While it is commonly perceived that Table Mountain pine communities require
high-severity crown fires for regeneration (e.g., [85,91]), additional evidence
(e.g., [14,52,75,77]) suggests that Table Mountain pine communities can
reproduce and persist under a regime of frequent, low-severity fire, and in some
cases, in the absence of fire [3,6]. High-severity fires certainly result in
reduced shading and competition, the opening of serotinous cones, and removal
of forest floor, thus providing seed and a favorable seed bed for germination and
establishment; and ample data provide evidence that Table Mountain pine reproduces
and persists after high-severity fires [15,33,37,56,57,61,91]. Low-severity
fires may not provide optimum conditions for Table Mountain pine regeneration [32].
For example, about 3 months following a low-severity, spring prescribed burn
on the Grandfather Ranger District, Pisgah National Forest, North Carolina, frequency
and cover of Table Mountain pine seedlings increased; however, seedlings were not
expected to survive due to shading and competition from overstory, midstory, and
understory species [71,79]. For a complete summary of this study, see
Early postfire response of southern Appalachian Table Mountain-pitch pine stands
to prescribed fires.
Several studies have found greater regeneration of Table Mountain pine after
high-severity fire than after low-severity fire. Zobel [91] sampled a recently burned
Table Mountain pine stand in western North Carolina and noted that all Table Mountain
pine cones were open, even though fire had been "light" in portions
of the area. However, 2 years after fire, regeneration persisted only in areas where
the overstory trees were killed, the undergrowth was almost completely killed,
and erosion had exposed mineral soil [91]. High-severity fire provided a
favorable seedbed for germination of Table Mountain pine following a lightning-caused
wildfire on Dovel Mountain, Shenandoah National Park, Virginia. The number of Table
Mountain pine seedlings on burned areas the second year after fire was considerably
higher than on unburned areas with high-severity, low-severity, and unburned patches
averaging 6,997, 1,489, and 386 seedlings/ha, respectively [33]. Regeneration of
Table Mountain pine following an April 1986 fire on Bote Mountain, Great Smoky
Mountains National Park, was most successful where fire severities were high. Study
plots were located on areas that experienced low-severity (surface fire only),
moderate-severity (surface fire with some scorching and torching of individual trees),
and high-severity (crown fire) fires. Overall Table Mountain pine seedling densities
were 1,250/ha, 15,312/ha, 18,304/ha in low-, moderate-, and high-severity plots,
respectively. Of all seedlings counted 75.4% were found growing where the organic
matter depth was less than 0.4 inches (1 cm) [61]. Pine regeneration (Table Mountain
pine and pitch pine combined) was greater after high-intensity fires (mean bark char
height of 25 feet (7.6 m)) than repeated low-intensity fires, when dormant season
prescribed burns were carried out in stands on xeric ridgetops in western North Carolina.
Pine regeneration was 9,440 stems/ha on high-intensity burned plots, 34 stems/ha on
low-intensity burned plots, and 7 stems/ha on control plots. Sparse regeneration on
low-intensity plots could be due to the amount of duff left on these sites, the type of
litter (hardwood litter detrimental to Table Mountain pine seedling survival), or the
amount of shading from remaining overstory trees [56,57].
Brose and Waldrop [14] provide evidence from 9 uneven-aged Table
Mountain pine-pitch pine stands across Georgia, Tennessee, and South
Carolina, that suggests frequent periodic or continuous pine and
hardwood recruitment under a regime of periodic surface fires
during the past 100 to 150 years. These fires were likely low- to
moderate-severity, given that cores and cross-sections were sampled from
living chestnut oaks which would have been killed by a high-severity
fire [14]. The results of this study suggest that successful seedling
establishment of Table Mountain pine can occur following low- and
moderate-severity fire.
Waldrop and Brose [75,77] report effects of
low, medium-low, medium-high, and high intensity fires on the
establishment of Table Mountain pine seedlings after prescribed burning
in the War Woman Wildlife Management Area of the Tallulah Ranger
District in Georgia. Sixty sample plots were surveyed at the end of the
1st and 6th growing seasons after burning. In the 1st growing season, postburn
pine density ranged from 1,396 seedlings/acre on the high
intensity plots to more
Other information: This fire study provides information on postfire responses of plant species in communities that include Table Mountain pine:
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available [21,55,66,89].
Morphology: Table Mountain pine is a native, slow-growing conifer. It is often small in stature and exceedingly limby [19]. It rarely grows beyond 66 feet (20 m) tall [21,66,92], though the tallest individual recorded was 95 feet (29 m) [91]. Table Mountain pine is typically around 16 inches (40 cm) DBH [21,66,92]. The maximum recorded DBH was 34 inches (94 cm) [91].
The trunks of Table Mountain pine are often crooked and have irregularly shaped cross-sections [23,91,92]. Older trees tend to be flat-topped, while young trees can vary in form from that of a large bush when open-grown, to slender with relatively small limbs when grown in a dense stand [91]. Table Mountain pine typically has long, low-lying, thick limbs on much of the trunk [23,91,92]. The limbs remain alive on over half of the length of the bole. Even in closed stands, where branches are smaller and limited to the upper trunk, Table Mountain pine retains branch stubs for long periods of time [91,92]. The bark of Table Mountain pine is broken by fissures into irregular plates [66] and is nearly smooth to flaky [55]. Zobel [92] states that bark thickness increases linearly with the increase in diameter.
Throughout its range, the needles of Table Mountain pine average 2.7 inches (6.8 cm) in length, ranging from 1.3 inches (3.3 cm) to 4.1 inches (10 cm). They are borne in a 2-needle fascicle. Three-needle fascicles may occur on the same tree but are rare [21,92]. Needles and fascicles are retained for 2 to 3 years [22,60].
Male cones are 0.6 inches (1.5 cm) long. Female cones are sessile, range from 1.7 to 4.1 inches (4.2-10 cm) long, and occur in whorls of 2 to 7. Cone scales are tough and armed with broad, stout, upwardly curving spines [21,23,55,66,92]. Female cones are typically serotinous, although serotiny varies among individuals [3] and populations [91,92]. See Seed dispersal for more information on the serotiny of this species. Seeds are triangular and approximately 0.25 inches (0.63 cm) long, with wings about 1 inch (2.5 cm) long [49]. The size of cones and seeds decreases with increasing elevation [92].
Table Mountain pine seedlings generally anchor their taproot into a rock crevice. Secondary or lateral roots then spread through soil and litter, taking up both moisture and nutrients. Other sinker roots descend into additional crevices, utilizing accumulated soil and the thin skins of finely weathered, nutrient-rich, moist soil-like rock which coat the crevice surface [19].
Age class structure: The age class structure of many Table Mountain pine stands suggests that fire is an important influence on stand structure and regeneration [91]. Many Table Mountain pine stands observed on the Chattahoochee National Forest, Georgia are represented by large DBH size classes, suggesting older age classes, and show no evidence of pine regeneration [70]. Williams and Johnson [86] report that the age distribution of Table Mountain pine in pine-oak forests near Blacksburg, Virginia, was bimodal with peaks in the seedling (10 year old) and large tree (45 to 80 year old) age classes. Estimated stem ages for the study area ranged from 1 to 124 years. There were few individuals in the 20- to 35-year age classes. This gap in age distributions suggests that recruitment may be episodic [86] (e.g., following periodic fire) in these populations.
The presence of many size classes suggests that some Table Mountain pine stands can persist for long periods in the absence of fire. Table Mountain pine stands that appear to be "permanent" are generally associated with a sparse understory, shallower litter, more rock outcrop, and less basal area, than stands that are moving towards a late-seral, oak-dominated forest, with 1 size class of pines, no pine reproduction, and a dense understory of shrubs [91]. Three Table Mountain pine stands located on a xeric, southwest shoulder of Looking Glass Rock, North Carolina, were reported to have continuous recruitment in the absence of fire for 87 years. The age structure of these stands suggests relatively continuous recruitment during each of 3, 20-year periods with a mortality rate of 50% per period, except for one period in which 2 severe droughts were thought to decrease recruitment and increase mortality of saplings and seedlings. Sites supporting continuous recruitment had shallow, rapidly draining soils and little or no mountain-laurel present [2].
A maximum age of 250 years is reported for Table Mountain pine. The oldest recorded individuals in the Appalachians were 227 and 205 years, and were found in the southwest corner of North Carolina [91].
Fire adaptations: Table Mountain pine has adaptations to fire that are consistent with both long- and short-return-interval fire regimes. Medium-thick to thick bark, a deep rooting habit, self-pruning limbs, and pitch production to seal wounds are characteristics of Table Mountain pine that suggest it is adapted to survive frequent, low-severity fire [3,39,47,52,67,73,76,85]. Delayed seed release from serotinous cones and trees that produce viable seed at a young age also allow Table Mountain pine populations to persist after infrequent, high-severity fire [47,73].
Table Mountain pine can sprout following injury [39,46,56,65], such as that from fire or animal damage [91], but no data in the literature describe resprouting after fire in Table Mountain pine. Table Mountain pine seedlings of "natural origin" usually have a crook just above or just below ground level which may serve to protect basal buds against fire [19,91].
FIRE REGIMES: Table Mountain pine was historically subject to a full range of fire types: frequent low-severity surface fires, mixed-severity fires, and stand-replacement fires [27,36,74]. Table Mountain pine is also adapted to a range of fire frequencies [3]. Fire occurs infrequently on contemporary Appalachian landscapes [41] where Table Mountain pine is common.
Fire histories developed for 2 Table Mountain pine communities in southwestern Virginia revealed that between 1758 and 1944, fires burned approximately every 5 to 10 years during the dormant season. Recent regeneration failure of Table Mountain pine and increasing dominance of oak species appear to coincide with fire exclusion practices initiated after 1950 [67,68]. Based on USDA Forest Service records, Wade and others [74] state that between 1800 and 1944 the fire interval in sampled Table Mountain pine stands averaged 10 to 12 years, and that it is currently 7 to 70 years with an average of 40 years [74]. The mean interval between fires, based on fire scars from pine forests in the Great Smoky Mountains National Park, for the period 1856 to 1940 was 12.7 years. Fires were more frequent, however, at lower elevations. Most of these fires were probably anthropogenic and may have been an important influence ever since Native Americans settled in the Little Tennessee River Valley [36].
Frost [27] uses the term polycyclic (communities with 2 or more kinds of fire cycles) to describe presettlement FIRE REGIMES in pitch pine-Table Mountain pine stands on dry, south-facing slopes. Past FIRE REGIMES in these communities consisted of a cycle of high-frequency, understory fires (about 5 to 7 years apart) interrupted periodically by a long fire-free interval (about 75 years) followed by stand-replacing fire. Frost categorizes Table Mountain pine as having a short fire-return interval (25 to 100 years). "Canopy thinning" occurs when fuel loading, fuel moisture, and wind create prolonged or severe fire behavior but fall short of initiating crown fire, and has been observed in pitch pine-Table Mountain pine stands in the southern Appalachians [27].
In the eastern United States, pitch and Virginia pine forests that Table Mountain pine is commonly associated with were subject to mixed FIRE REGIMES. Where burning by Native Americans was common, FIRE REGIMES in pitch pine communities were characterized by understory fires on a 2- to 10-year interval. Fire in Virginia pine was probably less frequent and resulted in higher tree mortality. These forest types are still characterized as mixed fire regime type because the fire return intervals are longer and the majority of wildfires occur during the growing season when damage is greater [74].
Based on species traits and presettlement site descriptions, Landers [42] suggests an "inferred fire regime" for Table Mountain pine stands in the southeastern United States, with "very intense fires" at a frequency of 2 per century [42]. Where Table Mountain pine forms even-aged, pure stands, Wade and others [74] classify the fire regime as typically stand-replacement at intervals of <35 to 200 years.
The following table provides fire return intervals for plant communities and ecosystems in which Table Mountain pine is important. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Fire regime information on vegetation communities in which Table Mountain pine may occur. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models [44]. These vegetation models were developed by local experts using available literature, local data, and/or expert opinion as documented in the PDF file linked from the name of each Potential Natural Vegetation Group listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model. Northeast Southern Appalachians Northeast Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics Percent of fires Mean intervalTable Mountain pine is typically fire-dependent, requiring fire to ensure optimal regeneration and maintenance [33,85]. Fire plays an important role in creating the environmental and biological conditions necessary for natural regeneration of Table Mountain pine forests [34]. Beginning in the 1930's, changes in land use and effective fire exclusion programs slowed or reversed pine forest expansion [85]. Fire exclusion in the southern Appalachians is thought to decrease regeneration in Table Mountain pine [17] and allow for accelerated succession to hardwood-dominated forests that ultimately threaten the perpetuation of Table Mountain pine populations [41,67].
Findings by Welch and others [79] on the first-year response of southern Appalachian Table Mountain pine and pitch pine stands to prescribed burning, suggest that prescribed fires in which objective is to restore these communities must open the canopy, reduce accumulated litter and duff layers, and expose regenerative buds of hardwoods to lethal temperatures in order to lessen postburn sprouting. Prescribed burns that do not accomplish these goals may further encourage succession towards hardwood-dominated stands [79]. For complete details of this study, see Early postfire response of southern Appalachian Table Mountain-pitch pine stands to prescribed fires.
Declines in Table Mountain pine populations during the era of fire exclusion have greatly reduced the seed source for this species. Oaks have spread into these communities and, in many cases, dominate the canopy. In addition, there is tremendous litter build-up on these areas. A review by Buckner and Turrill [15] recommends intense, small scale prescribed burning to clear the forest floor down to mineral soil, eliminate hardwood competition, and allow Table Mountain pine regeneration. If the previous Table Mountain pine community was much depleted, this process might have to be repeated on a 5- to 7-year cycle, similar to the "pulsed" prescribed fire regime used to manage other yellow or hard pines of eastern North America [84]. Such burning practices could restore Table Mountain pine populations on a local scale [15].
If management of declining populations of Table Mountain pine is to be effective, the development of a prescribed burning plan should consider tree age and burn season to ensure that an adequate and viable seed source is present. This conclusion was drawn from a study on the patterns of seed production in Table Mountain pine, which revealed that the number of seeds and viability of seeds was greatest in cones collected in the winter, even though cones are mature in the fall of the second year [31].
Table Mountain pine is endemic to the Appalachian Mountains and commonly dominates steep, rocky ridges and exposed escarpments too marginal for many tree species [23,28,41,91]. Throughout its range, Table Mountain pine is most commonly found on south- and west-facing slopes at elevations ranging from 1,000 to 4,000 feet (305-1,220 m) [7,12,91]. Elevation extremes are noted from about 150 feet (46 m) near Delaware to over 4,700 feet (1,430 m) in Tennessee. In the Great Smoky Mountains of Tennessee and North Carolina, it has been reported in elevations up to 5,800 feet (1,767 m). Outlying populations are associated with monadnocks (isolated mountain or rocky mass in an otherwise level area), and other eastern range extensions are along major rivers. Table Mountain pine has been reported around bogs on Mt. Pisgah, North Carolina, and at Big Meadows, Shenandoah National Park, Virginia [91].
Soils: Stands dominated by Table Mountain pine are usually associated with exposed rocky sites with shallow soil over bedrock or a very high rock content [23,42]. The soil series where Table Mountain pine dominates are generally stony; shallow, sometimes without profile development; strongly acidic (pH 4.5-5.5); infertile and of low productivity; and well to excessively drained [12,42,91].
On Looking Glass Rock, western North Carolina, stunted (<33 feet (<10 m) tall) Table Mountain pine survive where the soil depth in cracks and depressions in the granite is 4 to 16 inches (10-40 cm) [5].
Climate: The climate throughout Table Mountain pine's narrow range is warm, humid, and continental. Average monthly high temperatures range from 20 °F (-7 °C) in January to 85 °F (29 °C) in July. Mean annual precipitation ranges from 30 to more than 80 inches (760-2,030 mm) distributed evenly throughout the year [13,19]. The average number of frost-free days in Pennsylvania varies from 150 to 170, and from 170 to 180 in the mountains of Tennessee, North Carolina, and northern Georgia [19]. Table Mountain pine most often occurs on the warmest and driest microsites within these areas [91].
Table Mountain pine often survives fire, but trees can be top-killed or killed [71,75,77,79].
After passage of fire, the resin of the serotinous cones melts and the scales reflex for seed release and dispersal. Barden [3] reveals that 78% of cones opened after 2 minutes but before 4 minutes when heated in an oven at 210 °F (100 °C).
Table Mountain pine's serotinous cones are of special importance as a year-round food source for the American red squirrel [23,91]. Red squirrels may limit the growth and competitive ability of Table Mountain pine, as well as limiting the reserve seed crop, by destroying past growth and photosynthetic tissue when they "cut" branches and then remove cones on the ground [91].
Palatability/nutritional value: No information is available on this topic.
Cover value: No information is available on this topic.
Table Mountain pine is common in upland yellow pine communities that are dominated by
Table Mountain pine, pitch pine, shortleaf pine, and Virginia pine (Pinus virginiana)
with an understory of chestnut oak (Quercus prinus) [7,13]. It is
also often found in pure stands or co-dominant with pitch pine [30]. Other
understory tree species that may be present in Table Mountain pine stands are
red maple (Acer rubrum), black tupelo (Nyssa sylvatica), sourwood (Oxydendrum arboreum),
scarlet oak (Quercus coccinea), bear oak (Q. ilicifolia), white oak (Q. alba),
post oak (Q. stellata), southern red oak (Q. falcata), blackjack oak (Q. marilandica),
black oak (Q. velutina), American chestnut (Castanea dentata), black locust
(Robinia pseudoacacia), eastern hemlock (Tsuga canadensis), and sweet birch (Betula
lenta) [4,7,12,19,69]. Table Mountain pine populations in northeastern
Georgia are also associated with hickory (Carya spp.) and eastern white pine (Pinus
strobus) [12]. On Looking Glass Rock, western North Carolina, Table Mountain pine grows with
eastern redcedar (Juniperus virginiana) [5]. Mountain-laurel (Kalmia
latifolia) is the most common shrub species associated with Table Mountain pine stands. Other
ericaceous shrub species such as mountain fetterbush (Pieris floribunda), hillside blueberry
(Vaccinium pallidum), black huckleberry (Gaylussacia baccata), bear huckleberry
(G. ursina), and several species of rhododendron (Rhododendron spp.) are common
associates [12,23,85].
Table Mountain pine is associated with the Virginia pine-oak [10], Virginia pine
[11], pitch pine [45], shortleaf pine [80], and chestnut oak [18] cover
types, as recognized by the Society of American Foresters.
Table Mountain pine is a dominant species in the following vegetation types
and plant communities:
Table Mountain pine is a preferred species for the southern pine beetle and can be selected,
attacked, and killed [1,41,54]. Table Mountain pine is also susceptible to comandra blister rust,
which is a canker disease of hard pines caused by the fungus Cronartium comandrae [51].
Trees of all sizes are attacked by the pine twig gall scale which causes bark to swell and crack,
killing foliage and tree [19].
The needles of Table Mountain pine can be affected by hypoderma needle blight
which causes mortality of infected needles [9]. The European pine sawfly can defoliate trees of their previous year's
needles but seldom kills the trees [19]. The cones of Table Mountain pine are susceptible to Table
Mountain pine coneworm (Diorytria yatesi) [31], and cone boring insects may have a significant
effect on Table Mountain pine. The larva eats the part of the maturing cone between the central core
and the outer layer of the cone, destroying the seeds. Damage varies from year to year, but in some
years it appears to have destroyed the entire seed crop of an area. Heart rot is common in larger Table
Mountain pine trees, usually over 100 years old. It appears to enter most often through fire scars and
from long-persistent branch stubs characteristic of Table Mountain pine [91].
On Brush Mountain, Virginia, seed predators that attack cones of Table Mountain pine include red
squirrels, larvae of the mountain pine coneworm, and the shield-backed pine seed
bug [87].
Ice storms cause extensive damage to Table Mountain pine trees and can decrease basal area
[41,81]. In a study by Whitney and Johnson [81], over 82% of Table Mountain pine were
damaged by heavy glaze. Of these trees, 85% experienced 50% crown loss. Sampling was done two
years after storm. Seedlings did increase after the storm due to the canopy gap
created by fallen trees [81].
Table Mountain pine provides valuable soil and watershed protection [19,23] and wildlife habitat [23].
Wood Products: Table Mountain pine is a softwood species [63] and has limited economic importance for timber products because of its small stature and often poor stem shape. Small amounts of Table Mountain pine are harvested, along with other pines, for fuel and commercially for pulp, paper production, and small roundwood [19,23,49]. Table Mountain pine has some potential for small saw timber when reintroduced in mixture with naturally occurring hardwoods [90].
Table Mountain pine is commonly found on steep slopes with limited access that are likely to be unsuitable for timber production [86].
In northwestern North Carolina, pollen release at 1,500 feet (457 m) elevation begins the last week of March and ends during the first week in April; at 2,500 feet (762 m), pollen release begins about the second week in April and ends near the end of the third week. Cones ripen in autumn of the second season. The opening of cones depends on the degree of serotiny [19]. Seeds are shed from September to November [55], although on Brush Mountain, Virginia, seedfall of Table Mountain pine occurred throughout the year but was primarily concentrated in the spring and summer months [87].
Table Mountain pine's early spring development and reproductive activity (development of male and female strobili) could exclude it from extensively colonizing areas with later spring frosts. By "flowering" and initiating twig growth earlier, Table Mountain pine is more susceptible to frost damage than other pine species studied [91].
Table Mountain pine regenerates mainly from seed [23,52,91]. Table Mountain pine has one or more basal buds near the cotyledonary level with additional buds often appearing as a quasi whorl an inch or so above this point, allowing it to sprout after injury [19,39,46,56,65,91].
Fire aids the regeneration of Table Mountain pine in several ways. It opens the serotinous cones, consumes litter, exposes mineral soil, and eliminates competing vegetation, allowing more light and water for pine seedlings and minimizing allelopathic effects [91].
Pollination: Table Mountain pine is pollinated by wind [24].
Breeding system: Table Mountain pine is monoecious [19]. Feret and others [24] found that Table Mountain pine stands in southwest Virginia have large genetic variability within a relatively small area.
Table Mountain pine is predominantly outcrossed [29].
For information on how fire relates to Table Mountain pine genetic diversity see Recurrent fire and maintenance of genetic diversity.
Seed production: Table Mountain pine begins cone and viable seed production when saplings are 5 to 7 years old [15,47,49,76]. Della-Bianca [19] states that, although Table Mountain pine cones shed their seeds irregularly, large numbers of seeds are disseminated annually. On Looking Glass Rock, North Carolina, Table Mountain pine produced one whorl of 2 to 5 cones each year on the new growth of branches. Cones remained closed for 2 to 5 years after maturity, and then about 40% of them opened without fire. Cones remained attached to the stem for a decade or longer, whether or not they opened [3].
Patterns of seed production in Table Mountain pine were studied by Gray and others [31] to determine if Table Mountain pine seed viability and availability varied with tree age, cone age, and season. Cones were collected from stands where Table Mountain pine was the main component and where a wide range of age classes was present. Seed viability was determined in a greenhouse where cones were dried in an oven for a minimum of 12 hours at 140 °F (60 °C) to allow them to open. Following drying, seeds were extracted, wings removed and germination tests conducted. The average number of seeds per cone tended to be higher in the younger age classes (5-25 years); however, viability was lowest in the 5- to 10-year-old age class [31].
Average number of seeds/cone and percent viability of seeds for Table Mountain pine by tree age class [31] Tree age class (years) Average number of seeds/cone* Average percent viability of seed 5 to 10 46.0a, b 8.8b 11 to 25 51.9a 33.3a 26 to 50 43.5a, b 32.7a 51 to 75 41.5b 32.9a 76+ 37.9b 38.6a *Averages followed by the same letter do not differ at alpha=0.05Table Mountain pine cones open in response to heat. When cones were heated in an oven at 210 °F (100 °C), 9% opened within 2 minutes, 78% opened between 2 and 4 minutes, and 100% opened after 7.5 minutes [3]. McIntyre [49] observed that Table Mountain pine cones placed by a furnace "opened readily" at approximately 95 °F (35 °C), and that the temperature at the end of a Table Mountain pine branch in full sunlight in the field averaged 95 °F (35 °C). This suggests that cones in the shade may not be exposed to temperatures sufficient to open cones, and may therefore remain closed for several years until exposed to adequate temperature regimes [49].
Table Mountain pine seeds are dispersed with the aid of large wings [23].
Seed banking: Table Mountain pine maintains an aerial seed bank of viable seeds in serotinous cones an average of 9 to 11 years [3,6,49] and up to 30 years [91]. Table Mountain pine establishes from seed released from canopy seed banks after fire [59].
Germination: Germination of Table Mountain pine occurs after cones open and seeds are released, as long as there is a suitable seedbed [91]. Groeschl and others [33] state that overstory canopy reduction, a decrease in forest floor litter, and the elimination of dense shrub layers are necessary to ensure adequate germination and establishment of Table Mountain pine. In the past, infrequent, high-severity crown fires provided these conditions [3,33,85,91]. However, a field and greenhouse study by Waldrop [78] reported that germination was higher under shade than in full sun, and was highest under 63% shade. Germination on 2 and 4 inches (5 and 10 cm) of duff was comparable to germination on no duff. Results suggest that lower severity fires can produce a suitable seedbed for germination of Table Mountain pine [78]. Barden [2,3,6] describes stands of Table Mountain pine on an extremely xeric site in western North Carolina that exhibited continuous recruitment despite the absence of fire since 1889.
A greenhouse study by Mohr and others [52] compared germination rates of Table Mountain pine seeds on different duff depth and shade level combinations to determine the best microhabitat for germination and survival of Table Mountain pine seedlings. Seeds were placed on duff 0, 2, and 4 inches (0, 5, and 10 cm) deep, and shade levels were 0% (full sun), 38%, 52%, and 98%. Samples were watered twice a week during June, once a week in July, and every 10 days in August. Germination was not statistically different on different duff depths or under different shade levels (see table below). Seedling height varied little among duff depths, while shade had a significant effect on seedling height (see table below). Seedling survival was greatest with 2 or 4 inches (5 or 10 cm) of duff. Moderate shade (52%) with either 2 or 4 inches (5 or 10 cm) of duff was the best treatment combination in this study for Table Mountain pine seedling survival. These results suggest that germination and establishment of Table Mountain pine is possible after low-severity fire or possibly without fire.
Mean percent germination and seedling height by duff depth and shade level [52] Treatment level Mean percent germination Seedling height* (inches) Duff depth (inches) 0 70.7 3.5a 2 68.5 3.6a 4 63.3 3.8b Shade level (percent) 0 62.6 3.5a 38 67.3 3.9b 52 69.7 4.1b 98 70.6 3.0c *Means followed by the same letter within a treatment group are not significantly different at the 0.05 levelSeedling establishment/growth: The requirements for successful Table Mountain pine seedling establishment and growth are unclear, and may vary among sites and plant communities. Zobel [91] states that very few Table Mountain pine seedlings occur on sites without exposed mineral soil or on sites with a dense canopy or shrub layer. These microsite conditions often occur after fire [75]. Whether or not high-severity, stand-replacing fires are needed to create these conditions is unclear. A greenhouse study [52] found that seedling establishment of Table Mountain pine was most successful on 2 or 4 inches (5 or 10 cm) of duff and under moderate shade (52%) (see table above). These results suggest that establishment of Table Mountain pine may be possible after low-severity fire or possibly without fire. For complete details on how seedling establishment and regeneration is effected by fire, see Discussion and Qualification of Plant Response.
In Virginia, the low availability of suitable seedling habitat strongly limits recruitment of Table Mountain pine in pine-oak forests. Williams [84] found that Table Mountain pine seedlings occurred almost exclusively in open microsites with shallow pine litter, which are relatively rare in mature pine-oak forest. Summer drought also contributed to low seedling survivorship, particularly in very young seedlings. He concludes that optimal regeneration and maintenance of Table Mountain pine are unlikely in the absence of fire when occurring in pine-oak forests suitable for growth of hardwoods, particularly oaks. Increased oak dominance leads to site modifications that are detrimental to Table Mountain pine recruitment such as litter accumulation and shading [84,86,87].
Oak litter accumulation and available soil moisture impact Table Mountain pine seedling establishment. A greenhouse study was conducted by Williams and others [88] to distinguish these effects. Soil and litter were taken from a pine-oak forest on Brush Mountain, Virginia. Oak litter was comprised of chestnut oak and scarlet oak. Pine litter was comprised of Table Mountain pine and pitch pine needles. Litter-free flats lost more water than flats with litter, and there was little difference in soil moisture between the pine and oak litter flats. Leaf litter, water regime, and the interaction of these factors had significant (P=0.0001) effects upon seedling mortality and survival. Mean seedling emergence and mortality for Table Mountain pine are provided in the table below [88].
Mean seedling emergence and mortality (percent) for Table Mountain pine under different soil moisture regimes and leaf litter accumulations [88] Litter-free Pine litter Oak litter Watering interval Seedling emergence Mortality Seedling emergence Mortality Seedling emergence Mortality Daily 83.3 0.01 80 1.7 56 3.7 Eight-day 54.7 100 65.3 14.0 37.3 3.6 Fifteen-day 0.02 100 60.7 98.9 30 82.2Oak litter had a negative effect on Table Mountain pine seedlings when compared to that of pine litter and litter-free treatments, although it did not completely hinder recruitment. Several germinated but desiccated Table Mountain pine seeds were recovered from oak litter treatments during harvest of seedlings. Allelopathic effects are not believed to be the reason for lowered seedling emergence in oak litter, since the seedling mortality was similar between the oak and pine litter treatments. Further studies are needed to understand possible allelopathic effects of oak litter on establishment of Table Mountain pine [88].
Vegetative regeneration: Table Mountain pine can sprout from the base after the stem is injured [19,39,46,56,65,91]. It has one or more basal buds near the cotyledonary level with additional buds often appearing an inch or so above this point that elongate readily only after injury [19,65,91]. Seedlings of "natural origin" usually have a crook just above or just below ground level which may serve to protect basal buds against fire [19,91]. Some buds appear to be short-lived, but the sprouting of cut stumps of large Table Mountain pine trees suggest that some persist [65].
Table Mountain pine is a shade-intolerant and drought tolerant pioneer species that typically establishes stands following disturbance, such as fire [12,15,25,40,41,70]. In later seral stages, on sites suitable for growth of hardwood species, it is replaced by more shade-tolerant hardwoods, specifically oaks, with mountain-laurel understories [12,15,56,68]. Stands with dense mountain-laurel understories and established oaks lack regeneration niches needed by Table Mountain pine [70]. Outbreaks of southern pine bark beetle and ice storms hasten succession toward oak dominance because they both select against Table Mountain pine [12]. Regeneration of Table Mountain pine on sites favorable for the growth of oaks and other hardwoods, like the pine-oak forests of Brush Mountain, Virginia, occurs only after fire. On sites favorable for the growth of oaks, incorporating fire at frequent intervals would facilitate the maintenance of Table Mountain pine [87].
Table Mountain pine may produce self-maintaining or nonsuccessional populations [83]. Populations of Table Mountain pine occur and reproduce in the absence of fire on dry exposed ridges and bedrock outcrops [6].
The scientific name of Table Mountain pine is Pinus pungens Lamb. (Pinaceae) [26,38].
Hybrids: Dorman [20] suggests that natural hybridization occurs,
to a small degree, between Table Mountain pine and shortleaf pine (Pinus echinata),
and between Table Mountain pine and pitch pine (P. rigida). This conclusion is based on
occurrence of trees with intermediate morphological characteristics.
