Early postfire response of southern Appalachian Table Mountain-pitch pine stands to prescribed fires
Gucker, Corey, comp. 2007. Research Project Summary: Early postfire response of southern Appalachian Table Mountain-pitch pine stands to prescribed fires in North Carolina and Virginia. 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/welch-et-al-2007
Sources
Unless otherwise indicated, the information in this Research Project Summary comes from the following references:
- Turrill, Nicole Leigh. 1998. Using prescribed fire to regenerate Pinus echinata, P. pungens, P. rigida forests in the southern Appalachian Mountains. Knoxville, TN: University of Tennessee. 148 p. Dissertation [4].
- Welch, N. T.; Waldrop, T. A.; Buckner, E. R. 2000. Response of southern Appalachian table mountain pine (Pinus pungens) and pitch pine (Pinus rigida) stands to prescribed burning. Forest Ecology and Management. 136(1-3): 185-197 [5].
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 Table A1.
Study Location
Burned stands occurred on the Warm Springs Ranger District of the George Washington and Jefferson National Forests in Virginia and on the Grandfather Ranger District of the Pisgah National Forest in North Carolina.
Site Description
In the southern Appalachians, Table mountain pine and pitch pine occupy dry, south to southwest slopes with shallow, acidic, nutrient-poor soils.
Plant Community
Pitch pine was the canopy dominant of the 60-year-old Warm Springs stands. Table mountain pine and pitch pine shared the canopy in 77-year-old Grandfather stands. Associated canopy species included chestnut oak and scarlet oak, and species common in the midstory were blackgum and sourwood. Understory species included mountain-laurel, blueberries, and huckleberries. None of the stands were harvested or burned since the late 1930s or early 1940s.
Plant Phenology
Phenology of the vegetation before the spring and fall fires was not described, but vegetation was likely actively growing before the spring fire and beginning to senesce at the time of the fall fire.
Fire Description
The objective of prescribed burning was to encourage pine regeneration and decrease hardwood dominance in the mid- and understories. Researchers expected to better understand if spring or fall fires would accomplish these goals.
Both fall and spring prescription fires burned in pitch pine-dominated stands on the Warm Spring Ranger District. The fall fire was set using a ring firing technique in mid-October. Air temperature was 22 °C and relative humidity was 30% to 40% at the time of the fire. Flame lengths reached 1 to 3 m. The spring fire in mid-May was also ignited using the ring firing technique. Air temperature and relative humidity at the time of the fire were 26 °C and 40% to 60%, respectively. The fire produced flame lengths of 1 to 6 m. Char heights averaged 2 m for the spring and fall Warm Springs fires. Ring and head firing techniques were used to start the spring fire in Table Mountain pine-pitch pine stands on the Grandfather Ranger District. At the time of the fire, the air temperature was 27 °C, and relative humidity was 36% to 46%. Flame lengths ranged from 12 to 46 m, but char height averaged 4 m. Canopy scorch averaged 20%.
Fire Season/Severity Classification
| Fire Season | Fire Severity |
|---|---|
| Fall | Low |
| Spring | Low |
Fire Effects on Plant Community
Postfire effects were studied almost 1 year after the fall fire and approximately 3 months after the spring fires. Pre- and postfire species differences were not statistically analyzed.
Pitch pine and scarlet oak were the canopy (stems ≥10 cm DBH) dominants before and after the fall fire on the Warm Springs Ranger District. Canopy basal area and density of black oak and blackjack oak were reduced by the fire. Most species in the midstory (stems 9.9-2.5 cm DBH) were top-killed by the fall fire. For most species of hardwoods, sprout (stems <2.5 cm DBH) density was much greater after the fall fire; the exception was blackjack oak, which decreased in this size class. Researchers noted sassafras, pitch pine, and black oak seedlings in the postfire surface vegetation. Pre- and postfire vegetation is summarized by size class below.
| Overstory canopy (stems ≥10 cm DBH) | Prefire | Postfire (~1 year) | ||
|---|---|---|---|---|
| Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) | |
| blackjack oak | 0.6 | 56.3 | 0.2 | 12.5 |
| black oak | 0.8 | 62.5 | 0.2 | 12.5 |
| blackgum | 1.6 | 93.8 | 1.5 | 87.5 |
| chestnut oak | 1.5 | 93.8 | 1.2 | 75.0 |
| pitch pine | 11.3 | 206.3 | 9.6 | 168.8 |
| scarlet oak | 3.9 | 193.8 | 3.8 | 187.5 |
| white oak | 0 | 0 | 0.1 | 6.3 |
| Midstory (stems 2.5-10 cm DBH) | Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) |
| blackjack oak | 1.7 | 400.0 | 0 | 0 |
| black oak | 0.6 | 143.8 | 0 | 0 |
| blackgum | 0.5 | 112.5 | 0.2 | 37.5 |
| chestnut oak | 0.4 | 62.5 | 0.1 | 18.8 |
| common serviceberry | 0.1 | 12.5 | 0 | 0 |
| pitch pine | 0 | 6.3 | 0 | 0 |
| red maple | 0 | 6.3 | 0 | 0 |
| sassafras | 0.1 | 31.3 | 0 | 0 |
| scarlet oak | 0.2 | 37.5 | 0.1 | 18.8 |
| white oak | 0.1 | 6.3 | 0 | 0 |
| Saplings, sprouts, and shrubs (stems <2.5 cm DBH) | Density (# stems/ha) | Height (m) | Density (# stems/ha) | Height (m) |
| blackjack oak | 43.8 | 0.8 | 81.3 | 0.7 |
| black oak | 0 | 0 | 381.3 | 0.6 |
| blackgum | 0 | 0 | 75.0 | 0.4 |
| chestnut oak | 0 | 0 | 56.3 | 0.6 |
| huckleberry | 18.8 | 1.0 | 0 | 0 |
| mountain-laurel | 325.0 | 0.9 | 575.0 | 0.4 |
| red maple | 0 | 0 | 12.5 | 0.4 |
| rhododendron | 6.3 | 1.5 | 0 | 0 |
| sassafras | 406.3 | 2.2 | 1,537.4 | 0.5 |
| scarlet oak | 312.5 | 1.2 | 193.8 | 0.5 |
| Ground layer (≤1 m tall) | Cover (%/m²) | Frequency (%) | Cover (%/m²) | Frequency (%) |
| blackjack oak | 1.7 | 12.5 | 0 | 0 |
| black oak | 0 | 0 | 3.9 | 8.3 |
| blackgum | 0 | 0 | 0.1 | 3.1 |
| blueberry | 13.7 | 62.5 | 13.5 | 81.3 |
| roundleaf greenbrier | 0.0 | 3.1 | 0.1 | 3.1 |
| dwarf crested iris | 0 | 0 | 0.1 | 3.1 |
| huckleberry | 45.1 | 81.3 | 17.0 | 56.3 |
| mountain-laurel | 7.9 | 18.8 | 3.8 | 12.2 |
| panicgrass | 0.2 | 3.1 | 0.1 | 3.1 |
| pitch pine | 0 | 0 | 1.5 | 3.1 |
| red maple | 0.0 | 3.1 | 0 | 0 |
| sassafras | 3.9 | 28.1 | 3.7 | 46.9 |
| scarlet oak | 0.3 | 9.4 | 0.0 | 3.1 |
| vetch | 0.1 | 3.1 | 0 | 0 |
| western brackenfern | 4.0 | 81.3 | 3.9 | 56.3 |
Pitch pine and scarlet oak dominated the overstory before the spring fire on the Warm Springs Ranger District. The spring fire top-killed chestnut oak, white oak, sassafras, and red maple and reduced the basal areas and densities of scarlet oak, black oak, and blackgum in the canopy. The midstory was dominated by blackjack oak and sassafras before the fire and by blackgum and chestnut oak after the fire. Blackjack oak, scarlet oak, black oak, red maple, and hickory in the midstory were top-killed. However, most of these species (all but blackjack oak and hickory) sprouted and were present with increased density in the sapling size class (stems <2.5 cm DBH). Sassafras sprouts dominated the understory after the fire, and huckleberry dominated both the pre- and postfire ground layer (<1 m tall).
| Overstory canopy (≥10 cm DBH) | Prefire | Postfire (~3 months) | ||
|---|---|---|---|---|
| Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) | |
| black oak | 0.8 | 43.8 | 0.3 | 6.3 |
| blackgum | 0.3 | 25.0 | 0.1 | 12.5 |
| chestnut oak | 1.8 | 112.5 | 0 | 0 |
| pitch pine | 14.4 | 200.0 | 13.9 | 181.3 |
| red maple | 0.2 | 6.3 | 0 | 0 |
| sassafras | 0.2 | 1,838 | 0 | 0 |
| scarlet oak | 6.5 | 262.5 | 1.4 | 62.5 |
| white oak | 0.3 | 18.8 | 0 | 0 |
| Midstory (2.5-10 cm DBH) | Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) |
| blackjack oak | 1.1 | 306.3 | 0 | 0 |
| black oak | 0.3 | 50.0 | 0 | 0 |
| blackgum | 0.2 | 50.0 | 0.1 | 18.8 |
| chestnut oak | 0.5 | 106.3 | 0.1 | 18.8 |
| hickory | 0.0 | 6.3 | 0 | 0 |
| red maple | 0.0 | 6.3 | 0 | 0 |
| sassafras | 0.6 | 243.8 | 0.0 | 6.3 |
| scarlet oak | 0.5 | 81.3 | 0 | 0 |
| Saplings, sprouts, and shrubs (<2.5 cm DBH) | Density (# stems/ha) | Height (m) | Density (# stems/ha) | Height (m) |
| American chestnut | 0 | 0 | 6.3 | 0.4 |
| blackjack oak | 6.3 | 0.7 | 0 | 0 |
| black oak | 0 | 0 | 231.3 | 0.4 |
| blackgum | 0 | 0 | 25.0 | 0.4 |
| chestnut oak | 0 | 0 | 56.3 | 0.4 |
| huckleberry | 1,006.3 | 0.8 | 0 | 0 |
| mountain-laurel | 193.8 | 2.3 | 143.8 | 0.4 |
| red maple | 12.5 | 0.7 | 6.3 | 0.4 |
| sassafras | 537.5 | 1.0 | 2,675.0 | 0.5 |
| scarlet oak | 31.3 | 0.7 | 106.3 | 0.4 |
| Ground layer (≤1 m tall) | Cover (%/m²) | Frequency (%) | Cover (%/m²) | Frequency (%) |
| blackjack oak | 0.3 | 2.6 | 0 | 0 |
| black oak | 0 | 0 | 0.1 | 3.1 |
| blackgum | 0 | 0 | 0.0 | 3.1 |
| blueberry | 10.5 | 59.4 | 0.5 | 3.1 |
| huckleberry | 49.2 | 78.1 | 11.1 | 96.9 |
| mountain-laurel | 1.3 | 15.6 | 0.8 | 15.6 |
| red maple | 0.1 | 3.1 | 0 | 0 |
| sassafras | 6.5 | 37.5 | 5.1 | 65.6 |
| scarlet oak | 0.2 | 9.4 | 0.3 | 9.4 |
| western brackenfern | 1.2 | 28.1 | 1.1 | 31.3 |
| eastern teaberry | 0.1 | 6.3 | 0.0 | 3.1 |
Table Mountain pine and pitch pine dominated the pre- and postfire canopy following the spring fire on the Grandfather Ranger District. Basal areas of blackgum, Virginia pine, and red maple were not reduced by the fire. Basal areas and stem densities of all midstory species were reduced after the fire. American witchhazel, chestnut oak, scarlet oak, sassafras, and eastern white pine were killed or top-killed in the midstory. Blackgum dominated the midstory before and after the fire. Sourwood, red maple, blackgum, and mountain-laurel sprouts (<2.5 cm DBH) were common in the understory after fire. Mountain-laurel and blueberry dominated the postfire ground layer (<1 m tall).
| Overstory canopy (≥10 cm DBH) | Prefire | Postfire (~3 months) | ||
|---|---|---|---|---|
| Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) | |
| blackgum | 1.4 | 106.3 | 1.3 | 81.3 |
| chestnut oak | 0.9 | 56.3 | 0.4 | 18.8 |
| pitch pine | 9.0 | 256.3 | 5.3 | 137.5 |
| red maple | 1.1 | 68.8 | 0.9 | 50.0 |
| scarlet oak | 1.8 | 68.8 | 0.6 | 25.0 |
| sourwood | 0.7 | 56.3 | 0.3 | 18.8 |
| Table Mountain pine | 12.0 | 225.0 | 13.8 | 287.5 |
| Virginia pine | 2.2 | 62.5 | 2.4 | 56.3 |
| Midstory (2.5-10 cm DBH) | Basal area (m²/ha) | Density (# stems/ha) | Basal area (m²/ha) | Density (# stems/ha) |
| blackgum | 1.3 | 375.0 | 0.5 | 93.8 |
| chestnut oak | 0.2 | 37.5 | 0 | 0 |
| common serviceberry | 0.0 | 12.5 | 0 | 0 |
| eastern white pine | 0.0 | 6.3 | 0 | 0 |
| pitch pine | 0.2 | 43.8 | 0.1 | 12.5 |
| red maple | 0.5 | 150.0 | 0.2 | 68.8 |
| sassafras | 0.0 | 6.3 | 0 | 0 |
| scarlet oak | 0.1 | 43.8 | 0 | 0 |
| sourwood | 0.6 | 168.8 | 0.1 | 37.5 |
| Virginia pine | 0.1 | 12.5 | 0 | 0 |
| American witchhazel | 0.1 | 93.8 | 0 | 0 |
| Saplings, sprouts, and shrubs (<2.5 cm DBH) | Density (# stems/ha) | Height (m) | Density (# stems/ha) | Height (m) |
| blackgum | 0 | 0 | 552.5 | 12.9 |
| blueberry | 12.5 | 1.5 | 0 | 0 |
| chestnut oak | 6.3 | 2.9 | 26.0 | 4.7 |
| common sweetleaf | 12.5 | 4.0 | 195.0 | 8.2 |
| eastern white pine | 12.5 | 3.3 | 0 | 0 |
| mountain-laurel | 1,581.3 | 2.8 | 975.0 | 147.5 |
| red maple | 12.5 | 1.8 | 344.5 | 10.7 |
| rhododendron | 0 | 0 | 6.5 | 0.5 |
| scarlet oak | 12.5 | 2.9 | 19.5 | 5.1 |
| sourwood | 31.3 | 2.8 | 156.0 | 6.0 |
| American witchhazel | 31.3 | 2.8 | 19.5 | 4.5 |
| Ground layer (≤1 m tall) | Cover (%/m²) | Frequency (%) | Cover (%/m²) | Frequency (%) |
| blackgum | 0.1 | 1.6 | 0.0 | 3.1 |
| blueberry | 36.5 | 67.2 | 1.7 | 28.1 |
| roundleaf greenbrier | 2.3 | 45.3 | 0.1 | 9.4 |
| common sweetleaf | 0 | 0 | 0.0 | 3.1 |
| eastern white pine | 0.2 | 1.6 | 0 | 0 |
| beetleweed | 3.9 | 4.7 | 0.1 | 3.1 |
| huckleberry | 0 | 0 | 2.7 | 40.7 |
| mountain-laurel | 18.2 | 68.8 | 4.7 | 62.5 |
| panicgrass | 0.5 | 3.1 | 0 | 0 |
| red maple | 0.3 | 7.8 | 0.8 | 6.3 |
| rhododendron | 0 | 0 | 0.0 | 3.1 |
| scarlet oak | 0.4 | 7.8 | 0.9 | 9.4 |
| sourwood | 0.3 | 1.6 | 0 | 0 |
| Table Mountain pine | 0 | 0 | 0.1 | 3.1 |
| western brackenfern | 0.4 | 4.7 | 0 | 0 |
The average basal area and density of the canopy was significantly (P<0.05) lower on all sites after burning. Fire reduced the density of stems less than 25 cm DBH on all sites, and very few trees with stems larger than 20 cm DBH were top-killed. Stem density in the understory, however, was significantly (P<0.05) greater after the fires. Ground layer cover was significantly (P<0.05) lower after the fire. Litter depths were significantly (P<0.05) lower on postfire than prefire sites, but duff depths were only significantly (P<0.05) lower than prefire levels on the fall burned site. There were 15,000 pitch pine seedlings/ha after the fall fire and 8,000 pitch pine seedlings/ha after the spring fire on the Grandfather Ranger District.
The spring and fall prescribed fires in the southern Appalachians "were ineffective at opening the forest canopy". Trees with stems over 20 cm DBH were not killed, and the canopy "remained fairly intact". Postfire sprouting of hardwoods increased the density of hardwood stems in the understory on all 3 burned sites. Whether or not pine regeneration in the burned stands will be enough to maintain future pine dominance is unknown. The researchers predicted that many pine seedlings will not survive beneath the associated vegetation canopy.
The researchers suggested that prescribed fires that open both the canopy and the understory would produce conditions more conducive to pine seedling establishment and survival. However, they did not suggest the fire intensity and/or firing method that would open both the canopy and understory.
| Biophysical Setting | Mean Fire Interval (years) | Fire Severity Percent (%) | ||||||
|---|---|---|---|---|---|---|---|---|
| Code | Fire Regime Group | Low | Mixed | Replacement | All | Low | Mixed | Replacement |
| Series 13520 - Southern Appalachian Montane Pine Forest and Woodland | ||||||||
| 13520_53_54_57_59_60_61 | I-A | 5 | 101 | 88 | 5 | 89 | 5 | 6 |
| Summary | ||||||||
| Minimum | 5 | 101 | 88 | 5 | 89 | 5 | 6 | |
| Maximum | 5 | 101 | 88 | 5 | 89 | 5 | 6 | |
| Mean | 5 | 101 | 88 | 5 | 89 | 5 | 6 | |
| Median | 5 | 101 | 88 | 5 | 89 | 5 | 6 | |
| 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] | ||||||||
| Common name | Scientific name |
|---|---|
| red maple | Acer rubrum |
| common serviceberry | Amelanchier arborea |
| hickory | Carya spp. |
| American chestnut | Castanea dentata |
| beetleweed | Galax urceolata |
| eastern teaberry | Gaultheria procumbens |
| huckleberry | Gaylussacia spp. |
| American witchhazel | Hamamelis virginiana |
| dwarf crested iris | Iris cristata |
| mountain-laurel | Kalmia latifolia |
| blackgum | Nyssa sylvatica |
| sourwood | Oxydendrum arboreum |
| panicgrass | Panicum spp. |
| Table Mountain pine | Pinus pungens |
| pitch pine | Pinus rigida |
| eastern white pine | Pinus strobus |
| Virginia pine | Pinus virginiana |
| western brackenfern | Pteridium aquilinum |
| white oak | Quercus alba |
| scarlet oak | Quercus coccinea |
| blackjack oak | Quercus marilandica |
| chestnut oak | Quercus prinus |
| black oak | Quercus velutina |
| rhododendron | Rhododendron spp. |
| sassafrass | Sassafras albidum |
| roundleaf greenbrier | Smilax rotundifolia |
| common sweetleaf | Symplocos tinctoria |
| blueberry | Vaccinium spp. |
| vetch | Vicia spp. |
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