The Yellow lance Potential Habitat dataset is a polygon layer depicting high, moderate and low potential habitat locations for Yellow lance in NC counties.

The Yellow lance (Elliptio lanceolata) is a sand-loving species often found buried deep in clean, coarse to medium sand, although it can sometimes be found in gravel substrates. Yellow lances often are moved with shifting sand and eventually settle in sand at the downstream end of stable sand and gravel bars. This species depends on clean, moderate flowing water with high dissolved oxygen. This species is found in medium-sized rivers to smaller streams. Historically, the yellow lance ranged from the Patuxent River Basin in Maryland, to the Potomac River Basin in Maryland/Virginia, the Rappahannock, York, James, and Chowan River basins in Virginia, and the Tar and Neuse River basins in North Carolina.

The three levels are: Low, Moderate, and High Probability of Potential Habitat (based on similarity of environmental conditions to those found at known occurrence locations). The category thresholds were set based on the distribution of predicted values for known habitat. The High-Moderate threshold is set at the level where 90% of the observed potential habitat (species presence and reviewer judgments) falls within the High category (Presence Percent Correctly Classified). The Moderate-Low threshold were set at the level where 8% of the observed potential habitat (species presence and reviewer judgments) falls within the Moderate category and 2% within the Low category. The final thresholds for this species are 0.452 and 0.754 for the Low-Moderate and Moderate-High thresholds, respectively. Lower thresholds result in more of the range labelled as High probability of habitat and greater misclassification of known non-habitat locations. Higher thresholds result in more of the range labelled as Low probability of habitat and greater misclassification of known habitat locations.

Given the larger spatial unit of ecological models and ecological characteristics of aquatic species, the landscape scale environmental attributes of potential habitat varied greatly among sites and could closely resembled non-habitat sites. It is important to remember that potential habitat (and non-habitat) can occur at any classification level within a catchment and must be verified by a qualified biologist.

For more information please click here https://xfer.services.ncdot.gov/gisdot/Metadata/Atlas/TechDocs/

Datasets developed under Project ATLAS do not replace any NRTR work for future projects and may not be used as a replacement for site visits / field surveys by qualified professionals and hence should be used only as a supporting platform for decision making. Use of this dataset for project scoping or screening is merely pre-decisional.