid system as we
can, then look for patterns. We can revisit an area to supplement other
data we have about a quadrant identified in this search. We can make
standard characterizations about the quadrant, and perhaps contrast tree
populations from other quadrants with similar characteristics.

This process of picking areas to go back to is one way I use to increase
the Rucker index. Right now I am looking at a cluster of data showing
high concentrations of tall hemlocks in the area of Black Brook/Cold
River confluence. The tallest hemlocks are located in or next to
streams, within 200' to 300' elevation above the main river. The
tallest trees are located where slopes are 35 degrees or less. While 40
to 45 degree slopes exist adjacent to these areas, mostly at higher
levations, there is a 20' reduction in maximum observed heights in those
areas. Also present near the tall hemlocks are a significant population
of really nice Yellow Birch, including most of the known examples that
exceed 100' in height. Sugar Maple and to a lesser extent, American
Beech grow quite tall in these areas, but not to record heights. White
Ash does intermix with hemlock, but outside the hemlock areas it grows
much taller. Across Cold River but within sight, is the famous Ash
Flats, with champion White Ash and Bitternut Hickories.    

Of the top 25 hemlocks found, 9 occur in this area. 10 more occur in
the Trout Brook basin, and 4 near the entrance to the park. At least
80% of the tallest Hemlocks found at MTSF occur south of the Cold River,
and would probably lie within the boundaries of 9 quadrants (out of
60-80 total in MTSF.)

Another idea we are working on is time series measurements of selected
trees, to establish growth rates. We have some time series data for
MTSF, but it seems like only the beginning.


RE: Skiffley Creek and Dry Branch   Robert Leverett
  Nov 22, 2006 05:35 PST 

Josh, Jess, Mike,

The amount of acreage in the southern Appalachians with a RHI above
140 may cause us to have to introduce an area variable and begin looking
at the results of Rucker indexing through physical areas with indices
reaching thresholds to get a better appreciation for the extent of the
high canopy forest in various areas. We may be moving more toward a
calculus-like approach to Rucker Index Analysis (RIA) to better describe
an area. I have thought about mapping MTSF via the RHI as a series of
limited fixed-area plots chosen to capture different growing habitats.
More on this idea to come.

RE: Skiffley Creek and Dry Branch   Joshua Kelly
  Nov 22, 2006 10:09 PST 


Identifying and mapping the areas of highest RHI, RCHI, basal area, wood
volume, etc. is a very cool idea. By identifying such sites and quantifying
the physical properties that lead to their productivity and the tree
dimensions found there, much could be deduced about the way forests function
- at least in 2nd growth circumstances. I'm not sure the data set is
complete enough for the primary forests of our region.

I also like the idea of RIA's. I'm imagining maps with colored zones that
delineate the known potential canopy heights of different areas of forest.
Perhaps ENTS should invest in some GIS software? That would be fun, and

Fixed area plots was: RE: Skiffley Creek and Dry Branch   John Eichholz
  Nov 24, 2006 17:59 PST 


I have been thinking similarly (see my 11/14 post), that MTSF should be
divided into a series of plots that represent distinct growing areas,
especially areas that are contiguous areas of high growth, bounded by
lower growth areas. It seems at first that each grove would have a much
lower Rucker index than the forest as a whole, and would represent a
pinnacle of a particular soil/aspect/moisture/history that supports a
distinct forest type. I am thinking of forest type distinct from the
usual classifications such as "northern hardwoods", since we would be
looking at much more detail. I have started to enumerate subsites as I
explore a site, carrying a topo map printout to mark up. In the Cold
river basin I found the natural site boundaries to be a couple of
hectares extent. In Trout brook, they might be 2-5 hectares, enclosing
a particular hot spot or region of interest. That is not to say that
adjacent areas are always dull, but that they are of a different focus.
Anyway, I am looking forward to what you are thinking, and I will keep
developing the idea as well.

John Eichholz

p.s. Too bad our areas are not as big as the southern apps.