APPENDIX J 

NFMA ANALYSIS 

EXISTING AND HISTORICAL VEGETATION 

 
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J-1 

APPENDIX J 

NFMA Analysis 

Existing and Historical Vegetation 

This appendix presents a characterization of historical and existing vegetation conditions for a large landscape called the South George planning area. Five upland-forest indicators were used for analysis: 

potential vegetation, species composition, forest structure, tree density, and insect and disease 

susceptibility. 

The vegetation information summarized in this appendix was developed using the Most Similar Neighbor 

(MSN) imputation process (Crookston et al. 2002, Moeur and Stage 1995). The MSN algorithm uses 

canonical correlation analysis to derive a similarity function, and then chooses the most similar stand as a 

proxy from the global set of stands by comparing detailed design attributes (local variables) and lowerresolution indicator attributes (global variables). The most similar stand is selected by using the 

similarity function to maintain multivariate relationships between the global variables and the local 

variables. 

The South George planning area contains approximately 20,640 acres of National Forest System lands 

and was formed by combining two subwatersheds: South Fork Asotin Creek and George Creek. This 

appendix considers all 20,640 acres located in the planning area; acreages are rounded to nearest 10 acres. 

Potential Vegetation 

In the South George planning area, 34 potential vegetation types (PVTs) were identified (Table J-1). 

Twenty-seven of the PVTs are forest types, comprising 75% of the analysis-area acreage, and the other 

seven PVTs are nonforest types (25% of the planning area). 

PVTs representing equivalent temperature and moisture environments have been aggregated into higherlevel hierarchical units called plant association groups (PAG) and potential vegetation groups (PVG) 

(Powell et al. 2007). The 27 forest PVTs in the South George planning area were aggregated into 7 PAGs 

and 3 PVGs (table J-1) by using the information from Powell et al. (2007). 

The upland forest PVGs are dry forest (24% of forested acreage), moist forest (74%), and cold forest 

(only 2%). This appendix uses upland forest PVGs when reporting vegetation conditions for the South 

George planning area. Table J-2 presents certain biophysical characteristics of the forest PVGs. 

Species Composition 

Plant species occur in either pure or mixed communities called cover types. Tree species occurrence in 

the planning area was categorized by forest cover type, a classification of existing vegetation composition 

(Eyre 1980). Forest cover types reflect current tree species amounts in the South George planning area. 

Forest cover types are based on a predominance of tree stocking and are seldom pure – the grand fir type, 

for example, has a majority (50% or more) or plurality of grand fir trees but could also contain Douglasfir and other tree species (Eyre 1980). 
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Table J-3 summarizes existing species composition for the South George planning area. It shows that the 

predominant forest cover type is grand fir (36% of the planning area has grand fir as the majority or 

plurality species), followed by the Douglas-fir (12%) and ponderosa pine (11%) cover types. 

Note that the western larch and lodgepole pine forest cover types are relatively uncommon because each 

of them occupies less than 2% of the South George planning area (Table J-3).

Table J-1 Potential Vegetation Types (PVT) of the South George Planning Area 

PVG PVT and PAG PVT Acronym Acres 

Percent

of Total

Percent 

of Forest 

Dry Upland Forest

(3,672 acres; 18%) 

ponderosa pine/bitterbrush/elk sedge PIPO/PUTR/CAGE 70 < 1 1 

Douglas-fir/pinegrass PSME/CARU 300 1 2 

Douglas-fir/common snowberry PSME/SYAL 410 2 3 

Douglas-fir/ninebark PSME/PHMA 1,160 6 8 

Douglas-fir/big huckleberry PSME/VAME 300 2 2 

grand fir/elk sedge ABGR/CAGE 450 2 3 

grand fir/pinegrass ABGR/CARU 640 3 4 

grand fir/birchleaf spiraea ABGR/SPBE 340 2 2 

Warm dry upland forestland PAG 3,670 18 24 

Moist Upland Forest 

(11,503 acres; 56%) 

subalpine fir/false bugbane ABLA2/TRCA3 260 1 2 

subalpine fir/queencup beadlily ABLA2/CLUN 90 < 1 1 

subalpine fir/big huckleberry ABLA2/VAME 720 4 5

subalpine fir/twinflower ABLA2/LIBO2 590 3 4 

lodgepole pine(gf)/twinflower PICO(ABGR)/LIBO2* 40 < 1 < 1 

lodgepole pine(gf)/big huckleberry/pinegrass PICO(ABGR)/VAME/CARU* 50 < 1 < 1 

lodgepole pine(sf)/big huckleberry PICO(ABLA2)/VAME* 290 1 2 

lodgepole pine(sf)/big huckleberry/pinegrass PICO(ABLA2)/VAME/CARU* 110 1 1 

grand fir/twinflower ABGR/LIBO2 3,680 18 24 

grand fir/queencup beadlily ABGR/CLUN 1,760 9 11

grand fir/big huckleberry ABGR/VAME 2,940 14 19 

grand fir/grouse huckleberry-twinflower ABGR/VASC-LIBO2 10 < 1 < 1 

Cool moist upland forestland PAG 10,540 51 68 

grand fir/false bugbane ABGR/TRCA3 190 1 1 

grand fir/sword fern-ginger ABGR/POMU-ASCA3 150 1 1 

Cool very moist upland forestland PAG 340 2 2 

grand fir/Pacific yew/queencup beadlily ABGR/TABR/CLUN 260 1 2 

Cool wet upland forestland PAG 260 1 2 

Douglas-fir/oceanspray PSME/HODI 70 < 1 1 

Warm moist upland forestland PAG 70 < 1 1 

grand fir/Rocky Mountain maple ABGR/ACGL 290 1 2

Warm very moist upland forestland PAG 290 1 2 

Cold UF

(1%) 

subalpine fir/rusty menziesia ABLA2/MEFE 80 < 1 1 

grand fir/grouse huckleberry ABGR/VASC 180 1 1 

Cold moist upland forestland PAG 260 1 2 

st

(5,206 

acres; 

bluebunch wheatgrass-Sandberg’s bluegrass AGSP-POSA3 750 4 

mountain-mahogany/ID fescue-blue. wheat. CELE/FEID-AGSP 10 < 1 

Idaho fescue-bluebunch wheatgrass FEID-AGSP 3,730 18 

Idaho fescue (alpine) FEID (alpine)* 10 < 1 
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ninebark-common snowberry PHMA-SYAL* 630 3 

Sandberg’s bluegrass-onespike oatgrass POSA3-DAUN 10 < 1 

western needlegrass STOC* 70 < 1 

Nonforest PVTs 5,210 25 

Sources/Notes: Summarized from the South George vegetation database (NFS lands only). Powell et al. (2007) describes how PVTs were assigned to potential vegetation groups (PVG) and plant association groups (PAG).

* These PVTs are plant community types or plant communities; all others are plant associations. 

Table J-2 Biophysical characteristics for upland forest potential vegetation groups (PVG) 

PVG 

Area 

(Acres) 

Disturbances Fire 

Regime 

Patch 

Size 

Elevation 

(Feet) 

Slope 

(Percent) 

Dominant 

Aspects 

Dry 

Upland 

Forest 

3,670 Fire 

Insects

Harvest 

Frequent

Surface 

1-3,000 4,500 

(3410-5560)

40 

(10-60) 

Southeast 

South 

Southwest 

Moist 

Upland 

Forest 

11,500 Insects

Fire 

Diseases

Infrequent

Mixed 

1-10,000 4,960 

(3630-5970)

30 

(0-60) 

Southeast 

South 

Southwest 

Cold 

Upland 

Forest 

260 Wind 

Insects

Fire 

Replacem

ent 

1-5,000 Elevation, slope, and aspect were not 

summarized for the Cold PVG because it has 

too few acres to analyze. 

Sources/Notes: Area, elevation, slope, and aspects were derived from the South George 

vegetation database (NFS lands only). Patch size was taken from Johnson (1993). For elevation 

and slope, values are presented in this format: average (minimum-maximum). Fire regime 

names correspond to Schmidt et al. (2002). Disturbances and fire regimes were supplied by the 

author. 

Table J-3 Existing species composition (cover types) for the South George planning area 

Code Cover Type Description Acres 

Pct. of 

Total 

Pct. of 

Forested

Nonforest Nonforest cover types on lands with a nonforest site potential 5,210 25 

Herb-shrub Nonforest cover types on lands with a forest site potential 210 1 1 

PIPO Forest with ponderosa pine as the majority species 1,740 8 11 

mix-PIPO Mixed forest with ponderosa pine as the plurality species 510 3 3 

Ponderosa pine Forest with ponderosa pine as the majority or plurality species 2,250 11 15 

PSME Forest with Douglas-fir as the majority species 2,120 10 14 

mix-PSME Mixed forest with Douglas-fir as the plurality species 360 2 2 

Douglas-fir Forest with Douglas-fir as the majority or plurality species 2,480 12 16 

LAOC Forest with western larch as the majority species 310 2 2 

mix-LAOC Mixed forest with western larch as the plurality species 0 0 0 

Western larch Forest with western larch as the majority or plurality species 310 2 2 

PICO Forest with lodgepole pine as the majority species 80 < 1 1 

mix-PICO Mixed forest with lodgepole pine as the plurality species 220 1 1 

Lodgepole pine Forest with lodgepole pine as the majority or plurality species 300 2 2 

ABGR Forest with grand fir as the majority species 5,970 29 39 

mix-ABGR Mixed forest with grand fir as the plurality species 1,510 7 10 

Grand fir Forest with grand fir as the majority or plurality species 7,480 36 49 

PIEN Forest with Engelmann spruce as the majority species 350 2 2 
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mix-PIEN Mixed forest with Engelmann spruce as the plurality species 1,550 8 10 

Engelmann spruce Forest with Engelmann spruce as the majority or plurality species 1,900 9 12 

ABLA2 Forest with subalpine fir as the majority species 240 1 2 

mix-ABLA2 Mixed forest with subalpine fir as the plurality species 280 1 2 

Subalpine fir Forest with subalpine fir as the majority or plurality species 520 3 3 

Sources/Notes: Summarized from the South George vegetation database (NFS lands only). Forest cover types where 

one tree species comprises a majority of the composition (50% or more) are named for the species (Eyre 1980). For 

a cover type where no single species predominates, it is named for the plurality species preceded by “mix” to denote 

a mixed-species composition. 

About 25% of the South George planning area supports nonforest vegetation (Table J-1), much of which 

consists of dry meadows and bunchgrass communities dominated by Idaho fescue or bluebunch wheatgrass. In the context of the Umatilla National Forest, the South George planning area contains a higher 

proportion of nonforest vegetation than the Forest as a whole (Christensen et al. 2007). 

HRV Analysis for Species Composition

An historical range of variability (HRV) analysis was used to evaluate species composition for the South 

George planning area; HRV results are presented in Table J-4. It summarizes the current amount of each 

forest cover type by potential vegetation group (PVG), and the historical range is also shown. 

The information presented in Table J-4 suggests that the dry upland forest PVG currently supports too 

much of the Douglas-fir and grand fir forest cover types, and too little of the ponderosa pine cover type 

(Table J-4a); the moist forest PVG (Table J-4b) supports too much of the grand fir and spruce-fir forest 

cover types, and too little of the lodgepole pine, western larch, and Douglas-fir cover types. 

Even though percents and acreages are presented for the cold forest PVG (Table J-4c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-4a HRV analysis for species composition on the dry upland forest PVG 

 Historical Range Current Amount 

Cover Type Percent Acres Percent Acres HRV Interpretation 

Grass-forb 0-5 0-180 0 0 At low end of historical range 

Shrub 0-5 0-180 0 0 At low end of historical range 

Western juniper 0-5 0-180 0 0 At low end of historical range 

Ponderosa pine 50-90 1840-3310 32 1160 Below the historical range 

Douglas-fir 5-20 180-730 45 1670 Well above the historical range 

Western larch 0-10 0-370 0 0 At low end of historical range 

Broadleaved trees 0-5 0-180 0 0 At low end of historical range 

Lodgepole pine 0-5 0-180 0 0 At low end of historical range 

Grand fir 1-10 40-370 23 850 Well above the historical range 
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Table J-4b HRV analysis for species composition on the moist upland forest PVG 

 Historical Range Current Amount 

Cover Type Percent Acres Percent Acres HRV Interpretation 

Grass-forb 0-5 0-580 2 210 Within the historical range 

Shrub 0-5 0-580 0 0 At low end of historical range 

Ponderosa pine 5-15 580-1730 9 980 Within the historical range 

Douglas-fir 15-30 1730-3450 7 810 Below the historical range 

Western larch 10-30 1150-3450 3 310 Below the historical range 

Broadleaved trees 1-10 120-1150 0 0 Below the historical range 

Lodgepole pine 10-25 1150-2880 3 300 Below the historical range 

Western white pine 0-5 0-580 0 0 At low end of historical range 

Grand fir 15-30 1730-3450 58 6630 Well above historical range 

Spruce-fir 1-15 120-1730 20 2260 Above the historical range 

Table J-4c HRV analysis for species composition on the cold upland forest PVG 

 Historical Range Current Amount 

Cover Type Percent Acres Percent Acres HRV Interpretation 

Grass-forb 0-5 0-10 0 0 

This PVG contains too few acres 

(only 260) for an HRV analysis, 

which should not be completed 

for PVGs having less than 1,000 

acres in a planning area. It is 

also not appropriate to add the 

cold PVG acreage to another 

PVG for analysis purposes 

because each PVG represents a 

unique biophysical environment. 

Shrub 0-15 0-40 0 0 

Ponderosa pine 0-5 0-10 42 110 

Douglas-fir 5-15 10-40 0 0 

Western larch 5-15 10-40 0 0 

Broadleaved trees 0-5 0-10 0 0 

Lodgepole pine 25-45 60-120 0 0 

Grand fir 5-15 10-40 0 0 

Whitebark pine 0-10 0-30 0 0 

Spruce-fir 20-40 50-100 58 150 

Sources/Notes for tables A4a to A4c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Historical ranges were adapted by the author of this specialist

report from Morgan and Parsons (2001); they were based on multiple 1200-year simulations 

representing landscapes in a dynamic equilibrium with their disturbance regimes. 

Historical Species Composition

Two historical maps supplied species composition reference conditions for the South George planning 

area (Tables A5 and A6). 

The earliest historical mapping was based on the original public land survey completed for the Umatilla 

National Forest between 1879 and 1887 (table J-5). It shows that almost half of the South George 

planning area was dominated by deciduous conifer forest in the late 1800s (western larch; 45% of the 

area), followed by mixed-conifer forest with a predominance of either Douglas-fir or grand fir (38% of 

the area for three mixed-conifer types combined) and open ponderosa pine savanna (15% of the area). 
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Table J-5 Historical species composition for the South George planning area in the 1880s era 

Ecological System Name (from NatureServe 2003) Acres Percent 

No Trees (section corners & quarter corners without any bearing trees) 50 < 1 

Northern Rocky Mountain Lower Montane Riparian Woodland & Shrubland (riparian forest) 260 1 

Rocky Mountain Lower Montane Riparian Woodland & Shrubland (riparian forest) 2 < 1 

Rocky Mountain Ponderosa Pine Woodland (open ponderosa pine savanna) 3160 15 

Northern Rocky Mountain Montane Mixed Conifer Forest (mixed grand fir forest) 2760 13 

Rocky Mountain Montane Mesic Mixed Conifer Forest & Woodland (mixed grand fir forest) 260 1 

Rocky Mountain Montane Dry-Mesic Mixed Conifer Forest & Woodland (mixed Douglas-fir forest) 4870 24 

Northern Rocky Mountain Western Larch Woodland & Forests (western larch forest) 9290 45 

Rocky Mountain Subalpine Mesic Spruce-Fir Forest & Woodland (spruce-fir forest) 10 < 1 

Sources/Notes: Summarized from General Land Office survey notes collected at section corners and quarter-section corners between 1879 and 1887. Bearing-tree characteristics (species, diameter, and distance from corner) 

were entered into a database and then used to spatially interpolate species composition information across the 

Umatilla National Forest by using kriging and co-kriging analytical procedures (Powell 2008). 

The second historical map depicts composition conditions as they existed in the mid 1950s (Spada et al. 

1957), about 50 years before present (Table J-6 and figure A1). It shows that ponderosa pine forest was 

the predominant cover type, occupying more than 40 percent of the planning area acreage, followed by 

nonforest types (19%), grand fir forest (15%), and Douglas-fir forest (12%). 

Table J-6 Historical species composition for the South George planning area in 1957 

Mapped Type Inferred Vegetation Conditions Acres 

Percent

of Total

Percent 

of Forested

Douglas-fir Douglas-fir is the majority or plurality species 2,470 12 15 

Grand fir Grand fir is the majority or plurality species 3,180 15 19 

Lodgepole-Larch Lodgepole pine and western larch are the plurality species 1,980 10 12 

Ponderosa pine Ponderosa pine is the majority or plurality species 8,360 41 50 

Spruce-fir Engelmann spruce & subalpine fir are the plurality species 800 4 5 

Nonforest Nonforest cover types 3,840 19 

Sources/Notes: Summarized from “Forest type map of southeast Washington” (Spada et al. 1957). The author of 

this specialist report interpreted the 1957 map legend to derive the “inferred vegetation conditions.”
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Douglas-fir

Grand fir

Lodgepole pine-western larch

Nonforest

Ponderosa pine

Spruce-fir

Unknown

Figure A1 – Species composition reference conditions as they existed about 1957 (derived from a forest type map 

for southeast Washington, as prepared by Spada et al. 1957 – see sources and notes for Table J-6). 

Forest Structure 

Oliver and Larson (1996) developed a forest structure classification system incorporating four structural 

stages. Oliver and Larson’s (1996) system works well for conifer forests west of the Cascade Mountains, 

but it does not adequately characterize the diverse structural conditions of the interior Pacific Northwest. 

Therefore, the Oliver and Larson (1996) system was expanded to eight classes to include a wider 

spectrum of structural variation (O’Hara et al. 1996). 

Table J-7 uses the 8-class system developed by O’Hara et al. (1996) to summarize the acreages and 

percentages of forest structural stages for the South George planning area. It shows that the predominant 

structural stage is understory reinitiation (UR), followed by old forest single stratum (OFSS), stem 

exclusion open canopy (SEOC), and old forest multi strata (OFMS). 

Table J-7 shows that stand initiation (SI) and young forest multi strata (YFMS) are relatively uncommon 

structural stages – each of them occupies less than 5 percent of the South George planning area. 
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Table J-7 Existing forest structural stages for the South George planning area 

Code Forest Structural Stage Name Acres 

Percent 

of Total 

Percent 

of Forested

BG Bare Ground 0 0 0 

SI Stand Initiation 570 3 4 

SEOC Stem Exclusion Open Canopy 2,200 11 14 

SECC Stem Exclusion Closed Canopy 1,540 8 10 

UR Understory Reinitiation 4,610 22 30 

YFMS Young Forest Multi Strata 330 2 2 

OFMS Old Forest Multi Strata 1,720 8 11 

OFSS Old Forest Single Stratum 4,460 22 29 

NF Nonforest: grassland and shrubland 5,210 25 

Sources/Notes: Summarized from the South George vegetation database (NFS lands 

only). Forest structural stages are described in O’Hara et al. (1996). Structural stage, a 

derived field in the database, was calculated using queries from Hessburg et al. (1999a). 

HRV Analysis for Forest Structural Stages

An historical range of variability (HRV) analysis was used to evaluate forest structure for the South 

George planning area; HRV results are provided in Table J-8. It summarizes the current amount of each 

forest structural stage by potential vegetation group (PVG), and the historical range is also shown. 

For the dry forest PVG (Table J-8a), analysis results show that two structural stages are below HRV 

(stand initiation and young forest multi strata), and that one stage is above HRV (understory reinitiation). 

The other four stages (both forms of stem exclusion and both forms of old forest) are within their 

historical ranges. 

For the moist forest PVG (Table J-8b), two stages are below HRV (young forest multi strata and old 

forest multi strata), two stages are above HRV (stem exclusion open canopy and old forest single 

stratum), and the other three stages are within HRV (stand initiation, stem exclusion closed canopy, and 

understory reinitiation). 

Even though percents and acreages are presented for the cold forest PVG (Table J-8c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

The wildlife standard from the Eastside Screens (Forest Plan amendment #11; USDA Forest Service 

1995) has two possible scenarios to follow as based on HRV results for late-old structural stages (LOS), 

and it defines LOS to be the old forest multi strata and old forest single stratum structural stages. 

The wildlife standard directs that one of two scenarios is to be used: 

1. Scenario A is to be used whenever either one of the LOS stages is below HRV. If both LOS stages 

occur within a single PVG and one is within or above HRV and one below, scenario A is to be used. 

2. Scenario B is only to be used when both LOS stages for a particular PVG are within or above HRV. 

For the dry and moist PVGs, results of the Eastside Screens wildlife standard are presented in the Screens 

Interpretation columns of Tables A8a and A8b. 
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Table J-8a HRV analysis for forest structural stages on the dry upland forest PVG 

 Historical Range Current Amount HRV Screens 

Structural Stage Percent Acres Percent Acres Interpretation Interpretation 

Stand initiation 5-15 180-550 4 130 Below HRV 

Stem exclusion OC 5-20 180-730 8 280 Within HRV 

Stem exclusion CC 1-10 40-370 7 260 Within HRV 

Understory reinitiation 1-10 40-370 24 880 Above HRV 

Young forest MS 5-25 180-920 1 20 Below HRV 

Old forest MS 5-20 180-730 17 640 Within HRV 

Scenario B Old forest SS 15-55 550-2020 40 1450 Within HRV 

Table J-8b HRV analysis for forest structural stages on the moist upland forest PVG 

 Historical Range Current Amount HRV Screens 

Structural Stage Percent Acres Percent Acres Interpretation Interpretation 

Stand initiation 1-10 120-1150 3 400 Within HRV 

Stem exclusion OC 0-5 0-580 17 1910 Above HRV 

Stem exclusion CC 5-25 580-2880 11 1290 Within HRV 

Understory reinitiation 5-25 580-2880 30 3510 Within HRV 

Young forest MS 40-60 4600-6900 3 310 Below HRV 

Old forest MS 10-30 1150-3450 9 1080 Below HRV 

Scenario A Old forest SS 0-5 0-580 26 3010 Above HRV 

Table J-8c HRV analysis for forest structural stages on the cold upland forest PVG 

 Historical Range Current Amount HRV Screens 

Structural Stage Percent Acres Percent Acres Interpretation Interpretation 

Stand initiation 1-20 3-50 16 40 This PVG contains too few acres (only 

260) for an HRV analysis, which should 

not be completed for PVGs having less 

than 1,000 acres in a planning area. It is 

also not appropriate to add the cold 

PVG acreage to another PVG for 

analysis purposes because each PVG 

represents a unique biophysical 

environment. 

Stem exclusion OC 0-5 0-10 0 0 

Stem exclusion CC 5-20 10-50 0 0 

Understory reinitiation 5-25 10-60 84 220 

Young forest MS 10-40 30-100 0 0 

Old forest MS 10-40 30-100 0 0 

Old forest SS 0-5 0-10 0 0 

Sources/Notes for Tables A8a to A8c: Current amounts are summarized from the South George vegetation 

database (NFS lands only). OC refers to open canopy and CC to closed canopy; MS refers to multi strata and SS 

to single stratum. Upland forest potential vegetation groups (PVG) are described in Table J-1 and Powell et al. 

(2007). Historical percentages (H%) were derived from Hall (1993), Johnson (1993), and USDA Forest Service 

(1995), as summarized in Blackwood (1998). Forest structural stages are enumerated in Table J-7. For the 

purposes of an HRV analysis, the bare ground structural stage is combined with the stand initiation stage. 

Historical Forest Structural Stages

An historical map depicts forest structural stages as they existed in the mid 1950s (Spada et al. 1957), 

about 50 years before present (Table J-9 and figure A2). It shows that in the mid 1950s, about 60 percent 

of the South George planning area was dominated by old forest structural stages (the OFMS and OFSS 

stages; 60.1% of the acreage), followed by dense stands of relatively small-diameter trees (SECC; 15.9% 

of the acreage) and multi-layer stands (UR; 4.5% of the area). 
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Table J-9 Historical forest structural stages for the South George planning area 

Code Forest Structural Stage Name Acres 

Percent 

of Total 

Percent 

of Forested

BG Bare Ground 0 0 0 

SI Stand Initiation 100 1 1 

SEOC Stem Exclusion Open Canopy 100 1 1 

SECC Stem Exclusion Closed Canopy 3,280 16 20 

UR Understory Reinitiation 920 5 6 

YFMS Young Forest Multi Strata 0 0 0 

OFMS Old Forest Multi Strata 3,120 15 19 

OFSS Old Forest Single Stratum 9,280 45 55 

NF Nonforest: grassland and shrubland 3,840 19 

Sources/Notes: Summarized from “Forest type map of southeast Washington” (Spada et 

al. 1957). Forest structural stage codes and names are the same as those for Table J-7. 

Existing Forest Canopy Layering

One aspect of forest structure examines how the leaf area of a forest stand is arranged in a vertical 

dimension. Information about vertical forest structure indicates whether a stand has a single canopy 

layer, where canopy biomass is concentrated in a discrete band well above the ground, or if it has multiple 

layers resulting in continuous foliage from the ground surface up to the top of the tree canopy. 

After fires became larger and more severe in the mid 1990s, there was heightened concern about canopy 

layering because understory layers function as ladder fuel – like a ladder, low canopy layers are able to 

lift a surface fire up into the tree crowns, allowing it to spread rapidly as a crown fire. And because 

crown fires often consume most of a forest’s canopy foliage, they typically cause high amounts of tree 

mortality. 

Table J-10 summarizes the acreages and percentages of forest canopy layering for the South George 

planning area. It shows that the predominant canopy layering condition is single layer (61% of forested 

acreage), with the balance consisting of multiple layers (39%). 

Table J-10 Existing forest canopy layering for the South George area 

Forest Canopy Layering Description Acres 

Percent 

of Total 

Percent 

of Forested

Single layer 9,460 46 61 

Multiple layers 5,970 29 39 

None (nonforest polygons) 5,210 25 

Sources/Notes: Summarized from the South George vegetation database (NFS 

lands only). 
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J-11 

Old forest

Understory reinitiation

Stem exclusion

Stand initiation

Other

Figure A2 – Forest structure reference conditions as they existed about 1957 (derived from a forest type map for

southeast Washington, as prepared by Spada et al. 1957 – see sources and notes for table J-9). Note that the two old 

forest stages, and the two stem exclusion stages, as reported in Table J-9, were combined for this map depiction. 

HRV Analysis for Forest Canopy Layering

How much single-layer and multi-layer structure would have occurred historically on upland forest sites? 

Table J-11 presents an historical range of variability (HRV) analysis for canopy layering on upland-forest 

PVGs (Powell 2003). 

Table J-11a shows that for the dry forest PVG, both the single-layer and multiple-layers canopy 

conditions are within their historical ranges of variability. For the moist forest PVG (Table J-11b), both 

the single-layer and multiple-layers canopy conditions are outside their historical ranges of variability. 

Even though percents and acreages are presented for the cold forest PVG (Table J-11c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 
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Table J-11a HRV analysis for forest canopy layering on the dry upland forest PVG 

 Historical Range Current Amount 

Canopy Layering Percent Acres Percent Acres HRV Interpretation 

Single layer 25-100 920-3670 57 2090 Within the historical range 

Multiple layers 10-55 370-2020 43 1580 Within the historical range 

Table J-11b HRV analysis for forest canopy layering on the moist upland forest PVG 

 Historical Range Current Amount 

Canopy Layering Percent Acres Percent Acres HRV Interpretation 

Single layer 6-45 690-5180 64 7330 Above the historical range 

Multiple layers 55-100 6330-11500 36 4180 Below the historical range 

Table J-11c HRV analysis for forest canopy layering on the cold upland forest PVG 

 Historical Range Current Amount 

Canopy Layering Percent Acres Percent Acres HRV Interpretation 

Single layer 6-50 20-130 16 40 No interpretation because this 

Multiple layers 25-100 60-260 84 220 PVG contains too few acres. 

Sources/Notes for Tables A11a to A11c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are described 

in Table J-1 and Powell et al. (2007). Historical ranges were derived from Table J-8: the single-layer 

condition is a combination of SI, SEOC, SECC, and OFSS; the multiple-layers condition is a 

combination of UR, YFMS, and OFMS. 

Tree Density 

Suggested stocking guidelines (Cochran et al. 1994, Powell 1999) were used to analyze existing tree 

density levels for the South George planning area. By using the stocking guidelines in conjunction with 

PVGs, it was possible to estimate how much forest acreage is currently overstocked (Table J-12); the tree 

density analysis protocol is described in Powell (2009c). 

Results of the tree density analysis are summarized in Table J-12; it shows that the South George area has 

a relatively well-balanced distribution of tree density, with about a third of the forested acreage occurring 

in each of the three density categories (low, moderate, high). 

Table J-12 Existing tree density for the South George area 

Tree Density Category Acres 

Percent 

of Total 

Percent 

of Forested

Low 5,250 25 34 

Moderate 5,630 27 37 

High 4,570 22 30 

None (nonforest polygons) 5,210 25 

Sources/Notes: Summarized from the South George vegetation 

database (NFS lands only). Queries for assigning polygons to 

the tree density categories are provided in Powell (2009c). 
South George Vegetation and Fuels Management Project - DEIS 

J-13 

HRV Analysis for Tree Density

An historical range of variability (HRV) analysis was used to evaluate tree density for the South George 

planning area; results are provided in Table J-13. It summarizes the current amount of each tree density 

category by potential vegetation group (PVG), and the historical range is also shown. 

Table J-13a shows that the dry forest PVG has more acreage supporting high-density forest than would be 

expected, and less acreage supporting low-density forest. For the moist forest PVG (Table J-13b), all 

three of the tree density classes are within their historical ranges of variability. 

Even though percents and acreages are presented for the cold forest PVG (Table J-13c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-13a HRV analysis for tree density on the dry upland forest PVG

 Historical Range Current Amount 

Tree Density Class Percent Acres Percent Acres HRV Interpretation 

Low (<45% CC) 40-85 1470-3120 25 920 Below the historical range 

Moderate (45-55%) 15-30 550-1100 28 1020 Within the historical range 

High (>55% CC) 5-15 180-550 47 1730 Well above the historical range 

Table J-13b HRV analysis for tree density on the moist upland forest PVG 

 Historical Range Current Amount 

Tree Density Class Percent Acres Percent Acres HRV Interpretation 

Low (<65% CC) 20-40 2300-4600 36 4170 Within the historical range 

Moderate (65-75%) 25-60 2880-6900 40 4590 Within the historical range 

High (>75% CC) 15-30 1730-3450 24 2750 Within the historical range 

Table J-13c HRV analysis for tree density on the cold upland forest PVG 

 Historical Range Current Amount 

Tree Density Class Percent Acres Percent Acres HRV Interpretation 

Low (<55% CC) 15-30 40-80 61 160 

No interpretation because this 

PVG contains too few acres. Moderate (55-65%) 20-40 50-100 10 30 

High (>65% CC) 25-60 60-160 29 70 

Sources/Notes for Tables A13a to A13c: Current amounts are derived from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are 

described in Table J-1 and Powell et al. (2007). Historical ranges were taken from Schmitt and 

Powell (2008). 

Existing Forest Canopy Biomass

One result of severe wildfire seasons in the late 1990s and early 2000s is that land management activities 

(mechanical thinnings and prescribed fire) are being considered for millions of acres considered to be atrisk for uncharacteristic wildfire behavior and undesirable fire effects (GAO 1999, Gorte 1995, Laverty 

and Williams 2000). 

At-risk areas support uncharacteristic levels of forest canopy biomass (canopy bulk density), rendering 

them vulnerable to crown fire spread (Graham et al. 1999, 2004). Research shows that high canopy 
South George Vegetation and Fuels Management Project - DEIS 

J-14 

biomass causes forest stands to be more vulnerable to crown fire initiation at any age, and it also extends 

the duration of a stand’s exposure to crown fire hazard by 20 to 30 years (Keyes and O’Hara 2002). 

Forest canopy biomass was estimated for the South George planning area by relating stand-level 

thresholds of canopy bulk density to their corresponding stocking levels (Agee 1996, Keyes and O’Hara 

2002); the forest canopy biomass analysis protocol is described in Powell (2005). 

Results of the canopy biomass analysis are summarized in Table J-14. It shows that almost 88% of the 

upland forest acreage in the South George planning area has sufficient forest canopy biomass to sustain a 

crown fire (in Table J-14, 88% is a total for the moderate and high categories combined). 

In the context of the Umatilla National Forest, the South George planning area contains a greater 

proportion of high forest canopy biomass than the Forest as a whole (Christensen et al. 2007). 

Table J-14 Existing forest canopy biomass for the South George area 

Canopy Biomass Category Acres 

Percent 

of Total 

Percent 

of Forested 

Low (≤ .05 kg/m3) 2,130 10 14 

Moderate (.06-.09 kg/m3) 3,730 18 24 

High (≥ .10 kg/m3

) 9,570 46 62 

None (nonforest polygons) 5,210 25 

Sources/Notes: Summarized from the South George vegetation database 

(NFS lands only). Numerical values shown in parentheses for each 

category are canopy bulk density in kg/m3 of canopy volume. Powell 

(2005) provides the basis for assigning polygons to canopy biomass 

categories. 

HRV Analysis for Forest Canopy Biomass

An historical range of variability (HRV) analysis was used to evaluate forest canopy biomass for the 

South George planning area; HRV results are provided in Table A15. It summarizes the current amount 

of each canopy biomass category by potential vegetation group (PVG), and the historical range is also 

shown. 

Table J-15a and A15b show that both the dry and moist upland forest PVGs have more acreage 

supporting high canopy biomass than would be expected, and less acreage supporting low canopy 

biomass. Moderate amounts of forest canopy biomass are either within the historical range (dry PVG; 

Table J-15a) or below the historical range (moist PVG; Table J-15b). 

Even though percents and acreages are presented for the cold forest PVG (Table J-15c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-15a HRV analysis for forest canopy biomass on the dry upland forest PVG 

 Historical Range Current Amount 

Canopy Biomass Class Percent Acres Percent Acres HRV Interpretation 

Low (≤ .05 kg/m3) 60-90 2200-3300 15 530 Well below the historical range 

Moderate (.06-.09 kg/m3) 20-60 730-2200 42 1540 Within the historical range 

High (≥ .10 kg/m3) 10-20 370-730 44 1600 Well above the historical range 
South George Vegetation and Fuels Management Project - DEIS 

J-15 

Table J-15b HRV analysis for forest canopy biomass on the moist upland forest PVG 

 Historical Range Current Amount 

Canopy Biomass Class Percent Acres Percent Acres HRV Interpretation 

Low (≤ .05 kg/m3) 20-50 2300-5750 13 1490 Below the historical range 

Moderate (.06-.09 kg/m3) 50-70 5750-8050 18 2110 Well below the historical range 

High (≥ .10 kg/m3) 20-50 2300-5750 69 7900 Above the historical range 

Table J-15c HRV analysis for forest canopy biomass on the cold upland forest PVG 

 Historical Range Current Amount 

Canopy Biomass Class Percent Acres Percent Acres HRV Interpretation 

Low (≤ .05 kg/m3) 10-20 30-50 42 110 

No interpretation because this 

PVG contains too few acres. Moderate (.06-.09 kg/m3

) 20-60 50-150 30 80 

High (≥ .10 kg/m3) 60-90 150-230 29 70 

Sources/Notes for Tables A15a to A15c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are described in 

Table J-1 and Powell et al. (2007). Historical ranges for canopy biomass classes were derived by the 

author of this specialist report from Agee (1998). 

Insects and Diseases 

Disturbance processes influence forest composition, structure and density (Perera et al. 2004). Although 

many different disturbance processes have influenced vegetation conditions in the South George area to 

varying degrees in the recent past, forest insects have been particularly important as disturbance agents 

(see fig. 2-3). 

Information provided by the Pacific Northwest Region’s aerial survey program was used to assess recent 

impacts from forest insects; annual insect activity was recorded on a “sketch map” (fig. A3). Aerial 

detection sketch maps for a 19-year period (1990-2008) were used to summarize the spatial extent of 

recent activity for three groups of forest insects: defoliators, pine beetles, and mixed-conifer beetles. 

Acreage affected by forest insects in the South George planning area is summarized in figure A4; the 

annual areal extent of insect occurrence in the planning area is portrayed on maps in appendix B. 

Figure A4 shows that pine beetles (this category includes mountain pine beetle in either lodgepole pine or 

ponderosa pine, Ips beetle in pine, and western pine beetle) had relatively little impact in the South 

George planning area since 1990, with the most acreage affected being 680 acres in 2005. 

Figure A4 shows that mixed-conifer beetles (this category includes Douglas-fir beetle, fir engraver, 

spruce beetle, and western balsam bark beetle) had considerable impact in the planning area since 1990, 

with substantial acreage affected in 1990-1991, 2003, and 2007-2008. A quarter or more of the forested 

portion of the South George planning area was affected by mixed-conifer beetles in 1990, 1991, and 

2003. 

Figure A4 shows that defoliating insects (this category includes Douglas-fir tussock moth and western 

spruce budworm) had very little impact in the South George planning area since 1990. But in the late 

1940s and early 1950s, and then again in the 1980s, western spruce budworm was defoliating substantial 

acreages of mixed-conifer forest throughout the Blue Mountains, and we can expect another widespread 

outbreak of this forest insect in the near future. 
South George Vegetation and Fuels Management Project - DEIS 

J-16 

Figure A3 – Example of a sketch map prepared during aerial detection surveys to document the insects and other 

damaging agents affecting an area, and to estimate the magnitude of their impact. This example is for the Clarkston 

100K USGS quadrangle map and it depicts the spatial distribution of damaging agents (the red polygons) recorded 

during the 2009 aerial survey. This quadrangle was selected as an example because it includes the South George 

planning area. Although this sample has been reduced too much from its original size to allow the polygon labels to 

be readable, each of the red areas contains a label denoting the causal agent and a modifier providing an estimate of 

damage severity. A polygon label of 4-1A, for example, means that the primary damaging agent within the polygon 

was fir engraver (code 4 pertains to fir engraver), and that the magnitude or rate of tree damage was 1 tree per acre 

(the 1A portion of the label). This example of polygon labeling also demonstrates that the size of a polygon is 

related exclusively to the spatial distribution of the causal agent and has no bearing on the severity of damage – a 

large polygon can encompass much acreage and yet the damage levels across the area can be relatively light (such as 

1 tree per acre). 

Note: the maps in appendix B characterizing recent insect activity for the South George planning area were prepared 

using information collected from aerial detection surveys and published on maps such as the one shown here. 
South George Vegetation and Fuels Management Project - DEIS 

J-17 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

1990199119921993199419951996199719981999200020012002200320042005200620072008

AFFECTED AREA (Acres)

Other

Defoliators

Pine Beetles

Mixed Conifer Beetles

Figure A4 – Area affected by forest insects in the South George planning area. Affected areas 

(acres) were derived from aerial detection surveys completed by the Pacific Northwest Region of 

the Forest Service. Note that area figures include National Forest System (NFS) lands only. 

“Defoliators” includes Douglas-fir tussock moth and western spruce budworm; “pine beetles” 

includes mountain pine beetle in either lodgepole pine or ponderosa pine, Ips beetle in pine, and 

western pine beetle; and “mixed-conifer beetles” includes Douglas-fir beetle and fir engraver. 

“Other” includes balsam woolly adelgid, wood borers, needle diseases, and other miscellaneous 

agents. 

Existing Insect and Disease Susceptibility

Susceptibility is defined as a set of conditions that make a forest stand vulnerable to substantial injury by 

insects or diseases. Susceptibility assessments do not predict when insects and diseases might reach 

damaging levels; rather, they indicate whether stand conditions are conducive to declining forest health 

and increasing levels of tree mortality caused by insect and disease organisms. 

For this analysis, susceptibility was evaluated for six insect and disease agents because they have 

substantial amounts of habitat (host type) in the South George planning area: defoliators (representing 

western spruce budworm and Douglas-fir tussock moth), Douglas-fir beetle, fir engraver, bark beetles in 

ponderosa pine (representing western pine beetle and mountain pine beetle), dwarf mistletoe in Douglasfir, and root diseases (representing Armillaria and laminated root diseases). 

The insect and disease susceptibility protocol (Schmitt and Powell 2005) includes evaluation factors for 

three other insect or disease agents (spruce beetle, mountain pine beetle in lodgepole pine, and western 

larch dwarf mistletoe), but they were not included in this analysis because they have limited habitat in the 

South George planning area. 
South George Vegetation and Fuels Management Project - DEIS 

J-18 

Drought, ecological site potential (potential vegetation type), species composition and abundance, tree 

size, forest structure (canopy layering; structure class), stocking (tree density), intra-stand variability 

(clumpiness), and other biophysical factors influence susceptibility and vulnerability to insect and disease 

disturbances (Hessburg et al. 1999b, Lehmkuhl et al. 1994, Schmitt and Powell 2005). 

Each of the six agents was rated using four to seven biophysical factors (Douglas-fir beetle, for example, 

had six biophysical rating factors); scores from individual factors were summed and this total score used 

to assign a categorical rating of low, moderate, or high. Schmitt and Powell (2005) provides the basis for 

assigning total score values to a categorical susceptibility rating. 

The insect and disease susceptibility protocol is described in Schmitt and Powell (2005). Results of the 

insect and disease susceptibility assessment are summarized in Table J-16; they show that existing 

susceptibility is relatively high for two insect agents: 

• Defoliators (western spruce budworm and Douglas-fir tussock moth) 

• Fir engraver (a bark beetle species affecting true fir tree species) 

Table J-16 Existing forest insect and disease susceptibility for the South George planning area 

Insect or Disease 

LOW

SUSCEPTIBILITY 

MODERATE 

SUSCEPTIBILITY 

HIGH 

SUSCEPTIBILITY 

Acres Percent Acres Percent Acres Percent 

Bark beetles in ponderosa pine 3,410 22 10,460 68 1,570 10 

Defoliators (budworm/tussock moth) 2,070 13 6,070 39 7,300 47 

Douglas-fir beetle 3,680 24 11,260 73 490 3 

Dwarf mistletoe in Douglas-fir 7,600 49 4,930 32 2,900 19 

Fir engraver 3,640 24 4,280 28 7,510 49 

Root diseases (laminated/Armillaria) 4,340 28 5,580 36 5,520 36 

Sources/Notes: Summarized from the South George vegetation database (NFS lands only). Criteria for 

determining insect and disease susceptibility are described in Schmitt and Powell (2005). Note that susceptibility 

ratings were calculated for each insect or disease agent independently, so it is not appropriate to sum the acreage or 

percent values (down a column) by category. 

HRV Analysis for Susceptibility to Bark Beetles in Ponderosa Pine

An historical range of variability (HRV) analysis was used to evaluate susceptibility to bark beetles in 

ponderosa pine (western and mountain pine beetles) for the South George planning area; results are 

provided in Table J-17. It summarizes the current amount of each tree density category by potential 

vegetation group (PVG), and the historical range is also shown. 

Susceptibility to bark beetles in ponderosa pine was rated using the following factors (Schmitt and Powell 

2005): forest cover type; canopy species composition; overstory layer size class; clumpiness; tree canopy 

cover; and canopy layering. 

For the dry forest PVG (Table J-17a), HRV results show that bark-beetle susceptibility is below the 

historical range for the low and high categories, and well above the historical range for the moderate 

category. 

For the moist forest PVG (Table J-17b), HRV results show that bark-beetle susceptibility is well above 

the historical range for the moderate category, within the historical range for the high category, and below 

the historical range for the low category. 
South George Vegetation and Fuels Management Project - DEIS 

J-19 

Even though percents and acreages are presented for the cold forest PVG (Table J-17c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-17a HRV analysis for susceptibility to bark beetles in ponderosa pine on the dry 

upland forest PVG 

Bark Beetle 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 5-10 180-370 1 30 Below the historical range 

Moderate 15-30 550-1100 75 2750 Well above the historical range 

High 40-90 1470-3310 24 890 Below the historical range 

Table J-17b HRV analysis for susceptibility to bark beetles in ponderosa pine on the 

moist upland forest PVG 

Bark Beetle 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 40-70 4600-8050 29 3310 Below the historical range 

Moderate 15-35 1730-4030 65 7520 Well above the historical range 

High 5-25 580-2880 6 670 Within the historical range 

Table J-17c HRV analysis for susceptibility to bark beetles in ponderosa pine on the 

cold upland forest PVG 

Bark Beetle 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 55-95 140-250 30 80 

No interpretation because this 

PVG contains too few acres. Moderate 5-30 10-80 70 180 

High 0-5 0-10 0 0 

Sources/Notes for Tables A17a to A17c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are 

described in Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt 

and Powell (2005). Historical ranges are taken from Schmitt and Powell (2008). 

HRV Analysis for Susceptibility to Defoliating Insects

An historical range of variability (HRV) analysis was used to evaluate susceptibility to defoliating insects 

(western spruce budworm and Douglas-fir tussock moth) for the South George planning area; results are 

provided in Table J-18. It summarizes the current amount of each tree density category by potential 

vegetation group (PVG), and the historical range is also shown. 

Susceptibility to defoliating insects was rated using the following factors (Schmitt and Powell 2005): 

forest cover type; canopy species composition; tree canopy cover; and canopy layering. 

For the dry forest PVG (Table J-18a), HRV results show that defoliator susceptibility is well below the 

historical range for the low category and above the historical range for the moderate and high categories. 

This result agrees with empirical budworm damage experienced across the Blue Mountains during the last 

major budworm outbreak occurring between 1980 and 1992. 
South George Vegetation and Fuels Management Project - DEIS 

J-20 

For the moist forest PVG (Table J-18b), HRV results show that defoliator susceptibility is above the 

historical range for two categories (low and moderate) and within the historical range for one category 

(high). 

Even though percents and acreages are presented for the cold forest PVG (Table J-18c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-18a HRV analysis for susceptibility to defoliating insects on the dry upland 

forest PVG 

Defoliators 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 40-85 1470-3120 11 390 Well below the historical range 

Moderate 15-30 550-1100 53 1940 Above the historical range 

High 5-15 180-550 37 1350 Above the historical range 

Table J-18b HRV analysis for susceptibility to defoliating insects on the moist upland 

forest PVG 

Defoliators 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 5-10 580-1150 14 1640 Above the historical range 

Moderate 20-30 2300-3450 34 3920 Above the historical range 

High 35-90 4030-10350 52 5950 Within the historical range 

Table J-18c HRV analysis for susceptibility to defoliating insects on the cold upland 

forest PVG 

Defoliators 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 40-95 100-250 19 50 

No interpretation because this 

PVG contains too few acres. Moderate 15-25 40-60 81 210 

High 5-10 10-30 0 0 

Sources/Notes for Tables A18a to A18c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are 

described in Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt 

and Powell (2005). Historical ranges are taken from Schmitt and Powell (2008). 

HRV Analysis for Susceptibility to Douglas-fir Beetle

An historical range of variability (HRV) analysis was used to evaluate susceptibility to Douglas-fir beetle 

for the South George planning area; results are provided in Table J-19. It summarizes the current amount 

of each tree density category by potential vegetation group (PVG), and the historical range is also shown. 

Susceptibility to Douglas-fir beetle was rated using the following factors (Schmitt and Powell 2005): 

forest cover type; canopy species composition; overstory layer size class; clumpiness; and tree canopy 

cover. 
South George Vegetation and Fuels Management Project - DEIS 

J-21 

For the dry forest PVG (Table J-19a), HRV results show that Douglas-fir beetle susceptibility is below 

the historical range for the low and high categories, and well above the historical range for the moderate 

category. 

For the moist forest PVG (Table J-19b), HRV results show that Douglas-fir beetle susceptibility is below 

the historical range for two categories (low and high), and well above the historical range for one category 

(moderate). 

Even though percents and acreages are presented for the cold forest PVG (Table J-19c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-19a HRV analysis for susceptibility to Douglas-fir beetle on the dry upland forest 

PVG 

Douglas-fir Beetle

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 35-75 1290-2750 23 830 Below the historical range 

Moderate 15-30 550-1100 69 2530 Well above the historical range 

High 10-25 370-920 9 320 Below the historical range

Table J-19b HRV analysis for susceptibility to Douglas-fir beetle on the moist upland 

forest PVG 

Douglas-fir Beetle

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 30-60 3450-6900 23 2670 Below the historical range 

Moderate 20-40 2300-4600 75 8660 Well above the historical range 

High 10-30 1150-3450 2 170 Below the historical range 

Table J-19c HRV analysis for susceptibility to Douglas-fir beetle on the cold upland forest 

PVG 

Douglas-fir Beetle

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 45-95 120-250 71 180 

No interpretation because this 

PVG contains too few acres. Moderate 10-25 30-60 29 70 

High 5-10 10-30 0 0 

Sources/Notes for Tables A19a to A19c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are described 

in Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt and Powell 

(2005). Historical ranges are taken from Schmitt and Powell (2008). 

HRV Analysis for Susceptibility to Douglas-fir Dwarf Mistletoe

An historical range of variability (HRV) analysis was used to evaluate susceptibility to Douglas-fir dwarf 

mistletoe for the South George planning area; results are provided in Table J-20. It summarizes the 

current amount of each tree density category by potential vegetation group (PVG), and the historical 

range is also shown. 
South George Vegetation and Fuels Management Project - DEIS 

J-22 

Susceptibility to Douglas-fir dwarf mistletoe was rated using the following factors (Schmitt and Powell 

2005): forest cover type; canopy species composition; overstory layer size class; and canopy layering. 

For the dry forest PVG (Table J-20a), HRV results show that Douglas-fir dwarf mistletoe susceptibility is 

within the historical range for the low and moderate categories, and above the historical range for the high 

category. 

For the moist forest PVG (Table J-20b), HRV results show that Douglas-fir dwarf mistletoe susceptibility 

is within the historical range for two categories (low and moderate) and slightly below the historical range 

for one category (high). 

Even though percents and acreages are presented for the cold forest PVG (Table J-20c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-20a HRV analysis for susceptibility to Douglas-fir dwarf mistletoe on the dry upland 

forest PVG 

Douglas-fir Dwarf 

Mistletoe Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 25-55 920-2020 26 960 Within the historical range 

Moderate 15-40 550-1470 21 780 Within the historical range 

High 20-35 730-1290 53 1930 Above the historical range 

Table J-20b HRV analysis for susceptibility to Douglas-fir dwarf mistletoe on the moist upland 

forest PVG 

Douglas-fir Dwarf 

Mistletoe Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 30-65 3450-7480 56 6380 Within the historical range 

Moderate 20-45 2300-5180 36 4150 Within the historical range 

High 10-20 1150-2300 8 970 Below the historical range 

Table J-20c HRV analysis for susceptibility to Douglas-fir dwarf mistletoe on the cold upland 

forest PVG 

Douglas-fir Dwarf 

Mistletoe Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 40-90 100-230 100 260 

No interpretation because this 

PVG contains too few acres. Moderate 20-30 50-80 0 0 

High 0-10 0-30 0 0 

Sources/Notes for Tables A20a to A20c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are described in 

Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt and Powell (2005). 

Historical ranges are taken from Schmitt and Powell (2008). 

HRV Analysis for Susceptibility to Fir Engraver

An historical range of variability (HRV) analysis was used to evaluate susceptibility to fir engraver for the 

South George planning area; results are provided in Table J-21. It summarizes the current amount of each 

tree density category by potential vegetation group (PVG), and the historical range is also shown. 
South George Vegetation and Fuels Management Project - DEIS 

J-23 

Susceptibility to fir engraver was rated using the following factors (Schmitt and Powell 2005): forest 

cover type; canopy species composition; overstory layer size class; clumpiness; and tree canopy cover. 

For the dry forest PVG (Table J-21a), HRV results show that fir engraver susceptibility is above the 

historical range for the moderate and high categories, and below the historical range for the low category. 

For the moist forest PVG (Table J-21b), HRV results show that fir engraver susceptibility is well above 

the historical range for the high category, within the historical range for the moderate category, and below 

the historical range for the low category. 

Even though percents and acreages are presented for the cold forest PVG (Table J-21c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-21a HRV analysis for susceptibility to fir engraver on the dry upland forest 

PVG 

Fir Engraver 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 45-90 1650-3310 30 1090 Below the historical range 

Moderate 10-30 370-1100 47 1730 Above the historical range 

High 5-10 180-370 23 850 Above the historical range

Table J-21b HRV analysis for susceptibility to fir engraver on the moist upland forest 

PVG 

Fir Engraver 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 30-70 3450-8050 22 2500 Below the historical range 

Moderate 20-40 2300-4600 20 2350 Within the historical range 

High 10-20 1150-2300 58 6660 Well above the historical range 

Table J-21c HRV analysis for susceptibility to fir engraver on the cold upland forest 

PVG 

Fir Engraver 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 5-15 10-40 19 50 

No interpretation because this 

PVG contains too few acres. Moderate 25-60 60-160 81 210 

High 30-55 80-140 0 0 

Sources/Notes for Tables A21a to A21c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are described in Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt and 

Powell (2005). Historical ranges are taken from Schmitt and Powell (2008). 

HRV Analysis for Susceptibility to Root Diseases

An historical range of variability (HRV) analysis was used to evaluate susceptibility to root diseases 

(Armillaria and laminated) for the South George planning area; results are provided in Table J-22. It 

summarizes the current amount of each tree density category by potential vegetation group (PVG), and 

the historical range is also shown. 
South George Vegetation and Fuels Management Project - DEIS 

J-24 

Susceptibility to root diseases was rated using the following factors (Schmitt and Powell 2005): forest 

cover type; canopy species composition; and overstory layer size class.

For the dry forest PVG (Table J-22a), HRV results show that root disease susceptibility is close to what 

would be expected – the low category is just below the lower limit of the historical range, the moderate 

category is within the range but right at the upper limit, and the high category is just above the upper limit 

of the historical range. 

For the moist forest PVG (Table J-22b), HRV results show that root disease susceptibility is above the 

historical range for the low category, and within the historical range for both the moderate and high 

categories. 

Even though percents and acreages are presented for the cold forest PVG (Table J-22c), there are no HRV 

interpretations reported for this PVG because it has too few acres in the South George area to support a 

credible HRV analysis. 

Table J-22a HRV analysis for susceptibility to root diseases on the dry upland forest 

PVG 

Root Disease 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 30-60 1100-2200 29 1080 Just below the historical range 

Moderate 25-50 920-1840 50 1840 At upper edge of historical range 

High 5-20 180-730 21 760 Just above the historical range 

Table J-22b HRV analysis for susceptibility to root diseases on the moist upland forest 

PVG 

Root Disease 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 5-15 580-1730 27 3080 Above the historical range 

Moderate 20-50 2300-5750 33 3740 Within the historical range 

High 35-65 4030-7480 41 4690 Within the historical range 

Table J-22c HRV analysis for susceptibility to root diseases on the cold upland forest 

PVG 

Root Disease 

Susceptibility 

Historical Range Current Amount 

Percent Acres Percent Acres HRV Interpretation 

Low 35-70 90-180 71 180 

No interpretation because this 

PVG contains too few acres. Moderate 20-45 50-120 0 0 

High 5-15 10-40 29 70 

Sources/Notes for Tables A22a to A22c: Current amounts are summarized from the South George 

vegetation database (NFS lands only). Upland forest potential vegetation groups (PVG) are 

described in Table J-1 and Powell et al. (2007). Susceptibility criteria are described in Schmitt 

and Powell (2005). Historical ranges are taken from Schmitt and Powell (2008).