Research Project Summary: Changes in stand structure and composition after thinning and burning in low-elevation, dry ponderosa pine and Douglas-fir forests of northeastern Oregon



RESEARCH PROJECT SUMMARY CITATION:
Hauser, A. Scott, compiler. 2008. Research Project Summary: Changes in stand structure and composition after thinning and burning in low-elevation, dry ponderosa pine and Douglas-fir forests of northeastern Oregon. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

Sources:
Unless otherwise indicated, the information in this Research Project Summary comes from the following papers:

Metlen, Kerry L.; Fiedler, Carl E.; Youngblood, Andrew. 2004. Understory response to fuel reduction treatments in the Blue Mountains of northeastern Oregon. Northwest Science. 78(3): 175-185. [5].

Youngblood, Andrew; Metlen, Kerry L.; Coe, Kent. 2006. Changes in stand structure and composition after restoration treatments in low elevation dry forests of northeastern Oregon. Forest Ecology and Management. 234(1-3): 143-163. [6].

SPECIES INCLUDED IN THE SUMMARY:
Common names are used throughout this summary. For the list of the common and scientific names of species discussed in this summary and for links to FEIS species reviews, see the Appendix.

STUDY LOCATION:
The study was conducted in the northern Blue Mountains (lat 4540'N, long 11713'W), 45 km north of Enterprise, Oregon [5].

SITE DESCRIPTION:
The study area is includes almost 9,400 ha of plateaus, benches, and deeply incised drainages formed in highly fractured, ancient Columbia River basalt. Soil textures are fine to coarse loams, in some cases with high ash content. The climate is strongly continental. Weather data from Enterprise, Oregon, 100 to 400 m below the study area, indicate annual precipitation averaging 500 mm and a mean annual temperature of 7.4 C. Frost may occur at anytime of year. The Enterprise weather station may be in a rain shadow that receives less precipitation than the study area [6].

Environmental setting and characteristics of treatment sites [6]
Unit Treatment Size
(ha)
Elevation
(m)
Aspect
()
Slope
(%)
Heat load index Plant community
6A Thin 14.4 1,361 283 11 0.9078 Rocky Mountain Douglas-fir/pinegrass
7 Thin 11.9 1,305 292 21 0.8952 Rocky Mountain Douglas-fir/common snowberry
9 Thin 9.1 1,235 51 12 0.8258 Pacific ponderosa pine/bluebunch wheatgrass
22 Thin 8.8 1,380 286 8 0.9049 Rocky Mountain Douglas-fir/white spirea
8B Burn 10.1 1,170 82 8 0.8645 Pacific ponderosa pine/Idaho fescue
10B Burn 8.4 1,920 50 8 0.8733 Pacific ponderosa pine/Idaho fescue
21 Burn 10.4 1,373 230 18 0.9503 Rocky Mountain Douglas-fir/pinegrass
24 Burn 8.4 1,260 84 9 0.8579 Pacific ponderosa pine/Idaho fescue
6B Thin + burn 12.1 1,388 221 15 0.9219 Rocky Mountain Douglas-fir/pinegrass
8A Thin + burn 10.4 1,174 297 9 0.8955 Pacific ponderosa pine/Idaho fescue
10A Thin + burn 15.9 1,186 297 13 0.8903 Pacific ponderosa pine/Idaho fescue
1112 Thin + burn 11.0 1,185 274 9 0.9136 Pacific ponderosa pine/Idaho fescue
245 Control 13.8 1,286 218 11 0.8928 Pacific ponderosa pine/common snowberry
15 Control 15.1 1,113 108 18 0.8257 Rocky Mountain Douglas-fir/pinegrass
18 Control 7.5 1,333 296 26 0.8822 Rocky Mountain Douglas-fir/pinegrass
23 Control 12.0 1,379 345 10 0.8714 Rocky Mountain Douglas-fir/pinegrass
Heat load index based on aspect, slope, and latitude, with 1.0 being the warmest slope (southwest-facing).

PREFIRE PLANT COMMUNITY:
The study area is a mosaic of low-elevation (1,040-1,480 m), dry Pacific ponderosa pine and Rocky Mountain Douglas-fir forests. Warm, dry sites on gentle south-facing slopes are typified by Pacific ponderosa pine and open, low shrub- and grass-dominated communities. North-facing plateau slopes, draws, and swales with relatively deep soils are dominated by Rocky Mountain Douglas-fir and Pacific ponderosa pine [6].

Most of the area is in a stem exclusion, closed-canopy stage. Most stands are dominated by 70- to 100-year-old, even-aged Pacific ponderosa pines, with smaller Rocky Mountain Douglas-firs that have regenerated after extensive partial cutting. Within this mosaic are scattered large trees and remnants of old, unharvested stands. The study area historically had endemic levels of bark beetles. During the 1990s, the area was affected by increased levels of bark beetles, especially western pine beetle (Dendroctonus brevicomis) and eastern pine engraver (Ips pini) [6]. Grazing is a traditional land use in the study area and occurs on all treatment sites [5]. Indicator species analysis identified species differentially associated with treatment sites [6].

Species indicators, mean frequency, and mean cover in summer 1998, before treatments. Bold values indicate the pretreatment site with which the species was most strongly associated [6].
Species (life form) Indicator value (P)

Percent frequency (and cover) on pretreatment sites

Thin Burn Thin + burn Control
common snowberry (s) 45.7 (0.001) 83 (6.0) 61 (1.8) 78 (1.6) 52 (2.3)
heartleaf arnica (f) 38.7 (0.001) 77 (8.4) 60 (2.5) 70 (4.2) 58 (2.2)
white spirea (s) 33.0 (0.001) 63 (3.9) 27 (1.7) 44 (2.1) 27 (2.1)
Idaho fescue (g) 39.9 (0.001) 36 (5.8) 80 (15.8) 74 (12.2) 45 (5.4)
prairie Junegrass (g) 37.5 (0.001) 5 (0.3) 46 (2.2) 1 (3.0) 21 (0.8)
blue wildrye (g) 20.9 (0.001) 6 (0.3) 31 (3.3) 0 (0) 21 (2.0)
bluebunch wheatgrass (g) 15.6 (0.014) 6 (2.0) 32 (4.2) 32 (4.4) 4 (0.9)
California brome (g) 10.3 (0.001) 0 (0) 10 (6.5) 0 (0) 0 (0)
elk sedge (g) 25.5 (0.003) 65 (5.7) 14 (3.3) 30 (5.3) 60 (4.2)
western needlegrass (g) 16.9 (0.001) 19 (2.6) 9 (1.3) 0 (0) 22 (3.2)
western fescue (g) 15.3 (0.001) 0 (0) 1 (0.3) 0 (0) 12 (2.6)
purple oniongrass (g) 10.3 (0.001) 0 (0) 0 (0) 0 (0) 8 (4.1)
f=forb, g=graminoid, s=shrub.
Indicator value=relative abundance (i.e., relative density) relative frequency [1,6].

Study sites occur in the following plant communities and probably historically experienced the fire regimes described below:

Fire regime information on the vegetation community studied in this Research Project Summary. Fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Model [4]. This vegetation model was developed by local experts using available literature and expert opinion as documented in the PDF files linked from the Potential Natural Vegetation Groups listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model.
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Dry ponderosa pine (mesic) Replacement 5% 125    
Mixed 13% 50    
Surface or low 82% 8    
Mixed conifer (eastside dry) Replacement 14% 115 70 200
Mixed 21% 75 70 175
Surface or low 64% 25 20 25
*Fire Severities:
Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects.
Surface or low=Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area [2,3].

PLANT PHENOLOGY:
Phenology of vegetation was not described. Pretreatment measurements were made prior to the summer 1998 thinning treatments. Vegetation measurements in the first postfire year were taken in early summer [5].

FIRE SEASON/SEVERITY CLASSIFICATION:
Late summer/low

FIRE DESCRIPTION:
The research project aimed to promote forest sustainability by reducing potential for tree mortality due to mountain pine beetles and crown fire. Treatments were designed to favor Pacific ponderosa pine over Rocky Mountain Douglas-fir and to reduce tree basal area.

The researchers implemented 4 treatments with 4 replications of each: thin, burn, thin-burn, and control (no active management). Thinning occurred in summer 1998, and burning was conducted in mid-September 2000. The management goal was to modify stand structure such that mortality from bark beetles was reduced and 80% of the dominant and codominant trees could survive a wildfire occurring under 80th percentile weather conditions. To meet this goal, treatments aimed to reduce total basal area from about 26 m/ha to about 16 m/ha. In the thin treatment, all live trees ≥53 cm DBH, which represented late-successional and old stands, were left uncut; conifers within 9 m of dominant Pacific ponderosa pines were removed. The burn treatments aimed to reduce the basal area of Pacific ponderosa pines ≥51 cm DBH by <20%, with similarly sized Rocky Mountain Douglas-firs reduced by ≤30%. For trees ranging from 20 to 51 cm DBH, the burn treatments were designed to kill <30% of Pacific ponderosa pines and 40% of Rocky Mountain Douglas-firs. Targets for the thin-burn treatment were the same as for the thin-only and burn-only treatments; fire behavior was also managed to reduce accumulations of cured tree branches and tops left by thinning [6].

Burns were conducted as both backing and strip head fires under conditions suitable for low flame heights. All burns were "fairly complete," low-intensity fires that consumed 75% of the grasses and exposed <25% of mineral soil [5].



Fuel conditions and fire behavior for prescribed fires [6]

Treatment   

Burn Thin + burn
Unit 8B 10B 21 24 6B 8A 10A 1112
Ambient temperature (C) 20-24 20-24 12-23 13-21 12-21 20-24 20-24 12-23
Relative humidity (%) 33-48 33-48 23-50 25-49 24-76 33-48 33-48 23-50
Wind speed (m/s) 2.2 2.2 0.8-2.8 0.8-2.2 0.8-3.6 2.2 2.2 0.8-2.8
10-h fuel moisture(%) 13.7 (0.3) 12.8 (0.7) 15.0 (1.1) 12.2 (1.1) 12.9 (0.7) 17.8 (1.1) 17.6 (1.7) 16.4 (2.4)
1,000-h fuel moisture(%) 63.0 (6.2) 40.9 (7.2) 55.9 (8.1) 48.6 (7.0) 28.6 (2.7) 45.5 (3.4) 31.2 (4.0) 37.7 (4.5)
Mean flame length (m) 0.9 0.9 0.6 0.5 0.9 0.9 0.9 0.9
Fuel moisture in dead fuels 0.6 to 2.5 cm in diameter. Data are means (SE) from 5 samples.
Fuel moisture in dead fuels 7.6 to 20.3 cm in diameter. Data are means (SE) from 21 to 31 samples.

FIRE EFFECTS ON PLANT COMMUNITY:
Thinning, burning, and thinning followed by burning all modified forest structure and composition, but none reduced overstory canopy cover significantly. Only the thin-and-burn treatments reduced tree basal area to the level desired to meet management objectives. All active treatments reduced downed log density. Understory composition was little affected by treatments. Treatment effects on trees: On control sites, live basal area, live tree density, and seedling density tended to increase during the study. Thinning alone reduced overstory tree density but did not reduce overstory canopy cover and probably did not reduce susceptibility to crown fire. Burning alone reduced small trees, mainly Douglas-firs, but had little effect on the overstory. The thin-and-burn treatment reduced live basal area and live tree density more than thinning or burning alone, and produced the lowest seedling densities of all treatments [6].

Mean (SE) tree and seedling attributes before and after treatments [6]

Treatment   

Thin Burn Thin + burn Control

1998 (before treatment)

Live tree basal area (m/ha) 27.3 (2.4) 19.2 (2.3) 20.1 (1.1) 27.4 (4.7)
Live tree density (stems/ha) 698 (109) 286 (32) 398 (100) 469 (33)
Seedling density (stems/ha) No data (ND) ND ND ND

2004 (6 years after thinning, 4 years after burning)

Live tree basal area (m/ha) 19.6 (0.2) 19.5 (2.4) 16.0 (1.0) 28.4 (3.0)
Live tree density (stems/ha) 452 (72) 247 (24) 144 (15) 597 (17)
Seedling density (stems/ha) 966 (252) 27 (12) 16 (6) 1,595 (612)

Basal area of dead snags did not differ significantly among treatments, including controls. Mean basal area of snags was 2.8 m/ha in 1998 (88% Pacific ponderosa pine) and 2.6 m/ha in 2004 (58% Pacific ponderosa pine). Snag density averaged 46 stems/ha in 1998 and 53 stems/ha in 2004. Burn treatments, with or without thinning, tended to increase snag density relative to other treatments; thinning tended to reduce snags.

Treatment effects on coarse woody debris: All active treatments reduced downed log density relative to that on control sites (P=0.011). Log density was significantly less on burned sites than on thinned sites (P=0.003) and tended to be less on thinned-and-burned sites than on thinned-only sites. Length, volume, and cover of coarse woody debris did not differ significantly among treatments [6].

Mean (SE) coarse woody debris attributes in 2004, 6 years after thinning and 4 years after burning [6]

Treatment  

Thin Burn Thin + burn Control
Density (stems/ha) 156 (37) 30 (5) 61 (8) 195 (22)
Cumulative length (m/ha) 156.2 (30.0) 43.9 (11.4) 80.2 (26.1) 210.0 (53.0)
Volume (m/ha) 6.5 (1.0) 2.2 (0.5) 2.3 (0.6) 9.2 (1.8)
Cover (m/ha) 2.2 (0.2) 1.4 (0.2) 1.4 (0.2) 2.6 (0.3)

Treatment effects on understory vegetation: Total understory cover in the first postfire year was 95.7% on control sites, greater than on thinned-only sites (60.7%) and significantly greater than on burned-only sites (50.5%) or thinned-and-burned sites (42.3%). Species richness on burned sites (with and without thinning) did not differ significantly from that on control sites, but species richness on thinned-only sites was significantly less than on control sites. Cover of forbs was less on thinned than control plots in the first postfire year, perhaps due in part to increased slash on the ground. All active treatments had lower cover of elk sedge than control sites, but the difference was significant only on thinned sites. Prairie Junegrass cover was significantly greater on thinned-and-burned sites than on thinned-only or control sites [5]. The frequency and cover of understory species differed among treatment sites in 1998, before any treatments [6], so differences may not be attributable to treatments alone.

Understory species diversity did not change significantly in any treatment from 1998 to 2004. On thinned sites, the authors note that understory species composition was "remarkably stable and consistent" before and after treatment. Indicator species for thinning units in 1998, before thinning, were also indicators for thinned units in 2004, with similar cover and frequency. Eight nonnative species were found on thinned sites in 2004; the only one with more than trace cover was cheatgrass. On burned-only sites, several perennial species increased in frequency and cover from 1998 to 2004. These included heartleaf arnica, pinegrass, elk sedge, white spirea, and common snowberry. Cover of Idaho fescue decreased. The number of nonnative species on burned-only sites increased, but only 2 of these species (cheatgrass and Japanese brome) had more than "limited" cover in 2004. On thinned-and-burned sites, as on burn-only sites, bluebunch wheatgrass, elk sedge, white spirea, and common snowberry increased, while Idaho fescue decreased. Number of nonnative species increased from 2 to approximately 9. As in other treatments, cheatgrass was the most abundant nonnative species. Forty-nine indicator species were used to characterize the plant communities sampled, based on presence with more than trace cover in most treatments [6].

Species indicators, mean frequency, and mean cover in 2004, 6 years after thin treatments and 4 years after burn treatments. Bold values indicate the pretreatment site with which the species was most strongly associated [6].

Species (life form)

Indicator value (P) Percent frequency (and cover) on treatment sites
Thin Burn Thin + burn Control
common snowberry (s) 38.6 (0.001) 89 (10.5) 87 (3.5) 91 (3.8) 83 (6.9)
white spirea (s) 34.7 (0.001) 68 (6.8) 28 (2.6) 43 (5.4) 56 (2.4)
pinegrass (g) 33.7 (0.001) 91 (29.1) 81 (23.1) 75 (21.6) 81 (12.4)
heartleaf arnica (f) 29.2 (0.018) 86 (9.7) 74 (10.9) 63 (3.6) 81 (7.3)
houndstongue hawkweed (f) 26.7 (0.008) 77 (0.6) 74 (0.5) 66 (0.5) 55 (0.3)
Virginia strawberry (f) 26.4 (0.029) 70 (2.5) 63 (1.4) 56 (1.0) 72 (1.9)
paintbrush (f) 19.5 (0.001) 51 (0.4) 24 (0.4) 48 (0.4) 12 (0.3)
wormleaf stonecrop (f) 19.1 (0.011) 28 (3.8) 30 (1.2) 23 (0.3) 31 (0.3)
showy aster (f) 14.2 (0.003) 21 (1.2) 1 (0.3) 4 (2.0) 12 (0.3)
prairie Junegrass (g) 35.0 (0.001) 40 (1.7) 87 (1.5) 77 (1.2) 41 (0.7)
Idaho fescue (g) 34.1 (0.001) 73 (5.2) 93 (9.5) 81 (9.4) 71 (5.3)
western yarrow (f) 32.0 (0.031) 88 (2.1) 98 (1.8) 88 (1.0) 91 (0.9)
tiny trumpet (f) 24.5 (0.001) 23 (0.4) 63 (0.4) 65 (0.3) 40 (0.3)
miner's-lettuce (f) 20.2 (0.001) 10 (0.4) 33 (0.7) 8 (0.3) 27 (0.3)
bluebunch wheatgrass (g) 17.6 (0.017) 25 (2.6) 47 (4.0) 39 (5.5) 12 (3.2)
onespike oatgrass (g) 16.8 (0.001) 6 (4.7) 28 (5.5) 25 (1.3) 5 (8.2)
sticky phlox (f) 15.9 (0.011) 14 (3.7) 33 (1.9) 26 (0.5) 14 (0.4)
desertparsley (f) 14.1 (0.001) 16 (0.3) 31 (0.4) 29 (0.3) 8 (0.3)
stickywilly (f) 14.1 (0.002) 7 (0.5) 31 (0.5) 2 (0.3) 24 (0.6)
chaparral willowherb (f) 33.7 (0.001) 24 (0.3) 39 (0.4) 74 (0.4) 31 (0.6)
tailcup lupine (f) 33.5 (0.001) 75 (2.2) 56 (1.0) 77 (3.1) 63 (1.5)
Rocky Mountain goldenrod (f) 28.1 (0.001) 18 (2.2) 35 (1.4) 64 (1.1) 6 (0.8)
western stoneseed ( f) 25.3 (0.001) 44 (0.4) 43 (0.4) 62 (0.4) 15 (0.3)
arrowleaf balsamroot (f) 24.8 (0.003) 47 (1.8) 42 (2.2) 46 (4.7) 18 (0.7)
cheatgrass (g) 24.6 (0.006) 28 (3.7) 51 (2.9) 55 (3.8) 18 (0.9)
Douglas' knotweed (f) 23.7 (0.001) 24 (0.3) 30 (0.4) 45 (0.7) 27 (0.4)
pinkfairies (f) 23.0 (0.001) 12 (0.3) 25 (0.4) 44 (0.3) 5 (0.3)
meadow deathcamas (f) 17.2 (0.010) 38 (0.3) 43 (0.3) 51 (0.3) 21 (0.3)
neckweed (f) 15.7 (0.001) 2 (0.3) 14 (0.3) 29 (0.4) 5 (0.7)
Japanese brome (g) 15.1 (0.027) 11 (0.5) 30 (2.4) 38 (1.5) 21 (0.7)
North Africa grass (g) 12.8 (0.002) 1 (0.3) 18 (1.8) 25 (1.3) 0 (0)
prickly lettuce (f) 12.3 (0.001) 4 (0.3) 8 (0.3) 20 (0.3) 1 (0.3)
sagebrush mariposa lily (f) 11.1 (0.002) 12 (0.3) 16 (0.3) 25 (0.3) 4 (0.3)
narrowleaf pussytoes (f) 10.8 (0.001) 0 (0) 5 (0.3) 15 (0.3) 3 (0.3)
woods strawberry (f) 41.0 (0.001) 34 (3.2) 28 (2.2) 7 (1.3) 74 (3.0)
longstalk clover (f) 31.4 (0.001) 34 (12.3) 55 (11.6) 6 (3.1) 81 (8.5)
elk sedge (g) 29.9 (0.002) 66 (11.1) 59 (11.1) 57 (8.3) 81 (13.6)
sweetcicely (f) 26.4 (0.001) 3 (0.3) 1 (0.3) 3 (0.3) 32 (0.3)
largeleaf sandwort (f) 25.7 (0.001) 9 (1.1) 5 (1.1) 4 (0.3) 36 (1.1)
rose (s) 25.3 (0.009) 68 (1.2) 54 (1.1) 39 (0.5) 68 (1.4)
sticky cinquefoil (f) 19.0 (0.048) 26 (1.2) 33 (0.5) 27 (0.4) 55 (0.5)
Saskatoon serviceberry (s) 19.7 (0.001) 26 (0.4) 21 (0.3) 1 (0.3) 36 (0.6)
smallflower miterwort (f) 18.1 (0.001) 2 (0.3) 2 (0.3) 0 (0) 19 (1.0)
largeleaf avens (f) 16.3 (0.001) 1 (0.3) 0 (0) 1 (0.3) 17 (0.8)
purple oniongrass (g) 15.4 (0.001) 0 (0) 0 (0) 0 (0) 15 (0.8)
western needlegrass (g) 15.2 (0.011) 32 (1.0) 13 (1.3) 5 (0.4) 42 (0.7)
common selfheal (f) 14.9 (0.001) 4 (0.3) 0 (0) 2 (0.7) 17 (1.3)
common dandelion (f) 12.4 (0.014) 21 (0.3) 18 (0.3) 15 (0.3) 33 (0.3)
field pussytoes (f) 11.9 (0.001) 11 (0.3) 0 (0) 5 (0.3) 14 (1.8)
f=forb, g=graminoid, s=shrub.
Indicator value=relative abundance relative frequency [6]. Relative abundance=relative density [1].

FIRE MANAGEMENT IMPLICATIONS:
The thin treatments and burn treatments opened stands to some extent and altered tree species composition, but they did not reduce basal area to the target level for increasing resistance to crown fire and bark beetle attack (16 m/ha). The thin-and-burn treatment did achieve this management objective [6].

Activity fuels from thinning caused variable fire spread in thinned-burned stands because activity fuels occurred in relatively uniform, parallel strips that had higher fuel moisture than areas outside these strips [6].

Treatments caused minor changes in understory vegetation, indicating that "the majority of understory species have adapted to the same disturbance regimes" that the treatments aimed to mimic [6].

The authors suggest that repeated treatments are needed in 10 to 15 years to bring stand structure and composition more in line with historical conditions. They comment that one set of treatments is not likely to mitigate nearly 80 years of fire exclusion and fuel accumulation in low-elevation, dry forests [6].
SPECIES INCLUDED IN THE SUMMARY:
This Research Project Summary contains fire effects and/or fire response information on the following species. For further information, follow the highlighted links to the FEIS reviews of those species.

Appendix

Common name Scientific name
Forbs
western yarrow Achillea millefolium
field pussytoes Antennaria neglecta
narrowleaf pussytoes Antennaria stenophylla
heartleaf arnica Arnica cordifolia
arrowleaf balsamroot Balsamorhiza sagittata
sagebrush mariposa lily Calochortus macrocarpus
paintbrush Castilleja spp.
pinkfairies Clarkia pulchella
miner's-lettuce Claytonia perfoliata
tiny trumpet Collomia linearis
chaparral willowherb Epilobium minutum
showy aster Eurybia conspicua
woods strawberry Fragaria vesca
Virginia strawberry Fragaria virginiana
stickywilly Galium aparine
largeleaf avens Geum macrophyllum
houndstongue hawkweed Hieracium cynoglossoides
prickly lettuce Lactuca serriola
western stoneseed Lithospermum ruderale
desertparsley Lomatium spp.
tailcup lupine Lupinus caudatus
smallflower miterwort Mitella stauropetala
largeleaf sandwort Moehringia macrophylla
(Arenaria macrophylla)*
sweetcicely Osmorhiza berteroi
sticky phlox Phlox viscida
Douglas' knotweed Polygonum douglasii
sticky cinquefoil Potentilla glandulosa
common selfheal Prunella vulgaris
wormleaf stonecrop Sedum stenopetalum
Rocky Mountain goldenrod Solidago multiradiata
common dandelion Taraxacum officinale
longstalk clover Trifolium longipes
neckweed Veronica peregrina
meadow deathcamas Zigadenus venenosus
Graminoids
western needlegrass Achnatherum occidentale
California brome Bromus carinatus var. carinatus
Japanese brome Bromus japonicus
cheatgrass Bromus tectorum
pinegrass Calamagrostis rubescens
elk sedge Carex geyeri
onespike oatgrass Danthonia unispicata
blue wildrye Elymus glaucus
Idaho fescue Festuca idahoensis
western fescue Festuca occidentalis
prairie Junegrass Koeleria macrantha
purple oniongrass Melica spectabilis
bluebunch wheatgrass Pseudoroegneria spicata
(Pseudoroegneria spicatum)*
North Africa grass Ventenata dubia
Shrubs
Saskatoon serviceberry Amelanchier alnifolia
rose Rosa spp.
white spirea Spiraea betulifolia
common snowberry Symphoricarpos albus
Trees
Pacific ponderosa pine Pinus ponderosa var. ponderosa
Rocky Mountain Douglas-fir Pseudotsuga menziesii var. glauca
*For species that have undergone scientific name changes, names in parentheses are those used in the research papers.

REFERENCES:


1. Dufrene, Marc; Legendre, Pierre. 1997. Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecological Monographs. 67(3): 345-366. [61431]
2. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005. Interagency fire regime condition class guidebook. Version 1.2, [Online]. In: Interagency fire regime condition class website. U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; The Nature Conservancy; Systems for Environmental Management (Producer). Variously paginated [+ appendices]. Available: http://www.frcc.gov/docs/1.2.2.2/Complete_Guidebook_V1.2.pdf [2007, May 23]. [66734]
3. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior (Producers). 72 p. Available: http://www.landfire.gov/downloadfile.php?file=RA_Modeling_Manual_v2_1.pdf [2007, May 24]. [66741]
4. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models, [Online]. In: LANDFIRE. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; The Nature Conservancy (Producers). Available: http://www.landfire.gov/models_EW.php [2008, April 18] [66533]
5. Metlen, Kerry L.; Fiedler, Carl E.; Youngblood, Andrew. 2004. Understory response to fuel reduction treatments in the Blue Mountains of northeastern Oregon. Northwest Science. 78(3): 175-185. [55433]
6. Youngblood, Andrew; Metlen, Kerry L.; Coe, Kent. 2006. Changes in stand structure and composition after restoration treatments in low elevation dry forests of northeastern Oregon. Forest Ecology and Management. 234(1-3): 143-163. [64992]

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