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Research Project Summary: Black spruce experimental fires on lowland sites in Manitoba

RESEARCH PROJECT SUMMARY CITATION:
Uchytil, Ronald J., comp. 1991. Research Project Summary: Black spruce experimental fires on lowland sites in Manitoba. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/research_project_summaries/Chrosciewicz76/all.html [].

Source:
Unless otherwise indicated, the information in this Research Project Summary comes from this paper:

Chrosciewicz, Z. 1976. Burning for black spruce regeneration on a lowland cutover site in southeastern Manitoba. Canadian Journal of Forest Research. 6(2): 179-186 [1].

STUDY LOCATION:
The study took place 60 miles (97 km) east-southeast of Winnipeg, Manitoba.

SITE DESCRIPTION:
The site was typical of many lowland black spruce (Picea mariana) peatlands. It was situated on a gentle transition gradient between a well-drained upland and a poorly drained muskeg. The ground had 10- to 18-inch-high (25-46 cm), peaty hummocks and intermittent depressions. Extending to 10 inches (25 cm) below the depressions was the upper peat, which was mostly comprised of fibrous undecomposed debris. Below this was 16 inches (40 cm) of well-decomoposed mucky peat over fine-textured mineral soil.

PREFIRE PLANT COMMUNITY:
The community was a 100-year-old black spruce stand averaging 2,180 trees per acre (5,387/ha). Hummocks and depressions were covered with a continuous moss carpet. Feather mosses, mostly Schreber's moss (Pleurozium schreberi) and splendid feather moss (Hylocomium splendens), comprised 88% of this ground cover, and sphagnum mosses (Sphagnum spp.) averaged 12%. Collectively, scattered shrubs including Labrador-tea (Ledum groenlandicum), bog birch (Betula glandulosa), shrubby cinquefoil (Potentilla fruticosa), and prickly rose (Rosa acicularis) made up 20% of the ground cover. Other scattered shrubs and herbs included mountain cranberry (Vaccinium vitis-idaea), creeping snowberry (Gaultheria hispidula), bunchberry (Cornus canadensis), meadow horsetail (Equisetum pratense), twinflower (Linnaea borealis), and coltsfoot (Petasites spp.).

Study sites are classified in the following plant community and probably historically experienced the fire regime 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, local data, and expert opinion as documented in the PDF file linked from the Potential Natural Vegetation Group 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)
Northeast spruce-fir forest Replacement 100% 265 150 300
*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].

The area was logged 2.5 years before the prescribed burns were conducted. The logging operation removed only merchantable timber, leaving 800 trees per acre (1,977/ha). Slash was 10 to 25 inches deep (25-64 cm) and covered 52% of the ground. Under the slash was a litter layer of fallen needles about 3 inches (8 cm) deep. Logging reduced feather moss cover from 88% to 41%, sphagnum moss cover from 12% to 6%, and shrub cover from 20% to 10%, but increased grass cover from 10% to 20%, and sedge cover from 10% to 30%.

PLANT PHENOLOGY:
Phenology of black spruce was not provided, but spring growth had probably started by the time of the fires.

FIRE SEASON AND SEVERITY CLASSIFICATION:
spring, light severity
spring, moderate severity

FIRE DESCRIPTION:
Two areas were burned under different fire prescriptions, resulting in light-severity and moderate-severity fires. Conditions before igniting each fire were as follows:

  Light-severity fire Moderate-severity fire
Date 17 May 1976 29 May 1967
Cloud cover (%) 90 70
Air temperature (°F/C) 72/22 75/24
Relative humidity (%) 32 31
Wind speed (mph/kph) 9/14 9/14
Wind direction west southeast

The average flame height for both fires was 3 feet (1 m) with occasional trees crowning up to 40 feet (12 m). In general fires destroyed slash, surface litter, and aerial parts of vegetation including feather mosses and some sphagnum mosses. Stumps and discarded logs were only partially consumed.

The moderate-severity fire occurred about 2 weeks later than the light-severity fire, when fuels were drier. Peat under exposed feather mosses was dry to a depth of 1 inch (2.5 cm) on 17 May, and to a depth of 3 inches (8 cm) on 29 May. Although burning exposed 95% of the peat on both burns, fire burned deeper into peat on the moderate-severity burn. On the light-severity burn, average depth of burning was 3 (8 cm) inches on hummocks and 2 inches (5 cm) in depressions. On the moderate-severity burn, average depth of burning was 7 inches (18 cm) on hummocks and 4 inches (10 cm) in depressions.

FIRE EFFECTS ON TARGET SPECIES:
Of the residual black spruce trees left after logging, all were killed by the fire. Smaller trees were completely consumed, while larger trees were scorched. Cones in the upper crowns of scorched trees were unharmed and were responsible for good seedfall after the fire. Five years after burning, black spruce stocking was 94% (16,129 seedlings/acre) in areas where burning depth ranged from 4 to 7 inches (10-18 cm); 70% (3,075/acre) in areas where burning depth ranged from 2 to 3 inches (5-8 cm); and 35% (1,898/acre) in an unburned control. On both burned areas nearly all seedlings were found on exposed peat. A few were found on sphagnum. The average seedling height 5 years after burning was 11 inches (28 cm) on the moderate-severity burn and 8 inches (20 cm) on the light-severity burn.

FIRE MANAGEMENT IMPLICATIONS:
Burning following timber harvest can be used for the successful regeneration of black spruce on lowland sites. Black spruce can establish quickly from natural seedfall if adequate seed trees are present and the fuels are sufficiently dry to ensure moderately deep burning.

REFERENCES:

1. Chrosciewicz, Z. 1976. Burning for black spruce regeneration on a lowland cutover site in southeastern Manitoba. Canadian Journal of Forest Research. 6(2): 179-186. [7280]
2. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2008. Interagency fire regime condition class guidebook. Version 1.3, [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). 119 p. Available: http://frames.nbii.gov/frcc/documents/FRCC_Guidebook_2008.07.10.pdf [2010, May 3]. [70966]
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]
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