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Fire Study - Research Project Summary

Vegetation response to restoration treatments in ponderosa pine-Douglas-fir forests of western Montana

Written
May, 2006
Study Authors
Metlen et al.
Contributors
Metlen, Kerry L. - 1st Author
Fire Study Type
Research Project Summary

Metlen, Kerry L.; Dodson, Erich K.; Fiedler, Carl E. 2006. Research Project Summary: Vegetation response to restoration treatments in ponderosa pine-Douglas-fir forests of western Montana. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/fire-studies/metlen-et-al-2006

The study site is located at the University of Montana's Lubrecht Experimental Forest (46°53' N, 113°26' W), Missoula County, Montana, USA. This study is 1 of 13 in a nationwide network of Fire/Fire Surrogate (FFS) studies investigating the interdisciplinary effects of treatments designed to reduce fire hazard and restore the structure and function of fire-adapted forests.

Site Description

The mean yearly temperature at Lubrecht forest is 45 °F, and mean annual precipitation is 22 inches - nearly half falling as snow [7]. The Lubrecht study employed a randomized block design, with 3 blocks and 4 treatments (control, burn-only, thin-only, and thin-burn). Three, 90-acre blocks were delineated in moderately dense ponderosa pine-Douglas-fir forests on gentle to moderate slopes within 2.5 miles proximity. Each block was divided into 4 square treatment units of 22-acres each, with 1 replicate of each treatment in each block. Existing firebreaks predetermined the assignment of 1 burn treatment in 2 blocks; all other treatments were assigned randomly. A 6 × 6 grid of reference points (36 total) at 164-foot intervals was permanently established in each treatment unit. Site characteristics are summarized by block and treatment in the following table:

TreatmentBlockElevation (feet)Aspect (degrees)Slope (degrees)Habitat type* [8]Soil series
Control1431312513PSME/VACAWinkler
Control24137755PSME/VACATevis-Mitten
Control34097595PSME/VACABignell
Burn-only1441512710PSME/VACAWinkler
Burn-only242153365PSME/VACATevis-Mitten
Burn-only341473035PSME/VACABignell
Thin-only142701389PSME/VACAWinkler
Thin-only2415638PSME/VACATevis-Mitten
Thin-only34127988PSME/VACABignell
Thin-burn1445712310PSME/SPBEWinkler
Thin-burn24274118PSME/VACATevis-Mitten
Thin-burn340842637PSME/VACABignell
*PSME=Pseudotsuga menziesii var. glauca, SPBE=Spiraea betulifolia, VACA=Vaccinium caespitosum

This study occurs in the following vegetation classifications:

Ecosystems:

  • FRES21 Ponderosa pine
  • FRES20 Douglas-fir [3]

Kuchler Plant Associations:

  • K011 Western ponderosa forest [5]

SAF Cover Types:

  • 237 Interior ponderosa pine
  • 212 Western larch
  • 210 Interior Douglas-fir [2]

The research stands were primarily ponderosa pine and Douglas-fir in composition, with scattered western larch and lodgepole pine. Measured in basal area, species composition of the pretreatment stands was approximately 60% seral species (primarily ponderosa pine) and 40% shade-tolerant Douglas-fir. These stands regenerated following heavy harvesting in the early 1900s, in which nearly all merchantable-sized trees were removed. Most 2nd-growth trees were ~90 years old, with scattered clumps of regeneration and occasional trees >200 years old. All treatment areas had uneven-aged diameter distributions prior to treatment, with individual tree diameters ranging from 4 inches to 27 inches diameter at breast height (DBH). Typical of ponderosa forests in the region, the study area has been subject to moderate grazing over the last 100 years.

Regeneration of shade-tolerant Douglas-fir was abundant in the understory, while the most abundant undergrowth species included heartleaf arnica, white spirea, common snowberry, pinegrass, and Geyer's sedge.

Vegetation was sampled on modified Whittaker plots randomly located at 10 of the 36 reference points in each unit. Each 66 foot x 164 foot (0.25-acre) Whittaker plot was subdivided into ten, 33-foot × 33-foot (0.025-acre) subplots with two 3.3 foot × 3.3 foot (0.00025-acre) quadrats in opposite corners of each subplot. We identified all understory species on each 0.25-acre plot and sampled DBH of all trees >4 inches DBH. Saplings (trees >4.5 feet tall but <4.0 inches DBH) were tallied in five randomly selected 0.025-acre subplots within each plot. Twelve of the twenty quadrats (0.00025-acre) in each plot were randomly selected to sample understory richness and cover. All sampling locations were permanently marked with metal stakes to ensure accurate plot relocation in future sampling years.

Plant Phenology

Burns conducted in the spring coincide well with typical low-elevation prescribed underburning in western Montana. When the 1st broadcast burn was implemented in early May, buds were swelling in the overstory trees and the understory vegetation was just beginning to "greenup." The last burn (conducted in late June) was outside the normal spring burning season with significant "greenup," new conifer foliage extensively elongated, and many species in full flower.

Restoration treatments were designed to initiate the long-term process of moving stand density, structure, and species composition toward historical conditions, and to reduce the potential for stand-replacing fire. The objective of burning in the thin-burn treatment was to reduce the unnaturally high surface fuel loads resulting from the thinning operation while causing minimal overstory mortality. The objective of the burn-only treatment was to reduce the amount and continuity of canopy fuels and inflict significant tree mortality, especially in small and medium size classes. While pretreatment surface fuel loads were relatively modest, abundant canopy fuels precluded accomplishing long-term fuel reduction and stand structure objectives with a single burn. Burn prescriptions (see table below) were designed to balance concerns for safety, control, and fire behavior with the desire to restore historical structure and function to the forest.

General burn prescription parameters.
Air temperature55-80 °F
Relative humidity (RH)20-45%
Midflame wind speed0-8 mph
Maximum gusts12 mph
1-Hr fuel moisture6-12%
10-Hr fuel moisture8-18%
100-Hr fuel moisture12-20%
1000-Hr fuel moisture50-100%
Duff moisture40-80%

The restoration cutting prescription set an average target reserve basal area of 48 feet²/acre. Target stand structures were uneven-aged, with a long-term goal of one-half to two-thirds of the basal area in trees >20 inches DBH. Target species composition over the long-term is >90% basal area composition of ponderosa pine.

Units receiving cutting treatments were leave-tree marked. Low thinning removed most pole-sized trees (ladder fuels), improvement cutting removed most shade-tolerant Douglas-fir from the mid- and upper canopy, and selection cutting reduced overall stand density enough to induce regeneration of shade-intolerant ponderosa pine. A cut-to-length system was used to cut and limb trees on site, leaving nonmerchantable materials in place as a buffer between logging equipment and the soil. Merchantable timber was transported from the stand to a landing area using rubber-tired forwarders. This harvest system, coupled with winter logging, resulted in no significant soil compaction or exposed mineral soil [4].

Prescribed burning was initiated in all burn units using strip headfires to control fire intensity. Firing was slow in the thin-burn units to minimize overstory damage, but was increased in the burn-only units to induce tree mortality. Variation in weather conditions among burn days and in the volume and spatial distribution of fuels within each 22-acre unit led to variation in fire behavior among and within the 6 burn units:

TreatmentBurn-onlyThin-burn
Block123123
Wind speed (mph)1-31-31-32-54-83-6
Relative humidity range (%)35-4626-4820-4128-4227-4520-29
Temperature range (°F)48-5367-8567-8353-5657-6464-80
Flame length (feet)Nonslash1-40.5-20.5-21-21-20.5-1
SlashNANANA3-92-92-8
Flame depth (feet)Nonslash2-61-21-31-31-31-2
SlashNANANA4-103-104-10
Fine fuels* consumed (%)565840716671
Fine fuels* consumed (tons/acre)1.31.90.76.56.79.9
Duff (Oe, Oa) consumed (%)17.413.3214.210.414.4
*Fine fuels diameter <3 inches

Fire Season/Severity Classification

All 6 burns (3 in thinned units; 3 in unthinned units) were implemented in the spring of 2002 and were generally of low to moderate severity. Each 22-acre burn was completed in a single day. Silvicultural cuttings ("thinnings") were conducted in the winter of 2000/2001 over snow-covered soil. The following table contains treatment dates and burn severity (measured as degree of ground char).

TreatmentBlockBurn dateHarvest dateArea of a given burn severity* (%)
NoneLowModerateHigh
Burn-only15/15/2002NA405442
Burn-only26/25/2002NA39351313
Burn-only36/14/2002NA316621
Thin-only1NA3/01NANANANA
Thin-only2NA2/01NANANANA
Thin-only3NA2/01NANANANA
Thin-and-burn15/1/20022/013447163
Thin-and-burn26/6/20021/014837114
Thin-and-burn35/31/20022/011565173
*Burn severity: None = No duff burned, Low = Partial duff burned, Moderate = Most/all duff burned, High = All duff and much woody fuel burned

Our "low," "moderate," and "high" burn severity categories correspond well to Burned Area Emergency Response (BAER) severity classifications "lightly," "moderately," and "heavily" burned, respectively. Some of our low-severity areas fell under the BAER "scorch" category, but burn prescriptions were conducted under conditions such that these instances were limited.

Fire Effects on Plant Community

All variables are presented as untransformed values. Statistical tests were conducted on both pretreatment and change (posttreatment-pretreatment) data and P-values <0.05 were considered significant. Sapling density was significantly reduced by all active treatments, with the greatest reduction in the thin-burn treatment [6]. Restoration cutting resulted in significant overstory density reductions and achieved target basal areas to the nearest 0.5 feet ²/acre (averaged across the 22-acre units). Subsequent wind- and burning-related mortality further reduced overstory density and accentuated patchiness, particularly in the thin-burn treatments. Cutting increased proportional basal area composition of seral tree species (from about 60% to 75%). Density of trees and saplings before treatment and in 2003 (1 year after burning/2 years after harvest) are summarized in the following table:

Density measureYearControlBurn-onlyThin-onlyThin-burn
Saplings/acrePrefire805881537425
200392953042858
Trees/acrePrefire163179158143
20031611666155
Basal area (feet ²/acre)Prefire104998991
2003103944842

Understory richness increased significantly more in the thin-only and thin-burn treatments than in the burn-only and control. Forb and nonnative species richness increased more in all active treatments, particularly the thin-burn, than in the control. Native species richness increased significantly in the 2 treatments that included cutting. Mean plot-scale (0.25-acre) richness for all species (total), native species, nonnative species, graminoids, forbs, shrubs, and trees are summarized in the following table by treatment and year, with 1 standard error in parentheses. Letters represent significant differences between treatments, within years. See Metlen and Fiedler [6] for methods and details about richness and cover at the smaller spatial scale (0.00025-acre).

Plot-scale richnessYearControlBurn-onlyThin-onlyThin-burnP
TotalPrefire36.3 (1.3)34.5 (3.9)37.3 (2.3)36.1 (3.1)0.606
200457.3 (2.7)a59.7 (7.1)ab66.2 (4.1)bc68.6 (7.7)c0.024*
NativesPrefire34.1 (0.6)32.9 (3.2)34.8 (1.7)33.5 (2.0)0.632
200452.8 (1.8)a53.7 (5.2)ab59.3 (3.0)b58.4 (5.1)b0.036*
ExoticsPrefire2.2 (0.7)1.6 (0.8)2.3 (0.7)2.6 (1.1)0.440
20044.4 (0.9)a5.9 (2.0)b6.9 (1.1)b10.2 (2.7)c0.040*
GraminoidsPrefire6.1 (0.2)5.4 (0.4)6.8 (0.5)6.9 (0.5)0.013*
200412.5 (1.6)11.6 (2.1)14.0 (1.1)14.1 (2.0)0.211
ForbsPrefire20.7 (1.2)20.2 (2.6)19.5 (1.5)18.8 (2.3)0.510
200433.9 (1.5)a38.1 (4.3)b39.6 (1.9)b43.7 (5.8)c0.021*
ShrubsPrefire7.5 (0.6)6.8 (1.0)8.7 (1.1)8.1 (1.1)0.060
20048.8 (0.9)7.9 (0.8)10.2 (1.3)8.5 (1.5)0.162
Tree seedlingsPrefire2.0 (0.1)2.1 (0.3)2.3 (0.2)2.3 (0.4)0.635
20042.1 (0.0)2.2 (0.1)2.4 (0.2)2.3 (0.3)0.920
*P < 0.05

Richness of graminoids, shrubs, and tree seedlings was unchanged by treatment. However, broad life form groups can disguise the response of individual species. Species that were strongly affected by treatments were identified using indicator species analysis [1] contrasting treatments within years. Burning treatments created microsites suitable for colonization by seed-dispersed species and increased vigor resulting in greater cover of many sprouting perennial species. Similarly, many species responded to cutting by spreading via rhizomes or stolons. The following table displays species with significant indicator values (P<0.05), their generalized individual responses to treatments, and the observed mechanism for response in this study.

Common nameLatin nameTreatment responseResponse mechanism
Burn-onlyThin-onlyThin-Burn
common yarrowAchillea millefoliumNoneIncreaseIncreaseSeeds, rhizomes, increased vigor
rough bentgrassAgrostis scabraNoneIncreaseIncreaseSeeds, increased vigor
Holboell's rockcressArabis holboelliiNoneNoneIncreaseSeeds
kinnikinnickArctostaphylos uva-ursiNoneIncreaseNoneStolons, increased vigor
pinegrassCalamagrostis rubescensNoneIncreaseIncreaseRhizomes, seeds, increased vigor
musk thistleCarduus nutansNoneNoneIncreaseSeeds
Ross' sedgeCarex rossiiNoneNoneIncreaseSeeds, increased vigor
fireweedChamerion angustifoliumIncreaseNoneIncreaseSeeds
Canada thistleCirsium arvenseNoneNoneIncreaseSeeds, rhizomes
bull thistleCirsium vulgareIncreaseIncreaseIncreaseSeeds, increased vigor
miner's-lettuceClaytonia perfoliataNoneNoneIncreaseSeeds
blue-eyed MaryCollinsia parvifloraIncreaseNoneIncreaseSeeds, increased vigor
quill cryptanthaCryptantha affinisNoneNoneIncreaseSeeds
houndstongueCynoglossum officinaleNoneIncreaseIncreaseSeeds
mountain tansymustardDescurainia incanaNoneNoneIncreaseSeeds
shooting starDodecatheon pulchellumIncreaseIncreaseNoneSeeds, increased vigor
tall annual willowherbEpilobium brachycarpumIncreaseIncreaseIncreaseSeeds
glaucus willowherbEpilobium glaberrimumNoneIncreaseIncreaseSeeds
spreading fleabaneErigeron divergensNoneNoneIncreaseSeeds
deceptive groundsmokeGayophytum decipiensNoneNoneIncreaseSeeds
autumn dwarf gentianGentianella amarellaNoneIncreaseIncreaseSeeds
rattlesnake plantainGoodyera oblongifoliaNoneDecreaseDecreaseShade-adapted
houndstounge hawkweedHieracium cynoglossoidesNoneNoneDecreaseBurn mortality
Rocky Mountain juniperJuniperus scopulorumNoneNoneDecreaseBurn mortality
prairie JunegrassKoeleria macranthaNoneNoneIncreaseSeeds, increased vigor
prickly lettuceLactuca serriolaIncreaseNoneIncreaseSeeds
western larch seedlingsLarix occidentalisNoneNoneIncreaseSeeds
field cottonroseLogfia arvensisIncreaseIncreaseIncreaseSeeds
nodding microcerisMicroseris nutansIncreaseNoneNoneSeeds
narrowleaf minerslettuceMontia linearisNoneNoneIncreaseSeeds
Columbia ponderosa pine seedlingsPinus ponderosa var. ponderosaDecreaseNoneDecreaseBurn mortality
prostrate knotweedPolygonum aviculareNoneNoneIncreaseSeeds
selfhealPrunella vulgarisNoneNoneIncreaseSeeds
Wright's cudweedPseudognaphalium canescensIncreaseNoneIncreaseSeeds
Rocky Mountain Douglas-fir seedlingsPseudotsuga menziesii var. glaucaDecreaseNoneDecreaseBurn mortality
sheep sorrelRumex acetosellaNoneNoneIncreaseSeeds
wormleaf stonecropSedum stenopetalumNoneNoneDecreaseBurn mortality
prairie goldenrodSolidago missouriensisNoneIncreaseNoneRhizomes, seeds
Rocky Mountain goldenrodSolidago multiradiataIncreaseIncreaseIncreaseRhizomes, seeds
common dandelionTaraxacum officinaleNoneNoneIncreaseSeeds
yellow salsifyTragopogon dubiusNoneIncreaseIncreaseSeeds
cloverTrifolium spp.NoneNoneIncreaseStolons, seeds
dwarf huckleberryVaccinium caespitosumNoneIncreaseNoneRhizomes
common mulleinVerbascum thapsusIncreaseIncreaseIncreaseSeeds

Coniferous regeneration (<4.5 feet tall) was virtually eliminated from 0.00025-acre quadrats but was still present on 0.25-acre plots. Despite a significant reduction in seedling density at the small scale, regeneration maintained a broad-scale presence similar to that described historically (dispersed and patchy). Western larch regeneration increased significantly in the thin-burn treatment compared to the control, reflecting an adaptation for postfire establishment. Many locally rare, disturbance-adapted understory species also became more abundant after treatment, especially in the thin-burn. While abundance of most species was initially reduced by burning, 2 years after treatment abundance of most species in active treatments was equal or greater than that in the control. The following linked files provide cover and frequencies (by treatment) of all successfully identified species before treatment and in 2004 (2 years after burning and 3 years after harvest):

The thin-burn treatment resulted in conditions most similar to those described historically, with significantly reduced conifer sapling density and increased native understory richness and abundance of individual species. This treatment was also associated with the most negative aspect of restoration--nonnative species invasion [6].

The majority of understory species at this site were resilient to restoration treatments, especially when given several growing seasons to respond. Many native species that were locally rare prior to treatment benefited from active restoration treatments, especially the thin-burn. However, nonnative species responded similarly and may require specific management strategies to limit their establishment and spread following treatments intended to benefit natives.

Further monitoring will be necessary to determine long-term community trends. However, after 3 years of response, restoration treatments show promise for favoring disturbance-adapted native species, particularly locally rare and short-lived species that may have declined in ponderosa pine forests during a century of fire exclusion.

All active treatments successfully reduced some component of hazardous fuels: surface, crown, or both. Surface fuel accumulations were reduced in all size classes by the burn-only treatment. Although thinning increased fuel loads in the litter+1-hour, 10-hour, and 100-hour classes, burning following thinning (thin-burn treatment) reduced fuel loads below pretreatment levels in most classes. Pre- and immediate post-treatment fuel loadings are summarized below by treatment and size class.

TreatmentLitter+1-hour (Tons/acre)10-hour (Tons/acre)100-hour (Tons/acre)1000-hour (Tons/acre)Duff depth (inches)
PrePostPrePostPrePostPrePostPrePost
Control2.1n.s.*0.8n.s.1n.s.8.1n.s.1.3n.s.
Burn-only10.30.70.40.80.56.120.80.5
Thin-only0.92.80.73.30.73.34.24.210.8
Thin-burn0.90.40.70.90.72.13.82.61.10.7
*n.s. = not sampled

Crown fire hazard was modeled for all treatments using crowning index. Crowning index is defined as the windspeed needed to maintain a crown fire once fire has reached the main canopy. Lower crowning index values (e.g., <25 miles/hour) represent stand structures with relatively greater hazard, whereas higher values (e.g., >50 miles/hour) represent relatively low hazard. The least hazardous post-treatment conditions were achieved by the thin-burn treatment, though all active treatments reduced crown fire hazard. Thinning alone modestly increased crowning index, but when the thin-only treatment was followed by timber stand improvement (TSI) cutting of most saplings, crowning index increased substantially. However, should wildfire occur, potential mortality from crown scorch is elevated in the thin-only treatment due to increased loads of untreated surface fuels.

Modeled crowning index (mph) before and after different treatments.
Treatment typeControlBurn-onlyThin-onlyThin-only with TSIThin-burn
Pretreatment2121282830
Posttreatment2126375468

The Lubrecht FFS study provides evidence that alternative restoration treatments can modify potential fire behavior and differentially impact understory plant communities. Taken collectively, these results suggest that all active treatments promote a more open overstory and diverse understory community ― characteristics commonly associated with historically sustainable conditions. However, a mosaic of treatments (including untreated areas) would likely be needed to increase landscape-scale heterogeneity and improve longer-term sustainability of this ponderosa pine ecosystem.

This Research Project Summary is product #111 of the FFS study funded by the Joint Fire Sciences Program. For more information on the Lubrecht FFS study and links to products generated by this research, visit our website at www.forestry.umt.edu/ffslubrecht.

2020 LANDFIRE Biophysical Settings — Historical Fire Regime Characteristics
Biophysical SettingMean Fire Interval (years)Fire Severity Percent (%)
CodeFire Regime GroupLowMixedReplacementAllLowMixedReplacement
Series 10452 - Northern Rocky Mountain Dry-Mesic Montane Mixed Conifer Forest - Larch
10452_10_19III-A1376920237275419
Series 10451 - Northern Rocky Mountain Dry-Mesic Montane Mixed Conifer Forest - Ponderosa Pine-Douglas-fir
10451_10_19I-C395114819493813
Summary
Minimum395114819273813
Maximum1376920237495419
Mean886017528384616
Median886017528384616
Percentage of fires in 3 fire severity classes, derived from LANDFIRE succession modeling. Replacement-severity fires cause >75% kill or top-kill of the upper canopy layer; mixed-severity fires cause 26%-75%; low-severity fires cause <26%.
LANDFIRE. 2020. Biophysical settings models and descriptions, [Online]. Washington, DC: U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; U.S. Geological Survey; Arlington, VA: The Nature Conservancy, (Producers). Available: https://www.landfirereview.org/search.php [96496]

Table A1: Species Names

This Research Project Summary contains fire effects and/or fire response information on the following species. For further information, search species names to find FEIS reviews for those species.

Common nameScientific name
Trees
Rocky Mountain juniperJuniperus scopulorum
western larchLarix occidentalis
Rocky Mountain lodgepole pinePinus contorta var. latifolia
Columbia ponderosa pinePinus ponderosa var. ponderosa
quaking aspenPopulus tremuloides
Rocky Mountain Douglas-firPseudotsuga menziesii var. glauca
Scouler's willowSalix scouleriana
Shrubs
Rocky Mountain mapleAcer glabrum
Saskatoon serviceberryAmelanchier alnifolia
kinnikinnickArctostaphylos uva-ursi
mountain big sagebrushArtemisia tridentata ssp. vaseyana
snowbrush ceanothusCeanothus velutinus
prince's-pineChimaphila umbellata
green rabbitbrushChrysothamnus viscidiflorus
black hawthornCrataegus douglasii
oceansprayHolodiscus discolor
common juniperJuniperus communis
creeping barberryMahonia repens
menziesiaMenziesia ferruginea
green-flowered wintergreenPyrola chlorantha
whiteveined wintergreenPyrola picta
sidebells wintergreenPyrola secunda
wax currentRibes cereum
gooseberry currantRibes montigenum
Woods' roseRosa woodsii
thimbleberryRubus parviflorus
russet buffaloberryShepherdia canadensis
white spireaSpiraea betulifolia
common snowberrySymphoricarpos albus
dwarf huckleberryVaccinium caespitosum
big huckleberryVaccinium membranaceum
Graminoids
western needlegrassAchnatherum occidentale
Richardson needlegrassAchnatherum richardsonii
rough bentgrassAgrostis scabra
dense silkybentApera interrupta
nodding bromeBromus anomalus
cheatgrassBromus tectorum
purple pinegrassCalamagrostis purpurascens
pinegrassCalamagrostis rubescens
northwestern sedgeCarex concinnoides
Geyer's sedgeCarex geyeri
smallwinged sedgeCarex microptera
Nebraska sedgeCarex nebrascensis
chamisso sedgeCarex pachystachya
Ross' sedgeCarex rossii
California oatgrassDanthonia californica
timber oatgrassDanthonia intermedia
onespike danthoniaDanthonia unispicata
slender hairgrassDeschampsia elongata
squirreltailElymus elymoides
blue wildryeElymus glaucus
Altai fescueFestuca altaica
Idaho fescueFestuca idahoensis
western fescueFestuca occidentalis
foxtail barleyHordeum jubatum
mountain rushJuncus arcticus subsp. littoralis
prairie JunegrassKoeleria macrantha
field woodrushLuzula campestris
timothyPhleum pratense
Canada bluegrassPoa compressa
Wheeler bluegrassPoa nervosa
fowl bluegrassPoa palustris
Kentucky bluegrassPoa pratensis
Sandberg bluegrassPoa secunda
bluebunch wheatgrassPseudoroegneria spicata
tall trisetumTrisetum canescens
spike trisetumTrisetum spicatum
sixweeks grassVulpia octoflora
Forbs
common yarrowAchillea millefolium
pale agoserisAgoseris glauca
annual agoserisAgoseris heterophylla
onionAllium spp.
Menzies' fiddleneckAmsinckia menziesii
pearly everlastingAnaphalis margaritacea
Pacific anemoneAnemone multifida
pearly pussytoesAntennaria anaphaloides
raceme pussytoesAntennaria racemosa
pussytoesAntennaria spp.
spreading dogbaneApocynum androsaemifolium
Holboell's rockcressArabis holboellii
rockcressArabis spp.
ballhead sandwortArenaria congesta
thymeleaf sandwortArenaria serpyllifolia
foothill arnicaArnica fulgens
arnicaArnica spp.
Canadian milkvetchAstragalus canadensis
timber milkvetchAstragalus miser
arrowleaf balsamrootBalsamorhiza sagittata
Mariposa lilyCalochortus spp.
small camasCamassia quamash
bluebell bellflowerCampanula rotundifolia
musk thistleCarduus nutans
spotted knapweedCentaurea maculosa
big chickweedCerastium fontanum
nodding chickweedCerastium nutans
fireweedChamerion angustifolium
lambsquartersChenopodium album
blight goosefootChenopodium capitatum
narrowleaf goosefootChenopodium leptophyllum
sulphur Indian paintbrushCastilleja sulphurea
Canada thistleCirsium arvense
bull thistleCirsium vulgare
miner's-lettuceClaytonia perfoliata
blue virgin's bowerClematis occidentalis
blue-eyed MaryCollinsia parviflora
tiny trumpetCollomia linearis
Canadian horseweedConyza canadensis
quill cryptanthaCryptantha affinis
houndstongueCynoglossum officinale
mountain lady-slipperCypripedium montanum
mountain tansymustardDescurainia incana
roughfruit fairybellsDisporum trachycarpum
shooting starDodecatheon pulchellum
tall annual willowherbEpilobium brachycarpum
glaucus willowherbEpilobium glaberrimum
cutleaf daisyErigeron compositus
spreading fleabaneErigeron divergens
streamside fleabaneErigeron glabellus
shaggy fleabaneErigeron pumilus
prairie fleabaneErigeron strigosus
threenerve fleabaneErigeron subtrinervis
yellow avalanche-lilyErythronium grandiflorum
western showy asterEurybia conspicua
subalpine asterEurybia merita
woodland strawberryFragaria vesca
Virginia strawberryFragaria virginiana
yellow fritillaryFritillaria pudica
common gaillardiaGaillardia aristata
stickywillyGalium aparine
northern bedstrawGalium boreale
deceptive groundsmokeGayophytum decipiens
autumn dwarf gentianGentianella amarella
sticky purple geraniumGeranium viscosissimum
old man's whiskersGeum triflorum
rattlesnake plantainGoodyera oblongifolia
curlycup gumweedGrindelia squarrosa
hairy false goldenasterHeterotheca villosa
roundleaf alumrootHeuchera cylindrica
white hawkweedHieracium albiflorum
Canadian hawkweedHieracium canadense
houndstongue hawkweedHieracium cynoglossoides
narrowleaf hawkweedHieracium umbellatum
prickly lettuceLactuca serriola
blue lettuceLactuca tatarica
northern linanthusLinanthus septentrionalis
twinflowerLinnaea borealis
western stoneseedLithospermum ruderale
field cottonroseLogfia arvensis
nineleaf biscuitrootLomatium triternatum
silvery lupineLupinus argenteus
small tarweedMadia exigua
false Solomon's-sealMaianthemum racemosum
narrowleaf cowwheatMelampyrum lineare
Alaska oniongrassMelica subulata
yellow sweetcloverMelilotus officinalis
wild mintMentha arvensis
nodding microcerisMicroseris nutans
narrowleaf minerslettuceMontia linearis
strict forget-me-notMyosotis stricta
thinleaved owl's cloverOrthocarpus tenuifolius
sweetcicelyOsmorhiza berteroi
woolly groundselPackera cana
coiled lousewortPedicularis contorta
Alberta beardtonguePenstemon albertinus
penstemonPenstemon spp.
silverleaf phaceliaPhacelia hastata
slender phloxPhlox gracilis
slender-spire orchidPiperia unalascensis
common plantainPlantago major
prostrate knotweedPolygonum aviculare
Douglas' knotweedPolygonum douglasii
sticky cinquefoilPotentilla glandulosa
slender cinquefoilPotentilla gracilis
sulphur cinquefoilPotentilla recta
selfhealPrunella vulgaris
Wright's cudweedPseudognaphalium canescens
woodland pinedropPterospora andromedea
sharpleaf buttercupRanunculus acriformis
sheep sorrelRumex acetosella
curly dockRumex crispus
wormleaf stonecropSedum stenopetalum
lambstongue ragwortSenecio integerrimus
tall ragwortSenecio serra
Menzies' campionSilene menziesii
Oregon sileneSilene oregana
prairie goldenrodSolidago missouriensis
Rocky Mountain goldenrodSolidago multiradiata
hooded ladies-tressesSpiranthes romanzoffiana
longstalk starwortStellaria longipes
western asterSymphyotrichum ascendens
common dandelionTaraxacum officinale
western meadow-rueThalictrum occidentale
arrow thelypodyThelypodium sagittatum
field pennycressThlaspi arvense
yellow salsifyTragopogon dubius
cloverTrifolium spp.
largeflower triteleiaTriteleia grandiflora
stinging nettleUrtica dioica
woods valerianValeriana dioica
common mulleinVerbascum thapsus
thymeleaf speedwellVeronica serpyllifolia
hookspur violetViola adunca
meadow deathcamasZigadenus venenosus
Ferns
brittle bladderfernCystopteris fragilis

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Last updated March 25, 2026