Conservation Science & Stewardship
Calcareous Fens in New York
| New York Natural Heritage Program, 700 Troy-Schenectady Road, Latham, NY 12208, http://www.heritage.tnc.org/nhp/us/ny/ |
The Nature Conservancy Central and Western New York Chapter,
339 East Avenue, Suite #300, Rochester, NY 14604 |
Calcareous fens are rare natural communities that support many rare species in New York including the globally imperiled Hemileuca sp. 1 (Cryan's buckmoth), the federally threatened Clemmys muhlenbergii (Bog turtle), and a number of state rare plants. The New York Natural Heritage Program recognizes five types of calcareous fens: marl fen, rich graminoid fen, rich sloping fen, rich shrub fen, and medium fen. Calcareous fens differ from other wetlands in that they are open peatlands associated with groundwater discharge areas and calcareous bedrock. The presentation will describe the composition and structure of calcareous fens and compare them to other palustrine communities.
Calcareous fens are highly variable in groundwater chemistry,
landscape setting, species composition, and species abundance. To
focus conservation, The Nature Conservancy and the New York Natural
Heritage Program initiated a two year project in 1998, funded by the
Biodiversity Research Institute, to map and consistently classify
New York's calcareous fens. Goals of the project are to produce a
key to fen types, to link the New York fen classification to the national
classification, and to identify exemplary examples of each fen type.
In the first year of the project, thirty occurrences were surveyed
and we now have current information on over half of the high quality
calcareous fens known in the state. Preliminary results clarify differences
in fen types and assist in applying and assessing specifications used
to rank occurrences. The presentation will highlight examples from
the first year of the project.
- A Hydrogeologic study assessed fen water quality, quantity, and the potential recharge sources to the fens.
- A Seismic investigation provided information regarding the subsurface stratigraphy as well as recharge sources to the fens.
- A Paleoecological Analysis of the fens provided a long-term vegetational and successional context for future management strategies.
These definitions are preliminary and exploratory. Citations given with each definition are the general source of the definitions, but modifications may have been made to improve their application in the Midwest.
Bogs -A bog is a peatland, generally with the water table at or near the surface. The bog surface, which may be raised or level with the surrounding terrain, is virtually unaffected by the nutrient-rich groundwaters from the surrounding mineral soils, and thus is generally acid and low in nutrients (ombrotrophic). The dominant materials are weakly to moderately decomposed Sphagnum and woody peat, underlain at times by sedge peat. Bogs may be treed or treeless, and they are usually covered with Sphagnum spp. and ericaceous shrubs (National Wetlands Working Group 1988).
Fens - A fen is a peatland with the water table usually at or just above the surface. The waters are usually nutrient-rich and minerotrophic from mineral soils. The dominant materials are moderately to well decomposedsedge and/or brown moss peat of variable thickness. The vegetation consists predominately of sedges, grasses, reeds, and brown moses with some shrubs and, at times, a sparse tree layer (National Wetlands Working Group 1988).
Seeps - A seep is a wetland with saturated soil caused by water flowing to the surface in a diffuse, rather than concentrated, flow (White and Madany 1978). Soils can be muck or peat, the latter leading to some overlap with the definition of fens (e.g. calcareous seepage fens). The vegetation consists of graminoids, forbs, ferns, mosses, shrubs or trees.
Rooting/Floating Aquatic Marshes - An aquatic marsh is a wetland with intermittently or permanently flooded, or seasonally stable water regimes, featuring open expanses of standing or flowing water which are variously called ponds, pools, shallow lakes, oxbows, reaches, channels, or impoundments. These aquatic marshes are distinguished from deep-water by mid-summer depths of less than 2m, and from other wetlands by summer open water occupying 75% or more of the wetland surface. Open water is generally less than 8 ha. The vegetation, if present, is confined to submerged or floating aquatic plant forms (National Wetlands Working Group 1988).
Wet Meadows/Marshes - The wet meadows and marshes are mineral wetlands or peatlands that are periodically inundated by standing or slowly moving water or subject to seasonal saturation. Surface water levels may fluctuate seasonally, with declining levels exposing drawdown zones of matted vegetation or mudflats, or drying out of the surface horizon. The waters are rich in nutrients, varying from fresh to highly saline. The substrate usually consists of mineral material, although occasionally it consists of well-decomposed peat. Marshes characteristically show zonal or mosaic surface patterns composed of pools or channels interspersed with clumps of emergent sedges, grasses, rushes, and reeds, grading into closed-canopy meadows dominated by grasses and sedges (National Wetlands Working Group 1988).
Swamps - A swamp is a mineral wetland or peatland with standing water or water gently flowing through pools or channels. The water table is at or near the surface. There is pronounced internal water movement from the margin or other mineral sources; hence the waters are rich in nutrients. If peat is present, it is mainly well-decomposed wood, underlain at times by sedge peat. The vegetation is characterized by a dense cover of deciduous or coniferous trees or shrubs, herbs, and some mosses. (National Wetlands Working Group 1988).
Woody Floodplains/Riparian Zones - A floodplain
or riparian wetland is an area, typically with channel features, where
annual or periodic inundation of water occurs over the surface, often
with subsequent drying by early- or mid-growing season. Areas with more
slow draw-downs, such as back water sloughs, may overlap in concept
with swamps.
Relation of physiognomy
to wetland ecological groups.
| ECOLOGICAL GROUP | |||||||
| Physiognomy | Bogs | Fens | Seeps | Swamps | Marshes | Aquatic | Floodplain/Riparian |
| Treed(>25%) |  |
? | |
|
|
|
|
| Shrub/Dwarf-shrub (>25%) | |
|
|
|
|
|
|
| Herbaceous (>25%) | |
|
|
|
|
|
|
For more information contact Don Fabar-Langendoen @ dfaber-lang@tnc.org.
