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FOREST SERVICE HANDBOOK
DENVER, CO
FSH 2409.17 - SILVICULTURAL PRACTICES HANDBOOK
R2 Supplement No. 2409.17-92-2
Effective September 20, 1992
POSTING NOTICE. Supplements to this title are numbered consecutively. Post by
document name. Remove entire document and replace with this supplement.
Retain this transmittal as the first page of this document. The last supplement to
this Handbook was Supplement 2409.17-92-1 to Chapter 8.
Document Name
2409.17,9
Superseded New
(Number of Pages)
9
Digest: Updates Chapter 9, Sections 9.04d, 9.11b, and 9.12. Adds new regional stocking
guides. Supplement has 6 hard copy exhibits.
ELIZABETH ESTILL
Regional Forester
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9.04d - Forest Silviculturists. Where Land Management direction is unique to a
Forest, or where the expected response to stocking control is different for specific
geographic areas (Forests) and/or different habitat types, additional management
zones may be needed. Forest Silviculturists shall provide direction and input for
creating additional stocking charts as needed.
9.11b - Format. Stocking charts have been developed to comply with the Forest
Service National Standard. The stocking charts displayed in Exhibits 1-6 are
expressed in the Gingrich format. The Gingrich format has been adopted as the
National Forest system's standard for stocking guides because of it's simplicity and
ease of use. The vertical axis represents basal area (BA) and the horizontal axis
represents trees per acre (TPA). The sloping lines represent the Quadratic Mean
Diameter (QMD) of the stand. These lines are the description of a mathematical
relationship and are not based on a biological relationship.
9.12 - New Regional Stocking Guides. The stocking charts are to be used to
implement intermediate cuttings in even-aged, suitable timberland stands to
effectively meet land management direction and as guideline for individual stand
management.
The curves on the charts are expressions of biological relationships of stand density.
The top curve is the line of Average Maximum Density (AMD). This is the AMD
that occurs in natural, undisturbed stand of a given Quadratic Mean Diameter
(QMD). The AMD line is not meant to be the same as the maximum stand density
index line for the species.
Using the AMD relationships as a reference line, stocking charts were developed to
be compatible with the national standard format. The management zones (shaded
areas) are based on the assumption that timber is the dominate resource and may
have to be modified for other resources.
The Upper Limit Management Zone Curve (ULMZ, the top end of the shaded area)
represents the stocking level above which stand growth is reduced and the stand
tends toward stagnation. The Upper Limit Management Zone for spruce-fir, aspen,
lodgepole pine, and ponderosa pine (55, 60, 55, and 60 percent Relative Density,
respectively) are placed at the relative stand density where board foot volume
production is expected to be maximized on the best sites based on projection using
the whole stand model RMYLD.
For spruce-fir, lodgepole, and ponderosa pine, these density levels are in the high
risk category for infestation by bark beetles (Dendroctonus spp.) It is not intended
that stands be managed at or above this level of density. When stand competition
approaches this level, this should be a signal to the silviculturist that stocking
reduction may be appropriate because stand growth rates are being reduced due to
excessive competition and the risk of loss to bark beetle infestations is high. This
curve is expressed as a Relative Density (RD) percent which is a percentage of the
AMD curve.
The Lower Limit Management Zone curve (LLMZ, the lower end of the shaded area)
represents the stocking level below which site occupancy by the stand is lost and
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regeneration or invasion by competing vegetation would occur. This would result in
stand structures that are not even-aged.
This curve is also expressed as an RD percent. This lower level is at 20 percent
relative density for coniferous types. A higher level of 30 percent was set for aspen
to portray higher stand densities needed to minimize invasion by more tolerant
species.
The vertical lines at the right of the management zones are based on yield
projections using RMYLD in stands at various initial densities which receive no
additional intermediate density control throughout a rotation. Initial densities
greater than this right boundary were projected to have a negative impact on stand
board foot yield at rotation. The vertical lines at the lower left of the management
zone correspond to Regional minimum stocking standards for regenerated stands
(refer to FSH 2409.26b, chapter 70).
Regional Stocking Charts. Stocking charts for the major tree species in Region 2
can be found in exhibits 01-06. The charts and how they relate to forest cover types
are shown in Table 1.
TABLE 1
FOREST COVER TYPE
APPLICABLE STOCKING CHART
Aspen
Blue spruce
Bristlecone pine
Douglas-fir
Engelmann spruce
Engelmann spruce-Subalpine fir
Limber pine
Lodgepole pine
Jack pine
Ponderosa pine
Whitebark pine
White fir
White spruce
Pinyon-juniper
Aspen
Spruce-fir
Ponderosa pine
Douglas-fir/mixed conifer
Spruce-fir
Spruce-fir
Ponderosa pine
Lodgepole pine
Lodgepole pine
Ponderosa pine
Ponderosa pine
Douglas-fir/mixed conifer
Spruce-fir
Pinyon-juniper
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9.12 - Exhibit 01
R-2 STOCKING CHART FOR ENGELMANN SPRUCE-SUBALPINE SPRUCE
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 01
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9.12 - Exhibit 02
R-2 STOCKING CHART FOR ASPEN
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 02
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9.12 - Exhibit 03
R-2 STOCKING CHART FOR LODGEPOLE PINE
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 03
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9.12 - Exhibit 04
R-2 STOCKING CHART FOR PONDEROSA PINE
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 04
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9.12 - Exhibit 05
R-2 STOCKING CHART FOR PINYON-JUNIPER
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 05
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9.12 - Exhibit 06
R-2 STOCKING CHART FOR DOUGLAS-FIR/MIXED CONIFER
SEE THE PAPER COPY OF THE MASTE SET
FOR SECTION 9.12 - EXHIBIT 06