1994 Proceedings
North American Conference on Savannas and Barrens

The term "barrens" has had a long tradition of usage in American scientific literature, from Bartram (1766), Riddell (1835), and Engelmann (1863) to the present, but in recent years the trend has been to utilize other terms in its place; e.g., savanna. Reasons expressed for this are that "barrens" is too vague, that it is only a vernacular term for poor farmland, or that it lacks aesthetic appeal. Contrary to these claims, the literature reveals a remarkable consistency of usage and clarity of application by field botanists, ecologists, and other students of the natural landscape. The features most discussed are edaphic drought and soil infertility, and vegetation that is commonly a mosaic of scattered and stunted woody growth, herbaceous heliophytes and xerophytes, and exposed substrate. Many barrens are pyric, and support species adapted to both fire and droughty, infertile conditions. Barrens occur in areas climatically suitable for forest growth of large trees; consequently, barrens commonly possess regionally unique vegetation. Barrens types outside of the eastern United States and Canada; e.g., Canadian polar barrens (Bliss, Svoboda, and Bliss 1985), gravel barrens in Japan (Matsuo 1989), and Cuban serpentine barrens (Beurton 1986) are not discussed here.

Application of the term falls into three general categories: 1) as a habitat type for organisms; 2) as a vegetation type; and 3) as a natural community type.

Barrens As A Habitat Type

Barrens is a term used as a habitat type for certain species, particularly those that are more or less confined or modal to the type, including many endemics or near-endemics (Curtis 1959; Anderson 1971; Fairbrothers 1979; Keener 1983). Floristic manuals, ranging from wildflower guides to regional floras, reflect this usage. Many of the species listed are xerophytes and/or heliophytes, distinctive to barrens environments. A compilation of examples is given not only to show that the term is used (Table 1), but to illustrate the similar descriptors; e.g., dry, sandy, and open. The barrens term is also used as a habitat type for certain animals (Anderson 1971; Kerlinger and Doremus 1981; Wheeler 1988).

Barrens As A Vegetation Type

Many examples exist where barrens is used to identify a vegetation type. These include pine barrens, oak barrens, heath barrens, and barrens as predominantly grasslands. The most famous of these is the New Jersey Pine Barrens, an area of pitch pine (Pinus rigida), shortleaf pine (Pinus echinata), blackjack oak (Quercus marilandica), post oak (Quercus stellata) scrub oak (Quercus illicifolia), and various others (McCormick 1979). A pitch pine-scrub oak barrens has also been described for New York (Reschke 1990). Jack pine (Pinus banksiana) barrens are noted for Wisconsin (Curtis 1959; Vogl 1970) and New York (Stergas and Adams 1989; Reschke 1990). A notable barrens type in the southeastern coastal plain is the longleaf pine barrens. Although known by several names; e.g., longleaf pine - turkey oak sandhills, sandhill pine forest, xerophytic coniferous forest, etc., some authors have named the community pine barrens (Bartram 1766; Harper 1910, 1911; Fernald 1937; Frost and Musselman 1987). There is a close association of longleaf pine (Pinus palustris) with turkey oak (Quercus laevis) on these barrens, and in places turkey oak or other oak species may dominate. In these situations, names used include turkey oak barrens (Barry 1980; Myers 1990), scrub oak barrens (Barry 1980; Duncan and Duncan 1988), and sandhill woodland-barrens (Bridges and Orzell 1989). Oaks are also important in barrens community names outside of the southeast; e.g., oak barrens in Wisconsin (Curtis 1959), post oak barrens in Indiana (Aldrich and Homoya 1984; Dolan and Menges 1989), and (pitch pine)-scrub oak barrens in New York (Reschke 1990). In areas where rock is near the surface, communities termed cedar barrens are present (Gattinger 1901; McVaugh 1943; Carr 1944; Braun 1950; Cranfill 1991). Andropogon dominated barrens, such as occur in Tennessee and Kentucky, are referred to without a modifier; i.e., barrens (DeSelm 1993). Heath barrens, dominated by shrubby members of the Ericaceae, are reported by Hall and Aalders (1968), and Strang (1972), and Reschke (1990).

Barrens As A Natural Community Type

Instead of emphasizing the dominant vegetation, natural community classification commonly emphasizes non-biotic features. These names are especially useful, as they denote a major causative factor of the unique environment; e.g., edaphic conditions, such as sand. Two of the most well known and studied are serpentine barrens and shale barrens. Most of the serpentine barrens occur in Pennsylvania and Maryland (Pennell 1929; Wherry 1963; Tyndall and Farr 1990), but are also known from New York (Reschke 1990) and North Carolina (Mansberg and Wentworth 1984). Shale barrens are concentrated in the mid-Appalachian region, and are known for their many endemics or near-endemics (Allard 1946; Platt 1951; Core 1952; Keener 1983). Sand barrens are described for Minnesota (MacMillan 1899), Wisconsin (Curtis 1959), Pennsylvania (Wherry 1963) and Indiana (Homoya in press). Chert barrens have been reported for Missouri (Palmer 1910) and Indiana (Homoya in press). Barrens where the substrate is predominantly limestone have been described for West Virginia (Bartgis 1993), Indiana (Homoya in press), Virginia (Collins and Wieboldt 1992), Tennessee (Collins and Wieboldt 1992, DeSelm 1993), and Mississippi (Morris, Bryson and Warren 1993). Other references to bedrock barrens include sandstone (Reschke 1990, Homoya in press), granite (Winterringer and Vestal 1956), dolomite (Erikson, Brenner and Wraight 1942) and siltstone (Homoya in press).

A sample of barrens descriptions is given to illustrate the common theme of dryness, infertility, fire adaptability, and a vegetation mosaic of patchy woody growth with distinctive flora and fauna (Table 2).

SUMMARY

A review of the literature reveals a consistent suite of characteristics that distinguish barrens environments. These characteristics emphasize xeric and infertile edaphic conditions, a distinctive biota, and vegetation consisting of many xerophytes and heliophytes in a physiognomy that is commonly patchy, occurring as a mosaic of herbs, bare substrate, and stunted, gnarled trees and shrubs.

The term barrens has had a long history of use, and is well documented in scientific literature. It describes a real, relatively stable community type and should not be considered simply an edge, or a transitional phase between forest and prairie. Certainly not every landscape previously identified as barrens will meet the criteria listed above to distinguish barrens, but most examples generally do. Indeed, a broader application of the term may be appropriate, to include many areas identified as glade, scrub, scrub forest, xeric forest, sand prairie, sand savanna, and flatrock, among others. These terms are not necessarily being proposed for removal from usage, but rather to have them recognized as part of the barrens ecosystem concept. The term "barrens" was, and is, a good one, and should be maintained.

ACKNOWLEDGMENTS

The author wishes to thank Roger Hedge, Barbara Homoya, and Max Hutchison for their review comments. Gratitude is also expressed to John Bacone and Cloyce Hedge of the Division of Nature Preserves for support of this project.

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Table 1. Species and habitat descriptions as found in various botanical works, floras and plant field guides for the eastern United States.

• Eragrostis trichodes varpilifera--Sandybarrens (Fernald 1950)
• Calamovilfa longifolia--jack pines and sand barrens (Voss 1972).
• Polygala incarnata--Dry soil, upland woods, barrens (Gleason 1952).
• Celtis tenuifolia--Rocky hills and barrens (Gleason and Cronquist 1991).
• Comptonia peregrina--sand flats and barrens (Swink and Wilhelm 1979).
• Opuntia humifusa--In dry soils, mostly on shale barrens (Strausbaugh and Core 1970).
• Helianthemum canadense--Woodland borders, pine barrens (Radford, Ahles, and Bell 1968).
• Tephrosia virginiana--Open pinelands,...sand barrens (Isley 1990)
• Echinacea pallida var. angustifolia--cedar barrens (Cronquist 1980).
• Ascyrum hypericoides--pine barrens on sand hills and ridges (Godfrey and Wooten 1981).
• Quercus chapmanii--Sandy barrens and scrub (Duncan and Duncan 1988).
• Stylosanthes biflora--Dry soil, thin woods and barrens (Duncan and Foote 1975).
• Carex muhlenbergii--Dry open sand barrens (Fassett 1976).
• Trifolium reflexum--Prairies, barrens (Mitchell and Sheviak 1981).
• Artemesia glauca--rocky open barrens (Steyermark 1963).
• Aristida stricta--dry sandy ridges in the pine barrens (Chapman 1872).
• Quercus illicifolia--acid sandy or rocky soil, especially in pine-barrens (Small 1933).
• Hypericum denticulatum--Pine barrens, sandy soil (Peterson and McKenny 1968).
• Astragalus tennesseensis--Openings in cedar barrens (Barneby 1964).

Table 2.  Descriptions of barrens.

• "steep, south-facing slope...treeless openings of shale-flake talus" (Morse 1983).
• "land underlain by sand or gravel, from the upper levels of which mineral constituents other than silica have been leached...deficiency of mineral nutrients...markedly dry" (Wherry 1963).
• "acid, infertile, and droughty" (DeSelm 1990).
• "Soils are shallow, sandy and acidic" (Cranfill 1991).
• "severe soil moisture depletion" (Keith 1981).
• "unfavorable to plant growth" (Winterringer and Vestal 1956).
• "sparse cover with much intervening barren ground, dwarfing and xerophytism, and an enriched flora which is almost always unique for the region and which contains a number of endemics, ecotypes, morphological variants, and range disjunctions" (Mansberg and Wentworth 1984).
• "sandy or shallow soil with frequent fire, high acidity and scarce nutrients, and abundant heaths and crooked pines" (Forman 1979).
• "The predominantly sandy soils,...and not climate, determine the distinctive characteristics of pine barrens vegetation" (Whittaker 1979).
• "open canopy, small stature of vegetation, and exposed patches of sand (Frost and Musselman 1987).
• "(high temperature and evaporation)...low surface water supply...lack of available nutrients...severe and exacting environment" (Curtis 1959).
• "sparse cover with intervening bare ground, xerophytism, and a distinct flora" (Bridges and Orzell 1989).
• "high insolation temperatures and low moisture conditions at the surface" (Keener 1983).
• "sparsely wooded slope...outcrops of naked underlying rock" (Allard 1946).
• "thin soil over chalk,...some scrubby hardwoods" (Morris, Bryson, and Warren 1993).
• "The barrens are sufficiently different...to encourage local abundance of some species rarely encountered elsewhere in the area" (Anderson 1971).
• "rocky heathlands...closely correlated with topographic position and depth of soil over the impenetrable pan" (Strang 1972).
• "well-drained, infertile,...adapted to periodic fires" (Reschke 1990).