Description

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Urban Tree Canopy (UTC) Assessment for Washington, DC. This dataset consists of UTC metrics summarized by ward. The UTC Assessment is a top-down approach to analyzing the urban forest. Its purpose is to integrate high resolution land cover data with other GIS datasets to produce a set of detailed metrics on the urban forest that allow decision makers to know how much tree canopy currently exists (termed Existing UTC) and amount of land where is it biophysically feasible to establish tree canopy on (termed Possible UTC). Existing UTC is determined by extracting all features classified as tree canopy from a high resolution land cover dataset. Possible UTC is determined by identifying land where canopy could possibly exist and includes two subcategories: Possible-impervious and Possible-vegetation. Possible-impervious consists of all impervious land that, through modification, could support tree canopy. Examples of such features are sidewalks, minor driveways (through overhanging coverage), and playgrounds. Possible-vegetation consists of all land that is low-lying vegetation, primarily grass or shrubs, which could conceivably be converted to support tree canopy. Examples of such features include residential lawns and playing fields. Possible-vegetation also includes bare earth where no vegetation or impervious surfaces currently exist. UTC metrics do not serve to address the issues of where it is socially desirable or financially feasible to plant trees. Rather, the UTC metrics serve as the basis for beginning to form answers to these questions. UTC metrics are presented in the attribute table as both absolute area (in square meters) and relative area (percentage of land area) per parcel. For example, an Existing UTC Area (UTC_E_A) value of 13,677 and an Existing UTC Percentage (UTC_E_P) of 21.8 indicate that for the parcel in question the area of Existing UTC is 13,677 (in square meters) and 21.8% of that feature is tree canopy. Key ward attributes have been maintained to assist in joining this table to the original wards layer. The land cover dataset used to derive the UTC metrics for this dataset was generated from Quickbird color-infrared imagery acquired on September 7, 2006. The wards layer was current as of March 5, 2007.

Dataset Attributes

  • OBJECTID
    Number
  • Shape
    Number
  • WARD
    Number
  • NAME
    Text
  • REP_NAME
    Text
  • GIS_ID
    Text
  • WEB_URL
    Text
  • REP_PHONE
    Text
  • REP_EMAIL
    Text
  • REP_OFFICE
    Text
  • WARD_ID
    Text
  • LABEL
    Text
  • AREASQMI
    Number
  • SHAPE_Length
    Number
  • SHAPE_Area
    Number
  • OBJECTID
    Number
  • UTC_ID
    Number
  • UTC Land Area
    Number
  • UTC Existing Area
    Number
  • UTC Possible-Vegetation Area
    Number
  • UTC Possible-Impervious Area
    Number
  • UTC Possible Area
    Number
  • UTC Existing Percent
    Number
  • UTC Possibe-Vegetation Percent
    Number
  • UTC Possibe-Impervious Percent
    Number
  • UTC Possibe Percent
    Number
  • GIS_ID
    Text
  • WARD_ID
    Text
  • WardPly.FID
    Number

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