A calcareous glade is a type of ecological

community A community is a social unit (a group of people) with a shared socially-significant characteristic, such as place, set of norms, culture, religion, values, customs, or identity. Communities may share a sense of place situated in a given g ...

that is found in the central

Eastern United States The Eastern United States, often abbreviated as simply the East, is a macroregion of the United States located to the east of the Mississippi River. It includes 17–26 states and Washington, D.C., the national capital. As of 2011, the Eastern ...

Calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

glades occur where

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...

such as

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

occurs near or at the surface, and have very shallow and little

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

development. Due to the shallow soil and the extreme conditions created by it,

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s are often unable to grow in the glades. This creates a

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

that is usually sunny, dry, and hot. Calcareous glade

vegetation Vegetation is an assemblage of plants and the ground cover they provide. It is a general term, without specific reference to particular Taxon, taxa, life forms, structure, Spatial ecology, spatial extent, or any other specific Botany, botanic ...

is more similar to that of a

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

habitat than a grassland, being dominated by small spring annuals with occasional geophytic or

succulent In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...

perennials In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

. The usage of the words "glades" and "barrens" to describe dry, rocky communities in the United States is not uniform, and the terms are often used interchangeably. Calcareous glade communities can intergrade with dry rocky prairies, particularly in sloping habitats. Due to their unsuitability for agriculture, glade communities have survived to the present day at a higher rate than deeper-soil prairie communities.

Interior Low Plateau glades

The Interior Low Plateau is a region in the

Upper South The Upland South and Upper South are two overlapping cultural and geographic subregions in the inland part of the Southern United States. They differ from the Deep South and Atlantic coastal plain by terrain, history, economics, demographics, ...

that is known for its calcareous glade communities. This region is centered in

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

and

Kentucky Kentucky (, ), officially the Commonwealth of Kentucky, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the ...

, and extends into northern

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

, and southern

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...

, southern

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

, and southern

Ohio Ohio ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Erie to the north, Pennsylvania to the east, West Virginia to the southeast, Kentucky to the southwest, Indiana to the ...

. These glades are best developed in the area of the Central Basin (or Nashville Basin) in Tennessee, where they are geographically widespread and harbor high levels of endemism. Outside of the Central Basin, calcareous glades are found in lower numbers throughout the Interior Low Plateau, and species

endemism Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

is greatly reduced. Glades in the Interior Low Plateaus are characterized by species such as one-flower gladecress ('' Leavenworthia uniflora''), limestone skullcap ('' Scutellaria parvula''), widow's-cross stonecrop ('' Sedum pulchellum''), poverty dropseed ('' Sporobolus vaginiflorus'') and glade violet ('' Viola egglestonii'').

Central Basin cedar glades

The limestone glades of the Central Basin in Tennessee are often called "cedar glades". The name comes from the abundance of eastern red cedar (''

Juniperus virginiana ''Juniperus virginiana'', also known as eastern redcedar, red cedar, Virginian juniper, eastern juniper, red juniper, and other local names, is a species of juniper native to eastern North America from southeastern Canada to the Gulf of Mexico an ...

'') that occurs on the margins of the glades or in cracks in the bedrock where the roots can gain a foothold. Many of the characteristic plants that grow in the limestone glades of the Central Basin are endemics that occur nowhere else, or disjunct populations of plants that are widespread in the prairies of the central U.S. Some species with highly restricted ranges that occur in the glades of the Central Basin include the Tennessee coneflower ('' Echinacea tennesseensis''), Pyne's ground plum ('' Astragalus bibullatus''), leafy prairie clover ('' Dalea foliosa''), Tennessee milkvetch ('' Astragalus tennesseensis''), Nashville breadroot ('' Pediomelum subacaule''), and limestone fameflower ('' Phemeranthus calcaricus''). These glades can be saturated with water in the winter and spring, leading to "xerohydric" (dry/wet alternating) conditions.

Threats to the cedar glades

The central basin (or Nashville Basin) of Tennessee is one of the largest areas containing limestone glades. Because of the rapid growth of metropolitan

Nashville Nashville, often known as Music City, is the capital and List of municipalities in Tennessee, most populous city in the U.S. state of Tennessee. It is the county seat, seat of Davidson County, Tennessee, Davidson County in Middle Tennessee, locat ...

and the surrounding cities of Murfreesboro and

Lebanon Lebanon, officially the Republic of Lebanon, is a country in the Levant region of West Asia. Situated at the crossroads of the Mediterranean Basin and the Arabian Peninsula, it is bordered by Syria to the north and east, Israel to the south ...

, many of the limestone glades have been destroyed by development. The State of Tennessee and the Nature Conservancy have established a number of parks and preserves to protect important plant populations. Cedars of Lebanon State Park in Wilson County and Long Hunter State Park in Davidson County both protect substantial limestone glade ecosystems.

Limestone slope glades

The limestone slope glades of

are a globally vulnerable habitat consisting of limestone glades found on hillsides, which are wet in the spring but become very dry in the rest of the year. This provides habitat for unique species such as necklace glade cress, Butler's quillwort, and Crawe's sedge.

Endemic plant species

This is a list of calcareous glade-adapted plant species considered endemic to the Interior Low Plateau region. Some are found in only a single county of a single state. * '' Astragalus bibullatus'' * '' Astragalus tennesseensis'' * '' Castilleja kraliana'' (Cahaba paintbrush) * '' Clinopodium glabellum'' * '' Dalea cahaba'' * '' Dalea foliosa'' * '' Dalea gattingeri'' * '' Delphinium alabamicum'' * '' Echinacea tennesseensis'' * '' Eleocharis bifida'' (Cedar glade spike rush) * '' Erigeron dolomiticola'' (Cahaba daisy fleabane) * '' Hypericum dolabriforme'' (Glade St. John's wort) * '' Leavenworthia uniflora'' * '' Lithospermum decipiens'' (Deceptive marbleseed) * '' Lobelia gattingeri'' (Gattinger's lobelia) * '' Marshallia mohrii'' (Coosa Barbara's-buttons) * '' Pediomelum subacaule'' * '' Penstemon tenuiflorus'' (Limestone beardtongue) * '' Phemeranthus calcaricus'' (Limestone fameflower) * '' Physaria filiformis'' * '' Rudbeckia grandiflora'' (Largeflower coneflower) * '' Silphium glutinosum'' (Sticky rosinweed) * '' Sisyrinchium calciphilum'' (Glade blue-eyed grass) * '' Spigelia alabamensis'' (Alabama pinkroot) * '' Symphyotrichum kentuckiense'' (Miss Price's aster)

Ozark Mountains glades

Calcareous glades are well developed in the

Ozark Mountains The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, and Oklahoma, as well as a small area in the southeastern corner of Kansas. The Ozarks cover ...

. In

Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...

, the majority of these glades are found on dolomitic limestones, with less than 1% formed from calcitic limestone. Species indicative of Ozarkian calcareous glade communities include '' Cheilanthes feei'' (slender lip fern), '' Echinacea simulata'' (pale purple coneflower), '' Heliotropium tenellum'' (pasture heliotrope), ''

Isoetes butleri ''Isoetes butleri'', commonly known as limestone quillwort, is a species of plant in the quillwort family, a member of the lycophyte The lycophytes, when broadly circumscribed, are a group of vascular plants that include the clubmosses. Th ...

'' (limestone quillwort), '' Oenothera macrocarpa'' (Missouri evening primrose), and '' Ophioglossum engelmannii'' (limestone adder's-tongue). In Missouri, '' Physaria filiformis'' (Missouri bladderpod) is a species restricted to calcitic limestone glades.

Ridge and Valley glades

The

Ridge-and-Valley Appalachians The Ridge-and-Valley Appalachians, also called the Ridge and Valley Province or the Valley and Ridge Appalachians, are a physiographic province of the larger Appalachian Highlands division. The physiographic province is divided into three se ...

, which extend north from Pennsylvania south to Alabama, have significant calcareous glade communities. These glades often have dolomitic soils, resulting in a high magnesium content (in contrast to the glades of the Nashville Basin). In Virginia, these glades provide habitat for rare magnesiophiles such as Addison's leatherflower ('' Clematis addisonii''), tall larkspur ('' Delphinium exaltatum''), smooth coneflower ('' Echinacea laevigata''), and glade wild quinine ('' Parthenium auriculatum''). At the southern end of the Ridge and Valley in Alabama in Bibb County, species endemism of glade communities peaks. This area, known as a Ketona Dolomite Outcrops, was first recognized as ecologically significant in 1992. Since its discovery, eight new plant taxa to science have been described from this region, in addition to the 60 species of conservation concern found in or around this community. Revised edition of January 21, 2011 Endemic species of this area include '' Castilleja kraliana'', '' Dalea cahaba'', '' Liatris oligocephala'', '' Lithospermum decipiens'', and '' Spigelia alabamensis''.

References

{{reflist

External links

Center for Cedar Glade Studies at Middle Tennessee State University

Plant communities of the Eastern United States Habitats Plant communities of Kentucky Plant communities of Tennessee Plant communities of Alabama