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Forest Health Aerial Survey 2024 [Washington (State)]

State of Washington Geospatial Open Data Portal · 2024 Full Details

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Title
Forest Health Aerial Survey 2024 [Washington (State)]
Description
Every year since 1947, an insect and disease aerial detection survey is conducted across all forested lands in Washington state by the Washington Department of Natural Resources in cooperation with the USDA Forest Service. In practice, two aerial survey specialists positioned on either side of a high-wing aircraft sketch-map forest damage on tablet computers on a 4-mile grid 1000+ feet above the terrain. Recently killed and defoliated trees are recorded, building a historical record of forest health trends. Most of the mortality observed is caused by known insect and disease agents, although trees killed or damaged by abiotic events such as winter storms, wildfire, flooding, and landslides are also recorded. Defoliation damage presented in this dataset is active whereas mortality is passive as it typically takes a year or more for afflicted trees to exhibit the characteristic symptoms of decline (i.e., bright red, orange, or yellow foliage). Generally speaking, defoliation data is measured the year it occurs, and mortality data represents insect and disease activity that took place a year prior to the date it was recorded. Likewise, trees killed in a given year will not show in aerial survey data until the following year. Only trees displaying the distinctive colors and patterns of recent decline, otherwise known as "damage signatures," are documented. For example, when bark beetle damage is observed, a polygon is drawn on a digitized map denoting the location and range of the damage. Polygons are then given a shorthand code suggesting the most likely damage agent (e.g., code: 6L for mountain pine beetle in lodgepole pine) and a relative severity percentage of affected trees within. Trees that have been dead over a year appear white or grey and are excluded from these assessments. Surveyors choose from five damage severity categories when creating polygons: Very Light (1-3%), Light (4-10%), Moderate (11-29%), Severe (30-50%), and Very Severe (>50%). These five damage severity categories are then recalculated into "trees per acre" (TPA) estimates to remain consistent with historical WA DNR aerial detection survey datasets and reporting. Note: the causal agent of forest damage and mortality is an educated guess. Post-season ground surveys are implemented to validate observations made by aerial survey personnel and serve to reinforce accuracy as remote-sensing specialists. No vertical data is recorded.
Creator
Washington State Department of Natural Resources
Publisher
State of Washington Geospatial Open Data Portal
Temporal Coverage
2024
Date Issued
2025-08-20
Rights
This digital data and metadata, (hereinafter collectively referred to as the "information" are provided on an "AS IS"; "AS AVAILABLE"; and "WITH ALL FAULTS" basis. Neither Department of Natural Resources nor any of its officials and employees makes any warranty of any kind for this information, express or implied, including but not limited to any warranties of merchantability or fitness for a particular purpose, nor shall the distribution of this information constitute any warranty. The information is collected from various sources and will change over time without notice. DNR and its officials and employees assume no responsibility or legal liability for the accuracy, completeness, reliability, timeliness, or usefulness of any of the information provided nor do they represent that the use of any of the information will not infringe privately owned rights. The information is not intended to constitute advice nor is it to be used as a substitute for specific advice from a licensed professional. You should not act (or refrain from acting) based upon the information without independently verifying the information and, as necessary, obtaining professional advice regarding your particular facts and circumstances. References to any specific commercial product, process, and service by trade name, trademark, or manufacturer do not constitute or imply endorsement, recommendation, or favoring by DNR and its officials and employees. IN NO EVENT WILL DNR BE LIABLE TO YOU OR ANY THIRD PARTY FOR ANY DAMAGES ARISING OUT OF THE USE OF OR INABILITY TO USE THE DIGITAL DATA, EVEN IF DNR IS ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Access Rights
Public
Format
ArcGIS DynamicMapLayer
Language
English
Date Added
April 25, 2026
Provenance Statement
The metadata for this resource was last retrieved from State of Washington Geospatial Open Data Portal ArcGIS Hub on 2026-04-25.

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Cite and Reference

  • Citation
    Washington State Department of Natural Resources (2025). Forest Health Aerial Survey 2024 [Washington (State)]. State of Washington Geospatial Open Data Portal. https://geo.wa.gov/maps/wadnr::forest-health-aerial-survey-2024 (web service)
  • BTAA Geoportal Link

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