Sand/Dune: Open sandy beaches above high tide, barren active dunes, and similar areas of barren, largely unvegetated sand. Does not include stabilized thickly vegetated dunes.

Scientific Name (Association or Ecological System): The name of the Association or Ecological System adopted for use by NatureServe; Association names are based on the scientific names of the dominant and diagnostic species. For more information please see Classification of Ecological Communities.

Scientific Name (Species): The scientific name for an element adopted for use by NatureServe; generally based on standard botanical or major zoological taxonomic references. For more information please see Classification Sources.

Shallow Water: The littoral zone: characterized by the frequent presence of rooted aquatic plants, disturbance by wave action, and periodic exposure during drawdown (during drought, for example). Some lakes and ponds are all shallow water; in some others, shallow water is restricted to shores and bays.

Society of American Foresters Cover Types: Society of American foresters (SAF) cover type names. Cover types are a finer scale of resolution within the SAF regions.

Society of American Foresters Region Names: Society of American Foresters region name(s). Values include: EAST - boreal forest, northern forest, central forest, southern forest, tropical forest; WEST - northern interior (boreal), high elevations, middle elevations interior, north pacific, low elevations interior, south pacific.

Spatial Scale and Pattern (See Matrix, Large Patch, Small Patch, Linear): In principle, ecosystems can be defined at any geographic scale, from a rotting log or vernal pond to the entire biosphere. Our decision was to focus on meso-scale ecological system units, which includes temporal and geographic scales intermediate between stand and landscape-scale analyses. These \"meso-scales\" constrain the definition of system types to scales that are of prime interest for conservation and resource managers who are managing landscapes in the context of a region or state.

There are four categories for spatial patterns that encompass all types of terrestrial ecological systems. In each of these instances, an expected spatial scale is included as initial guidance for defined ecological systems within a given area. Review of broadscale ecological pattern for a given region should result in an initial suite of system types that would fall into each of these categories. For example, matrix-forming forests may predominate a given area. Knowledge of compositional variation can be used to initially characterize system types that typically occur in patches ranging from 2,000 on up to 100,000 hectares. Both large patch and small patch systems tend to appear nested within matrix system types, while linear system types occur along riverine corridors, coastal areas, and major physiographic breaks (e.g. cliff faces). While in most instances, the spatial pattern categories are mutually exclusive, there may be instances where the same ecological system type forms the matrix in one part of its range, while occurring as a large patch type elsewhere.

Special Habitat Factors: Indicate(s) the special habitat factor(s) that contribute significantly to the survival or reproduction of the species. Values include: standing snag/hollow tree, fallen log/debris, burrowing in or using soil, benthic, subterranean obligate.

Species Name ( Alliance Floristic Composition)
The scientific name(s) of notable component plant species for the Alliance.

Species Name (Association Floristic Composition) The scientific name(s) of notable component species for the Association. For more information see Classification of Ecological Communities.

Species Impacts: Comments that describe the impacts of this species on other species, especially if this species is a pest, weed, or exotic.

Spring/Spring Brook: Points of concentrated groundwater discharge, either concentrated (at a distinct orifice) or diffuse (at a seep). The outflow channel is classified as a spring brook as far downstream as the spring waters' characteristics (relatively constant temperature, nutrient-poor) are maintained.

Stewardship Overview: A general stewardship summary of the management concerns for this species. Also, indicates whether the species is at risk, or whether it is a pest or weed.

Strictly Isolated Wetlands:These types are defined where >80% of all known occurrences have very infrequent interchange of both surface water and ground water between the wetland and regulated (potentially navigable) water bodies. This condition may be inferred where occurrences are geographically isolated and near-impermeable substrates are characteristic.

NOTE: These definitions were developed solely to facilitate the generation of a classification of isolated wetland ecological system types from NatureServe\'s databases, to create linkages to rare species, and to allow documentation of scientific methodology. They are NOT intended to be a guide for defining individual on-the-ground occurrences of isolated wetlands for regulatory or other purposes. These definitions do not represent an endorsement by NatureServe (a non-advocacy organization) of any particular regulatory or other use by the Environmental Protection Agency, the Army Corps of Engineers, or other federal and state agencies.

Subaquatic: Subterranean aquatic. Underground waters, above and below the water table.

Subnational Status: The conservation status of a species or community from a state or province perspective, characterizing the relative rarity or imperilment of the element. Developed by NatureServe and its natural heritage member programs. For more information see NatureServe Conservation Status.

Subnational Rank (NatureServe Subnational Conservation Status) For more information see NatureServe Conservation Status.

Subterranean Habitat(s): Subterranean habitat(s) where the element is found. Values include: subterrestrial, subaquatic.

Subterrestrial: Subterranean terrestrial (air-filled) habitats, ranging from large caves to interstitial crevices below soil horizons.

Subtypes: List of any widely used labels describing typical occurrences of the species (e.g., nest, den, old growth).

Suburban/Orchard: Human-maintained habitats, generally characterized by open-grown trees, lawns, and small buildings. Does not include rural residential areas where human dwellings are scattered within or widely adjacent to more or less natural ecosystems or cropland.

Summary: A summary of the geographic range, structure, composition, environmental setting, and distinguishing features of the association or alliance.

Ecological Community: For more information see Classification of Ecological Communities.