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A REPORT ON
THE
PERMANENT PLOI' TASK FDRCE
Robert 0. eurtii
ABSTRAcr. A task force on pennanent plot standards has reviewed
problems and needs within the USDA Forest Service and has recommended
ways to improve programs and the quality and consistency of data used
for growth and yield systems. Its reccmnendations are now being
implemented.
INTRODUGriON
In recent years, the Forest Service has becaue increasingly aware of the
need to develop growth and yield systems to meet the needs of the
National Forests. A 1983 in-Service report listed a series of problems
perceived as obstacles to such development within the Forest Service.
One obstacle was "the lack of quantitative growth and yield data over
broad geographic regions and for an array of forest types, which often
limits research, development, and implementation."
Regions and Stations were asked to prepare joint growth and yield action
plans; and to review the needs, infonnation available, and future plans
for their respective areas. These plans were summarized in a 1985
in-Service report that listed issues and recommended several actions at
the national level. Arrong these were the statements ( 1) that "the lack
of quantitative data bases is the primary lirnitation to development and
implementation of m:x:lels, " and ( 2) that there is a need for "provision
for establishment and maintenance of pennanent growth and yield plots on
National Forest lands, " which will "require a well planned long-tenn
data collection and analysis ccmnitment...." One of several specific
recommendations was that the Chief establish a task force including
Timber Management Research, Timber Management, Forest Inventory and
Analysis, and Land Management Planning to develop standards for
1
Principal Mensurationist, USDA Forest Service, Pacific Northwest
Research Station, Forestry Sciences Laboratory, 3625 - 93rd Avenue S.W.,
Olympia, WA 98502.
Presented at the IUFRO Forest Growth Modeling and Prediction Conference,
Minneapolis, MN, August 24-28, 1987.
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establishing permanent plots on National Forest lands to serve growth
and yield research, forest inventory and survey, and rronitaring of
forest plans.
This task force was established in early 1986 and consisted of Dwane Van
Hooser, Jim Brickell, Gyde Lund, Neil L amson, Bob Bailey, and me as
chairman. I will summarize the main points in our report. Though it
may include sane things peculiar to the Forest Service, I think many of
you will recognize our problems in your own organizations.
OBJEcriVES
Our instructions were "to develop standards for establishment of
permanent plots.... " We took this to include the uses of permanent
plots, factors affecting their design and measur ement, and practical
qliestions dealing with organization and objectives, in addition to
measurement procedures. We understood our assignment to refer only to
permanent plots that involve measurement of timber. We did not think we
could or should specify procedures for the entire country in great
detail, and much of our report is a discussion of principles and past
experience that should guide any permanent plot program.
USES OF PERMANENT PLOI'S
Permanent plots have two main uses, to measure change and to determine
how change is influenced by stand attributes and stand treatment.
Two goals can be distinguished (Curtis and Hyink, 1985) : to estimate
the current " growth trend" of the existing forest and to estimate
"response to treatment. "
These goals are not the same, and they generally c annot be met fran the
same data. The different objectives of inventory, monitoring, and
research lead to different plot designs and different sampling designs.
Inventory and monitoring plots represent the growth of the present
forest, which is the result of past actions and past conditions.
For
answers to "what if" questions, such as choices among alternative
treatments and management regimes, or forecasts of the results of stand
treatments different fran those that produced the present forest, we
need data fran research plots that are designed to provide response data
for a wide range of initial conditions and stand treatments.
Growth and yield systems intended to answer the "what if" questions must
rely primarily on research data. Suitable inventory and rronitoring
plots can provide useful supplemental information for system
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construction and are necessary for system calibration,
evaluation,
and
Definitions and measurement standards must be consistent
application.
We must measure the same variables by
for both types of data.
consistent procedures.
Our report included an extended discussion of designs and recanmended a
minimum set of me asurements that should be routine on all permanent
plots that may be used either for system developnent or as input to
system applications.
I am not going to go through these, but I will
mention some past difficulties that have repeatedly been encountered.
PAST PROBLEMS, NEEDS, AND OPPORTUNITIES
DESIGN AND MEASUREivlENT
Historically,
permanent plots have been established by individual
scientists and local v.x::>rk units, for a variety of purposes.
They have
often been useful for purposes other than those originally intended.
Design and me asurement procedures have generally been determined by the
individual or unit.
These individuals and units have differed widely in
knowledge, experience, and objectives and have had similar difficulties
and made similar mistakes.
Inventory plots have perhaps been rrore
standardized, but designs and standards have changed repeatedly and
differ among administrative units.
The result is inconsistency between data sets.
Measurements present in
one set are lacking in another or were taken to different standards not
,easily convertible to a camon basis.
Difficulties are often canpounded
by poor documentation and by differences in data codes and formats.
Screening data and trying to reconcile data from different sources can
be an alrrost endless task,
and one that makes up a substantial part of
the total cost of system developnent.
Additional problems occur repeatedly in much existing data and severely
reduce or destroy their value.
with large edge effects,
These include such things as small plots
ages recorded by broad classes, poor height
samples and sloppy height me asurements, anission of small trees,
and so
on.
As an example,
one may get data for a set of plots that include stand
Is this age at breast height? Total age? An age determined by
age.
boring? Years since planting? Is it an actual average of measured
values, or merely a broad class value? If it is a mean of measured
values, is it based on all tree classes?
Daninants only?
Or what?
On
inquiry, one may discover that the only person who knc:Ms retired last
year and IrOVed to Florida.
The list is endless.
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Permanent plots are expensive, and we cannot afford to have individuals
doing their own thing and repeating past mistakes.
New permanent plots
generally should be established only as part of a carefully planned and
thoroughly reviewed program.
We need minimum standard procedures that
These procedures need to recognize differences
are routinely followed.
in objectives, but they should provide for compatible procedures and
compatible measurements on a
common
set of basic variables.
DATA !'1ANAGEMENT
Database management and data
sunmarization
have been continuing sources
of major costs and frustrations to all who attempt to use or recover
available information.
This is particularly true if the data cane fran
a source over which the current user has no control.
Any system of permanent plots generates huge am:Junts of data that must
be entered, edited, updated, and surnnarized in a variety of ways.
We
have universally underestimated the time and cost and the expertise
required.
The Forest Service has no standard and generally applicable programs for
performing these tasks.
Each unit has developed its own procedures and
programs.
unit capabilities vary widely, and people often are unaware
of what others have already done.
The result has been a large and
redundant expenditure of resources on program developnent, and we still
did not have widely available, efficient, consistent, easy-to-use
standard programs.
QUALITY OJNTROL
Tight quality control is an essential part of any permanent plot
program.
This requires ( 1) defined measurement standards and
procedures,
( 4)
( 2)
field checks,
( 3)
adequate data editing procedures,
specialized personnel with adequate supervision.
and
Plot establishment and remeasurement must be supervised by competent
people for whom this is a major duty.
Personnel on Forest Service
Ranger Districts who spend only a small part of their time on this
activity cannot be expected to have the needed expertise.
OJORDINATION
BE'IWEEN THE NATIONAL FDREST SYSTEM ( NFS) AND RESEARrn
Research staff working in growth and yield and NFS staff concerned with
inventory and management planning have often lacked communication and
understanding.
Many researchers lack familiarity with current
inventory procedures and existing inventory data.
Often they know
canrron
little about the planning process and its information needs.
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Conversely,
they have had little oppJrtunity to influence inventory and
rronitaring procedures to make such data rrore useful and rrore ca.npatible
with research-developed growth and yield information.
There is a need
to p rarote dialogue and carrron understanding.
Much of the existing research permanent plot data is the product of
informal cooperation between NFS and Research.
But there has rarely
been a comprehensive program to establish permanent plots to a
consistent design over a region or
type,
of growth and yield system developnent.
Permanent plots for rronitoring
" growth
specifically to meet the needs
We need such programs.
trends" in operationally managed
But "treatment
stands are logically part of the inventory system.
response" studies are also necessary, and they require a series of
installations across the range of site conditions and possible
treatments.
These installations could be installed and maintained as a
joint effort of Stations and Regions.
Objectives and plans should be
developed jointly by Stations and Regions, with Stations having primary
responsibility for design and data analysis, and NFS much of the
responsibility for maintenance and treatment applications.
a:DPERATION WITH OI'HER OWNERS
National Forest planning inventories and forest plan monitoring are
their nature specific to National Forest ownership.
by
This is not true of data used for rrodel developnent and for evaluation
of treatment reSpJnse and silvicultural altematives.
change their characteristics across a property line.
Species do not
Data frcm similar
lands in other ownerships are equally applicable and are often essential
for broadening the range of combinations of sites, age classes, and
treatments represented.
We in the Forest Service should not be thinking of plots on National
Forest lands as the only source--or even the primary source--of
treatment response information and data for rrodel developnent.
carefully planned cooperative programs that include other owners and
other users of permanent plot data provide major opportunities for
savings in time and rroney and enhanced program effectiveness.
programs can benefit all parties.
These
Cooperatives can be used to roth plan and install permanent plots,
for pool ing and analyzing data.
The leverage they provide makes
and
possible much more extensive programs than would be possible for either
the Forest Service or any other organization acting independently.
Cooperatives also help to preserve program continuity and to prarote the
use of compatible and consistent data collection procedures.
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Successful cooperative programs require careful planning and long-term
cannibnent.
The Forest Service must be actively involved in program
planning and in subsequent implementation and data analyses to ensure
that p:rogram direction remains consistent with Forest Service needs.
Paying the dues and attending the annual briefing are not enough.
Ccoperatives are often the rrost pranising and rrost cost-effective means
for developing the treatment response information needed for system
developnent.
They may be the only means feasible under prospective
The costs will be far less than
personnel and funding constraints.
those of any attempt to go it alone.
CDNI'INUITY
AND FUNDING
Any p:rogram to develop the needed data bases will require continuity in
programs, procedures, and personnel.
!lbst of our present knowledge and our data bases for growth and yield
work are the product of the past efforts of a few farsighted and
dedicated individuals.
Pe:rrnanent plot programs that depend on the
support and interest of a particular individual are highly vulnerable to
personnel changes, and managers are constantly tempted to sacrifice
long-term goals to irrmediate canpeting needs·.
TASK FORCE REcx::M'-1ENDATIONS
The Task Force made several specific recanrnendations in its report,
which I have condensed here:
Continuity in programs,
1.
There should be:
•
procedures, and personnel are essential.
clear policy direction emphasizing long-term ccmnitrnent,
with attendant guidelines; and •
a funding mechanism that specifically allocates funds to these
activities, rather than leaving allocation to the local managers'
discretion.
2.
Measurements taken and procedures used in inventories, rroni taring,
and stand examinations should
response studies.
similar manner,
be canpatible with those used in treatment
The same basic variables should be measured in a
as specified in the manuals proposed in our report.
3. The Forest Service should adopt a nationwide standard minimum set of
core variables to be used on all permanent plots that include
measurement of timber.
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There is need for:
•
national manual direction documenting the core requirements for
permanent plot procedures and measurements; and
•
Region and Station handbooks documenting Region and Station
standard procedures, including but not limited to the standard·
minimum set of variables.
These should be subject to Washington
Office review and approval.
Where feasible and appropriate, definitions, standards,
and
reccmmendations in the Task Force report should be incorporated in the
new "Resource Inventory Handboo k"
(discussed by Lund,
in press), now in
preparation.
4.
Several research scientists with growth and yield backgrounds should
be added to the working group preparing the Forest Service "Resource
Inventory Handbook" ( 1) to prcxrDte consistency and compatibility between
research definitions and needs and those used by NFS and Forest
Inventory and Analysis, and ( 2) to ensure that guidelines for monitoring
are based on a common understanding of definitions and objectives and
will produce data compatible with prospective growth and yield system
needs.
5. The Forest Service should have standard ccmputer prcgrams for
database management and permanent plot data surrmarization, with versions
suitable for use on microcomputers and on its Data General
minicanputers.
Programs and procedures now in use should be surveyed to identify
( 1)
( 2) further developnent needed
to produce generally applicable systems; and ( 3) documentation,
the systems best suited to general use;
training,
6.
and support needed to make these systems widely available.
Within each Region in the National Forest System, the primary
responsibility for training, quality control, manual developnent,
forth, should be given to one person with expertise in this area.
and so
Responsibility for plot installation and maintenance should be at the
Forest level rather than at the District level, with technical
coordination and data management at the Region and Station level.
7.
Policy direction and funding procedures should specifically
encourage cooperative arrangements with other land management and
research organizations for collecting, sharing, and analyzing data.
The
Forest Service should be active in the planning and operation of such
cooperatives.
1087
IMPLEMENTATION
The Task Force recanmendations have been accepted in principle, and
Only time will tell the
me asures to implement them are nt::M in progress.
extent of the changes, but we feel that the Task Force has clarified the
problems and pointed the organization toward better coordination and
rrore effective work in this area.
The Task Force has certainly been a
valuable educational experience for its members.
LITERATURE CITED
CUrtis, R. 0., and D. M. Hyink.
1985.
Data for growth and yield
rrodels.
In:
D. D. Van Hooser and N. Van Pelt, caupilers.
Proceedings--Growth and yield and other rnensurational tricks:
regional technical conference.
a
United States Department of
Agriculture Forest Ser.vice, General Technical Report INT-193.
p. 1-5.
Lund, H. Gyde.
(In press).
Developing resource inventory policies for
national land and resource evaluating and planning.
In:
H. Gyde
Lund, Miguel caballero-Deloya, and Raul Villareal-Canton, eds.
and resource for national planning in the tropics.
Land
United States
Department of Agriculture Forest Service, General Technical Report
wo.
1088