Name:
Schizachyrium scoparium - Sporobolus heterolepis - Juniperus communis Alvar Grassland & Shrubland Group
Reference:
NatureServe Biotics 2019
Description:
This alvar grassland and shrubland group is found in the temperate-boreal transition of the Great Lakes basin. The group is characterized by distinctive scrub and herb flora, of eastern tallgrass prairie elements and eastern subboreal elements, with less than 10% tree cover. It is found primarily in an arc along the Niagara Escarpment from northern Lake Michigan across northern Lake Huron and eastern Ontario and northwestern New York State. The climate is humid and subhumid, and sites are centered on areas of glaciated horizontal limestone/dolomite (dolostone) bedrock pavement with a discontinuous thin soil mantle. This group can be divided into two main variants: (1) open grasslands and pavements, with shrubs <25% cover and (2) shrublands, where shrubs are >25%. These two variants are distinguished by the amount of exposed bedrock, the cover of herbaceous plants (mostly grasses and sedges), the cover of shrubs, and the cover of trees (<10% cover).<br /><br />Alvar grasslands are typically dominated by <i>Schizachyrium scoparium, Deschampsia cespitosa, Sporobolus heterolepis, Eleocharis compressa, Carex crawei, Juniperus horizontalis, Carex scirpoidea</i>, and <i>Packera paupercula</i>. Other characteristic grasses and herbs include <i>Sporobolus neglectus, Sporobolus vaginiflorus, Trichostema brachiatum</i>, and <i>Allium schoenoprasum</i>. In parts, there is a mosaic of pavement and grassland areas dominated by characteristic native species, such as <i>Sporobolus neglectus, Sporobolus vaginiflorus, Panicum philadelphicum, Poa compressa, Oligoneuron album, Danthonia spicata, Trichostema brachiatum, Packera paupercula, Carex crawei</i>, and <i>Panicum flexile</i>. In more exposed areas, there is a mosaic of mossy patches and exposed bedrock that is covered with crustose and foliose lichens.<br /><br />In shrubby areas, the dominant shrub is the short to tall shrub <i>Juniperus communis</i>, mixed with <i>Juniperus horizontalis</i> and/or <i>Dasiphora fruticosa ssp. floribunda</i>, or a mix of scrub forms of tree species such as <i>Picea glauca, Thuja occidentalis, Larix laricina, Abies balsamea</i>. Mixed among the shrubs are <i>Danthonia spicata, Oligoneuron album, Packera paupercula, Clinopodium arkansanum</i>, and <i>Tetraneuris herbacea</i>. Characteristic tall shrubs (2 to 5 m tall) include scrub forms of trees such as <i>Juniperus virginiana, Thuja occidentalis</i>, and <i>Quercus macrocarpa</i>. Alvars are maintained by associated geologic, hydrologic, and other landscape processes. In particular, most types of alvar tend to flood each spring, then experience moderate to severe drought in summer months. They include open pavement, grassland, and shrubland/woodland types. Alvar communities occur in an ecological matrix with similar bedrock and hydrologically influenced communities. Four key ecological processes influence Great Lakes alvar communities: (1) hydrology and soil moisture regime, (2) fire regime and land-use history, (3) herbivory: browsing by deer and grazing by cattle, and (4) the invasion of exotic plant species.
Accession Code:
urn:lsid:vegbank.org:commConcept:39773-{CA1FB512-3D53-4EA7-857B-97A675CEFC9F}
Plot-observations of this Community Concept:
0
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