Fire Study - Research Project Summary

Effects of fall and spring prescribed burning in sagebrush steppe in central Oregon

Written

July, 2018

Study Authors

Sapsis and Kauffman

Contributors

Elena Ulev - 1st Compiler, Janet L. Fryer - 2nd Compiler, D. Tirmenstein - 3rd Compiler

Fire Study Type

Research Project Summary

Ulev, Elena; Fryer, Janet L.; Tirmenstein, D., comps. 2008. [revised 2018]. Research Project Summary: Effects of fall and spring prescribed burning in sagebrush steppe in central Oregon. 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/sapsis-and-kauffman-2018

Sources

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

Sapsis, David B. 1990. Ecological effects of spring and fall prescribed burning on basin big sagebrush/Idaho fescue--bluebunch wheatgrass communities. Corvallis, OR: Oregon State University. 105 p. Thesis. [2].
Sapsis, David B.; Kauffman, J. Boone. 1991. Fuel consumption and fire behavior associated with prescribed fires in sagebrush ecosystems. Northwest Science. 65(4): 173-179. [3].

Species Included in this Summary

Common names are used throughout this summary. For a complete list of the common and scientific names of species mentioned in this summary see table A1.

Revisions

On 30 March 2018, information from the Fire Case Study in the western juniper Species Review in FEIS was added to this Research Project Summary.

The study was conducted on the Sheep Rock Unit of the John Day Fossil Beds National Monument in central Oregon [2,3]. The site is approximately 5 miles (10 km) west of Dayville, Oregon [2].

Site Description

Aspect: north
Slope: 20%-60%
Elevation: 2,297-2,625 feet (700-860 m)
Soils: very stony, clay-loams on moderately deep, well-drained slopes
Annual precipitation: 10-14 inches (250-360 mm); mean of 11 inches (290 mm) at a weather station about 1 mile (2 km) from the study site [2,3]

Photo of a broad, dry valley as viewed from an elevated area behind a conifer tree branch.

Photo Credit

USDA, Forest Service photo by Janet Fryer.

Sheep Rock Unit of the John Day Fossil Beds National Monument.

Plant Community

The prefire plant community was a steppe community dominated by basin big sagebrush in the overstory and bluebunch wheatgrass-Idaho fescue in the understory. Dominant forbs included common yarrow and basalt milkvetch. Western juniper grew as scattered individuals, many of which were seedlings.

Study sites are classified in the plant community shown in the LANDFIRE Biophysical Settings section and probably historically experienced the fire regime described there.

Photo of a dry hillslope and arroyo with scattered small tress and shrubs, brown grasses, and bare soil and rock.

Photo Credit

USDA, Forest Service photo by Janet Fryer.

A western juniper seedling that established beneath a basin big sagebrush canopy in the Sheep Rock Unit, John Day Fossil Beds National Monument.

Fuels

Fuels were partitioned into the following categories [1,2]:

1-hour timelag: live and dead forbs and grasses, and woody debris from 0 to 0.25 inch (0-0.63 cm) DBH
10-hour timelag: woody debris 0.25 to 1.00 inch (0.63-2.54 cm) DBH
100-hour timelag: woody debris >1 inch (2.54 cm) DBH

The prefire biomass of herbaceous fuels in both burn units exceeded minimum threshold values needed for fire spread. Total prefire aboveground biomass was significantly higher in fall- than in spring-burned plots, and moisture content of soil and vegetation was generally higher in spring- than fall-burned plots [2,3] (table 2).

Table 2—Mean prefire aboveground biomass and moisture content measures on fall and spring burn plots [2,3].
Fuel variable	Fire treatment
Fuel variable	Fall	Spring
Prefire aboveground biomass (Mg/ha)
Standing live basin big sagebrush	4.11	1.67^a
Canopy cover of basin big sagebrush (%)	15	7.5
Standing dead basin big sagebrush	1.96	1.26^a
Grass/forbs	3.01	2.67^a
1-hour timelag	1.80	0.86^a
10-hour timelag	2.22	1.03^a
100-hour timelag	2.72	1.35^a
Total aboveground biomass	10.59	6.23
Moisture content (%)
Soil surface	2.90	3.21
Dead grass/forbs	8.88	7.36
Live grass	not sampled due to lack of vegetation	142.60
Sagebrush foliage	97.19	186.02^a
10-hour timelag	4.59	4.99
^aWithin rows, significant difference between treatments (P < 0.05).

Plant Phenology

Phenology of the vegetation before the fall and spring fires was not provided, but vegetation was likely actively growing before the spring fire and beginning to senesce at the time of the fall fire.

Fire Season/Intensity Classification

Fall (9/25/1987), moderate to high intensity
Spring (5/24/1988), low intensity

Fire Description

The research objective was to examine the effects of fall and spring burning in a basin big sagebrush/Idaho fescue-bluebunch wheatgrass plant community, including fuel consumption and plant species' responses to fire treatments, and to reduce western juniper density [2,3].

Prefire data for the fall fire were collected in July and August 1987, and fall burning was conducted on 25 September 1987. Postfire data for the fall fire were collected in May and June 1988 (postfire year 1) and June and July 1989 (postfire year 2). For the spring prescribed fire, prefire data were collected in April and May 1988, and spring burning was conducted on 24 May 1988. Postfire data for the spring fire were collected in June and July 1989 (postfire year 1); data were not collected for the spring fire in postfire year 2. Each burn unit was 30 × 50 m in area [2,3].

Both burns were ignited with drip torches using a strip-head firing pattern. Overall, pretreatment fuel loads ranged from 22.3 to 53.5 tons/acre (5-12 Mg/ha). Fuel loads averaged 46.8 tons/acre (10.5 Mg/ha) in fall treatment units and 27.8 tons/acre (6.2 Mg/ha) in spring treatment units. Large amounts of herbaceous fuels (>13.4 tons/acre (3.0 Mg/ha)) were present on both burn units [2] (table 3).

Table 3—Burning Conditions [2,3].
Variable	Fall	Spring
Time of burn	9:35-13:45	12:35-15:26
Temperature, ^oF (^oC)	59-64 (15-18)	73-77 (23-25)
Relative humidity, %	41-48	21-24
Windspeed, miles/h (km/h)	0-9.3 (0-15)	0-10.5 (0-17)
Soil moisture content, %	2.90	3.21
Dead herbaceous moisture content, %	8.88	7.36^a
10-hr timelag moisture content, %	4.59	4.99
Sagebrush foliage moisture content, %	97.19	186.02^a
Live grass moisture content, %	not applicable	142.60
^aWithin rows, significant difference between treatments (P < 0.05).

Fire Behavior

Fine fuel moisture was higher in the fall than in the spring fire, resulting in a more intense fire and greater biomass consumption. Flame lengths of the fall fire averaged over 13 feet (4 m) compared to <6.5 feet (2 m) for the spring fire. Because fireline intensity varies exponentially with flame length, this resulted in a more than seven-fold difference in fireline intensity. Rate of spread of the flame front was six times faster in the fall fire, even though temperatures were lower and relative humidity higher in the fall than in the spring fire. Total biomass consumption was significantly greater in fall fire (93%) than in the spring fire (84%); the fall fire consumed about twice as much fuel [2] (table 4).

Table 4—Fire Behavior [2,3].
Variable	Fall	Spring
Flame length, feet (m)	13.58 (4.14)	5.71 (1.74)^a
Fireline intensity, kW/m	6441	883^a
Reaction intensity (heat release rate, kW/m²)	2.17	1.12
Flame depth, feet (m)	33.96 (10.35)	8.40 (2.56)^a
Rate of spread, feet/s (m/s)	5.15 (1.57)	0.75 (0.23)^a
Heat/area in flaming front, kJ/m²	3,253	3,935
Total energy (flaming & smoldering, kJ/m²)	18,119	9,267
Residence time, s	6.92	11.66^a
Fuel consumption, tons/acre (Mg/ha)	43.72 (9.80)	23.33 (5.23)^a
^aWithin rows, significant difference between treatments (P < 0.05).

Fuel Consumption and Residual Fuel Loads

Fuel consumption was significantly greater on fall- than on spring-burned plots for 10-hour and 100-hour fuels as a result of higher fuel loads and lower fuel moisture. Total postfire biomass of residual fuels was not significantly different between treatments [2,3] (table 5).

Table 5—Mean fuel consumption and residual fuel loads in fall and spring prescribed burn plots [2,3].
Fuel component	Treatment
Fuel component	Fall		Spring
Fuel consumption (Mg/ha and % consumption)
Fine fuels	3.64	95%	2.76	92%
1-hour timelag	1.65	92%	0.66	77%
10-hour timelag	1.90	86%	0.54	52%^a
100-hour timelag	2.63	97%	1.27	94%^a
Total biomass	9.8	93%	5.23	84%^a
Residual fuel loads (Mg/ha)
Fine fuels	0.23		0.23
1-hour timelag	0.15		0.20
10-hour timelag	0.32		0.49
100-hour timelag	0.09		0.08
Total biomass	0.79		1.00
^aWithin rows, significant difference between treatments (P < 0.05).

Fire Effects on Plant Community

Response of Dominant Bunchgrasses

Both bluebunch wheatgrass and Idaho fescue showed good survivorship and recovery from the fires. Postfire survivorship, abundance, growth, and production of seed-bearing culms were generally higher for bluebunch wheatgrass than for Idaho fescue [2], probably due to bluebunch wheatgrass's larger stature.

Survivorship

Bluebunch wheatgrass showed higher survivorship than Idaho fescue after the fall prescribed fire. Survival of both species was greater after spring than fall fires, likely due to their higher moisture contents in spring. Most individuals killed by fall fires were located near basin big sagebrush plants [2] (table 6).

Table 6—Mean first-year mortality of bluebunch wheatgrass and Idaho fescue after prescribed fires, based on 3-32 individually marked plants [2].
Species	Treatment
Species	Mortality after fall Rx fire	Mortality after spring Rx fire	Control
Bluebunch wheatgrass	5.2^a	4.4^b	0^b
Idaho fescue	20.1^a	3.5^b	0.7^b
^aWithin rows, significant difference between treatments (P < 0.10).

Density

Mean density of bluebunch wheatgrass was relatively constant across treatments. Density of Idaho fescue was greater on fall-burned plots compared to control plots throughout the study period [2] (table 7).

Table 7—Mean density (plants/m²) of bluebunch wheatgrass and Idaho fescue by treatment and year [2].
Year	Treatment
Year	Fall	Spring	Control
Bluebunch wheatgrass
Prefire	2.2	3.3	1.8
Postfire year 1	2.2	3.8	1.8
Postfire year 2	1.9	ND*	2.0
Idaho fescue
Prefire	18.8^a	3.2	1.7
Postfire year 1	17.3^a	2.2	1.5
Postfire year 2	17.3^a	ND	1.2
*ND indicates no data were collected. ^aWithin rows, significant difference between fire treatment and control (P<0.1).

Basal cover of bluebunch wheatgrass increased after the fire on fall-burned plots, but did not increase on spring-burned plots or control plots. Basal cover of Idaho fescue was relatively stable across time on burned and control plots [2] (table 8).

Table 8—Mean basal cover (cm²) of bluebunch wheatgrass and Idaho fescue by treatment and year [2].
Sample timing	Treatment
Sample timing	Fall	Spring	Control
Bluebunch wheatgrass
Prefire	198.5^a	161.2	189.3
Postfire year 1	214.7^ab1	148.9	153.6
Postfire year 2	271.2^b1	ND*	171.8
Idaho fescue
Prefire	60.9	40.5	66.1
Postfire year 1	46.9	45.6	56.8
Postfire year 2	54.8	ND	48.6
*ND indicates no data were collected. Within rows, different superscripted letters denote a significant difference between years within treatments; a superscripted number denotes a significant difference between treatment and control within a year (P<0.1).

Mean basal area of bluebunch wheatgrass increased by 36% from prefire levels to postfire year 2 after fire prescribed fire; the decrease observed after spring prescribed fire was not significant. Idaho fescue showed decreases after fall and spring fires, but none were significant [2] (table 9).

Table 9—Mean basal area (cm²) of bluebunch wheatgrass and Idaho fescue by treatment and year [2].
Sample timing	Treatment
Sample timing	Fall	Spring	Control
Bluebunch wheatgrass
Prefire	198.5^a	ND*	189.3
Postfire year 1	214.7^ab1	161.2	153.6
Postfire year 2	271.2^b1	148.9	171.8
Idaho fescue
Prefire	60.9	ND	66.1
Postfire year 1	46.9	40.5	56.8
Postfire year 2	54.8	45.6	48.6
*ND indicates no data were collected. Within columns, different superscripted letters denote a significant difference between years within treatments. A superscripted number denotes a significant difference between treatment and control within years (P < 0.1).

Growth and Reproduction

Fire effects were variable for height and flowering culm production for both bluebunch wheatgrass and Idaho fescue. Mean maximum height of bluebunch wheatgrass and Idaho fescue on fall burns significantly decreased from prefire levels in postfire year 1 but significantly increased between postfire year 1 and postfire year 2. By postfire year 2, mean number of flowering culms had significantly increased on fall-burned compared to prefire and control plots for bluebunch wheatgrass but had decreased for Idaho fescue. Spring burning decreased maximum height of bluebunch wheatgrass compared to prefire and control plots, but spring burning did not significantly change the number of bluebunch wheatgrass's flowering culms compared to prefire numbers. For Idaho fescue, spring burning significantly increased the mean number of flowering culms and maximum plant height compared to the number of culms and maximum plant height on prefire and control plots [2] (table 10).

Table 10—Mean maximum height (cm) and number of flowering culms of bluebunch wheatgrass and Idaho fescue by treatment and year [2].
Sample timing	Treatment
	Fall		Spring		Control
	height	number	height	number	height	number
Bluebunch wheatgrass
Prefire	67.1^a	33.6^a	64.8^a	17.1	70.0^a	4.6^a
Postfire year 1	59.5^b	11.6^b1	59.6^b1	16.7	63.8^b	28.1^b
Postfire year 2	83.1^c1	58.7^c1	ND*	ND	73.4^a	22.6^c
Idaho fescue
Prefire	42.7^a	17.7^a	19.4^a	0.0^a	39.6^a	22.4^a
Postfire year 1	14.7^b1	0.0^b	26.2^b1	2.3^b1	18.3^b	0.0^b
Postfire year 2	36.8^a	11.1^c1	ND	ND	39.0^a	6.9^c
*ND indicates no data were collected. Within columns, different superscripted letters denote a significant difference between years within treatments. A superscripted number denotes a significant difference between treatment and control within years (P < 0.1).

Response of Annual Grasses, Forbs, and Woody Species

Plant species diversity increased in the sagebrush steppe community on both fall-and spring-burned plots compared to prefire levels. The prescribed fires generally increased annual forb abundance and decreased abundance of annual grasses and woody species. Fall fires in particular stimulated growth of bluebunch wheatgrass, but they temporarily reduced the size and abundance of Idaho fescue plants [2].

Density

Prescribed burning generally reduced the density of annual grasses compared to prefire densities. The exception was small sixweeks grass, which increased the year after fall fire but returned to prefire density in postfire year 2. Both fall and spring burning caused high mortality of basin big sagebrush, broom snakeweed, and western juniper, the only tree on study plots. Fire had no significant effect on green rabbitbrush density [2] (table 11).

Table 11—Mean density (plants/m²) of species with significant responses to fire, by treatment and year. 1987 is the prefire year for the fall treatment; 1988 is the prefire year for the spring treatment [2].
Species	Treatment
	Fall			Spring		Control
	1987 (prefire)	1988 (postfire yr 1)	1989 (postfire yr 2)	1988 (prefire)	1989 (postfire yr 1)	1978	1988	1989
Annual grasses
rattlesnake brome	23	0	2	3.0	0	13	0	0
soft brome	82^a	10^b	0^b	37^a	0^b	160^a	0^b	0^b
cheatgrass	446^a	43^b	169^b	552	85^b	524	662	476
small sixweeks grass	1.9	11	1.9	0	0	0	0	0
Shrubs
basin big sagebrush	3,033^a	0^b	0^b	987	133	1,334	1,334	1,334
shadscale	133	0	0	0	0	667	667	667
green rabbitbrush	33	33	33	240	240	44	44	44
broom snakeweed	500	0	0	400	112	889	1,121	946
Tree
western juniper	456	0	0	369	0	733	733	1,040
Within treatments, different superscripted letters denote a significant difference between years (P < 0.10).

Frequency

Out of a total of 59 plant species, relatively few showed changes in frequency compared to prefire levels. In 12- × 24-inch (30 × 60 cm) quadrats sampled for species presence/absence, only 10, 9, and 4 species showed significant changes in frequency after fall fire, spring fire, and control treatments, respectively. Both fall and spring burning caused a short-term reduction in cheatgrass, but cheatgrass returned to prefire levels by the second postfire year on the fall burn. Sagebrush Mariposa lily frequency increased greatly following fall burning. Western yarrow and basin big sagebrush increased greatly after spring burning; increases in basin big sagebrush were due mostly to germinants [2] (table 12).

Table 12—Mean frequency (%) of plant species in 12 × 24-inch quadrats that had significant responses to fire, by treatment and year. 1987 is the prefire year for the fall treatment; 1988 is the prefire year for the spring treatment [2].
Fire timing	Species	Year
Fire timing	Species	1987	1988	1989
Fall	Annual grasses
	rattlesnake brome	22^a	2^b	4^b
	cheatgrass	87^a	54^b	84^a
	Annual forbs
	spring draba	0^a	0^a	59^b
	Canadian horseweed	0^a	2^a	15^b
	chaparral willowherb	4^a	3^a	14^b
	jagged chickweed	45^a	11^b	55^c
	threadleaf phacelia	0^a	1^a	27^b
	tall tumblemustard	1^a	1^a	27^b
	Perennial forbs
	sagebrush Mariposa lily	2^a	3^a	20^b
	yellow salsify	9^a	12^a	3^b
Spring	Annual grasses
	soft brome	*ND	27^a	3^b
	cheatgrass	ND	89^a	73^b
	Annual forbs
	jagged chickweed	ND	33^a	72^b
	prickly lettuce	ND	9^a	24^b
	Perennial forbs
	western yarrow	ND	46^a	67^b
	smallflower woodland-star	ND	24^a	0^b
	bigseed biscuitroot	ND	15^a	1^b
	sagebrush false dandelion	ND	20^a	4^b
	Shrub
	basin big sagebrush	ND	13^a	50^b
Control	Annual grass
	rattlesnake brome	10^a	0^b	0^b
	Perennial forbs
	western yarrow	2^a	17^b	39^b
	nineleaf biscuitroot	0^a	17^b	1^a
	Shrub
	basin big sagebrush	2^a	9^a	33^b
*ND indicates no data were collected. Within rows, different superscripted letters denote a significant difference between years (P < 0.10).

Changes in pre- and postfire frequency are listed in table 13 [2].

Table 13—Changes in relative plant frequency (%) in 12-inch x 24-inch quadrats relative to prefire conditions. "+" indicates significant increase, "-" indicates significant decrease, "0" indicates no significant change (P < 0.1). Dashes (—)indicate the species was not found on that treatment unit [2].
Common name	Scientific name	Response to treatment
Common name	Scientific name	Fall fire^a	Spring fire^b	Control^c
Annual grasses
rattlesnake brome	Bromus brizeformis	- -	0	- -
soft brome	Bromus hordaceus (Bromus mollis)*	0 0	-	0 0
cheatgrass	Bromus tectorum	- 0	-	0 0
small sixweeks grass	Vulpia microstachys (Festuca microstachys)*	0 0	0	0 0
Perennial grasses
squirreltail	Elymus elymoides (Sitanion hystrix)*	0 0	—	—
Idaho fescue	Festuca idahoensis	0 0	0	0 0
needle and thread	Hesperostipa comata (Stipa comata)*	0 0	—	—
prairie Junegrass	Koeleria macrantha (Koeleria cristata)*	0 0	—	0 0
bulbous bluegrass	Poa bulbosa	—	0	—
Kentucky bluegrass	Poa pratensis	0 0	0	0 0
Sandberg bluegrass	Poa secunda (Poa sandbergii)*	0 0	0	0 0
bluebunch wheatgrass	Pseudoroegneria spicata (Agropyron spicatum)*	0 0	0	0 0
Annual forbs
pale madwort	Alyssum alysoides	0 0	0	0 0
bristly fiddleneck	Amsinckia tessellata	—	0	—
rough eyelashweed	Blepharipappus scaber	—	0	—
sticky chickweed	Cerastium glomeratum (C. viscosum)*	0 0	0	0 0
thyme-leaf sandmat	Chamaesyce serpyllifolia (Euphorbia serpyllifolia)*	0 0	0	—
lambsquarters	Chenopodium album	0 0	—	—
miner's-lettuce	Claytonia perfoliata (Montia perfoliata)*	0 0	—	—
Canadian horseweed	Conyza canadensis	0 +	0	—
maiden blue-eyed Mary	Collinsia parviflora		0	—
pinnate tansymustard	Descurainia pinnata	0 0	—	—
spring draba	Draba verna	0 +	0	0 0
chaparral willowherb	Epilobium minutum	0 +	0	0 0
redstem stork's bill	Erodium cicutarium	—	—	—
stickywilly	Galium aparine	0 0	0	—
common sunflower	Helianthus annuus	0 0	0	—
jagged chickweed	Holosteum umbellatum	+ +	+	0 0
branched lagophylla	Lagophylla ramosissima	0 0	—	0 0
clasping pepperweed	Lepidium perfoliatum	0 0	0	0 0
threadleaf phacelia	Phacelia linearis	0 +	0	0 0
longhorn plectritis	Plectritis macrocera	0 0	0	0 0
tall tumblemustard	Sisymbium altissimum	0 +	0	0 0
common dandelion	Taraxacum officinale	—	—	—
Perennial forbs
common yarrow	Achillea millefolium	0 0	+	+ +
low pussytoes	Antennaria dimorpha	0 0	0	0 0
basalt milkvetch	Astragalus filipes	0 0	0	0 0
woollypod milkvetch	Astragalus purshii	—	0	—
sagebrush mariposa lily	Calochortus macrocarpus	0 +	0	—
heart-podded hoary cress	Cardaria draba	0 0	0	—
bull thistle	Cirsium vulgare	—	0	—
largeflower hawksbeard	Crepis occidentalis	—	0	0 0
threadleaf fleabane	Erigeron filifolius	0 0	—	0 0
desert yellow fleabane	Erigeron linearis	0 0	0	—
shaggy fleabane	Erigeron pumilus	0 0	0	—
Blue Mountain buckwheat	Eriogonum strictum	0 0	0	—
prickly lettuce	Lactuca serriola	0 0	+	0 0
smallflower woodland-star	Lithophragma parviflorum	—	-	—
bigseed biscuitroot	Lomatium macrocarpum	0 0	-	0 0
nineleaf biscuitroot	Lomatium triternatum	0 0	0	+ 0
sagebrush false dandelion	Nothocalais troximoides (Microseris troximoides)*	0 0	-	0 0
silverleaf phacelia	Phacelia hastata	—	0	—
woolly groundsel	Packera cana (Senecio canus)*	0 0	0	0 0
spearleaf stonecrop	Sedum lanceolatum	0 0	0	0 0
Munro's globemallow	Sphaeralcea munroana	0 0	—	—
common mullein	Verbascum thapsus	—	0	—
Shrubs
basin big sagebrush	Artemisia tridentata subsp. tridentata	0 0	+	0 +
shadscale saltbush	Atriplex confertifolia	0 0	—	0 0
green rabbitbrush	Chrysothamnus viscidiflorus	0 0	—	—
broom snakeweed	Gutierrezia sarothrae	0 0	0	0 0
Tree
western juniper	Juniperus occidentalis	0 0	—	0 0
*For species that have undergone scientific name changes, scientific names in parentheses are those used in the research papers. ^a1st value is for postfire year 1 (1988) relative to prefire (1987); 2nd value is for postfire year 2 (1989). ^bRelative to prefire (1988). ^c1st value is for 1988 relative to 1987; 2nd value is for 1989 relative to 1987.

Response of western juniper: Both treatments killed all western juniper (100% reduction in density) and increased relative abundance of native herbaceous species. Western juniper density on control plots increased 40% over the study period due to seedling establishment. Western juniper seedling establishment was likely promoted by higher-than-average precipitation in 1989 [2] (table 14).

Table 14—Mean density of western juniper [2].
Treatment	Density (stems/ha)
Year	1987	1988	1989
Fall	456	0	0
Spring	not applicable	369	0
Control	733	733	1,040

Fire Effects on the Seed Bank

In greenhouse trials using soil and duff collected from burned and unburned plots, both fall and spring fires caused significant reductions in viable soil-stored seed populations. Plots were located in a flat area dominated by cheatgrass. Fall fire significantly reduced the number of viable cheatgrass, spring draba, and jagged chickweed seeds. Spring fire reduced the number of viable cheatgrass and redstem stork's bill seeds [2] (table 15).

Table 15—Greenhouse trials of burned and unburned soil and duff samples by fire treatment. Data are mean number of germinants in paired burned and unburned soil samples (3.1 in²) collected to a 1-inch depth [2].
Species and season of burning	Treatment
Species and season of burning	Burned	Unburned
Fall
Cheatgrass	19*	184
Spring draba	8.2*	95
Redstem stork's bill	0.6	3.8
Jagged chickweed	5.4*	151
Common dandelion	0.2	1.4
Spring
Cheatgrass	4.0*	161
Spring draba	12.8	67
Redstem stork's bill	4.2*	2.0
Jagged chickweed	0	2.0
*Significant difference between burned and unburned treatments (P < 0.05).

Fire behavior and fuel consumption in basin big sagebrush plant communities differed greatly between fall and spring burning. Differences in active flaming were likely related to fuel moisture, and differences in fuel consumption and total energy released were likely related to fuel availability. Both fall and spring burning shifted plant community composition toward dominance by forbs, bluebunch wheatgrass, and Idaho fescue. Abundance all woody species except green rabbitbrush was reduced by the fires. High postfire frequency of basin big sagebrush germinants on spring-burned plots suggests that basin big sagebrush may reestablish from seed relatively quickly from the spring fire [2].

Both spring and fall fires changed stand structure and succession to dominance by native perennial grasses and forbs. However, since this 1987-1989 research project was conducted, cover of nonnative, invasive grasses—including cheatgrass, medusahead, and ventenata—has increased in John Day Fossil Beds National Monument [1], increasing continuity of fine fuels and chances of shifting the fire regime to a grass/fire cycle [4]. In order to preserve remaining big sagebrush communities, fire management at the Monument as of 2018 was focused on protecting sagebrush communities from fire. Prescribed fire is not used in big sagebrush communities in the Monument due to likely postfire increases in cover of nonnative annual grasses [1].

2020 LANDFIRE Biophysical Settings — Historical Fire Regime Characteristics
Biophysical Setting		Mean Fire Interval (years)				Fire Severity Percent (%)
Code	Fire Regime Group	Low	Mixed	Replacement	All	Low	Mixed	Replacement
Series 11250 - Inter-Mountain Basins Big Sagebrush Steppe
11250_1_7_8_9_10_19	IV-A			59	59	0	0	100
Summary
Minimum				59	59	0	0	100
Maximum				59	59	0	0	100
Mean				59	59	0	0	100
Median				59	59	0	0	100
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

Table A1—Common and scientific names of plant species included in this Summary.
Common name	Scientific name
Annual grasses
rattlesnake brome	Bromus briziformis
soft brome	Bromus hordeaceus (Bromus mollis*, annual or biennial)
cheatgrass	Bromus tectorum
small sixweeks grass	Vulpia microstachys (Festuca microstachys)*
medusahead	Taeniatherum caput-medusae
ventenata	Ventenata dubia
Perennial bunchgrasses
bluebunch wheatgrass	Pseudoroegneria spicata (Agropyron spicatum)*
squirreltail	Elymus elymoides (Sitanion hystrix)*
Idaho fescue	Festuca idahoensis
needle and thread	Hesperostipa comata (Stipa comata)*
prairie Junegrass	Koeleria macrantha (Koeleria cristata)*
bulbous bluegrass	Poa bulbosa
Kentucky bluegrass	Poa pratensis
Sandberg bluegrass	Poa secunda (Poa sandbergii)*
Annual forbs
pale madwort	Alyssum alysoides
bristly fiddleneck	Amsinckia tessellata
rough eyelashweed	Blepharipappus scaber
sticky chickweed	Cerastium glomeratum (Cerastium viscosum)*
thyme-leaf sandmat	Chamaesyce serpyllifolia (Euphorbia serpyllifolia)*
lambsquarters	Chenopodium album
miner's-lettuce	Claytonia perfoliata (Montia perfoliata)*
maiden blue-eyed Mary	Collinsia parviflora
Canadian horseweed	Conyza canadensis (annual or biennial)
pinnate tansymustard	Descurainia pinnata
spring draba	Draba verna
chaparral willowherb	Epilobium minutum
redstem stork's bill	Erodium cicutarium
stickywilly	Galium aparine
common sunflower	Helianthus annuus
jagged chickweed	Holosteum umbellatum
branched lagophylla	Lagophylla ramosissima
clasping pepperweed	Lepidium perfoliatum (annual or biennial)
threadleaf phacelia	Phacelia linearis
longhorn plectritis	Plectritis macrocera
tall tumblemustard	Sisymbrium altissimum (annual or biennial)
yellow salsify	Tragopogon dubius (annual or biennial)
Perennial forbs
common yarrow	Achillea millefolium
low pussytoes	Antennaria dimorpha
basalt milkvetch	Astragalus filipes
woollypod milkvetch	Astragalus purshii
sagebrush Mariposa lily	Calochortus macrocarpus
Canadian horseweed	Conyza canadensis (biennial or perennial)
prickly lettuce	Lactuca serriola (biennial or perennial)
smallflower woodland-star	Lithophragma parviflorum
bigseed biscuitroot	Lomatium macrocarpum
nineleaf biscuitroot	Lomatium triternatum
sagebrush false dandelion	Nothocalais troximoides
common dandelion	Taraxacum officinale
Shrubs
basin big sagebrush	Artemisia tridentata subsp. tridentata
shadscale	Atriplex confertifolia
green rabbitbrush	Chrysothamnus viscidiflorus
broom snakeweed	Gutierrezia sarothrae
Tree
western juniper	Juniperus occidentalis
*For species that have undergone chnages in their scientific name, the scientific names in parentheses are those used in the research papers.

1. Rodhouse, Thomas. 2018. [Personal communication to Janet Fryer]. 9 July. Regarding fire management and control of western juniper at John Day Fossil Beds National Monument. Kimberly, OR: U.S. Department of the Interior, National Park Service. Unpublished information on file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT; FEIS files. [9276]

2. Sapsis, David B. 1990. Ecological effects of spring and fall prescribed burning on basin big sagebrush/Idaho fescue--bluebunch wheatgrass communities. Corvallis, OR: Oregon State University. 105 p. Thesis. [16579]

3. Sapsis, David B.; Kauffman, J. Boone. 1991. Fuel consumption and fire behavior associated with prescribed fires in sagebrush ecosystems. Northwest Science. 65(4): 173-179. [16594]

4. Zouhar, Kris. 2003. Bromus tectorum. 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/species-reviews/brotec [92768]

Last updated May 29, 2026

Effects of fall and spring prescribed burning in sagebrush steppe in central Oregon

Effects of fall and spring prescribed burning in sagebrush steppe in central Oregon

Citation

Image Gallery

Introduction

Sources

Species Included in this Summary

Revisions

Study Location

Site Description

Prefire Plant Community and Fuels

Plant Community

Fuels

Plant Phenology

Fire Description

Fire Season/Intensity Classification

Fire Description

Fire Behavior

Fuel Consumption and Residual Fuel Loads

Fire Effects

Fire Effects on Plant Community

Response of Dominant Bunchgrasses

Survivorship

Density

Growth and Reproduction

Response of Annual Grasses, Forbs, and Woody Species

Density

Frequency

Fire Effects on the Seed Bank

Fire Management Implications

LANDFIRE Biophysical Settings

Appendix

Table A1

References