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Research Project Summary: Early postfire effects of a prescribed fire in the southern Appalachians of North Carolina

RESEARCH PROJECT SUMMARY CITATION:
Gucker, Corey L, comp. 2007. Research Project Summary: Early postfire effects of a prescribed fire in the southern Appalachians of North Carolina. 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/Elliott99/all.html [ ].

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

Elliott, Katherine J.; Hendrick, Ronald L.; Major, Amy E.; Vose, James M.; Swank, Wayne T. 1999. Vegetation dynamics after a prescribed fire in the southern Appalachians. Forest Ecology and Management. 114(2-3): 199-213 [1].

SPECIES INCLUDED IN THE SUMMARY:
Common names are used throughout this summary. For a complete list of the common and scientific names of species discussed in this summary, see the Appendix.

STUDY LOCATION:
Fire effects were studied in the Wine Spring Creek Watershed in the southern Appalachian Mountains of western North Carolina's Nantahala National Forest (35 °N latitude, 83 °W longitude).

SITE DESCRIPTION:
The prescribed fire burned a south-facing slope of 35% to 60% at 1,500 to 1,700 m elevation. Fine-loamy, mixed, mesic Typic Hapludult and loamy, mixed, mesic Lithic Dystrochrept soils occur at the upper slope and ridge. Coarse-loamy to loamy-skeletal, mixed, mesic Typic Haplumbrept soils occur at the mid- and low-slope positions. Annual temperature and precipitation in this area average 10.4 °C and 1,900 mm, respectively.

PREFIRE PLANT COMMUNITY:
At the low-slope position, researchers described the vegetation as a mesic, near-riparian community. Overstory dominants were red maple and hickory. Midslope supported a dry, mixed-oak community dominated by chestnut oak, scarlet oak, red maple, hickory, and sourwood. Ridges and upper slopes were xeric pitch pine/chestnut oak forests. Communities had not burned for at least 70 years prior to this prescribed fire.

Historic fire regime characteristics for Appalachian oak-hickory-pine and eastern dry oak communities are summarized 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 [3]. 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.
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)		 Minimum interval
(years)		 Maximum interval
(years)
Appalachian oak-hickory-pine Replacement 3% 180 30 500
Mixed 8% 65 15 150
Surface or low 89% 6 3 10
Oak (eastern dry-xeric) Replacement 6% 128 50 100
Mixed 16% 50 20 30
Surface or low 78% 10 1 10
*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. 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. 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 [2,3].

PLANT PHENOLOGY
Phenology of the vegetation was not described prior to the April 1995 prescribed fire; some vegetation may have initiated growth by this time. Without the precise date of the fire and climate conditions in the months prior, it is difficult to describe the phenology of the vegetation as a whole.

FIRE SEASON/SEVERITY CLASSIFICATION:
Spring/low to high

FIRE DESCRIPTION:
The Forest Service, US Department of Agriculture, burned this southern slope to promote oak and pitch pine regeneration in the long unburned and "degraded" community. Increased severity was predicted as the fire burned upslope. Researchers hoped that burned sites would have increased forage production, decreased mountain-laurel abundance, and increased pitch pine and oak (Quercus spp.) recruitment.

Strip head fires were used to burn the approximately 300-ha study area. On the ridge, the fire was stand replacing, and the understory was consumed [1,5]. At the low-slope position, the fire was patchy and burned only the understory. Aboveground flame temperatures and heat penetration were measured using heat-sensitive painted tiles. Flame temperatures were measured 1 and 2 m above ground. Belowground heat penetration was measured at the forest floor and in the mineral soil. Temperatures produced and heat penetration depths are summarized below [5].

Above- and belowground temperatures produced by the fire at low, mid-, and ridge positions
Slope position Flame temperature (°C) Average (range) of soil heat penetration (mm)
  1 m 2 m 45 °C 59 °C
Low slope <52 <52 0.5 (0-3) 0.6 (0-4)
Mid-slope <52 to 160 <52 to 90 18.2 (1-52) 16.8 (4-52)
Ridge <52 to >800 <52 to >800 27.5 (9-55) 24.0 (7-55)

FIRE EFFECTS ON PLANT COMMUNITY:
Overstory dominance on the ridge was unchanged by the fire. Pitch pine, chestnut oak, and scarlet oak dominated the canopy vegetation both before and after the fire. Density- and basal area-based species richness were significantly (P≤0.05) reduced by the fire. Decreased richness was a result of American chestnut, blackgum, black locust, sassafras, and eastern hemlock mortality. Nearly all canopy species had decreased frequency, density, and basal area after the fire.

Pre- and postfire frequency, density, and basal area of canopy species on the ridge
Ridge Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo prefire 3 mo prefire 3 mo
American chestnut 21 0 29 0 0.11 0
blackgum 14 0 29 0 0.17 0
black locust 7 0 7 0 0.01 0
Carolina silverbell 7 7 7 7 0.15 0.15
chestnut oak 93 64 239 146 5.22 3.33
common serviceberry 43 21 109 70 0.97 0.67
eastern hemlock 7 0 7 0 0.26 0
hickory 36 21 128 50 1.38 0.80
northern red oak 21 14 17 14 0.07 0.07
pitch pine 93 78 637 441 12.45 9.67
red maple 50 21 108 41 2.14 1.21
sassafras 7 0 3 0 0.01 0
scarlet oak 57 36 121 60 2.26 1.55
sourwood 50 50 96 77 1.60 1.40
white oak 7 7 7 7 0.02 0.02
Total   1,545a* 913b 26.84a 18.86b
*Values with the same letters are not significantly different (P≤0.05) between time periods.

The average percent mortality following the fire ranged from 18.5% to 30.6% for the dominant overstory species (pitch pine, chestnut oak, and scarlet oak). For associated overstory species, mortality ranged from 25.0% to 100%.

Average mortality of overstory species on burned ridge
Species N Mortality (%) SE
American chestnut 3 100 0
chestnut oak 12 30.6 13.3
common serviceberry 4 25.0 25.0
hickory 5 57.5 17.5
pitch pine 12 18.5 8.6
red maple 7 42.8 20.2
scarlet oak 8 29.2 16.0

Total density and basal area of understory vegetation on the ridge was significantly (P≤0.05) lower following the fire. However, total density and basal area increased with increased time since fire, although basal area and density had not recovered to prefire levels within a year of the fire. Mountain-laurel density and basal area were significantly (P≤0.05) lower after burning. Pitch pine understory density increased after the first postfire year.  Black locust, chestnut oak, and scarlet oak densities were significantly (P≤0.05) greater after the ridge burned. White oak, northern red oak, and black oak were not present in the understory after the fire.

Pre- and postfire frequency, density, and basal area of understory species on the ridge
Ridge Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo  1 yr, 3 mo prefire 3 mo 1 yr, 3 mo prefire 3 mo 1 yr, 3 mo
Understory species (≥1 cm basal diameter, <5 cm DBH)
American chestnut 21 0 21 952 0 413 0.536 0 0.184
black locust 14 0 28 10b* 0 813a 0.002 0 0.119
black oak 36 0 0 19 0 0 0.010 0 0
chestnut oak 50 14 21 505b 25c 720a 0.244 0.024 0.097
deerberry 0 0 7 0 0 317 0 0 0.025
common serviceberry 36 7 7 76a 6b 3b 0.027 0.008 0.001
flame azalea 7 0 7 159a 0 19b 0.038 0 0.002
hickory 14 0 14 82 0 161 0.022 0 0.025
mountain-laurel 100 21 14 8,651a 248b 168b 4.97a 0.127b 0.403b
northern red oak 36 0 0 368a 19b 0 0.187 0.002 0
pitch pine 21 0 7 165 0 317 0.212 0 0.035
red maple 43 14 14 168 13 82 0.045 0.010 0.011
sassafras 36 7 36 321b 82c 571a 0.050 0.191 0.102
scarlet oak 50 7 50 295b 6c 1,997a 0.078b 0.008b 0.222a
sourwood 7 0 14 10 10 29 0.001 0.001 0.004
sweet birch 0 0 7 0 0 79 0 0 0.006
white oak 28 0 0 397 0 0 0.096 0 0
Total     12,178a 409c 5,692b 6.522a 0.371c 1.236b
*Values with the same letters are not significantly different (P≤0.05) between time periods.

The number of pitch pine seedlings increased by 358% in the third postfire month but was 35% of the prefire number a year following the fire. Common serviceberry seedlings increased by 350% a year after the fire.

The coverage of ground layer vegetation on the ridge slightly exceeded prefire levels by the first postfire year. Black oak, white oak, sourwood, and black locust were present in the prefire surface layer but were not present a year after the fire. Red maple, chestnut oak, and sassafras had greater cover after than before the fire. Blueberry, buffalo nut, mountain sweetpepperbush, and flame azalea all had greater than prefire cover levels 1 year after the fire. Pitch pine, present with low cover in prefire vegetation, was absent from the ground layer after the fire. Most herbs and vines present in the prefire community had increased cover in the first postfire year. Sedge and goldenrod species present in the prefire community, however, were absent from the community a year after fire. Bedstraw, western brackenfern, greater tickseed, common goldstar, bellwort, Michaux's saxifrage, New York fern, plains snakecotton, little bluestem, and panicgrass were only found on the ridge after the fire.

35.6
Pre- and postfire cover of herb-layer vegetation on the ridge
Time since fire Prefire 3 mo 1 year, 3 mo
Ground layer species
Trees cover (%)
American chestnut 0 0.7 0
black locust 0.02 0.5 0
black oak 0.06 0.08 0
chestnut oak 0.25 0.10 1.29
common serviceberry 0.06 0.08 0.08
northern red oak 0.08 0.08 0.25
pitch pine 0.10 0.08 0
red maple 0.25 0.08 1.17
sassafras 0.10 0.25 2.88
scarlet oak 0.08 0.03 0.21
sourwood 0.02 0.5 0
white oak 0.03 0 0
Shrubs
blackberry 0 0 0.12
black huckleberry 1.03 1.88 0.96
blueberry 2.28 2.28 5.17
buffalo nut 0.18 0.08 0.67
flame azalea 0.02 0.25 1.46
mountain-laurel
(clone density = #/ha)		 28.0 3.67
(11,307)		 11.4
(9,285)
mountain sweetpepperbush 0.07 0.03 0.96
smooth sumac 0 0.03 0
Forbs
bedstraw 0 0.13 1.33
bellwort 0 0.03 0
common goldstar 0 0.05 0
beetleweed 0.40 0.10 0.92
greater tickseed 0 0.05 0
goldenrod 0.02 0 0
Indian cucumber 0.02 0 0.12
Michaux's saxifrage 0 0.02 0.29
narrowleaf cowwheat 0.22 0.02 1.17
New York fern 0 0.02 0
plains snakecotton 0 0 0.12
trailing arbutus 0.55 0.10 0.33
western brackenfern 0 0.10 0.42
Graminoids
little bluestem 0 0.23 0.54
panicgrass 0 0 2.75
sedge 1.08 0.10 0
Vines
greenbrier 0.63 0.40 2.71
Total 10.6 37.7
Species richness 24 33 26
Pielou evenness index 0.32 0.61 0.77

The fire at the midslope position was less severe than that at the ridge. Total pre- and postfire overstory density and basal area were not significantly (P≤0.05) different, and pre- and postfire differences in individual overstory species frequency, density, and basal area were little to none.

Pre- and postfire frequency, density, and basal area of overstory species at the midslope position
  Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo prefire 3 mo prefire 3 mo
blackgum 22 22 156 156 0.99 0.99
black locust 56 44 89 64 0.66 0.53
Carolina silverbell 11 11 44 33 0.26 0.23
chestnut oak 56 44 99 94 6.47 6.44
cucumber-tree 11 11 5 5 0.04 0.04
common serviceberry 33 33 38 38 0.27 0.27
eastern hemlock 22 22 22 22 0.94 0.94
hickory 67 67 173 178 2.84 2.89
red maple 200 100 626 606 9.01 9.02
scarlet oak 22 22 38 27 4.00 3.91
sourwood 67 67 153 137 3.16 3.11
sweet birch 22 22 5 5 0.03 0.03
Total     1,448a* 1,365a 28.69a 28.42a
*Values with the same letters are not significantly different (P≤0.05) between time periods.

Total density and basal area of midslope vegetation was significantly (P≤0.05) reduced by the fire. Red maple, American chestnut, mountain-laurel, and sourwood had significantly (P≤0.05) lower density and basal area after the fire. Hickory, Carolina silverbell, cucumber-tree, buffalo nut, white oak, black locust, and eastern hemlock were present in the prefire community but were not present 3 months after the fire. Rosebay, a dominant in the prefire understory, remained dominant after the fire with relatively little change in density or basal area after the fire.

Pre- and postfire frequency, density, and basal area of understory species at the midslope position
  Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo prefire 3 mo prefire 3 mo
Understory species (≥1 cm basal diameter, <0.5 cm DBH)
American chestnut 44 11 573a* 20b 0.127a 0.002b
blackgum 11 11 123a 10b 0.012a 0.012a
black locust 11 0 15 0 0.008 0
buffalo nut 11 0 123 0 0.047 0
Carolina silverbell 22 0 494 0 0.064 0
chestnut oak 11 11 25 5 0.012 <0.001
cucumber-tree 11 0 123 0 0.019 0
eastern hemlock 11 0 10 0 0.002 0
hickory 11 0 5 0 0.006 0
mountain-laurel 67 11 4,691a 123b 4.497a 0.422b
northern red oak 22 0 20 0 0.010 0
red maple 56 22 326a 15b 0.494a 0.019a
rosebay 22 11 1,605a 1,358a 7.231a 7.789a
sourwood 22 11 138a 25b 0.015a 0.002b
white oak 22 0 247 0 0.020 0
Total   8,518a 1,556b 12.56a 8.25b
*Values with the same letters are not significantly different (P≤0.05) between time periods.

The fire at the low-slope position was less severe than that at the ridge or midslope. Total pre- and postfire canopy density and basal area were not significantly (P≤0.05) different, and pre- and postfire differences in individual species frequency, density, and basal area were little to none.

Pre- and postfire frequency, density, and basal area of overstory species at the low-slope position
  Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo prefire 3 mo prefire 3 mo
American chestnut 11 11 11 11 0.001 0.001
American witchhazel 11 11 11 11 0.02 0.02
blackgum 11 11 22 22 0.07 0.07
black locust 22 22 22 22 0.94 0.94
Carolina silverbell 22 11 44 15 0.13 0.05
chestnut oak 33 33 32 32 0.63 0.62
cucumber-tree 11 11 30 39 0.16 0.18
common serviceberry 44 33 47 37 0.28 0.24
eastern hemlock 89 89 238 243 3.80 3.87
hickory 78 78 186 167 6.64 6.62
northern red oak 33 33 21 21 0.61 0.63
red maple 89 89 333 328 6.54 6.59
sassafras 11 11 5 5 0.07 0.07
scarlet oak 33 33 21 21 3.12 3.16
sugar maple 11 11 5 5 0.04 0.04
sourwood 11 11 22 22 0.78 0.78
striped maple 44 44 64 64 0.49 0.50
white oak 22 22 36 36 2.88 2.90
tuliptree 22 22 15 15 0.48 0.51
Total   1,167a* 1,117a 27.72a 27.82a
*Values with the same letters are not significantly different (P≤0.05) between time periods.

The low-severity fire at the low slope increased total understory stem density, though not significantly. Hawthorn, which was not present before the fire, had a density of 123 stems/ha 3 months after the fire. Postfire densities of American chestnut, white ash, Carolina silverbell, and buffalo nut were more than double the prefire densities 3 months after spring burning. Densities of flame azalea, eastern hemlock, northern red oak, and hickory decreased by more than half, and mountain magnolia and chestnut oak were absent after the fire.

Pre- and postfire frequency, density, and basal area of canopy species at the low-slope position.
  Frequency (%) Density (stems/ha) Basal area (m²/ha)
Time since fire prefire 3 mo prefire 3 mo prefire 3 mo
Understory species (≥1 cm basal diameter, <0.5 cm DBH)
American chestnut 33 44 138 592 0.044 0.115
buffalo nut 11 33 123 370 0.051 0.135
Carolina silverbell 33 33 59 138 0.022 0.031
chestnut oak 11 0 5 0 <0.001 0
cucumber-tree 33 44 207 301 0.056 0.074
common serviceberry 33 22 30 54 0.016 0.037
eastern hemlock 22 22 143 20 0.400 0.019
flame azalea 11 11 864 370 0.320 0.200
hawthorn 0 11 0 123 0 0.014
hickory 11 11 40 10 0.006 0.007
mountain magnolia 11 0 5 0 <0.001 0
northern red oak 22 22 133 64 0.026 0.005
red maple 22 22 30 44 0.010 0.021
sugar maple 33 33 138 158 0.026 0.032
striped maple 22 22 133 153 0.018 0.026
sourwood 11 11 5 10 0.002 <0.001
sweet birch 11 11 5 10 <0.001 <0.001
white ash 11 22 15 79 0.005 0.017
white oak 22 11 10 34 0.001 0.003
tuliptree 22 33 69 118 0.011 0.020
Total   2,153a* 2,652a 1.015a 0.758a
*Values with the same letters are not significantly different (P≤0.05) between time periods.

FIRE MANAGEMENT IMPLICATIONS:
This southern slope was burned to encourage oak and pitch pine regeneration in the long unburned and "degraded" community. Researchers hoped that burned sites would have increased forage production and decreased mountain-laurel abundance. On the ridge, the abundance of red maple was reduced by the fire, and growth and recruitment of several oak species increased in the understory. The fire decreased mountain-laurel density and basal area on the ridge and midslope positions. However, without later postfire sampling it is unclear whether or not pitch pine and oak regeneration will be successful before mountain-laurel density and basal area recover to prefire levels. The early mortality of postfire pitch pine seedlings suggests that successful pitch pine regeneration may require another prescribed fire or canopy-opening disturbance. Low postfire precipitation, high postfire basal area, and/or the lack of litter and duff consumption may have increased postfire pitch pine seedling mortality. In the understory, blueberries, black huckleberry, little bluestem, and panicgrasses increased in number, increasing wildlife forage in the area.

While the spring fire in the southern Appalachians increased wildlife forage and encouraged oak regeneration, it did not allow for successful regeneration of pitch pine. A high-severity fire, burning when pitch pine cone crops are good, may produce an environment conducive to successful pitch pine recruitment. Researchers suggest an initial high-severity fire and subsequent low-severity fires at 5- to 10-year intervals may encourage pitch pine and oak dominance and limit mountain-laurel density.
SPECIES INCLUDED IN THE SUMMARY:
This Research Project Summary contains fire response information on the following species. For further information, follow the highlighted links to the FEIS reviews for those species.

Appendix
Common name Scientific name
striped maple Acer pensylvanicum
red maple Acer rubrum
sugar maple Acer saccharum
common serviceberry Amelanchier arborea
sweet birch Betula lenta
sedge Carex spp.
hickory Carya spp.
American chestnut Castanea dentata
mountain sweetpepperbush Clethra acuminata
greater tickseed Coreopsis major
hawthorn Crataegus spp.
trailing arbutus Epigaea repens
white ash Fraxinus americana
plains snakecotton Froelichia floridana
beetleweed Galax urceolata
bedstraw Galium spp.
black huckleberry Gaylussacia baccata
Carolina silverbell Halesia carolina
American witchhazel Hamamelis virginiana
common goldstar Hypoxis hirsuta
mountain-laurel Kalmia latifolia
tuliptree Liriodendron tulipifera
cucumber-tree Magnolia acuminata
mountain magnolia Magnolia fraseri
Indian cucumber Medeola virginiana
narrowleaf cowwheat Melampyrum lineare
blackgum Nyssa sylvatica
sourwood Oxydendrum arboreum
panicgrass Panicum spp.
pitch pine Pinus rigida
western brackenfern Pteridium aquilinum
buffalo nut Pyrularia pubera
white oak Quercus alba
scarlet oak Quercus coccinea
chestnut oak Quercus prinus
northern red oak Quercus rubra
black oak Quercus velutina
smooth sumac Rhus glabra
flame azalea Rhododendron calendulaceum
rosebay Rhododendron maximum
black locust Robinia pseudoacacia
blackberry Rubus spp.
sassafras Sassafras albidum
Michaux's saxifrage Saxifraga michauxii
little bluestem Schizachyrium scoparium
greenbrier Smilax spp.
goldenrod Solidago spp.
New York fern Thelypteris noveboracensis
eastern hemlock Tsuga canadensis
bellwort Uvularia spp.
deerberry Vaccinium stamineum
blueberry Vaccinium spp.

REFERENCES:

1. Elliott, Katherine J.; Hendrick, Ronald L.; Major, Amy E.; Vose, James M.; Swank, Wayne T. 1999. Vegetation dynamics after a prescribed fire in the southern Appalachians. Forest Ecology and Management. 114(2-3): 199-213. [30079]
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. 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 [66533]
5. Vose, James M.; Swank, Wayne T.; Clinton, Barton D.; Knoepp, Jennifer D.; Swift, Lloyd W. 1999. Using stand replacement fires to restore southern Appalachian pine-hardwood ecosystems: effects on mass, carbon, and nutrient pools. Forest Ecology and Management. 114(2-3): 215-226. [30149]
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