Understanding Oregon's Last Remaining Old Growth Forests
In 2012, Oregon had approximately 3,450,000 hectares of Old Growth forests left. While that is substantial, it is less than 10% of Oregon's original Old Growth (Oregon Wild).
Of our remaining Old Growth, about 630,000 hectares (18%) are located on private land. Due to more stringent state and federal regulations for Old Growth on public lands, forests located on private lands are at greater risk of harvest.
This map shows Old Growth in Oregon compared with private land, highlighting where the most At-Risk Old Growth exists in Oregon. While Old Growth can be lost to wildfires, harvesting continues to pose a threat.
As described in the Disclaimers & Limitations section below, this map should only be taken as a starting point and not authoritative on Old Growth in Oregon. There are many incorrect artifacts, and critically the Old Growth data is from 2012 while the satellite imagery is from 2024, limiting but not nullifying the usefullness of this exercise.
Data
Key Old Growth Locations
These locations represent substantial concentrations of Old Growth forests on private lands.
Blue River
East Portland
Reedsport
Shady Cove
Methodology
Oregon State Boundary data is from derived from the Oregon Geographic Information Council (OGIC) GEOHub Data
Old Growth data is from the Landscape Ecology, Modeling, Mapping & Analysis (LEMMA) group at Oregon State University. LEMMA provided a 2012 Gradient Nearest Neighbor (GNN) structure plot with comprehensive forest information on the West Coast. From this data, the Old Growth raster tiles were created by a reclassification of the raster by pixels with the Late Successional Old Growth (LSOG) classification, which corresponds to a canvas cover greater than 10% and average tree diameterers. Pixels are at 30 meter resolution.
Private Land data is derived from the BLM OR Ownership dataset. Private lands are coarsely derived by selecting the inverse of city and county, state, tribal, and federal agency owned lands.
Lastly, At Risk Old Growth is considered as the overlap of Old Growth located within private land. Old Growth on private land can be considered to be at the greatest threat, as approximately 90% of timber harvests occur on private lands nationally, even considering that private land comprises only approximately 40% of land in Oregon (Congressional Research Service).
Disclaimers & Limitations
This information is furnished for educational purposes only. All work shown is free and available for reuse under MIT Licensce, and is derived from publically available data. This map should not be considered as authoritative but rather as a starting point for further understanding. Among other limitations:
- Map resolution is at 30 meters or greater.
- Private land classification may be adjusted
- Some compression and simplification of layers is done for performant web rendering
- LEMMA GNN data used to derive old growth is from 2012, while the private land data is from 2024. Why the discrepancy? 2012 is the most recent dataset provided by LEMMA, aside from the 2017 collection. This map could be improved through a new classification of Old Growth from 2024 satellite imagery.
- USFS timber harvesting on public lands was ommitted due to its minor overall contribution to timber harvests in Oregon.
Additional Resources
Understanding is crucial to preservation; patchy data on "Where Old Growth forests are" has historically contributed to plausiable deniability for the harvest of Old Growth in Oregon, as recently as in 2019. While Old Growth locations are not perfectly understood or mapped in Oregon or across the country, there are a few adjacent efforts underway;
Stand.Earth Forest Eye is an innovative database for tracking logging transactions. A higher-fidelity, monthly-monitoring approach of Old Growth logging can be considered the gold standard for this project. The Forest Eye project is currently focused solely on British Columbia but could be expanded in the future.
Oregon Wild collaborates with NASA to quantify clearcutting along the Oregon Coast Range, and continues to work towards mapping old growth in Oregon.
Global Forest Watch is an excellent resource for all forest types, loss and gain to all purposes including wildfire.
Wilderness Photographer Lucas Cometto has beautifully captured some of Oregons most famous old growth forests, including Arcadia Cedar Grove, Valley of the Giants, and more.