All Ruckered out    Edward Frank
   Apr 25, 2004 10:10 PDT 

Bob and others,

Rucker Index Terminology

There has been a number variants of the original Rucker Site Index proposed
and experimented with in the last few months. It is important that some
sort of a standard terminology be determined so that the various
incarnations of "Rucker" not be confused. Colby Rucker for example is
actually a person and not an index at all!!

Rucker Site Index: The average height of the ten tallest individuals of
each of the ten tallest species on a site. Commonly referred to as simply
the Rucker Index.

Rucker Combined Index: The average of the height times cbh of the ten
largest individuals of each of the ten largest species on a site.

Rucker Site Iteration Table: This would consists of a table of multiple
Rucker Site Index iterations made for a particular site. Colby Rucker,
March 6, 2004 writes: The first iteration is a measure of both maximum
height potential and the diversity of the dominant species. Ten species is
high enough to offset the high numbers associated with the emergent giants,
and low enough so that few sites are pressed into averaging numbers from
interface species that are much smaller than the shorter species on a site
with greater dominant diversity.   Higher numbers in succeeding iterations
are correlated to large acreage and second growth monotony.

Rucker Species Index: The average height of the ten tallest individuals of
a particular species on a site. Concept mentioned first in a post
by Apr 17, 2004 14:51 PDT 

Rucker Species Average Index: The average of the ten highest Rucker
Species Indexes for a particular site. Concept mentioned first in a post
by Apr 17, 2004 14:51 PDT 
(I understand this is not how it was used in a table recently forwarded to

One of the strengths of the Rucker Site index is that it uses the same
criteria for all sites, i.e. 10 species. Some of the recent discussions
have considered the ramifications if the number of species in these indexes
were increased from 10 to 13, 14, or whatever the data would support. I
think these ideas have valid arguments in their favor and some drawbacks as
well, but certainly the options should be explored. I myself have posted
suggesting a Rucker 20 Site Index incorporating the tallest 20 species in
order to encourage measurement of a wider variety of species.    

I propose that for sake of consistency and to allow valid comparisons to be
made between the possible variations, the base Index name be reserved for
those including 10 individuals or averages, no more or no less. If a
number other than 10 is used that number should be included in the index
title or abbreviation. For example if the index was expanded to include 14
species rather than the base ten for a site that would be referred to as a
Rucker 14 Site Index, or Rucker 14 Index. A species average index including
13 species, such as appeared on a table sent to me for MTSF, would be
referred to as a Rucker 13 Species Average Index. This would standardize
the terminology and allow someone to easily differentiate between possible