Phragmites 1968 is a 1:12,000-scale, polygon feature-based layer that includes areas where phragmites existed in 1968 along the lower Connecticut River corridor from the towns of Portland and Cromwell south to Long Island Sound.  This layer was published at the same time as the Phragmites 1994 layer in order to depict the historic differences in phragmites growth between 1968 and 1994.  The Phragmites 1968 layer was compiled using 1:12,000 black and white digital orthophotos obtained in 1968 as part of a Connecticut Department of Environmental Protection aerial mapping survey.  This data represents a particular point in time (1968).  It is not updated and does not depcit current conditions.  Features are polygon locations that represent the approximate location of phragmites growth in 1968.  Attribute information is comprised of the NAME68 attribute that identifies one of 25 general locations of phragmites growth.  Other attributes include AV_LEGEND that depicts the existence of phragmites, and ACREAGE that depicts the size of each polygon in acres.  Data was compiled at a 1:12,000 scale.

Phragmites 1968 is 1:12,000 scale data that depicts the locations of phragmites growth in 1968.  Use this layer to show the extent of phragmites growth in 1968 along the lower Connecticut River corridor.  In addition, this layer can be used with Phragmites 1994 that depicts the locations of phragmites growth in 1994.  The use of both of these layers can more clearly demonstrate the extent of invasive growth of phragmites between 1968 and 1994.  Not intended for maps printed at map scales greater or more detailed than 1:12,000 scale (1 inch = 1,000 feet).

For additional information, refer to the complete report generated as a result of the study that commissioned the publication of the Phragmites 1968 and Phragmites 1994 layers.   This report is entitled "Spatial Pattern of Phragmites Australis (CAV) Trin ex Steuf. Within the Tidelands of the Connecticut River, 1994"  and was authored by Nels Barrett (United States Department of Agriculture Natural Resources Conservation Service, 344 Merrow Road, Suite A., Tolland, Connecticut 06084 USA) and Sandy Prisloe (University of Connecticut Cooperative Extension System, College of Agricultural and Natural Resources, P.O. Box 70, Haddam, CT 06438 USA).  

publication date

None. The data is in the public domain and may be redistributed.

No restrictions or legal prerequisites for using the data. The data is suitable for use at appropriate scale, and is not intended for maps printed at scales greater or more detailed than 1:12,000 scale (1 inch = 1,000 feet). Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information.

Includes Phragmites 1968 features such as the location and size of the polygon.  Attributes include AV_LEGEND, which identifies the polygon as phragmites, ACREAGE, which identifies the size of the polygon in acres, and NAME68, which identifies the general location (one of 25 areas) of the feature.  This layer is best symbolized as a single feature type.  

Phragmites growth in 1968 represented as polygon features.

State of Connecticut, Department of Environmental Protection

Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap. Polygons do not overlap other polygons.  No automated procedures or tests were performed to guarantee desired topology other than visual inspection.

The completeness of the data reflects the feature content of the data sources, which include the digital orthophotos (Source 1).  The Phragmites 1968 layer is complete in the sense that it accurately reflects 1968 phragmites information available at the time the layer was created.  This data is not updated and represents a particular point in time (1968).  This data does not represent all of the phragmites in Connecticut.  

The Phragmites 1968 layer retains the feature types and information identified by the State of Connecticut, Department of Environmental Protection and obtained from the 1968 digital orthophotos.  Accuracy level of attributes is not known.  The AV_LEGEND attribute contains the string "Phragmites" for every feature.  The NAME68 field identifies the particular location (25 total locations) of the feature.  The ACREAGE attribute is a calculated field that depicts the area in acres of each feature.

Horizontal accuracy of this layer is consistent only with the source data (1:12,000 scale digital orthophotos) from which features were compiled.  Feature locations were determined by using a stereoscope with the 1:12,000 orthophotos and identifying ground control points, e.g., large boulders, road/stream crossings, intersections, etc., on the photos.  An overall horizontal accuracy level cannot be determined.  

Phragmites 1968

Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.