Ohio subset of Plant Communities of the Midwest ... - NatureServe

Rocky Uplands (Glades, Rock Barrens, Outcrops and Alvars): Alvar Shrublands
Juniperus communis - (Juniperus virginiana) - Rhus aromatica - Viburnum rafinesquianum /
Oligoneuron album Shrubland
Common Juniper - (Eastern Red-cedar) - Fragrant Sumac - Downy Arrow-wood / Prairie Goldenrod
Shrubland
Juniper Alvar Shrubland
CEGL005212
DESCRIPTION: Shrubs dominate, with over 25% cover of tall, short, and dwarf-shrubs; the average is about 43%
cover of shrubs, with less than 10% of that being tall shrubs. Characteristic tall shrubs (2-5 m tall) are scrub forms of
trees such as Juniperus virginiana, Thuja occidentalis, and Quercus macrocarpa. Tree forms (>5 m tall) of these
species may be present, but trees have less than 10% cover in the community. Other less common trees (>5 m tall)
that may be present include Carya ovata, Ulmus thomasii, and Fraxinus americana. Characteristic short shrubs (0.5-2
m tall) include Juniperus communis, Cornus racemosa (= Cornus foemina ssp. racemosa), Rhus aromatica, Prunus
virginiana, and Viburnum rafinesquianum. Some dwarf-shrubs (under 0.5 m tall) are usually present, including
Arctostaphylos uva-ursi and Symphoricarpos albus. Characteristic vines include Toxicodendron radicans and Vitis
riparia. The herb layer forms a dry, grassy meadow between the shrubs; average cover of herbs is about 23%. The
most abundant herbs are Danthonia spicata, Oligoneuron album (= Solidago ptarmicoides), and Carex umbellata.
Less than 50% of the ground surface is exposed limestone bedrock, which is usually covered with lichens, mosses,
and algae (Reschke et al. 1998).
Stands occur on very shallow soils (usually less than 30 cm deep) over flat limestone outcrops (pavements). Moisture
varies over the season, but summer droughts are typical. Grikes (eroded cracks in the rock up to 2 m or more deep
and extending 5 to 30 m in length) may occur, with shrubs and trees rooted in the cracks (Reschke et al. 1998).
Summer droughts are typical (Reschke et al. 1998).
COMMENTS: 1, MCS. More northern stands may be more heavily dominated by Juniperus communis, and species
such as Abies balsamea, Aquilegia canadensis, Arctostaphylos uva-ursi, and Picea glauca may be more common,
and deciduous trees and shrubs are less common. Juniper Alvar Shrublands often occur in a patchy landscape
mosaic with other alvar communities, including Tufted Hairgrass Wet Alvar Grassland, Deschampsia caespitosa -
(Sporobolus heterolepis, Schizachyrium scoparium) - Carex crawei - Packera paupercula Herbaceous Vegetation
(CEGL005110); Little Bluestem Alvar Grassland, Sporobolus heterolepis - Schizachyrium scoparium - (Carex
scirpoidea) / (Juniperus horizontalis) Herbaceous Vegetation (CEGL005234); Annual Alvar Pavement-Grassland,
Sporobolus neglectus - Sporobolus vaginiflorus - Isanthus brachiatus - Panicum philadelphicum - (Poa compressa)
Herbaceous Vegetation (CEGL005235); Alvar Nonvascular Pavement, Tortella tortuosa - Cladonia pocillum -
Placynthium spp. Sparse Vegetation (CEGL005192); and Poverty Grass Dry Alvar Grassland, Danthonia spicata -
Poa compressa - (Schizachyrium scoparium) Herbaceous Vegetation (CEGL005100).
CONSERVATION RANK: G3. This community occurs throughout the Great Lakes basin in New York, Ontario, Ohio,
Michigan, and Wisconsin. Thirty-five occurrences of this community were documented, with a total of about 7768
acres (3144 ha). Juniper alvar shrubland occurs in small to large patches; some of the larger patches form a smallscale
matrix within which smaller openings of alvar grasslands and pavements may occur. Sizes of currently known
occurrences range from under 10 acres to about 1600 acres (4 to about 650 ha). The global rank of this community
(as compared to G2-ranked alvar grasslands with similar numbers of occurrences and acres) reflects our expectation
that there are more examples of this community that we have not surveyed, including some sites too disturbed to be
considered viable. The threats to this community do not seem to be as imminent as threats to the alvar grasslands,
and since the soils are only briefly saturated (just after a rainfall), they are less vulnerable to disturbance by off-road
vehicles.
DISTRIBUTION: This juniper alvar shrubland type occurs throughout the Great Lakes region of the United States and
Canada, in northern New York, southern Ontario, northern Ohio, northern Michigan, and eastern Wisconsin.
USFS ECOREGIONS: 212Ee:CCC, 212H:CC, 222Qa:CCC
CONSERVATION REGIONS: 48:C
STATES: MI NY OH WI PROVINCES: ON
MIDWEST HERITAGE SYNONYMY: MI alvar-shrubland +
OH shoreline alvar +
WI alvar shrubland =
OTHER SYNONYMY:
USNVC HIERARCHY: JUNIPERUS COMMUNIS SHRUBLAND ALLIANCE (III.A.3.N.a)
PLANT COMMUNITIES OF THE MIDWEST – 2001. APPENDIX: ASSOCIATION DESCRIPTIONS
291