Pitch pine survival may be affected by tree size, bark thickness, time since last fire, surface soil conditions, fire severity, and/or fire season. Fires first produce damage to pitch pine foliage and well-developed buds; additional heat is required to damage or kill the cambium. If dormant buds along the trunk and within the crown survive, pitch pine survives through crown regrowth and/or epicormic sprouting. Fires that kill dormant buds in the crown or along the trunk may still not produce sufficient temperatures to damage basal buds and kill the tree. Large trees are often less susceptible to fire damage than small trees because of thicker bark and higher crowns. However, old trees with low "vigor" are more likely to be fire killed than younger, more vigorous trees. Fire severity also affects survival and postfire regeneration. "Large head fires" killed 68% of 5- to 8-inch (13-20 cm) DBH pitch pines. "Slow-burning side fires" rarely killed trees of that size class. Fire season may also affect pitch pine survival and regeneration method. Fire damage is typically less when air temperatures are low than when temperatures are high and fuels are dry [94].
In pitch pine-dominated stands of Burlington County, New Jersey, a "light" prescribed fire killed pitch pine trees less than 6 inches (15 cm) in DBH, but a severe fire killed trees in the 11- to 15-inch (28-38 cm) DBH size class in open-canopy, upland sites [90]. Fourteen months after an April 1933 surface wildfire in mixed-oak stands in Ulster County, New York, 6 live "butt-scorched" trees found in August were still alive. The surface fire killed the continuous mountain-laurel understory [155].
A cross section from a pitch pine that was 12 inches (30 cm) at stump height in Monroe County, Pennsylvania, revealed that the tree survived and recorded 9 fires over its nearly 120-year lifespan. Researchers noted that the growth rate slowed with successive fires [20], but it seems that tree age may have also reduced growth rate.This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [45,53,112,135,159]).
Aboveground description: Pitch pine is a hard pine with highly variable growth forms [44,86]. It grows as a prostrate shrub on Fire Island, New York [86]. On the Mt Everett ridgetop in the Taconic Mountains of Massachusetts, pitch pine occurs as a low-growing, 1-foot (0.3 m) mat and as a single-stemmed tree, 10 feet (3 m) tall. The largest prostrate mats measure over 10 m² [117]. Dwarf-stature pitch pines ranging from 20 inches (50 cm) to 13 feet (4 m) tall occur in the in plains area of the New Jersey Pine Barrens. In an area 22 miles (35 km) from the Pine Barrens, pitch pine trees reach 100 feet (30 m) tall [86]. Studies revealed that dwarf and tall-tree pitch pine populations in the Pine Barrens were almost genetically identical [62].
As a tree, pitch pine is medium sized and rarely grows beyond 82 feet (25 m) tall and 3 feet (1 m) DBH. Branching is often irregular [13,23,39,53]; branches can be twisted or gnarled [89], and self-pruning is poor [45]. Crown and branch forms can be affected by growing conditions. Suppressed trees, fire-damaged trees, or trees released through heavy logging usually have drooping, slender branches along the lower trunk. Dead branches are persistent and contain more resin than live branches [89]. Trunks are straight to somewhat curved [23] and covered with thick, large, rough, irregular plates of bark [13,44]. Often there are stubby branches or needle bundles on the trunk [39,70]. In Great Smoky Mountains National Park, bark thickness increased with increasing DBH until trees reached 9 inches (25 cm) in DBH, when bark thickness decreased with increased DBH [64]. Pitch pine is not considered long lived. On the Mt Everett ridgetop, pitch pine averaged 78 years old, but age ranged from 12 to 170 years [117]. For more on pitch pine growth and longevity, see Growth.
Pitch pine needles are most often in bundles of 3. Needles measure up to 5.9 inches (15 cm) long and are stiff and straight to twisted. Pitch pine retains needles for 2 to 3 years [23,44,45,112]. Mature pitch pine cones measure 1 to 3.5 inches (3-9 cm) long and wide and often occur in clusters. Cone scales are thick with stout spines [23,38,112,159]. Male cones are produced at the base of the current year's growth and are often more abundant on low branches. Female cones are more common on upper branches and mature in the fall of the second year following pollination. Pitch pine produces serotinous and nonserotinous cones. Nonserotinous cones shed seed soon after they mature but persist a long time [44,45,53,86,135]. For more on factors that affect serotinous cone production, see Serotinous and nonserotinous cone production. Both cone and seed size increase from northeastern to southwestern populations, as does the number of viable seeds produced per cone [86]. Pitch pine produces smooth, winged seeds. Seeds are typically 4 to 5 mm long, and wings measure 15 to 20 mm [23,44,45].
Belowground description: While Hosie [70] suggests that pitch pine produces short lateral and taproots, others indicate that the pitch pine root system may reach 10 feet (3 m) deep [44], and that lateral root extension may exceed 6 feet (2 m) in 6 years of growth [169]. It is likely that site conditions affect root growth and structure.
Pitch pine roots can grow through and below the water table [44]. Mycorrhizal associations are common. Trappe [161] provides a list of 7 fungi associated with pitch pine.
In the Lebanon State Forest in New Jersey, roots of 1- to 30-year-old pitch pine trees were excavated and studied. Trees grew in partial shade, with "moderate competition", and on well-drained Lakewood sand soils. First-year seedlings had taproots that ranged from 3 inches (8 cm) to 1 foot (0.3 m) deep. Elongation of the taproot was best for seedlings growing in clean, loose sand in full sun. Elongation decreased with shading and increased humus. Mycorrhizae were found on the roots of 2-month-old seedlings. Trees beyond the sapling stage had definite and "fairly strong" taproots that typically divided at 2- to 3-foot (0.6-0.9 m) depths. Taproot prominence decreased as trees aged. The researcher described the taproot of an 85-year-old pitch pine as weak, but noted that some long roots reached 8 feet (2 m) deep. Three trees had roots extending and growing into the water table. There was also some root grafting observed. In only one case was grafting with another species, shortleaf pine. The table below summarizes some root system characteristics for young pitch pine trees [108].
Root system characteristics of pitch pine trees from 1 to 30 years old excavated from the Lebanon State Forest, NJ Tree age (years) Tree size Maximum taproot depth Maximum length of primary lateral root Other notes 1 3 inches 8 inches 3 inches 4 11 inches 18 inches 15 inches 8 22 inches 27 inches 33 inches 10 or more primary laterals 12 4 feet 4 feet 8 feet 3 other laterals measured 4 feet; primary laterals to 3.5 feet deep 17 14 feet 5 feet 19 feet 30 22.5 feet;Hybrids: Pitch pine à loblolly pine hybrid descriptions are provided in 2 sources [89,145], and pitch pine à pond pine hybrids are described by Little and others [89].
Fire adaptations: Pitch pine has numerous fire adaptations that allow it to establish and/or regenerate on burned sites. Postfire pitch pine regeneration may be through bole and crown sprouting from epicormic buds protected by thick bark, sprouting from basal buds protected by crooks and/or soil, and/or through seedling establishment from seed in nonserotinous cones or opened serotinous cones [93]. In a 1930s survey completed by 41 leading foresters of the time, asked to rate a list of tree species in order of increasing fire resistance, pitch pine was considered most resistant. Foresters were asked to consider trees between 40 and 80 years old [153].
FIRE REGIMES: Pitch pine forests have been aptly described as "fire-dependent ecosystems" by Vogl [167]. Pitch pine forests support vegetation with various fire-adapted regeneration strategies and persist in and foster environments conducive to ignition, combustion, and fire spread. Vogl further substantiates his claim by noting that exclusion of fire or decreased fire frequency in pitch pine forests produces more "dramatic" effects than increased fire frequency [167].
Early anthropogenic fires: While much of the information regarding the burning done by Native Americans is speculative, there is ample evidence of widespread, frequent burning after eastern United States settlement by Europeans. Often the lack of lightning in the Northeast is considered evidence of Native American fire starts; however, while lightning is rare compared to the western United States, it does occur (see Fire season, weather, and fuels). Early written accounts, a lack of lightning, and the existence of many fire-tolerant or fire-adapted species and landscapes suggests that Native Americans burned at least portions of Virginia. Fire was likely used to maintain travel routes and to find and gather food [15]. Fossil pollen and charcoal records from the Horse Cove bog in Macon County, North Carolina, indicate that fires have been important for the last 3,900 years. Because of the lack of lightning in the area, researchers suspect selective burning by Native Americans contributed much to the charcoal record [35]. There is considerable evidence that early European settlers burned in the New Jersey Pine Barrens and some speculation that Native Americans did too. Lightning is rare in the Pine Barrens, especially compared to the occurrence of lightning in western US forests. Early European settlers burned clearings around cranberry (Viburnum spp.) bogs and set fires to cover up illegal timber harvests. Locomotives were another ignition source. Generally, fires in the Pine Barrens were not controlled since the pines were not valued for timber, and often flames of fires in nearby timber-valued forests were directed to the Pine Barren plains during fire fighting [101]. For more on the use of fire by Native Americans in the Northeast, see Day [32].
Fire season, weather, and fuels: Climate, fuels, and terrain in pitch pine habitats are favorable to fire. Often pitch pine trees have drooping, slender branches along the lower bole, and persistent dead branches contain more resin than live branches [89]. In the New Jersey Pine Barrens, a long growing season, high maximum temperatures, strong winds, and level to rolling terrain encourage fire ignition and spread [101]. In dwarf pitch pine-dominated plains, vegetation regeneration provides enough fuel to carry another fire 4 to 5 years after a crown fire [176].
Fire records and weather data from Maine indicate that severe fire years occur about every 15 years and are associated with short periods (1-2 months) of "intense" drought [130,131]. In Pennsylvania, lightning ignitions burned large areas in drought years. From 1912 to 1917, lightning struck pitch pine trees 417 times: 139 times in July and 169 times in August. From 1960 to 1997, lightning-caused fires burned 2,279 acres (922 ha), and there were lightning fires in nearly every year [139]. At least a few lightning ignitions occur each year in the New Jersey Pine Barrens. Most lightning comes from June to September. As many as 26 ignitions have been recorded in a year, and ignitions increase with drought and "dry lightning" events [176]. National Forest records from northern Georgia and southern Virginia indicated that there were 6 lightning fires/year/400,000 ha between 1960 and 1971. Ninety percent of lightning fires occurred from April to August, and 40% in May. Human-caused fires were most common from March to May and October to December, when litter was driest. Human-caused fires were often more severe than lightning-caused fires [5].
Past/present fire-return intervals and fire behavior: Dwarf pitch pine communities burned at 5- to 15-year intervals, and tree-sized pitch pine forests and woodlands burned at 15- to 150-year intervals. Fire-return intervals of about 30 years or more increase the likelihood of associated deciduous tree reproduction, and as fire-return intervals increase, so does the chance of pitch pine replacement by hardwoods.
Fire scars on 4 eastern white pine and 2 pitch pine trees from the east ridge of Catocin Mountain Park in Thurmont, Maryland, revealed that the time between 2 successive fires ranged from 5 to 49 years. The mean fire-return interval from 1813 to 1900 was 29 years. From 1813 to 1985, the mean fire-return interval was 21.5 years. Fire occurrence increased in the early 1900s, but there were no fires in the area after Park establishment in 1936 [37].
Fire scar data show that western Great Smoky Mountains National Park mixed-pine forests of upper southern slopes burned on average every 12.8 years between 1856 and 1940. From 1920 to 1949, 96% of the mixed-pine forests burned. After creation of the Park in the 1930s and the active exclusion of fire, the average sizes of lighting-caused and human-caused fires were 8.4 acres (3.4 ha) and 13.3 acres (5.4 ha), respectively. With fires of this size, in would take 2,000 years to burn the 22,000-acre (9,100 ha) study area within the western part of the Park [65]. Fire exclusion converted xeric sites occupied by open-canopy forests with rich herbaceous understories, which were common in the early 20th century, to mature, closed-canopy stands with low herbaceous cover and richness by the late 20th century. Researchers predict that these canopy structure changes will affect fire behavior. In the early 20th century, open-canopy stands had limited woody fuels but a highly flammable understory; fire ignition will likely be more difficult, spread more limited, and fire size smaller in closed-canopy than historically open-canopy stands [66].
Age structure and fire scars from Table Mountain pine-pitch pine stands in the southern Appalachians revealed an all-aged distribution and frequent periodic or continuous regeneration from about 1800 to 1950 in 3 northern Georgia and 2 southern South Carolina stands. Age structure suggested that stand-replacing fires were unlikely, and periodic, low-to moderate-severity surface fires were common in these stands. In another South Carolina stand and 3 stands in Tennessee, age distribution was unimodal, suggesting stand-replacing events had occurred; however, evidence of stand-replacing fire was lacking. Researchers suggested that these stands have been maintained through recurring low- to moderate-severity surface fires and likely a variety of other disturbances such as droughts, hurricanes, insect outbreaks, thunderstorms, and logging. All stands experienced 3 to 8 fires since the 1850s, but pine regeneration has been rare since the 1950s [14]. Frost [49] suggests that Table Mountain pine-pitch pine forests in the southern Appalachians burned at 5- to 7-year intervals in "understory shrub fires" and less frequently, every 75 years, in "catastrophic" stand-replacing fires before European settlement.
New Jersey Pine Barrens: Researchers have extensively studied fire ecology in pitch pine communities of the New Jersey Pine Barrens and found that fire frequency decreases from the dwarf pitch pine plains to the tree-sized pitch pine barrens. From fire scars and tree dating, Lutz [101] proposed that fires in plains communities burned on average of every 6 years. Transition communities burned at 12-year intervals, and barrens communities burned at 16-year intervals. Fire severity was greatest on the plains, because of the low stature of the vegetation, greater air movement, and higher evaporation rates, which produced drier fuels. For brief community descriptions, see Habitat Types and Plant Communities. Others reported that fire intervals range from 6 to 8 years in the plains and 16 to 26 years in tall pitch pine forests in the Lebanon State Forest (McCormick and Gill, cited in [51]).
From fire tolerance rankings created from an in-depth analysis and review of the distribution and fire tolerance of New Jersey's Pine Barrens species, Windisch [176] estimated the fire-return interval and fire behavior for upland communities and peripheral habitats in the barrens. Reported fire frequencies and behaviors were those that would perpetuate the vegetation type [176].
Fire behavior descriptions and fire-return intervals for upland and peripheral New Jersey Pine Barrens communities Plant community Dominant species Physiognomy Mean fire-return interval (years) Typical fire type Fire ecology pine plains dwarf, serotinous pitch pine; shrub oaks¹ open shrubland <1 m tall 5-15 mixed crown and surface MFRI* allows shrub oaks and pitch pine to regenerate but too frequent for tree-form oaks and pines pine plains dwarf, serotinous pitch pine; shrub oaks closed shrubland 1-3 m tall sporadic 15-60 mixed crown and surface sporadic MFRI of 15-60 years reduces ground cover diversity, fire "intensity" increases as canopy and heath cover increase pitch pine-shrub oak barrens tree-form, serotinous and nonserotinous pitch pine; shrub oaks open-canopy pitch pine; lacks tree oaks² 15-25 more crown than surface tree-form pitch pine prevails over dwarf form, MFRI too frequent for tree oaks and shortleaf pine to reproduce successfully pitch pine-post oak-shrub oak woodland tree-form, serotinous and nonserotinous pitch pine; 5-10% post oak; shrub oaks open-canopy pitch pine; sparse post oak understory 25-30 more crown than surface 20-30 year MFRI allows post oak but not other tree oaks to reproduce pitch pine-tree oak-shrub oak woodland tree-form, serotinous and nonserotinous pitch pine; tree oaks; shrub oaks open-canopy pitch pine-oak; 5-25% tree oak cover 30-40 more crown than surface MFRI allows tree oaks to reproduce but frequent enough to keep canopy open and shrub oak dominance mixed pine-tree oak-shrub oak woodland tree-form, nonserotinous pitch pine; shortleaf pine; tree oaks; shrub oaks open-canopy mixed pine-oak ; 5-25% tree oak cover 30-40 more surface than crown less "intense" burning allows shortleaf pine to codominate pine-oak forest tree-form, nonserotinous pitch pine; shortleaf pine; tree oaks; <5% shrub oaks closed-canopy pine-oak; 25-50% tree oak cover 40-60 mixed crown and surface MFRI allows strong tree oak reproduction and codomination; fire frequent enough for pitch pine successful reproduction oak-pine forest tree oaks; tree-form, nonserotinous pitch pine; shortleaf pine closed-canopy oak-pine; >50% tree oak cover 60-100 surface fire predominant; crown fire rare MFRI allows strong tree oak reproduction and is frequent enough for pine persistence oak-pine-holly (Ilex spp.) forest tree oaks; tree-form, nonserotinous pitch pine; shortleaf pine; <5% hickory closed-canopy oak-pine; >50% tree oak cover 100-150 surface fire predominant; crown fire rare MFRI allows for tree oak and holly dominance, hickory present but limited by fire; pines persist but not dominant ¹shrub oaks: blackjack and bear oak; ²tree oaks: post, scarlet, white, and/or chestnut oaks.Increased pitch pine associated with European settlement disturbances: In parts of Maine, New York, Massachusetts, and West Virginia, disturbances and fires associated with land clearing and cultivation by early European settlers increased the abundance and prevalence of pitch pine. Pollen and charcoal records from the Newfield Marsh of southern Maine suggest that disturbances and fire regime changes occurred with European settlement of the area. Over the past 200 years, vegetation dominance has shifted to more "fire-prone, xeric-species". Early seral pitch pine-dominated communities dominating the Waterboro Barrens were likely present in presettlement time but with distribution limited to severely or repeatedly burned sites, xeric southern or western slopes, and areas of exposed bedrock. Increases in pitch pine-dominated communities are thought to be a result of postsettlement disturbances including logging, charcoal manufacture, and blueberry (Vaccinium spp.) cultivation [28].
Using pollen records, historic maps, and early logging and land clearing records, researchers concluded that the range of pine barrens and dwarf pine plains in central Suffolk County, New York, expanded over the last 3 centuries due to increased human disturbances. After European settlement of the area, fire frequency increased as land was burned for cultivation and grazing. Sparks thrown from wood- and coal-burning locomotives also increased the fire frequency. Mixed oak-pitch pine and pitch pine-mixed oak forests were abundant before substantial European settlement (1640-1680), but pitch pine-oak/heath woodlands, pitch pine-scrub oak (bear and/or dwarf chestnut oaks) barrens, and dwarf pine plains probably covered less than 17,000 acres (7,000 ha) before substantial European settlement. By the late 19th century, pine barrens covered about 250,000 acres (100,000 ha) in Suffolk and eastern Nassau counties. Fire exclusion in the 20th century led to some conversion of pitch pine barrens and woodland vegetation back to pitch pine-mixed oak or mixed oak-pitch pine [79].
Pollen and charcoal sediment from ponds on Cape Cod revealed that vegetation changes over a 2,000-year period were most dramatic during European settlement. Ponds were in pitch pine-mixed oak forests. Although archaeological evidence indicates that Native Americans were present from the Holocene, their impacts on the vegetation were not considered substantial. The first European settlements on Cape Cod occurred in the 1630s, but most areas were unoccupied until 1700. Prior to European settlement, beech and hickory (Fagus and Carya spp.) pollen was more common than at present. With European settlement, herbs and grasses increased, suggesting forest clearing and the creation of an open landscape. Charcoal influx was significantly (P<0.05) greater in postsettlement than presettlement time. Fires were more common in the past 300 years than in the previous 1,500 years [128,129]. "Following the decline of oak and other hardwood taxa, pitch pine has become a more common feature of the modern forests" [128]. Pitch pine especially increased during the 20th century as fields and pastures were abandoned and reforestation began [128,129].
Charcoal and pollen from sediment cores taken from Green Pond in Augusta County, West Virginia, suggest that pitch pine dominance in the uplands surrounding the pond is likely a result of increased fires after European settlement, which began about 1750 [132].
Decreased pitch pine associated with fire exclusion: While pitch pine has increased in some areas due to increased fire frequencies associated with European settlement, in the same and other areas, fire exclusion since the early 1900s has allowed hardwoods to replace pitch pine. Aerial photos of the central Pine Barrens of Long Island showed that in 1938, 90% of the study area was open-canopy vegetation such as dwarf pine plains, pitch pine-scrub oak woodlands, heathlands, pitch pine-heath woodland, and scrub oak shrublands. From 1938 to 1994, wildfire size decreased, annual area burned decreased, and there were no fires in over 70% of the study area. Open-canopy barrens decreased to about 45% of the study area, mostly due to conversion of pitch pine-scrub oak to pitch pine-oak forests, although some of decreases were the result of residential and industrial development. Most wildfires occurred in the spring when winds were high, humidity was low, and surface fuels and litter were dry, but deep duff was moist. Researchers indicated that preserving open-canopy barrens will require active fire management [74].
From historical documents and forestry reports, Arabas [3] calculated a mean fire-return interval of 10 years for the 1888 to 1978 time period for a 500-acre (200 ha) study area in the Nottingham Serpentine Barrens of Pennsylvania. From 1937 to 1993, dominance of the study area changed from open- to closed-canopy vegetation. Fires were not actively suppressed in the area before 1930, but with increased fire exclusion the average annual area burned decreased from 200 acres (100 ha) before 1957 to 67 acres (27 ha) after 1957. Since about 1950, the area dominated by pitch pine savannahs and woodlands has decreased, and the area dominated by hardwood forests (75-100% deciduous tree cover) has increased [3].
Fire records and published primary and secondary literature show that an average of 55,280 acres (22,369 ha) of the 1,400,000-acre (550,000 ha) New Jersey Pine Barrens burned annually in wildfires from 1906 to 1939. This decreased to an average of 20,050 acres (8,115 ha)/year from 1940 to 1977. In the early 1900s, fire size averaged 110 acres (45 ha), and between 1940 and 1977, average fire size decreased to 15 acres (6 ha). Extensive fires occurred when there were drought conditions and high winds, which in this area can occur in any month of the year. Area burned in wildfires decreased after 1940. This may have been the result of decreased railroad usage, effective fire suppression, and/or increased winter and spring prescribed fires [46].
The following table [83] provides fire-return intervals for plant communities where pitch pine occurs. This list may not include all the plant communities in which pitch pine occurs. Find 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 pitch pine may occur. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models [83]. 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. 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 intervalPrescribed fire is often necessary to suspend succession to hardwood-dominated stands and to maintain pitch pine populations. Deep-burning fires are necessary to convert sprout-origin pitch pine stands to seed-origin stands in New Jersey. Guidelines on the use of prescribed fire in pitch pine and pitch pine-hardwood stands to achieve various management goals are provided by Little [93].
In the Warm Springs District of the George Washington and Jefferson National Forests of Virginia, researchers promoted pitch pine regeneration through spring and subsequent fall prescribed fires. Fires burned in stands that were succeeding to scarlet and chestnut oak because of about 60 years of fire exclusion. The spring fire decreased hardwood canopy dominance, and the fall fire opened the canopy, exposed mineral soil, and stimulated pitch pine regeneration [163]. In the Nantahala National Forest, pitch pine regeneration was "good" in stands that were selectively logged and burned [26]. In mixed oak-pitch pine forests in the Nantahala National Forest, mid-September prescribed fires following clearcutting produced temperatures of only 113 to 138 °F (45-59 °C) at 1 to 2 inches (2.5-5 cm) below the soil surface. Large woody fuel consumption was minimal and likely a reason for the low soil temperatures produced. Researchers described the fires as "high intensity, low duration". At the time of the fire, mineral soils and duff were moist, resulting in minimal duff consumption. Soil temperatures and penetration depths were measured through thermologgers and tiles with temperature-sensitive paint [126].
A discussion on the use of prescribed fire to regenerate pines in southern habitats is provided by Van Lear and Waldrop [165]. Considerations of wildlife needs and management goals are included.
Soil/mycorrhizae: Soil nutrients were measured periodically for up to 5 years after felling and burning in mixed oak-pine stands in the Nantahala National Forest. For study results, see Knoepp and others [77]. Changes in ectomycorrhizal diversity and soil nutrient availability following prescribed fires in pitch pine-mixed oak communities in southern New Jersey are presented by Tuininga and Dighton [162]. For information on fire's effect on soils within mixed oak-pitch pine forests of the New Jersey Pine Barrens, see Burns [21].Pitch pine occupies a wide variety of harsh sites that include dry sand plains, rocky ridges, and swamps [13,44].
Climate: A humid climate prevails throughout pitch pine's range. Annual precipitation averages between 37 to 56 inches (940-1,420 mm) and is well distributed throughout the year. The frost-free season typically lasts 112 to 190 days. Low temperatures can reach -40 °F (-40 °C) in the northern part of pitch pine's range, and highs of 100 °F (40 °C) occur in the southern range [99]. Pitch pine is considered tolerant of cold, drought, and salt spray, and while persistent in a variety of climates, humid climates with well-distributed rainfall are preferred [86]. Some report that pitch pine is susceptible to sea spray damage and may be restricted from extreme coastal locations [59].
Seventy-five years of records show that pitch pine habitats in the southern Piedmont average 47 inches (1,200 mm) of evenly distributed precipitation/year and a frost-free period of 196 days [27]. New Jersey Pine Barrens average 45 to 50 inches (1,100-1,300 mm) of evenly distributed precipitation/year. Growing seasons are long, winters are mild, and summers are hot in the Pine Barrens [101].
At the Pitch Pine Ecological Preserve of Haut-Saint-Lauret, near pitch pine's northernmost extent, January temperatures average 14 °F (-10 °C), and July temperatures average 69.4 °F (20.8 °C). Average annual precipitation is 38 inches (975 mm)/year. Precipitation is delivered throughout the year, with slight increases in the summer. The number of frost-free days averages 159. Pitch pine occupies a wide range of edaphic conditions on the Preserve, and after an in-depth study of the area, researchers concluded that it is not climate but a lack of suitable habitat that restricts pitch pine's distribution in the area [110].
Cold tolerance: Pitch pine needles are tolerant of very cold temperatures, and cold tolerance increases as climates become cooler. One-year-old pitch pine seedlings grown from seed collected in the northern half of pitch pine's range had an average stem and needle tissue cold tolerance of 21.7 °F (-5.7 °C) in October and -25.1 °F (-31.7 °C) in January. Stems were less cold-tolerant than secondary needles in midwinter [6]. Needles collected from trees in Acadia National Park were tolerant to at least -85 °F (-65 °C). Freezing tests on entire 1-season-old pitch pine seedlings revealed no needle damage after exposure to -48 °F (-55 °C) [57].
Drought tolerance: Drought conditions are tolerated by pitch pine, but insect outbreaks coupled with very dry conditions may produce mortality. Researchers observed no pitch pine mortality in an oak-pine forest during drought conditions from 1984 to 1991 in the Coweeta Basin watershed. The drought was severe both in terms of duration and accumulated precipitation deficit, which was 24% to 31% below normal precipitation from 1985 to 1988. Measurements in 1985 and in 1991 revealed no change in pitch pine density, and basal area increased from 1985 to 1991 [41]. Smith [150] observed pitch pine mortality in the Coweeta Basin during this time in a southern pine beetle outbreak area.
Flood tolerance: Experimental studies found that young pitch pine seedlings are better able to survive root flooding than older seedlings and saplings and that "flood hardening" can occur. Researchers compared the growth and survival of 3-month-old seedlings, 15-month-old seedlings, and 5-year-old saplings in flooded conditions. Seedlings exposed to flooding in their first growing season were more flood tolerant than those not exposed to flooding. Mortality was 3 times more likely in nonexposed than flood-exposed seedlings. Nonexposed seedlings experienced at least 50% mortality after 10 weeks of root flooding, while flood-exposed seedlings experienced 50% mortality after 16 weeks of root flooding. Flooded seedlings developed expanded lenticels along the stems and produced roots near and above the soil surface [30].
Elevation: Pitch pine occupies habitats from sea level to over 5,600 feet (1,700 m) throughout its range. Generally, higher-elevation habitats are occupied in the southern than northern part of pitch pine's range [39,45,97]. In the Adirondack Uplands, pitch pine occurs between 100 and 1,040 feet (30-317 m) [78].
Soils: Soils in pitch pine habitats are often dry, thin, infertile, and sandy or gravelly in texture [99]; however, soils from rapidly draining to swampy are tolerated [87]. Sopodosol, Alfisol, Entisol, and Utisol soil orders are common in pitch pine habitats [99]. Pitch pine occupies limestone and sandstone soils in the Adirondack Uplands [78] and "poor" soils along the Atlantic Coast from Delaware to Maine [38]. In the Harvard Forest of north-central Massachusetts, cluster analyses orient pitch pine at the "nutrient-impoverished" end of the fertility gradient [173]. In the Black and Craggy mountains of North Carolina, pitch pine occurs in xeric pine forests on southern slopes with low-nutrient soils having pH levels of 3.4 to 4.5 [106]. In xeric rock outcrops in the Shawangunk Mountains, pitch pine trees occur on soils that range from 3 to 14 inches (8-35 cm) deep [1].
Soils in New Jersey's pine barrens and plains may contain high levels of aluminum (>500 ppm possible). These levels do not, however, affect pitch pine seedling growth or the relative distributions of dwarf and tree-size pitch pine [2]. Soils in the pine barrens are acidic with leached A2 horizons, and pitch pine occupies sites with excessively drained, imperfectly drained, very poorly drained, and mucky swamp soils [87]. In the Pitch Pine Ecological Preserve of Haut-Saint-Lauret, pitch pine occurs on thin (≤8 inches (20 cm) of organic or mineral deposits), dry, acidic (pH <4) soils overlaying bedrock [109] but is also the most abundant species in bogs [110].
Burned soils: For information on the effect of fire on soils within the oak-pitch pine forests in the New Jersey Pine Barrens, see Burns [21]. Changes in soil nutrients were measured periodically for up to 5 years after felling and burning in mixed oak-pine (pitch pine dominant) in the Nantahala National Forest in western North Carolina. For results, see Knoepp and others [77].
Pitch pine provides habitat and food for many wildlife species. Trees are used as cover, nesting, and foraging habitat. Deer browse seedlings and new sprouts, and small mammals and birds consume seeds.
Deer: Deer browse pitch pine seedlings and young pitch pine spouts. On Fire Island, where white-tailed deer populations doubled over a 5-year-period, pitch pine needles were "fairly common" in summer diets [122]. On upland sites in the New Jersey Pine Barrens, young pitch pine is important winter deer browse [100]. In a 1937 study by Little (cited in [100]), pitch pine was browsed most in an area of New Jersey where pitch pine, Virginia pine, and shortleaf pine grew together. Sixty-five percent of pitch pine seedlings or new sprouts were browsed.
Small mammals: Squirrels commonly feed on pitch pine seeds. In the Barrens Grouse Habitat management Study Area in central Pennsylvania, 512 red squirrel feeding sites were located. Feeding sites contained small piles of pitch pine cone fragments, but no intact cached cones were found. Primary feeding sites tended to be near pitch pine trees with cones [179]. Additional information on squirrel predation of pitch pine seed is presented in Seed predation.
Birds: Numerous bird species utilize pitch pine habitats for roosting, nesting, mating, and foraging. Eastern towhees feed on pitch pine seeds. In the plains of the New Jersey Pine Barrens, the researcher observed eastern towhee feeding on pitch pine seeds released from serotinous cones and taking seed from opened cones. Within 1 week of a wildfire, there were almost no pitch pine seeds on the soil surface [17].
Pine warblers "favor" pitch pine forests with tall trees. Pine warbler populations in Massachusetts have declined since the 1940s and 1950s due to forest succession to oak in the absence of fire [34]. Wild turkeys in the Nathaniel Mountain Refuge of West Virginia utilized Virginia pine and pitch pine thickets on southern aspects as winter roosting habitat [54]. The red-cockaded woodpecker also uses pitch pine and pitch pine habitats. Red-cockaded woodpecker cavities have been found in pitch pine. Good foraging habitats for the woodpecker are southern pine or pine-hardwood stands with pine trees ≥9 inches (20 cm) DBH. Pure hardwood stands "are of little value" [69]. Pitch pine provided 13% of the red-cockaded woodpecker cavity trees found in the London, Somerset, and Stearns ranger districts of the Daniel Boone National Forest. Average DBH of the 6 pitch pine cavity trees was 15.7 inches (39.9 cm) [75].
In the Barrens Grouse Habitat management Study Area, downy woodpeckers and black-capped chickadees occurred more in pitch pine in the winter than expected based on availability of pitch pine habitats. Winter avifauna foraged in the rough pitch pine bark. In the spring, great-crested flycatchers, blue jays, black-capped chickadees, black-and-white warblers, Nashville warblers, and chestnut-sided warblers were observed in pitch pine more than expected [180]. In the Lebanon State Forest, eastern towhees and Carolina chickadees foraged less in oaks than in pines as the breeding season progressed from May to July. Pine warblers foraged mainly in pitch pine, and used oak trees less than expected based on foliage density from May to July in both oak- or pitch pine-dominated forests [16]. In southeastern Massachusetts pine barrens with an open pitch pine canopy and a dense bear oak understory, eastern towhees, common yellowthroats, and prairie warblers made up 40% to 70% of the total breeding bird density within the study area. Prairie warblers foraged more often in pitch pine than common yellowthroats. When foraging above ground, eastern towhees preferred pitch pine and deciduous trees. Widely spaced pitch pine were important male prairie warbler song posts [115].
In pitch pine-scrub oak habitats southeastern Plymouth County, Massachusetts, researchers found that the majority of rare and declining bird species within a 72,731-acre (29,433 ha) study area were positively associated with early seral, open-canopy habitats. However, the majority of the study area was dominated by late-seral, closed-canopy habitats. Rare bird species hotspots made up just 2% of the total study area, suggesting active Habitat management may be necessary for the area's declining bird species [56].
Snakes: Pinesnakes utilized pitch pine habitats near the Toms River in Ocean County, New Jersey. Female pinesnakes were often located near pitch pine. For located males, 73% of the time the nearest vegetation was blueberry (Vaccinium spp.) or pitch pine. Males were found under logs or bark more often than females [19].
Insects: Diverse tiger beetles, plant hoppers, moths, and butterflies occur in pitch pine habitats. In bear oak, blackjack oak, and pitch pine pygmy forests of New Jersey's Burlington and Ocean counties, pitfall trapping of 2 tiger beetles (Cicindelidae unipuncata and Megacephala virginica) was more successful than expected, suggesting these species are more common than previously realized [10]. Five species of plant hoppers were collected from pitch pine-bear oak barrens from New Jersey. The planthoppers were considered characteristic of northeastern pitch pine-bear oak communities [172].
Many moths and butterflies that utilize pitch pine habitats are of conservation concern. The endangered Karner blue butterfly is common in the pitch pine barrens of the Albany Pine Bush. In southern New England and southeastern New York, 56 Lepidoptera species of conservation concern are associated with pitch pine-bear oak barrens, ridgetop pitch pine-scrub oak barrens, scrub oak shrublands, heathlands, and maritime shrublands. Pitch pine-scrub oak communities and heathlands are the most important habitats for approximately 41% of state-listed rare and/or endangered Lepidoptera in Massachusetts and 23% of those listed in Connecticut. An additional 11 rare Lepidoptera species feed on pitch pine and are restricted to or reach their greatest abundance in pitch pine-scrub oak barrens in southern New England and southeastern New York. The sandy substrates in pitch pine-scrub oak communities are important nesting and/or foraging habitat for many arthropods. The greatest threats to these habitats are destruction and fragmentation, especially in New York, Connecticut, Massachusetts, and New Hampshire, where pitch pine-scrub oak vegetation has decreased "substantially" from historic extents. The lack of fire that maintains early seral communities is another threat [168].
In pitch pine-scrub oak habitats southeastern Plymouth County, Massachusetts, researchers found that the majority of rare and declining bird species within a 72,731-acre (29,433 ha) study area were positively associated with early seral, open-canopy habitats. However, the majority of the study area was dominated by late-seral, closed-canopy habitats. Rare moth species hotspots made up just 3% of the total study area, suggesting active Habitat management may be necessary for the area's declining moth species [56].
Nutritional value: The nutrient concentrations in 1-year-old pitch pine leaves collected for 18 months in the Brookhaven Forest, New York, are provided by Woodwell [178]. Pitch pine leaves had much lower nutrient concentrations than associated vegetation in oak-pine forests. A database compiled by Pardo and others [127] also provides nutrient values for pitch pine. Values are from data presented in northeastern US publications and can be sorted by stand age, sample period, and/or region.
Cover value: Information on use of pitch pine as cover has been integrated into Importance to Livestock and Wildlife.
Pitch pine is often dominant in pine barrens vegetation in the northeastern
United States. On extremely harsh sites it may represent a climax vegetation
type [1], but most often pitch pine forests are early seral and are replaced by
oaks (Quercus spp.) and other hardwoods in the absence of fire
[25,96,171]. In the Appalachian region, pitch pine is common on ridges with Virginia pine (Pinus virginiana)
and Table Mountain pine (P. pungens) [22,106]. Pitch pine is a
dominant species in the following vegetation types and communities.
General/eastern United States:
pitch pine forests, cover type 45 recognized by the Society of American
Foresters [97]
northern pine barrens on the Atlantic Coast Plain north of Delaware Bay [24]
pitch pine and pitch pine-oak communities in central New Jersey, central Long
Island, near Albany in upstate New York, and on Cape Cod, Massachusetts [58]
oak-pine forests dominated by scarlet oak (Q. coccinea), chestnut oak
(Q. prinus), pitch pine, Virginia pine, and Table Mountain pine in the Blue
Ridge Province from Pennsylvania to northern Georgia [154]
pitch pine-oak forests throughout New England, but best
represented on Cape Cod and Martha's Vineyard, Massachusetts [171]
mixed deciduous forests of pitch pine, red maple (Acer rubrum), gray
birch (Betula populifolia), and quaking aspen (P. tremuloides)
open-canopy pitch pine forests
pitch pine/heath communities
pitch pine/bear oak (Q. ilicifolia) communities in Waterboro Barrens [28]
pitch pine vegetation associations on Mt Desert Island off the southern coast;
may contain red pine (Pinus resinosa) and/or eastern white pine (P.
strobus) in the canopy; understory dominants are common juniper (Juniperus communis)
in open stands and black huckleberry (Gaylussacia baccata) in closed
stands [114]
pitch pine/kinnikinnick (Arctostaphylos uva-ursi)
pitch pine/wavy hairgrass (Deschampsia flexuosa)
pitch pine-black oak/yellow sedge (Q. velutina/Carex pennsylvanica)
pitch pine/bear oak/broom crowberry (Corema conradii)
pitch pine-white oak (Q. alba)-black oak/black huckleberry
pitch pine/bear oak-northern bayberry (Myrica pennsylvanica) on Cape Cod National Seashore [40]
pine plains communities or plains vegetation in the Pine Barrens are described by several
authors; plains communities are dominated by pitch pine
trees <10 feet (3 m) tall and by shrubby bear and blackjack oak (Q. marilandica) [55,101,104]
communities dominated by the same species as the plains but with more open
canopies and taller vegetation are called transition communities by Lutz [101], pygmy forests by
Olsson [124]
barrens communities support pitch pine trees >25 feet (7.6 m) tall [101]
pitch pine-post oak (Q. stellata) forests [105]
pitch pine-black oak forests in the Pine Barrens [105]
pitch pine-bear oak communities
pitch pine-swamp doghobble (Eubotrys racemosa) in the Pine Barrens [124]
pitch pine lowlands forest; canopy dominated by 15- to 20-foot (4.6-6.1 m)-tall
pitch pine
pitch pine-oak (black oak, blackjack oak, post oak)
oak-pitch pine (black oak, chestnut oak, white oak and/or scarlet oak) in the
Pine Barrens [104]
mesic pitch pine-bear oak forest types
dry pitch pine lowland forest types
wet pitch pine lowland forest types
pitch pine-red maple swamps in the Pine Barrens [181]
pitch pine-bear oak communities in High Point State Park [120]
pine barrens; nearly pure pitch pine with scattered white and
scarlet oak and a dense bear oak shrub layer
pine plains; tall shrub communities dominated by dwarf pitch pine and bear oak on Long Island [125]
closed-canopy pitch pine forests; few shrubs and a well-developed herbaceous
layer
open-canopy pitch pine forests; stunted trees and an extensive bear oak or
ericaceous (Ericaceae) shrub understory
dwarf-pitch pine communities; dense 7- to 10-foot (2-3 m)-tall pitch pine in canopy, black huckleberry and
Blue Ridge blueberry (Vaccinium pallidum) dominate the understory in the Hudson Valley [146]
scarlet oak-pitch pine forests on low southern slopes
pitch pine-scarlet oak forests on
upper southern slopes of the Thompson Gorge in the southeastern Blue Ridge
Mountains [118]
xeric pine forests; dominated by pitch and Table Mountain pine in Black and Craggy
mountains [106]
pine-oak/heath (Ericaceae) vegetation types in the Wine Spring Creek watershed of the Nantahala
National Forest; scarlet oak, chestnut oak, and pitch pine dominate
the canopy and mountain-laurel (Kalmia latifolia) the understory [107]
Carolina hemlock (Tsuga caroliniana) bluff communities scattered throughout
the Blue Ridge Mountains and in the upper Piedmont
low elevation rocky summit communities, rare in the Piedmont and the Blue
Ridge Mountains
ultramafic outcrop barren communities, scattered in the Piedmont and the Blue Ridge
Mountains [141]
yellow pine (Virginia pine and pitch pine, with eastern white pine) forest types
scarlet oak-yellow pine (Table Mountain and pitch pine) forest types in
western Great Smoky Mountains National Park [22]
shortleaf pine-pitch pine forests
chestnut oak-pine (pitch and Virginia pine) forests
pine forests dominated by pitch and shortleaf pine with an open heath layer on Pine
Mountain [12]
yellow pine (Virginia pine and pitch pine, with eastern white pine) forest types
scarlet oak-yellow pine (Table Mountain and pitch pine) forest types in western Great Smoky Mountains
National Park [22]
A review of the ethnobotanical uses of pitch pine indicates that the Iroquois, Shinnecock, and Cherokee all utilized pitch pine. The Iroquois used the pitch to treat rheumatism, burns, cuts, and boils. Pitch also worked as a laxative. A pitch pine poultice was used by both the Iroquois and the Shinnecock to open boils and to treat abscesses. The Cherokee used pitch pine wood in canoe construction and for decorative carvings [111].
Wood Products: Pitch pine wood is coarse grained and resinous [44]; it has been noted as an excellent source of turpentine [23].
Pitch pine has numerous fire adaptations that allow it to establish and/or regenerate on burned sites. Postfire pitch pine regeneration may be through bole and crown sprouting from epicormic sprouts protected by thick bark, basal sprouting from the root crown, which is protected by crooks and/or soil, and/or through establishment from seed in nonserotinous or opened serotinous cones [93]. As damage from fire increases, the predominant form of postfire regeneration changes from bole and crown sprouting to basal sprouting to seedling establishment [94].
© Tom Palmer, Friends of the Blue Hills. Photos taken 10 weeks after a late April fire
Pitch pine reproduces sexually and asexually. Sexual regeneration occurs through seed from serotinous and nonserotinous cones. Asexual reproduction occurs through basal and epicormic sprouting [93].
Pollination: Pitch pine cones are wind pollinated [86].
Breeding system: Pitch pine trees are monoecious. Outcrossing is most common, and severe inbreeding depression can occur with selfing [86].
Seed production: Farrar [44] reports that "good" crops of pitch pine cones are produced every 4 to 9 years. Seed predation can be high and affect seed survival and success. Pitch pine trees as young as 3 years old may produce cones. Researchers observed seed cones on trees less than 3 feet (1 m) tall in Maine's Acadia National Park [57].
In 1996 and 1997, pitch pine in Acadia National Park averaged 60 full-sized seeds/cone, and the range was 12 to 84 full-sized seeds/cone. The average number of viable seeds/fertile scale was 0.4. Researchers reported that the theoretical maximum number of viable seeds/fertile scale was 2.0, assuming no disease, predation, fertilization problems, or abortion [57].
Seed predation: Squirrels, eastern towhees, and likely other wildlife feed on pitch pine seeds. High levels of seed predation and rapid seed removal can occur. Studies in Acadia National Park revealed 85% cone survival in 1996 and a decrease by 6 times in 1997, due largely to squirrel predation [57]. Helm and others [68] noted that squirrel predation can affect collections of pitch pine cones from coastal locations in Massachusetts, New York, and/or New Jersey. Eastern towhees fed on pitch pine seed released from serotinous cones and picked seeds from opened cones 1 year following a wildfire in the New Jersey Pine Barrens. Within 1 week of burning, there were almost no pitch pine seeds on the soil surface [17].
© Tom Palmer, Friends of the Blue Hills. Photo taken 38 days after an early May fire.
Serotinous cones were rare except from populations on or near the Coastal Plain when cones were collected throughout the pitch pine range (Quebec south to Georgia and west to Kentucky and central Ohio). Cones came from 509 trees in 79 stands. In the plains area of the New Jersey Pine Barrens, serotinous cone production was nearly 100%. Away from the Coastal Plain, just 9 trees produced serotinous cones. Six of these trees were in Clinton County, Pennsylvania, and regenerated after an "extremely" severe fire. Researchers concluded that serotinous cone production was advantageous on sites that burned severely and frequently but disadvantageous on sites that did not experience frequent, severe fires. They suggested that the distribution pattern of serotinous cone producing populations was dictated by the combined effects of fire occurrence, fire severity, and gene flow through pollen and seed dispersal [85].
Givnish [52] studied pitch pine in the New Jersey Pine Barrens and suggested that fire history was more important than gene flow in determining serotinous cone production at a scale beyond a few kilometers. Within the plains, serotiny averaged 98.8% in upland sites and 84% in lowland sites. Generally, serotinous cone production decreased with increasing distance from the plains; however, sites 2 to 12 miles (3-19 km) to the northeast, southeast, and west of plains averaged 90% to 98% serotinous cone production. These sites were downwind and in the likely direction of fire advancement from the center of the plains [52].
Some studies suggest that levels of serotinous cone production may decrease on sites burned less frequently or less severely than in the past. In the Central Pine Barrens of Long Island, New York, serotiny levels were about 90% on undisturbed dwarf pine plains but decreased to around 50% in cleared areas where taller, single-stemmed pitch pines were establishing. Researchers suggested that the lack of fire to open serotinous cones led to the invasion and successful establishment of seeds from surrounding pitch pine woodlands (unpublished data reported in [74]).
Seed dispersal: Studies of pitch pine seed dispersal were lacking as of the writing of this review (2007). However, several studies indicate that seeds from nearby stands can be important to the regeneration of burned stands when on-site seeds are consumed [7] or when there is a lack of fire to open serotinous cones [74]. Wildlife likely aid in the dispersal of pitch pine seed [17,57,68]. In a review, Fowells [47] reports that although pitch pine seed is winged, wind does not disperse seed long distances.
Seed banking: High levels of seed predation [17,57,68] suggest that the pitch pine seed bank is not long lived.
Germination: Based on field studies, pitch pine seed germination is best on exposed mineral soil sites that are protected from predation. In the barrens of central Pennsylvania, overall germination was better when seeds were covered with litter and protected from predation. Seedlings on unprotected sites rarely survived 2 growing seasons. Poor germination occurred on unmanipulated seed beds in aspen (Populus spp.), scrub oak (bear and chestnut oak), and grass (poverty oatgrass (Danthonia spicata) and bluestem (Andropogon spp.)) communities [11]. Studies conducted in Orono, Maine, revealed that pitch pine germination decreased in seed beds with low moisture-holding capacities under relatively high temperatures [33,57].
In controlled experiments, pitch pine germination was best at 77 °F (25 °C), and final germination percentages decreased with decreasing soil moisture [103]. Pitch pine cones collected from coastal locations in Massachusetts, New York, and New Jersey averaged 45.5 germinants/cone when grown under controlled conditions [68]. Seeds in serotinous cones are protected from high temperatures. For more on this, see Cone survival and seedling establishment.
Temperature, pH, light levels: Controlled experiments were conducted on pitch pine seed collected from fall-harvested cones from the barrens of Centre County, Pennsylvania. The optimum germination temperature was 77 °F (25 °C). At 77 °F (25 °C), the germination percentage averaged 82.7% and ranged from 52% to 100% for 24 replicates. No seeds germinated at 40 °F (5 °C) or 50 °F (10 °C) after 60 days, and germination averaged just 16% at 59 °F (15 °C). As soil moisture of Hagerstown silt loams decreased, germination was delayed and final germination percentages were significantly reduced (F=1%). Pitch pine seeds germinated better in dark than light conditions. At pH levels of 4.5 to 8.3 there were no significant (F=1%) differences in germination percentages [103].
Seedling establishment/growth: A combination of field and controlled studies suggests that pitch pine seedling establishment is most successful on thick mineral soils with high light levels. However, on rapidly draining soils decreased light levels may improve seedling establishment and/or growth [33,57].
Pitch pine seedlings grow slowly. One-year-old seedlings may reach maximum heights of only 0.4 inch (1 cm) on moist sites and 0.2 inch (0.5 cm) on dry sites. Growth rates increase substantially once seedlings reach a foot (0.3 m) tall. Under favorable conditions, growth rates may reach 2 feet (0.6 m)/year [93].
Sun and substrate effects: Field studies in Acadia National Park showed that pitch pine seedlings and saplings occurred in depressions where soil depth averaged 4.1 inches (10.5 cm) and duff layer thickness averaged 0.6 inch (1.5 cm). Researchers evaluated the conditions where 100 young pitch pine trees (1-13 years old) covered almost 1 acre (0.6 ha). Researchers concluded that thick mineral soil is favorable to pitch pine establishment [57].
Pitch pine seedlings grown from seed collected in Acadia National Park were monitored under controlled conditions. Seedling dry mass production was best in peat substrates exposed to full sun. Seedlings grown in sand exposed to full sun accumulated the least mass, and seedlings in sand or peat under low light (60% interception) conditions grew better than seedlings in sand and full sun. Temperatures were 7 to 9 °F (4-5 °C) cooler under shade cloth, and dry mass was evaluated after the first year of growth [33,57].
Seed origin effects: Site conditions affected seedling growth more than seed origin in a reciprocal transplant study of dwarf and normal-stature pitch pine seed collected from populations on Long Island. Regardless of seed origin, seedlings at the dwarf population site grew more slowly, experienced more mortality, and developed multiple stems more often than seedlings at the normal-stature site. However, there were differences with respect to seed origin and site related to reproductive age. Seedlings grown from seed collected in the dwarf population reproduced earlier than those from normal-stature sites, but dwarf-population seedlings reproduced earliest at normal-stature sites. Researchers concluded that plastic phenotypic environmental responses affected growth and survival more than genetic differences [42]. In a provenance study, pitch pine trees grown from seed collected from the southern part of the Atlantic Coast Plain grew larger than those from the seed collected from the northern Atlantic Coast Plain [80].
Growth: Pitch pine growth can be affected by tree age, site conditions, and/or climate. Ledig and Fryer [86] reported that the pitch pine growth rate decreases at an "early" age. In southeastern New York, growth of pitch pine trees from 40 to 314 years old on the ridges of the Ramapo and Shawangunk mountains was monitored. For all sites, the average radial growth rate was 1.09 mm/year. Trees less than 51 years old had higher growth rates than trees over 99 years old. Growth rates ranged from a high of 2 to 3 mm/year in young trees during "favorable" years to a low of 0.25 mm/year in older trees during drought conditions [147]. The growth of pitch pine on Mt Everett in the Taconic Mountains was very slow. The radial growth rate for the area averaged 0.47 mm/year, and some trees grew as slowly as 0.08 mm/year [117].
Pitch pine trees in North Carolina's Thompson Gorge grew most in the spring and fall. The average range of increases in circumference was 0.133 to 0.535 inch/year and averaged 0.24 inch/year for 11 sites monitored for 3 years [118]. Pitch pine tree-ring growth was significantly correlated (P<0.05, r=0.53) with annual precipitation and temperature in a dry rock outcrop in the Shawangunk Mountains. Drought conditions produced decreased growth. Over the last 120 years in the area, pitch pine tree-ring growth was slow and averaged 0.33 mm/year [1].
On Nantucket Island, the growth of young, 3- to 8-year-old pitch pines was better within clumps of northern bayberry. Average annual growth rates of 20 young (3-8 years) and 20 older (11-25 years) pitch pine trees growing within and outside of clumps of northern bayberry were compared. In both age classes pitch pine grew more within northern bayberry clumps, but growth differences were only significant (P=0.01) for young pitch pines [160].
Vegetative regeneration: Pitch pine regenerates vegetatively through basal sprouting and epicormic branching [44,86], and layering may occur [38]. On Long Island's Napeague Beach, low pitch pine branches buried by sand grew roots, and plants spread [38]. However, on Mt Everett, prostrate-growing pitch pine did not reproduce by layering, but epicormic branching and basal sprouting occurred [117].
Sprouting from dormant basal buds in crooks and stools: Buds that give rise to basal or root crown sprouts form in the axils of primary needles just above the seedling cotyledons. Basal buds produce stem tissue, and sprouts are not adventitious. Buds are closely spaced, appearing clustered or whorled. Buds may occur under ground because of soil movement or litter accumulation and may form small clusters of fascicled needles. Sprouts arising from basal buds also form basal buds. Strong lateral branches can form from these buds even in the absence of stem injury [157].
Basal buds are protected by thick bark and/or basal crooks. Crooks form as seedling stems bend and grow horizontally before turning upright. Open-grown seedlings may form a crook at the root crown in the first year of growth. Shade-grown seedlings may not form well-developed crooks until 3 to 9 years old. In a stand of "spindly" pitch pine trees suppressed by bear oak growth, approximately 50% had poorly developed crooks, which researchers suspected would be susceptible to fire. After a prescribed fire burned pitch pine seedlings (<0.5 inch (1.3 cm) diameter), only seedlings with well-developed crooks had over 55% postfire sprouting. Researchers observed basal sprout production in pitch pine trees as old as 79 years. In New Jersey's West Plains region, sprouts came from stools that were 40 to 83 years old. The lifespan of dormant buds and stubby basal branches is estimated at 40 to 55 years. Older stools may produce many more sprouts than seedling crooks. In the plains region, as many as 249 one-year-old sprouts were produced by a single stool. Researchers suggested that stool age may affect sprout growth, and that dwarf pitch pines result from very slow-growing sprouts from old stools [91]. In southern New Jersey, the largest trees producing basal sprouts were 8 inches (20 cm) in diameter [134].
The theory that old stools produce slow-growing pitch pine sprouts was substantiated in a study in the Pine Plains of New Jersey, where researchers attempted to release stems through removal of competing vegetation with fire or herbicides. Dominant stems in the plains were about 11 feet tall (3.4 m) and 27 years old. Stems were produced when stools were 40 to 60 years old. Release attempts did not encourage the production of vigorous stems likely to reach tree size. Researchers concluded that the many-decade-old plains stools were only capable of producing slow-growing, scrubby sprouts, and that the only way to convert the Pine Plains to tree-sized pitch pine forests was through seedling establishment [92]. When pitch pine seedlings were planted in dwarf pitch pine-dominated areas of southern New Jersey, planted seedlings reached the height of 50-year-old plains sprouts in 17 years, suggesting that sprouts from stools grew more slowly than seedlings [98].
The number and height of sprouts from cut pitch pine trees near Mt Misery in Burlington County, New Jersey, generally increased with tree age until trees reached 34 years of age. A total of 25 pitch pine trees, thought to be of seed origin, were cut and monitored for 2 years. Sprout number and height generally increased with tree age but gradually decreased in trees over 34 years old. A 95-year-old pitch pine produced 59 sprouts within 2 months of cutting, but the entire tree died within 2 years of cutting. Average and maximum sprout heights were greatest in 4- to 11-year-old trees. Two trees, 30 and 32 years old, produced 303 and 330 sprouts 2 months after cutting, but no sprouts survived due, in part, to severe sprout browsing [2].
Epicormic or stem sprouting: Stem sprouts come from buds at the internodes of multinodal stems. These latent buds may be hidden under the bark or may develop into short branches with isolated or few fascicles (see photo above). Severe injury such as fire can trigger prolific, profuse dormant bud growth along the stem [158]. For more on epicormic sprouting after fire, see Crown or bole sprouting.
Sprout vs. seedling growth: Pitch pine's predominant regeneration strategy may depend on site conditions, stem origin, and/or disturbance regimes. Vegetative regeneration was rare in the Pitch Pine Ecological Preserve of Haut-Saint-Lauret, Quebec. Regeneration was abundant and continuous since the last fire in 1957, but was not through vegetative means. Researchers suggested that pitch pine may be a physiographic climax type in the outcrop habitats [110]. For more on pitch pine sprout and seed production after fire, see Sprouting and seedling establishment.
Commonly pitch pine is an early seral species that is replaced by hardwoods in the absence of fires that expose mineral soil and allow light to the reach the forest floor. However, in some very harsh habitats, pitch pine may represent a climax forest species. Clements [25] characterized pitch pine-dominated forests as fire subclimaxes. In New England and upstate New York, for example, pitch pine is considered a subclimax species that is maintained through fire [96,171]. On Mt Desert Island, the pitch pine vegetation association is a pioneer type that in the absence of disturbance is eventually replaced by red and/or white spruce (Picea rubens, P. glauca) [114]. Ledig and Fryer [86] indicate that successional replacement of pitch pine communities is rapid when fire is excluded.
In xeric rock outcrops in the Shawangunk Mountains, pitch pine forests were characterized as a "physiographic climax" following a study of stand age, tree growth rates, and climate data. Pitch pine trees as old as 320 years occurred in the area. While small amounts of black tupelo (Nyssa sylvatica) and chestnut oak were present, site conditions were thought too severe for these trees to dominate. Researchers noted a lack of pitch pine recruitment since the 1970s, but noted that pitch pine turnover likely occurred through tree-by-tree replacement [1]. In the Pitch Pine Ecological Preserve of Haut-Saint-Lauret, pitch pine may be a physiographic climax type in the outcrop habitats [110].
Shade: Pitch pine is generally considered shade intolerant [44]. Results of a 1950s questionnaire showed that 35% of foresters surveyed rated pitch pine as intermediate in shade tolerance, 45% rated it as intolerant, and 20% rated it very shade intolerant [4].
Old field succession: Invasion by pitch pine occurs early after the abandonment of agricultural or pasture lands. Hotchkiss and Stewart [71] considered pitch pine a "pioneer" tree after studying secondary succession in abandoned fields in what is now the Patuxent Research Refuge in Maryland. In the southwestern Piedmont of Virginia, dendrochronological studies indicate that the oldest pitch pine in the area established in 1904. Fields were abandoned in the early 1900s. At time of study (2002), pitch pine was successionally "over mature" and no longer dominant due to increases in scarlet and chestnut oak [27].
On Martha's Vineyard, eastern redcedar (Juniperus virginiana) is often the first tree to establish after field abandonment. Pitch pine seedlings typically appear 15 to 40 years after field abandonment. Once pitch pine trees reach 50 to 100 years old, oak prominence increases. Sassafras (Sassafras albidum), beech (Fagus spp.), sweetgum (Liquidambar styraciflua), and pignut hickory (Carya glabra) appear when oaks are 125 to 300 years old [123].
The rapidity of old field invasions on the Burlington-Colchester-Essex sand plains of Vermont was associated with seed tree distance. In fields abandoned for about 10 years, pitch pine density was 1 tree/25 m² when the nearest seed tree was 890 feet (270 m) away. When the nearest seed tree distance was 560 feet (170 m), pitch pine density was 3 trees/25 m². When the nearest seed tree distance was 250 feet (75 m), pitch pine density was 7 trees/25 m². Pitch pine density decreased to about 1 tree/25 m² after fields had been abandoned for about 60 years. The researcher noted that pitch pine appeared to pave the way for the establishment of eastern white pine, which commonly occurs beneath the shade of pitch pine [72].
Pitch pine dominance decreased as old field succession progressed in southern New Jersey. Researchers monitored succession for 18 years in a shortleaf pine-pitch pine stand that established on an old field, abandoned in 1932, in what is now the Green Bank State Forest. In 1953, when the study was initiated, there were few hardwoods over 0.55 inch (1.4 cm) DBH. Periodic winter burning (March 1954, 1957, and 1962) was conducted on some sites. By 1971, hardwood densities increased greatly while the number of pines decreased greatly, regardless of winter burning. Researchers suggested that this successional pattern is natural for areas that support an oak-hickory climax [95].
Forest succession: In most cases, pitch pine is an early seral species that is replaced by hardwoods, spruces, or other pines in the absence of severe disturbance. In the Southeast, pitch pine is a temporary type that is replaced by hardwoods or shortleaf pine on mesic and xeric sites, respectively. The deep shortleaf pine taproot is able to penetrate rock crevices beneath shallow mountain soils, so shortleaf pine has better stability than pitch pine, which produces shallower roots [169].
On Mt Everett, pitch pine is a dominant species but its replacement or continued dominance of the harsh sites is unclear. Pitch pine recruitment has been continuous since the 1860s, although surveys of the area suggested no "significant" fires burned in the 20th century. Researchers suggest that winter storms, harsh climatic conditions, poor soils, high winds, droughts, and slow growth rates may maintain pitch pine's dominance. However, the importance of red maple and oaks increased over the 20th century, and these species grow faster than pitch pine, suggesting a possible hardwood conversion [117].
Insect outbreaks: Southern pine beetles can act as a successional agent in pitch pine forests. "Overmature" and/or stressed pitch pine trees are preferred by southern pine beetles, which often contribute to the turnover of forests to pine and hardwood seedlings and saplings [81]. In pitch pine-dominated pine-oak forests in the Coweeta Basin, a drought-induced southern pine beetle attack accelerated the loss of pitch pine and succession to mixed oak-hardwood stands. Pitch pine regeneration was lacking in the study plots, but there was some regeneration in disturbed sites (roadsides, areas of fallen trees) outside of the study area. Pitch pine was lost at a rate of up to 10 ha/year when southern pine beetle populations reached epidemic proportions. The researcher noted that without fire, southern pine beetle outbreaks may accelerate the conversion of pitch pine-dominated forests to mixed oak-hardwood woodlands [150].
Fire: Pitch pine is well adapted to postfire regeneration through asexual and sexual means. Most of the information regarding pitch pine regeneration and succession following fire is provided in Fire Effects.
The scientific name of pitch pine is Pinus rigida P. Mill. (Pinaceae) [43,45,76,135,159].
Pitch pine belongs to the hard pine or Diploxylon subgenus [133].
Hybridization:
Pitch pine hybridizes naturally with shortleaf pine (P. echinata)
[45], pond pine (P. serotina), and loblolly pine (P. taeda) [89,145] where
distributions overlap.
Pitch pine has survived planting on and/or naturally colonized coal mines, anthracite mines, and landfill sites.
Coal mines: On coal mine spoils in Pennsylvania, pitch pine survival was 36% ten years after planting. The researcher noted pitch pine's usefulness in the revegetation of dry sites with acidic soils [166]. Plantings were more successful than seedings on areas strip mined for coal in Ohio. Pitch pine survival ranged from 82% to 95% on 1- to 8-year-old plantings. When pitch pine was seeded, germination rates ranged from 4% to 22%, and first-year survival was 22% to 60% [88].
On black waste from anthracite mining in Pennsylvania, natural colonization by pitch pine was variable. Pitch pine was confined to steep north slopes with sparse abundance, although there was a nearby seed source [144].
Landfill: On the closed Fresh Kills Landfill on Staten Island, New York, surviving planted pitch pines averaged 4.86 feet (1.48 m) tall after 1 to 1.5 years [138].
