Damage to forested areas in the North Pacific LCC, USA, 2003

Sep 29, 2011
This dataset is a compilation of forest insect, disease and abiotic damage mapped by aerial detection surveys on forested areas in the United States. At this time, the National Aerial Survey Data Standards require only mortality and defoliation data be collected and reported. However, many cooperators collect data on other types of damage and therefore, the national database has been designed to accommodate these data. Low-level flights, typically 1,000 to 2,000 feet above ground level, are used to map forest damage. Observers use paper maps, typically 1:100,000 scale USGS maps, upon which they record the damage. There is also a digital sketchmap system that may be used. The digital system uses GPS to display the plane's current location on screen along with an electronic version of a variety of base maps. It allows the observer to record damage areas directly in a GIS database. Due to the nature of aerial surveying, there may be areas within the delineated polygons that are unaffected. For example, an area with a patchy mosaic of forest insect activity may be recorded as one larger polygon by the observer. During aerial surveys, only fading trees (those with yellow, brown, or red foliage) or those with some defoliation are mapped. Older dead trees which have lost their foliage or have dull colored foliage are not typically mapped for two primary reasons: 1) it is harder to see older dead trees that may have lost their needles and 2) it prevents recording trees that were mapped in a prior year's survey. Overview surveys are a 'snap shot' in time and therefore may not be timed to accurately capture the true extent or severity of a particular disturbance activity. Specially designed surveys with modified flight patterns and timing may be conducted to more accurately delineate the extent and severity of a particular disturbance agent. Special surveys are conducted when resources are available to address situations of sufficient economic, political or environmental importance.

Data Provided By:
USDA Forest Service, Forest Health Technology Enterprise Team (FHTET)
Content date:
not specified
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Contact Organization:
USDA Forest Service, Forest Health Protection, Forest Health Technology Enterprise Team
Contact Person(s):
  • Frank Krist
Use Constraints:
Users need to exercise caution regarding the spatial accuracy of these data due to the subjective nature of aerial sketchmapping and the varying scales of source materials. Comparison with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from rounding of decimal coordinates during conversion, changes in mapping conventions over time, change in assignment of damage casual agent, and type of data collection. Any products (hardcopy or electronic) using these data sets shall clearly indicate their source. If the user has modified the data in any way, they are obligated to describe the modifications on all products. The user specifically agrees not to misrepresent these data sets, nor to imply that changes made were approved by the USDA Forest Service.
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