Pitch Pine – Scrub Oak Woodland

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System: Terrestrial
Subsystem: Shrubland
PA Ecological Group(s): Central Appalachian – Northeast Pine – Oak Rocky Woodland

Global Rank:G4 rank interpretation
State Rank: S2S3

General Description

This community type occurs on dry, sandy, acidic soils. It is usually found on rocky ridges and summits of low to moderate elevations. This community may occur on ridgetop acidic barrens sites, associated with other acidic barrens communities. Trees are drought-stressed and of small stature. Pitch pine (Pinus rigida) is usually the dominant tree, contributing between 25% and 75% relative cover, although in southern Pennsylvania, Virginia pine (P. virginiana), and table-mountain pine (P. pungens) may accompany or replace pitch pine. Eastern white pine (P. strobus) may also occur but is not common. Hardwoods may be present but do not contribute more than 25% of the tree layer. Hardwood associates include blackgum (Nyssa sylvatica), sassafras (Sassafras albidum), sweet birch (Betula lenta), chestnut oak (Quercus montana), scarlet oak (Q. coccinea), black oak (Q. velutina), gray birch (B. populifolia), and red maple (Acer rubrum). Scrub oak (Q. ilicifolia) often forms a dense understory. Other shrub species, which may be locally abundant include low shrubs like low sweet blueberry (Vaccinium angustifolium), lowbush blueberry (V. pallidum), sweet-fern (Comptonia peregrina), and black huckleberry (Gaylussacia baccata), or may have an additional layer of taller shrubs like mountain laurel (Kalmia latifolia), and highbush blueberry (V. corymbosum). Herbaceous species include bracken fern (Pteridium aquilinum), common hair-grass (Deschampsia flexuosa), poverty grass (Danthonia spicata), little bluestem (Schizachyrium scoparium), ricegrass (Oryzopsis asperifolia), three-awn (Aristida dichotoma), trailing arbutus (Epigaea repens), teaberry (Gaultheria procumbens), cow-wheat (Melampyrum lineare), Pennsylvania sedge (Carex pensylvanica) and/or other sedges (C. communis, C. lucorum), pink lady’s slipper (Cypripedium acaule), and wild sarsaparilla (Aralia nudicaulis). Reindeer lichens (Cladonia spp. and Cladina spp.) are abundant in some areas. This community may occur as part of the Ridgetop Acidic Barren Complex.

Rank Justification

Imperiled in the jurisdiction because of rarity due to very restricted range, very few populations, steep declines, or other factors making it very vulnerable to extirpation. This community type is relatively uncommon, typically occurs in small- to medium-sized patches, and is vulnerable to loss due to succession without active management. It is also fire-dependent, and in decline due to widespread fire suppression over much of the last century.

Identification

  • Shrub layer includes a strong component of scrub oak (Quercus ilicifolia)
  • Total tree canopy is between 10% and 60%
  • Pitch pine forms 25%-75% of the tree canopy; combined hardwood cover is less than 25%
  • Dry, acidic, sandy soil; often on ridges or summits with exposed bedrock

* limited to sites with higher soil calcium
Vascular plant nomenclature follows Rhoads and Block (2007). Bryophyte nomenclature follows Crum and Anderson (1981).

International Vegetation Classification Associations:

USNVC Crosswalk:

None

Representative Community Types:

Pitch Pine Rocky Summit (CEGL006116)

NatureServe Ecological Systems:

None

NatureServe Group Level:

Central Appalachian - Northeast Pine - Oak Rocky Woodland (G906)

Origin of Concept

Fike, J. 1999. Terrestrial and palustrine plant communities of Pennsylvania. Pennsylvania Natural Diversity Inventory. Pennsylvania Department of Conservation and Recreation, Bureau of Forestry, Harrisburg, PA. 86 pp.

Gawler, S. C. 2017. Pitch Pine Rocky Summit (CEGL006116). NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. (Accessed: January 6, 2022).

Pennsylvania Community Code*

JP : Pitch Pine – Scrub Oak Woodland

*(DCNR 1999, Stone 2006)

Similar Ecological Communities

The Pitch Pine – Scrub Oak Woodland may occur alongside others in the Ridgetop Acidic Barrens Complex. The barrens types represent a group of communities with open-canopies found on high elevation ridgetops and summits (350m – 670m), where low soil moisture, shallow soils, high wind velocities, frequent fires, and usually a history of cutting have limited tree growth.

The Pitch Pine – Scrub Oak Woodland is most similar to the Dry Oak Heath Woodland. They differ in the cover of pitch pine or other conifers; the Dry Oak – Rocky Woodland has less than 25% cover of pitch pine or other conifers.

The tree and shrub species composition may be similar to the Pitch Pine – Mixed Oak Forest, however, forest types have a greater than 60% total tree canopy cover, while woodlands are less than 60%. The Low Heath Shrubland also has a similar species composition, but will have less than 10% tree canopy cover.

The Pitch Pine – Mixed Hardwood Woodland was previously recognized and has been combined with the Pitch Pine – Scrub Oak Woodland.

This community often co-occurs with several other types in the Ridgetop Acidic Barrens Complex:

  • Dry Oak – Rocky Woodland 
  •     
  • Red Spruce Rocky Summit (rare; confined to high elevations) 
  •    
  • Scrub Oak Shrubland 
  •    
  • Low Heath Bedrock Outcrop (confined to high elevation)  
  • Little Bluestem – Pennsylvania Sedge Opening  
  • Pitch Pine – Heath Woodland  
  • Pitch Pine – Scrub Oak Woodland

The communities that create the Ridgetop Acidic Barrens Complex form a mosaic that are related by successional stage. The herbaceous types occur more sporadically throughout shrubland, woodland, and forest types based on time since fire, clearcutting, or other disturbance. The arrangement of different types within a site, and the pace of succession, is also determined by differences in environmental variables such as aspect, soil depth, elevation, exposure, and microclimate. In general, the physiognomy becomes more open at higher elevations and on southern exposures. Where fires are frequent, pitch pine will typically be present. In the absence of fire, other pines (white pine, Virginia pine, shortleaf pine, or Table Mountain pine) may accompany or replace pitch pine, or pine may be absent altogether. Frost pockets may play a role in maintaining open areas; this is especially true of the Little Bluestem – Pennsylvania Sedge Opening type. Long-term fire suppression may cause the distinctive vegetation of the herbaceous openings to give way to more mesic species typical of the surrounding forests at lower elevations.  

The forest types that most typically surround these communities are the Dry Oak – Heath Forest and Pitch Pine – Mixed Oak Forest.

Fike Crosswalk

Pitch Pine – Scrub Oak Woodland and Pitch Pine – Mixed Hardwood Woodland (no longer recognized)

Conservation Value

Acidic barrens communities can host a number of rare plant species and an exceptional diversity of rare butterflies, moths, and other insects. Barrens communities can arise as a result of a variety of human-induced and natural disturbances; many have their origin in the 19th or 20th century, while others have persisted longer through a combination of periodic human-induced disturbance dating to pre-settlement times and edaphic factors (Copenheaver et al., 2000; Kurczewski, 1999; Latham, 2003; Motzkin & Foster, 2002). Latham (2003) suggests that the diversity and presence of rare plant species in barrens is correlated with the overall age of the barrens, with newer barrens less likely to host rare plants. Animal diversity appears to be less sensitive to age; perhaps because many of these species are highly mobile. Both plant and lepidopteran species can be sensitive to successional stage and time since disturbance; some require very open, grassy areas, while others can also inhabit shrublands and woodlands with partial shade. The species of conservation value are not necessarily indicator species for the community type, and may also occupy other types of habitathabitats, but barrens sites are one of the habitats importantof particular impotance for their conservation. Species of great conservation value that are associated with barrens include many species of Lepidoptera (moths and butterflies) which have barrens plants as hosts, plants that can withstand the acidic, thin soils, and vertebrate species who thrive with hot, dry conditions. Examples of invertebrates that can be found in barrens include waxed sallow moth (Chaetaglaea cerata; G3G4/S2S3), twilight moth (Lycia rachelae; G5/S2?), and flypoison borer moth (Papaipema sp. 1; G2G3/S2S3). The timber rattlesnake (Crotalus horridus; G4/S2S3) and eastern hognose snake (Heterodon platirhinos; G5/S3S4) can utilize barrens. A few plant species that are associated with barrens include variable sedge (Carex polymorpha; G3/S2), dwarf iris (Iris verna; G5/S1), and sand blackberry (Rubus cuneifolius; G5/S1).

Threats

The primary threats to acidic barrens communities are succession and fire suppression. Many of the unique species that inhabit these barrens are most successful in the early stages of succession, such as grasslands and open shrublands, and are therefore particularly vulnerable to the effects of succession over the long-term. Pitch pine are known to not germinate and establish well without fire. Spongy moth (Lymantria dispar) outbreaks also threaten barrens, which often have a strong component of oak species in the tree and shrub layers. However, spongy moth control agents can also threaten the unique butterfly and moth species that inhabit barrens.

Studies across a number of sites in New England and Pennsylvania demonstrate that many barrens are disturbance-dependent ecosystems that, in the absence of disturbance, move through succession to forest rapidly (Copenheaver et al., 2000; Kurczewski, 1999; Latham, 2003; Motzkin & Foster, 2002). These studies have observed similar patterns of barrens succession to forest, sometimes even mesic forest, in recent decades.

Changes in land use and fire suppression over the last century are at the root of these patterns of succession. Through meticulous efforts to identify historic land use and changes in vegetation over time, researchers have documented that barrens are correlated with areas that burned frequently, primarily from Native American use of fire. Fires occurred primarily during the dormant season, presumably in the

fall and early spring (Stambaugh et al. 2018). Wildfires caused by later anthropogenic activity, such as railroads, would have also contributed to the maintenance of barrens vegetation. The cessation of these land use practices, and the advent of widespread, long-term fire suppression, is correlated with succession of grasslands and open shrublands to dense shrub thickets and forests. Charcoal production retards vegetation such that former heaths resemble barrens, but it appears the mechanism is a more profound and persistent alteration of soil chemistry.

The Pitch Pine – Heath Woodland is also threatened by the southern pine beetle (Dendroctonus frontalis). The southern pine beetle is a native beetle of the southeastern United States that feeds primarily on pines such as pitch, shortleaf, Virginia, and white. Outbreaks occur every 6-12 years and can last for 2-3 years. The southern pine beetle feeds on phloem in the inner bark, which ultimately girdles and kills the tree (Liu, n.d.). Additionally, the southern pine beetle has experienced an unprecedented northward expansion in recent years due to mild winters and climate models predict the range to expand to almost the entirety of Pennsylvania (aside from much of the Northern Allegheny Plateau) by 2050, and north into Canada by 2080 (Lesk et al., 2017). The southern pine beetle does not currently overlap with the native range of this community type, however it is considered a serious long-term threat. This community type may also be impacted by the spotted lanternfly (Lycorma delicatula). The spotted lanternfly is newly established in Pennsylvania and has been found to lay eggs and feed on a number of common hardwood trees, vines, and shrubs in Pennsylvania (Barringer & Ciafré, 2020). This invasive pest may weaken hardwood associate trees in this type but may only represent a small threat since hardwood trees are not dominant. However, the black sooty mold which proliferates on honeydew produced by spotted lanternfly may pose a severe threat to native flora under/around mass-feeding sites.

Other threats include loss of this community due to development of cell phone towers, wind turbines, and utility lines, or trampling by visitors on ATVs.

Management

It is important to develop a site-wide management plan at acidic barrens to maintain multiple successional stages. Appropriately applied prescribed fireis the optimal tool for barrens management. Where it is not feasible to use fire as a management tool, a combination of cutting and soil scarification can be used to mimic its effects.

Plans should also consider specific needs of barrens indicator species and rare species. To avoid severe reduction of lepidopteran populations, prescribed burning should not be undertaken across an entire site at once. In a given year, unburned areas should be left as refugia for these species.

Spongy moth control programs should balance maintenance of oaks and lepidopterans, using control agents specific to the spongy moth where possible, or leaving some untreated areas as refugia for native lepidopteran populations.

Research Needs

The USNVC recognizes two associations dominated by pitch pine and various oak and hardwood species for Pennsylvania: an association in the Mid-Atlantic north to New England (CEGL006116) and a South-Central Appalachian regional association documented as occurring in Pennsylvania and West Virginia (CEGL006557). The environmental settings are similar in both cases. In the New England type, species with more southerly ranges such as black oak, scarlet oak, and blackgum may be absent, while species with more northern affiliations such as Canada mayflower, star-flower, sheep laurel, myrtle-leaf blueberry, red spruce, and Rhodora may be present. It is uncertain at this time whether these types are significantly distinct within Pennsylvania; however, PNHP data corroborate observations of PNHP ecologists who do not observe two distinct associations. Furthermore, outside of Pennsylvania, the Central Appalachian type is only documented from a few plots in New River Gorge, West Virginia, where the fit of the type is not ideal; it is possible these two associations should be combined within the NVC as well. More plot data should be collected to better characterize this type in the regions it occurs within the state, and to determine whether the regional split currently adopted by NatureServe (separating New England vs. Central Appalachian examples of this type) is valid within the state.

Site-specific research into historical land management, fire frequency, and vegetation patterns has greatly enhanced understanding of barrens systems at other locations in the northeastern region, but very few Pennsylvania sites have been studied. The origins and timeline of many of our barrens sites in Pennsylvania remains unknown.

There is a need to adapt and/or develop management techniques specialized to this region and its species of concern. In some areas, barrens have completely succeeded to forest. Research should focus on identifying specifically where shrub and herbaceous barrens once existed, identifying characteristics of optimal restoration sites, and identifying successful management techniques for restoring the herbaceous and shrub component of barrens mosaics.

Trends

Barrens ecosystems have declined due to succession and fire suppression in recent decades. Rare species that are particularly dependent on open barrens habitats have also declined across Pennsylvania.

Range Map

range map

Pennsylvania Range

The Pitch Pine – Scrub Oak Woodland is found in the following USEPA Level III (Level IV) Ecoregions: Northern Allegheny Plateau (60), North Central Appalachians (62), Blue Ridge (66), Ridge and Valley (67) and Central Appalachians (69).

Global Distribution

Connecticut, Massachusetts, Maryland, Maine, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island

Barringer, L., & Ciafré, C. M. (2020). Worldwide feeding host plants of spotted lanternfly, with significant additions from North America. Environmental Entomology, 49(5), 999-1011.

Copenheaver, C. A., White, A. S., & William A. Patterson III. (2000). Vegetation Development in a Southern Maine Pitch Pine-Scrub Oak Barren. Journal of the Torrey Botanical Society, 127(1), 19-32.

Illick, J. S., and Aughanbaugh, J. E. 1930. Pitch pine in Pennsylvania. Pa. Dept. Forests and Waters Res. Bul. 2.

Kurczewski, F. E. (1999). Historic and Prehistoric Changes in the Rome, New York Pine Barrens. Northeastern Naturalist, 6(4), 327-340.

Latham, R. E. (2003). Shrubland longevity and rare plant species in the northeastern United States. Forest Ecology and Management, 185(1-2), 21-39. https://doi.org/10.1016/S0378-1127(03)00244-5

Lesk, C., Coffel, E., D'Amato, A. W., Dodds, K., & Horton, R. (2017). Threats to North American forests from southern pine beetle with warming winters. Nature Climate Change, 7, 713-717. https://doi.org/10.1038/nclimate3375

Liu, H. (n.d.). Southern Pine Beetle: Forest Insects& Diseases Fact Sheet. Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry, Division of Forest Health.

Motzkin, G., & Foster, D. R. (2002). Grasslands, heathlands and shrublands in coastal New England: Historical interpretations and approaches to conservation. Journal of Biogeography, 29(10-11), 1569-1590.

Ordnorff, S., & Patten, T. (Eds.). (2007). Management Guidelines for Barrens Communities in Pennsylvania (p. 208). The Nature Conservancy.

Schweitzer, D.F. & Rawinski, T.J. (1987) Northeastern pitch pine ⁄ scrub oak barrens. Eastern heritage task force. The Nature Conservancy, Boston, MA.

Cite as:
Braund, J., E. Zimmerman, A. Hnatkovich, and J. McPherson. 2022. Pennsylvania Natural Heritage Program. Pitch Pine – Scrub Oak Woodland Factsheet. Available from: https://www.naturalheritage.state.pa.us/Community.aspx?=16096 Date Accessed: May 19, 2024

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