Eleven major ecozones were used in NY-GAP. These ecozone boundaries were defined based on a review of Bailey?s Ecoregions (Bailey 1995), USFS Ecological Units (Keys et al. 1995), and NYSDEC Ecozones (Davis 1977, Dickinson 1979, Dickinson 1983, Will et al. 1982). NY-GAP ecozones are based on major and minor ecozone boundaries from the NYSDEC Ecozone map; however, in some cases NYSDEC minor ecozones were combined to form NY-GAP ecozones that differ from NYSDEC Ecozones. For example, Tug Hill is a separate ecozone in the NY-GAP map, but is combined with the St. Lawrence and Black River Valleys to make a major ecozone in the NYSDEC map. The Hudson Highlands and Taconic Highlands from the NYSDEC ecozone map were combined to make the NY-GAP Hudson Valley Ecozone. The NY-GAP Catskill Ecozone is composed of the six easternmost minor ecozones from the NYSDEC Appalachian Plateau Ecozone. We created this new ecozone from the NYSDEC map to differentiate the more mountainous areas in the Catskills from the rest of the Appalachian Plateau, and to align the NY-GAP Ecozones more closely with the USFS Ecological Units and Bailey?s Ecoregions. The USFS Ecological Unit map separates the Catskill Mountains from the Appalachian Plateau and defines them as part of the Adirondack ?New England Mixed Forest?Coniferous Forest?Alpine Meadow Province, a province that extends north through Vermont and into Maine.