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Brief Summary

    Danthonia compressa: Brief Summary
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    Danthonia compressa is a species of grass known by the common names mountain oatgrass, flattened oatgrass, and slender oatgrass.

Comprehensive Description

Distribution

    Distribution
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    Mountain oatgrass occurs in the eastern United States and southeastern
    Canada. It occurs from extreme southeastern Ontario east through
    southern Quebec to Nova Scotia and south through New England and the
    Appalachian Mountain region to northern Georgia. In the southeastern
    United States, mountain oatgrass is restricted to the Appalachian
    Mountains [10,12,20].
    Occurrence in North America
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    CT DE GA KY ME MD MA NH NJ NY
    NC OH PA RI SC TN VT VA WV NB
    NS ON PQ

Morphology

    Description
    provided by Fire Effects Information System Plants
    Mountain oatgrass is a native, perennial bunchgrass. The culms are
    slender, compressed, sometimes decumbent, and 12 to 32 inches (30-80 cm)
    tall. The leaves are mostly at or near the base and up to 8 to 10
    inches (20-25 cm) long. The inflorescence is a panicle; slender
    branches bear two or three spikelets. The awn is bent and 0.2 to 0.3
    inches (0.6-0.8 cm) long [4,10,12,20].
    Physical Description
    provided by USDA PLANTS text
    Perennials, Terrestrial, not aquatic, Rhizomes present, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly basal, below middle of stem, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath hairy, hispid or prickly, Leaf sheath hairy at summit, throat, or collar, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades very na rrow or filiform, less than 2 mm wide, Leaf blades 2-10 mm wide, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Leaf blades more or less hairy, Leaf blades scabrous, roughened, or wrinkled, Ligule present, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet 3-10 mm wide, Spikelets with 3-7 florets, Spikelets with 8-40 florets, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Inflorescence disarticulating between nodes or joints of rachis, rachis fragmenting, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the fl orets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes equal to or longer than adjacent lemma, Glumes 4-7 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 5-7 nerved, Lemma 8-15 nerved, Lemma body or surface hairy, Lemma apex dentate, 2-fid, Lemma distinctly awned, more than 2-3 mm, Lemma with 3 awns, Lemma awn less than 1 cm long, Lemma awned from tip, Lemma awn from sinus of bifid apex, Lemma awn twisted, spirally coiled at base, like a corkscrew, Lemma awn once geniculate, bent once, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Palea keels winged, scabrous, or ciliate, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Habitat

    Habitat characteristics
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    In the southern Appalachians, mountain oatgrass is a frequent species on
    grassy balds which occupy well-drained sites on ridges, broad slopes,
    and dome-shaped summits between 5,000 and 6,000 feet (1,500-1,800 m) in
    elevation. Grassy balds occur on slopes of all aspects but are most
    commonly found on south, southwest, and west aspects. Mountain oatgrass
    grows on dry sites but is susceptible to drought [19,26]. On wetter
    areas of grassy balds, mountain oatgrass dominance gives way to sedges
    (Carex spp.) [26].
    Habitat: Ecosystem
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    More info on this topic.

    This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

    FRES15 Oak - hickory
    Habitat: Plant Associations
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    More info on this topic.

    This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

    More info for the term: forest

    K100 Oak - hickory forest
    K104 Appalachian oak forest
    Key Plant Community Associations
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    More info for the terms: fern, forest, herbaceous

    Mountain oatgrass occurs in forest openings, open woods, and mountain
    meadows.

    Mountain oatgrass is dominant in grassy balds of the southern
    Appalachian Mountains. Other herbaceous plants occurring in grassy
    balds include redtop (Agrostis alba), timothy (Phleum pratense), Canada
    bluegrass (Poa compressa), Kentucky bluegrass (P. pratense), red fescue
    (Festuca rubra), five-fingers (Potentilla canadensis), and sheep sorrel
    (Rumex acetosella) [4,18,26,27]

    On the Allegheny Plateau in Pennsylvania, deciduous forests which failed
    to regenerate after logging support a dense groundcover of mountain
    oatgrass, rough goldenrod (Solidago rugosa), tall flat-topped white
    aster (Aster umbellatus), and bracken fern (Pteridium aquilinum) [13].

    Mountain oatgrass is listed as a dominant species in the following
    publication:

    Vegetation of the Great Smoky Mountains [27]

General Ecology

    Fire Ecology
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    More info for the terms: fire regime, forest, low-severity fire

    Mountain oatgrass occurs in oak (Quercus spp.) woods and grassy mountain
    meadows which occasionally experience either lightning or human-caused
    fire. Lightning commonly strikes the peaks and ridges of the southern
    Appalachian Mountains from April through August [1]. Grassy balds in
    the Pisgah National Forest of North Carolina respond favorably to fire,
    becoming thick and lush. The low-severity fires burn very little of the
    surface detritus [18]. Mountain oatgrass basal buds and dormant seeds
    probably survive low-severity fire.

    FIRE REGIMES :
    Find fire regime information for the plant communities in which this
    species may occur by entering the species name in the FEIS home page under
    "Find FIRE REGIMES".
    Fire Management Considerations
    provided by Fire Effects Information System Plants
    More info for the terms: fire suppression, fuel

    Prescribed fire is used to maintain grassy balds in the southern
    Appalachian Mountains. Woody species are invading many grassy balds
    because of fire suppression and decreased grazing [18]. Prescribed
    burning was as effective as mowing in preventing woody species
    establishment in Big Meadows, Shenandoah National Park, Virginia.
    Biomass in the area prescribed burned in April was equal to the unburned
    control by the end of the summer [7].

    Grassy balds respond well to fall fires. The fuel is less compact and
    favorable weather conditions last longer in the fall than in the spring
    [18].
    Growth Form (according to Raunkiær Life-form classification)
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    More info on this topic.

    More info for the term: hemicryptophyte

    hemicryptophyte
    Immediate Effect of Fire
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    Fire probably kills the culms and leaves of mountain oatgrass.
    Life Form
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    More info for the term: graminoid

    Graminoid
    Plant Response to Fire
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    More info for the term: litter

    Dormant seeds in the soil or litter germinate after fire. Mountain
    oatgrass seedlings began growing 1 week after a spring fire on Gregory
    Bald in the Great Smoky Mountains National Park [18]. Poverty grass, a
    close relative of mountain oatgrass, regenerated from a seedbank after
    fire on an upland site in Michigan [22].
    Post-fire Regeneration
    provided by Fire Effects Information System Plants
    More info for the terms: graminoid, ground residual colonizer, secondary colonizer

    Tussock graminoid
    Ground residual colonizer (on-site, initial community)
    Secondary colonizer - off-site seed
    Regeneration Processes
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    More info for the terms: litter, seed

    Mountain oatgrass reproduces by seed. Large amounts of seed are
    produced annually, some of which remain dormant in the litter for at
    least several years [13]. Mountain oatgrass also sprouts from
    perennating buds at the base of the culms.

    In two populations in North Carolina, mountain oatgrass produced an
    average of 50 percent cleistogamous flowers [6].
    Successional Status
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    More info for the terms: cover, forest, herbaceous

    Facultative Seral Species

    Mountain oatgrass grows in full sun and in open woods. It does not
    persist under closed canopies [4]. It establishes on disturbed sites
    including recently logged and burned areas [14,18].

    Grassy balds are persistent successional communities. The origin of
    grassy balds is not fully understood, but former forests may have died
    from ice storms, blow downs, fire, or climate change. Woody species
    establishment is often delayed on these sites by dense herbaceous
    cover, harsh environment, fire, and/or grazing [3,19].

    Grassy balds in the Appalachian Mountains are succeeded by Rhododendron
    spp. thickets, American green alder (Alnus viridis ssp. crispa)
    thickets, or spruce (Picea spp.)-fir (Abies spp.) forests. A dense
    carpet of moss (Polytrichum commune) advances into the grassy bald at
    the edge of the spruce-fir forest and suppresses mountain oatgrass [5].

Cyclicity

    Phenology
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    More info on this topic.

    Mountain oatgrass generally flowers from June to August [20]. In North
    Carolina, mountain oatgrass flowers from mid-June to early July [4].

Management

    Management considerations
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    More info for the term: tree

    The dense growth habit and competitive nature of mountain oatgrass
    restricts tree seedling establishment [26]. Where tree establishment is
    desired, herbicides easily control existing mountain oatgrass.
    Glyphosate does not impede germination of residual dormant seeds, but
    Bromacil delays germination for more than 1 year [13].

    Mountain oatgrass is host to the systemic parasitic fungus Atkinsonella
    hypoxylon [6].

Benefits

    Importance to Livestock and Wildlife
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    Mountain oatgrass is not considered a regionally important forage
    species [11,17], although it is an important pasture grass in the
    Appalachian highlands [4,6].

Taxonomy

    Common Names
    provided by Fire Effects Information System Plants
    mountain oatgrass
    flattened oatgrass
    slender oatgrass
    Taxonomy
    provided by Fire Effects Information System Plants
    The currently accepted scientific name of mountain oatgrass is Danthonia
    compressa Austin [10,12,20]. It is in the family Poaceae. There are no
    currently accepted infrataxa. Mountain oatgrass may intergrade with
    poverty grass (Danthonia spicata), a closely related species [4,12].