Calcarous wetland habitat

Calcarous wetland habitat
 
 
 
 
 
 
 
 
 

- general -
Calcareous habitats occur around outcrops of calcareous (calcium-rich) bedrock such as limestone, dolomite, and marble. These occurrences are limited to relatively small areas in the Appalachian Ridge and Valley physiographic region and adjacent portions of the Allegheny Plateau, Taconic Highlands, New England Uplands, and the New York - New Jersey Highlands.
 

- threats -
Calcareous fens and their wetland matrices are in delicate balance with their physical, chemical, and biological environments.  Some fens have been destroyed outright by filling, dumping, impoundment, mining, or other alterations. Many habitats appear to have been degraded by nutrient loading from agricultural runoff, stormwater drainage, dump leachate, or other source, and siltation. Many of the rural areas containing calcareous wetlands and uplands are under high development pressure, especially for second home development.  Habitat complexes, natural corridors, and species populations are frequently fragmented by roads, pipelines, buildings, fences, walls, and other structures.
 

- details -
The conditions in these outcrop areas are quite unique.  Groundwater and soils found in association with calcareous bedrock are generally rich in mineral nutrients, especially calcium, and are slightly acidic to slightly basic (pH ranges from 6.0 to 7.8). Groundwater is also generally abundant and near to the surface in calcareous bedrock. The relatively high nutrient levels and pH contrast with the more acidic, nutrient-poor conditions found in surrounding crystalline rock areas. High cation levels (calcium, iron, and magnesium) in calcareous soils and groundwater may also directly or indirectly inhibit the growth of some plant species and favor others. 

The vegetative communities growing on these habitats are often distinct from surrounding areas.  Especially in wetlands and on mesic soils, these habitats frequently support lush vegetation and unique assemblages of calcicolous plants, i.e., those plants able to grow and develop on calcareous soils. Some upland communities growing directly on calcareous outcrops with thin, xeric (dry) soils are sparsely vegetated, have few trees, and are dominated by dry, prairie species. Carbonate outcrops are often juxtaposed with other sedimentary or metamorphic bedrock of different erodibility, resulting in a variety of ridgetop, slope, and lowland habitats within the same general landscape. Several of the wetland and upland communities, such as rich sloping fens and rich shrub fens, found in association with calcareous bedrock are globally or regionally rare. 

Two regions within the office's project area have notable concentrations of calcareous wetland habitats, including fens: the upper Wallkill River valley in northwestern New Jersey and the Taconic ridge and valley area at the three-state junction of New York, Connecticut, and Massachusetts. 
These areas contain important habitats for rare plants and the federally listed threatened bog turtle (Clemmys muhlenbergii).  They are also important for several groups of rare insects. Rare plant species associated with these calcareous wetlands include handsome sedge (Carex formosa), blunt spikerush (Eleocharis obtusa var. ovata), Torrey's bulrush (Scirpus torreyi), hemlock-parsley (Conioselinum chinense), blazing-star (Chamaelirium luteum), Virginia bunchflower (Melanthium virginicum), swamp birch (Betula pumila), larger Canadian St. John's-wort (Hypericum majus), spreading globe flower (Trollius laxus ssp. laxus), hoary willow (Salix candida), marsh valerian (Valeriana sitchensis ssp. uliginosa), and Schweinitz sedge (Carex schweinitzii). Surveys of calcareous wetlands in Connecticut have revealed an amazing diversity of insects, with over 500 species of Lepidoptera (butterflies and moths) and over 50 species of Odonata (damselflies and dragonflies), including many rare species. 

Calcareous cliffs and talus slopes in the project area occur primarily in the limestone outcrops along the edge of the Allegheny Plateau, such as the Helderberg Escarpment and the Great Vly Wildlife Management Area near the Hudson River in Ulster County, New York. Smooth cliff-brake (Pellaea glabella) is a rare plant species often associated with these cliff communities. Solution caves that are created in these outcrops, as well as mines, serve as winter hibernacula for bats such as the small-footed bat (Myotis sodalis), northern long-eared myotis (Myotis septentrionalis), and the federally listed endangered Indiana bat (Myotis sodalis). A limestone mine near the Hudson River has one of the largest hibernacula for Indiana bat in the eastern United States. 

Other rare calcareous communities include limestone woodlands, calcareous shoreline outcrops, calcareous riverside seep communities, marl fens, calcareous seepage swamps, and rich hemlock-hardwood swamps. Several areas have significant areas of calcareous bedrock, including the upper Hudson River valley in northern New York, the upper Housatonic River watershed in western Connecticut (the "marble valley" region), the Paulins Kill valley in northwestern New Jersey, and the Neversink and Delaware River shorelines along the western slopes of the Shawangunk - Kittatinny Ridge.