• CASE NAME
• REFERENCES
• SEASON/SEVERITY CLASSIFICATION
• STUDY LOCATION
• PREFIRE VEGETATIVE COMMUNITY
• TARGET SPECIES PHENOLOGICAL STATE
• SITE DESCRIPTION
• FIRE DESCRIPTION
• FIRE EFFECTS ON TARGET SPECIES
• FIRE MANAGEMENT IMPLICATIONS

CASE NAME:

Natural and artificial regeneration of grand fir after prescribed burning clearcuts on Newman Ridge, western Montana

REFERENCES:

Adams, D. F.; Robinson, E.; Malte, P. C.; [and others]. 1981 [1]
Beaufait, W. R.; Hardy, C. E.; Fischer, W. C. 1977 [20]
DeByle, N. V. 1981 [51]
Shearer, R. C. 1975 [160]
Shearer, R. C. 1981 [161]
Shearer, R. C. 1982 [162]

SEASON/SEVERITY CLASSIFICATION:

Spring, summer, and fall 1969/low to moderate [161,20]

STUDY LOCATION:

Newman Ridge is located between Two Mile and Ward creeks on the Lolo National Forest, western Montana, near the boarder of northeastern Idaho (latitude 47^o17' N, longitude 115^o17' W) [162,51,161,160].

PREFIRE VEGETATIVE COMMUNITY:

Overstory species composition was: Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca), 34%; western larch (Larix occidentalis), 26%; Rocky Mountain lodgepole pine (Pinus contorta var. latifolia), 17%; Pacific ponderosa pine (Pinus ponderosa var. ponderosa), 9%; mixed grand and subalpine firs (Abies grandis and A. lasiocarpa), 7%; western white pine (P. monticola), Engelmann spruce (Picea engelmannii), and western redcedar (Thuja plicata), 7%. [162].

Seven habitat types were identified on Newman Ridge. The warmest and driest was the Rocky Mountain Douglas-fir/ninebark (Physocarpus malvaceus) type on convex southwest slopes. Other habitat types included grand fir/queencup beadlily (Clintonia uniflora) on concave east, northwest, and protected south-facing slopes; grand fir/beargrass (Xerophyllum tenax) on upper west-facing slopes; western redcedar/queencup beadlily in the fool's huckleberry (Menziesia ferruginea) phase on concave north- and northeast-facing slopes; Rocky Mountain Douglas-fir/blue huckleberry (Vaccinium membranaceum) in the beargrass phase on upper south-facing slopes; subalpine fir/queencup beadlily in the fool's huckleberry phase on north slopes along the ridge; and subalpine fir/beargrass type in the blue huckleberry phase on south slopes near the ridge [162,51].

TARGET SPECIES PHENOLOGICAL STATE:

Not stated, but grand fir adjacent to the burns would have been in growth and cone-development phase during the summer fires and probably dispersing seed during and after the fall fires.

SITE DESCRIPTION:

Elevation at Newman Ridge ranges from 4,400 to 5,400 feet (1,341-1,646 m), with slopes averaging 55% and ranging from 44 to 76%. Soils belong to the Craddock series and are classified as Andic Cryochrepts. They have developed in place or in colluvium from argillites and quartzites of the Belt Formations. There is a 2- to 3-inch- (5-8 cm) thick surface loess deposit containing ash from the Mt. Mazama and Glacier Peak volcanic eruptions. Average precipitation is nearly 40 inches (1020 mm), two-thirds of which falls as snow [51,160].

FIRE DESCRIPTION:

Silvicultural management objectives were site preparation for conifer regeneration, particularly western larch, and fuels reduction [51,160,20].

A total of 9 study sites were selected: 2 each facing north, south, and west, and 3 sites facing east. The units were clearcut, skidded to promote uniform slash, and burned after slash had cured. Fall fires were lit after rains moistened fuels. The sites were broadcast burned using center-firing, flank-firing ignition, a combination of both, and strip head-firing [161]. Spring and summer fires were accomplished in 1969; fall fires were lit after rains in September 1970. Prefire duff depth across sites averaged 2.1 inches (5.2 cm). Mean slash loading was 104 tons per acre (287 t/ha). Mean depth of fuel loading by exposure was north, 6.2 cm; east, 5.8 cm; west, 4.5 cm; and south, 4.35 cm. Approximately 88% of dead and down woody fuels was greater than 10 cm in diameter; 10% was 1 to 10 cm diameter; needles, and twigs up to 1 cm diameter, were 1% each. Mean fuel loads by size class were [20]:

	Mean mass
	tons/acre	t/ha
duff	22.9	63.1
needles	1.4	3.9
0 to 1 cm	1.1	3.0
1 to 10 cm	10.7	29.5
> 10 cm	90.5	249.3
Total	126.5	348.5

Mean moisture content of fuels (% oven-dry weight) varied as follows [20]:

		Duff			Slash
Unit	Burn date	lower half	upper half	Litter	needles	0-1cm	1-10 cm
North-1	July 14	54	17	10	6	10	11
North-2	July 25	63	16	8	8	13	8
East-1	July 9	80	12	7	9	12	13
East-2	July 25	63	16	8	8	13	8
East-3	July 25	63	16	8	8	13	8
South-1	June 4	104	7	5	8	5	13
South-2	July 16	73	43	9	5	8	22
West-1	June 1	88	21	6	13	11	24
West-2	July 18	40	20	8	5	9	11

Weather variables for the 1969 spring and summer fires follow. Weather variables for the fall fires (28 and 29 September 1970) were not reported [20].

	June 1	June 4	July 9	July 14	July 16	July18	July25
min. humidity (%)	28	23	28	36	27	26	36
max. temp (oF)	68	85	75	65	72	76	79
fine fuel moisture (%)	16	13	10	13	10	10	11
buildup index	18	29	38	49	56	63	88

FIRE EFFECTS ON TARGET SPECIES:

Natural postfire grand fir establishment occurred from seed blown in from parent trees adjacent to the burns. In addition to natural seeding, bareroot seedlings were planted on Newman Ridge from 1970 through 1975. Grand fir seedlings continued to establish throughout the 15-year postfire study period. Overall, grand fir seedlings increased from an average frequency of 12% in postfire year 5 (1974) to 18% in postfire year 15 (1984) [160].

The best seed year was 1971 for all tree species; conifers otherwise experienced either poor seed crops or crop failures from 1969 to 1973. In 1971, grand fir seed rain into the clearcuts from adjacent parent trees was good. It took an average of 16 filled grand fir seeds to produce 1 seedling. The cumulative average number of sound seed of grand fir from 1969 through 1974 on 8 clearcuts on Newman Ridge is listed below by distance from seed source [161]: