BARRENS AS AN ECOLOGICAL TERM: AN OVERVIEW OF USAGE
IN THE SCIENTIFIC LITERATURE
Michael A. Homoya
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 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).
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).
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).
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.
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.
Aldrich, J. R. and M. A. Homoya. 1984. Natural barrens and post oak flatwoods in Posey and Spencer Counties, Indiana. Proceedings Indiana Acad. Science 93:291-301.
Allard, H. A. 1946. Shale barren associations on Massanutten Mountain, Virginia, Castanea 11:71-124.
Anderson, R. 1971. Butterflies of the serpentine barrens of Pennsylvania. Entomology News 82:5-12.
Barneby, R. C. 1964. Atlas of North American Astragalus. Part II. New York Botanical Garden Memoirs 13:597-1188.
Barry, J. M. 1980. Natural Vegetation of South Carolina. Univ. of South Carolina Press, Columbia.
Bartgis, R. L. 1993. The limestone glades and barrens of West Virginia. Castanea 58:69-89.
Bartram, J. 1766. Diary of a Journey Through the Carolinas, Georgia, and Florida. American Philos. Society, Philadelphia, Pennsylvania.
Beurton, C. 1986. Phyllode-producing Zanthoxylum taxa in Cuba. Feddes Repert 97:29-41.
Bliss, L. C., J. Svoboda and D. I. Bliss. 1985. Polar deserts, their plant cover and plant production in the Canadian high arctic. Holarctic Ecology 7:305-324.
Braun, E. L. 1950. Deciduous Forests of Eastern North America. Blakiston: Philadelphia, Pennsylvania.
Bridges, E. L. and S. L. Orzell. 1989. Longleaf pine communities of the West Gulf Coastal Plain. Natural Areas Journal 9:246-263.
Carr, L. G. 1944. A new species of Houstonia for the cedar barrens of Lee County, Virginia. Rhodora 46:306-310.
Chapman, A.W. 1872. Flora of the Southern United States. Ivison, Blakeman, Taylor, and Co: New York, New York.
Collins, J. L. and T. F. Wieboldt. 1992. Trifolium calcaricum, (Fabaceae), a new clover from limestone barrens of eastern United States. Castanea 57:282-286.
Core, E. L. 1952. The ranges of some plants of the Appalachian shale barrens. Castanea 17:105-116
Cranfill, R. 1991. Flora of Hardin County, Kentucky. Castanea 56:228-267.
Cronquist, A. 1980. Vascular Flora of the Southeastern United States: Volume 1. Asteraceae Univ. of North Carolina Press, Chapel Hill.
Curtis, J. T. 1959. The Vegetation of Wisconsin. Univ. of Wisconsin Press, Madison.
DeSelm, H. R. 1990. Flora and vegetation of some barrens of the eastern Highland Rim of Tennessee. Castanea 55:187-206.
Dolan, R. W. and E. S. Menges. 1989. Vegetation and environment in adjacent post oak (Quercus stellata) flatwoods and barrens in Indiana. American Midland Naturalist 122:329-338.
Duncan W. H. and M. B. Duncan. 1988. Trees of the Southeastern United States. Univ. of Georgia Press, Athens.
Engelmann, H. 1863. Remarks upon the causes producing the different characters of vegetation known as prairies, flats, and barrens in southern Illinois, with special reference to observations made in Perry and Jackson counties. American Journal of Sciences 86:384-396.
Erickson, R. O., L. G. Brenner, and J. Wraight. 1942. Dolomitic glades of east-central Missouri. Annals Missouri Botanical Garden 29: 89-101.
Fairbrothers, D. E. 1979. Endangered, threatened, and rare vascular plants of the pine barrens and their biogeography. In: R. T.Forman, ed. Pine Barrens: Ecosystem and Landscape. Academic Press, New York.
Fassett, N. C. 1976. Spring Flora of Wisconsin. University of Wisconsin Press, Madison.
Fernald, M. L. 1937. Local plants of the inner Coastal Plain of southeastern Virginia. Rhodora 39:321-366.
Forman, R. T. (ed.). 1979. Pine Barrens: Ecosystem and Landscape. Academic Press, New York, New York.
Frost C. C. and L. J. Musselman. 1987. History and Vegetation of the Blackwater Ecological Preserve. Castanea 52:16-46.
Gattinger, A. 1901. Flora of Tennessee and Philosophy of Botany. Tennessee Bureau of Agricultural Statistics and Mines, Nashville.
Gleason, H. A. 1952. The New Britton and Brown Illustrated Flora of the Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
Godfrey, R. K. and J. W. Wooten. 1981. Aquatic and Wetland Plants of Southeastern United States: Dicotyledons. Univ. of Georgia Press, Athens.
Hall, I. V. and L. E. Aalders. 1968. The botanical composition of two barrens in Nova Scotia. Natural Canada. 95:393-396.
Harper, R. M. 1910. A quantitative study of the more conspicuous vegetation of certain natural divisions of the Coastal Plain, as observed in traveling from Georgia to New York in July. Bulletin Torrey Botanical Club. 37:405-428.
Homoya, M. A. Indiana barrens: classification and description. Castanea. (in press).
Isely, D. 1990. Vascular Flora of the Southeastern United
States Volume 3. Part 2: Leguminosae (Fabaceae)
Keener, C. S. 1983. Distribution and biohistory of the Mid-Appalachian shale barrens. Botanical Review 49:65-115.
Keith, J.H. 1981. The relationship of barrens to karst landforms in Harrison Co., Indiana. In: Cave Research Foundation 1979 Annual Report. Adobe Press, Albuquerque, New Mexico.
Kerlinger, P. and C. Doremus. 1981. Habitat disturbance and the decline of dominant avian species in pine barrens of the northeastern USA. American Birds 35:16-20.
Macmillan, C. 1899. Minnesota Plant Life. Pioneer Press: St. Paul, Minnesota.
Mansberg, L. and T. R. Wentworth. 1984. Vegetation and soils of a serpentine barren n western North Carolina. Bulletin Torrey Botanical Club. 111:273-286.
Matsuo, K. 1989. Biosystematic studies on the genus Plantago: 1. Variations in Plantago japonica and its related species, with special reference to it identity. ACTA Phytotaxon Geobot 40:37-60.
McCormick, J. 1979. The vegetation of the New Jersey Pine Barrens. In: R.T. Forman, ed. Pine Barrens: Ecosystem and Landscape. Academic Press, New York, New York.
McVaugh, R. 1943. The vegetation of the granitic flatrock of the southeastern United States. Ecological Monographs 13:119-166.
Mitchell, R. S. and Sheviak, C. J. 1981. Rare Plants of New York State. New York State Museum, Albany.
Morris, M. W., C. T. Bryson, and R. C. Warren. 1993. Rare vascular plants and associate plant communities from the Sand Creek Chalk Bluffs, Oktibbeha County, Mississippi. Castanea 58: 250-259.
Morse, L. E. 1983. A shale barren on Silurian strata in Maryland. Castanea. 48:206-208.
Myers, R. L. 1990. Scrub and high pine. In: R.L. Myers and J.J. Ewel, eds. Ecosystems of Florida. Univ. of Central Florida Press, Orlando.
Palmer, E. J. 1910. Flora of the Grand Falls chert barrens. Transactions. of the Academy of Science. XIX:97-112.
Pennell, F. W. 1929. On some critical species of the serpentine barrens. Bartonia 12:1-23.
Peterson, R. T. and M. McKenny. 1968. A Field Guide to Wildflowers. Houghton Mifflin, Boston, Massachusetts.
Platt, R. G. 1951. An ecological study of the mid-Appalachian shale barrens and the plants endemic to them. Ecological Monographs. 21:269-300.
Radford, A. E., H. E. Ahles, and C. R. Bell. 1968. Manual of the Vascular Flora of the Carolinas. Univ. of North Carolina Press, Chapel Hill.
Reschke, C. 1990. Ecological Communities of New York State. New York State Department of Environmental Conservation, Latham.
Riddell, J. L. 1835. A Synopsis of the Flora of the Western States. E. Deming, Cincinnati, Ohio.
Small, J. K. 1933. Manual of the Southeastern Flora. J. Small. New York, New York.
Stergas, R. G. and K. B. Adams. 1989. Jack pine barrens in northeastern New York: Postfire macronutrient concentrations, heat content, and under-story biomass. Canadian Journal of Forest Research 19: 904-910.
Steyermark, J. A. 1963. Flora of Missouri. Iowa State University Press, Ames.
Strang, R. M. 1972. Ecology and land use of the barrens of western Nova Scotia. Canadian Journal of Forest Research 2:276-290.
Strausbaugh, P. D. and E. L. Core. 1970. Flora of West Virginia. Seneca Books, Grantsville, West Virginia.
Swink, F. and G. Wilhelm. 1979. Plants of the Chicago Region. The Morton Arboretum, Lisle, Illinois.
Tyndall, R. W. and P. M. Farr. 1990. Vegetation and flora of the Pilot Serpentine Area in Maryland. Castanea 55:259-265.
Vogl, R. J. 1970. Fire and the northern Wisconsin pine barrens. Proc. Tall Timbers Fire Ecology Conference. 10:175-209.
Voss, E. G. 1972. Michigan Flora Part I. Gymnosperms and Monocots. Cranbrook Institute of Science, Bloomfield Hills, Michigan.
Wheeler, A. G. 1988. Diabrotica cristata, a chrysomelid (Coleoptera) of relict Midwestern prairies discovered in eastern serpentine barrens. Entomological News 99:134-142.
Wherry, E. T. 1963. Some Pennsylvania barrens and their flora. Bartonia 33:7-11.
Whittaker, R. H. 1979. Vegetational relationships of the Pine Barrens. In: R. T. Forman. Pine Barrens: Ecosystem and Landscape. Academic Press: New York, New York.
Winterringer, G. S., and A. G. Vestal. 1956. Rock-ledge vegetation in southern Illinois. Ecological Monographs. 26:165-130.