Carex crawei occurs in limestone pavement areas (alvars) usually where there is no canopy and graminoids dominate. In these alvar systems, it can also occur in seasonally wet depressions of less vegetated areas. Carex crawei also grows on calcareous cobble shores of lakes and rivers usually in seepy areas and where ice scour occurs. Carex crawei also occurs in marl fens. In these marl fens it prefers growing where the substrate is visible and the vegetation is not dense (New York Natural Heritage Program 2006). Dry to usually moist, open ground, often associated with calcareous gravels or limestone pavements, in wet meadows, fens, prairie swales, beach pools, shores and glades, less commonly edges of white-cedar thickets, prairie patches along rights-of-way, streams, ditches, and quarries (Cochrane and Naczi 2002). Wet meadows, shores, and rock-ledges in calcareous districts (Gleason and Cronquist 1991). Calcareous shores, gravels, meadows, and glades (Fernald 1970).

Alvar grassland A community that occurs on shallow soils over level outcrops of calcareous bedrock (limestone or dolomite). Apparently alvar grasslands are restricted to areas that are seasonally flooded in spring or after heavy rainfall, as well as seasonally dry by late summer. Alvar pavement-grassland This community consists of exposed, flat limestone or dolostone pavement with grassy or mossy patches interspersed throughout. Some examples may be solely grassland with no pavement. Calcareous shoreline outcrop A community that occurs along the shores of lakes and streams on outcrops of calcareous rocks such as limestone and dolomite. The vegetation is sparse; most plants are rooted in rock crevices.

Cobble shore A community that occurs on the well-drained cobble shores of lakes and streams. These shores are usually associated with high-energy waters (such as high-gradient streams), and they are likely to be scoured by floods or winter ice floes. Marl fen A wetland that occurs on a bed of marl. Marl is a whitish substance that is deposited from water that has a lot of calcium dissolved in it. The whitish substance is calcium carbonate, people used to harvest marl to lime agricultural fields. The marl substrate is always saturated, may be flooded, and has a very high pH, generally greater than 7.5. The main source of water is always groundwater. The plants are often sparse and stunted. Marl fens may occur as small patches within a rich graminoid fen. Riverside ice meadow A meadow community that occurs on gently sloping cobble shores and rock outcrops along large rivers in areas where winter ice floes are pushed up onto the shore, forming an ice pack that remains until late spring. The ice scours the meadow, cutting back woody plants.

Wild Chives (Allium schoenoprasum) Yellow Sedge (Carex flava) Dioecious Sedge (Carex sterilis) Twig Rush (Cladium mariscoides) Tufted Hairgrass (Deschampsia cespitosa) (Eleocharis compressa var. compressa) Creeping Juniper (Juniperus horizontalis)

Northern Bayberry (Myrica pensylvanica) Balsam Ragwort (Packera paupercula) Alderleaf Buckthorn (Rhamnus alnifolia) Shining Ladies'-tresses (Spiranthes lucida) Northern Dropseed (Sporobolus heterolepis) Shore Aster (Symphyotrichum tradescantii) Mountain Death Camas (Zigadenus elegans ssp. glaucus)