Common (Translated Scientific) Name: Barrens Dropseed - Poverty Dropseed - Fluxweed - Philadelphia Panicgrass - (Canada Bluegrass) Alvar Grassland

Colloquial Name: Annual Alvar Pavement Grassland

Hierarchy Level:  Association

Type Concept: Annual alvar pavement-grasslands occur in Ontario and New York in the central and eastern Great Lakes region on shallow soils (usually less than 10 cm deep) over flat limestone and dolostone outcrops (pavements). At some sites there is a distinctive soil moisture regime of alternating wet and dry seasons; they are often saturated in early spring and late fall, and they are subject to severe summer drought in most years (except unusually wet years). Due to the very shallow soils, and often saturated conditions during freeze-thaw cycles in early and late winter, needle ice often forms in the soils, causing frost-heaving of the shallow soils. This community typically occurs in a landscape mosaic with other alvar communities and consists of a mosaic of pavement and grassland areas dominated by characteristic native species, such as Sporobolus neglectus, Sporobolus vaginiflorus, Panicum philadelphicum, Poa compressa, Oligoneuron album, Danthonia spicata, Trichostema brachiatum, Packera paupercula, Carex crawei, and Panicum flexile. There is usually less than 10% cover of shrubs. There may be nearly equal cover of grassy vegetation, and exposed rock covered with nonvascular plants. Lichens and mosses are common on "pavement" rock outcrops that occur as patches within this mosaic.

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This community typically occurs in a landscape mosaic with other alvar communities; the most common associated communities are Tufted Hairgrass Wet Alvar Grassland, ~Deschampsia cespitosa - (Sporobolus heterolepis, Schizachyrium scoparium) - Carex crawei - Packera paupercula Grassland (CEGL005110)$$; Juniper Alvar Shrubland, ~Juniperus communis - (Juniperus virginiana) - Rhus aromatica - Viburnum rafinesqueanum / Oligoneuron album Shrubland (CEGL005212)$$; Alvar Nonvascular Pavement, ~Tortella tortuosa - Cladonia pocillum - Placynthium spp. Sparse Vegetation (CEGL005192)$$; Little Bluestem Alvar Grassland, ~Sporobolus heterolepis - Schizachyrium scoparium - (Carex scirpoidea) / (Juniperus horizontalis) Grassland (CEGL005234)$$; and Poverty Oatgrass Dry Alvar Grassland, ~Danthonia spicata - Poa compressa - (Schizachyrium scoparium) Grassland (CEGL005100)$$.

Similar NVC Types: No Data Available

note: No Data Available