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Oregon's Forest Atlas 2010 online edition
Oregon Forestland Classification of Tree Sizes
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The structure of forest stands is an important factor in assessing biological diversity and economic value of forested ecosystems. Tree size class distribution in Oregon forests is constantly changing as a result of vegetation growth and death, and natural disturbances such and insects and disease, fire, windstorms, floods, volcanic eruptions, and climate change. Human alteration of Oregon’s forest predates European settlement, but has increased significantly over the past 150+ years of Oregon statehood. Tree sizes and size distribution can serve as indicators of changes to ecosystems and as indicators of the status of other organisms and ecosystem processes that are difficult to measure directly.

Map for download and viewing
Map showing tree sizes throughout Oregon
This map depicts Oregon’s forest coverage expressed as relative tree diameter sizes, ranging from shrubs and seedlings up to those trees greater than 30 inch diameter at breast height (DBH)
JPG version of the map - ( 3.1 Mb file)
Data description for this map 

Detail 'zoom-in' of central Oregon
Detail area of the Three Sisters region of central Oregon
A 'map zoom' provides additional detail of data for the Three Sisters area of the Cascade Mountain range.

Map of the zoom area
JPG version of the map - ( 4.5 Mb file)

Important information about Forest Atlas map products
Data for the Forest Atlas was compiled by staff with the Oregon Department of Forestry in 2010 using data generated by the U.S. Forest Service PNW Research Station in Corvallis, Oregon State University and the Oregon Department of Forestry.
This product is for informational purposes, and may not be suitable for legal, engineering or surveying purposes. This information or data is provided with the understanding that conclusions drawn from such information are the responsibility of the user.

Data contained within the map products does not necessarily reflect conditions at a fine-detail level.  Some data models rely on site information at least one year old. All information published herein is gathered from sources which are thought to be reliable, but the reader should not assume that the information is official or final, especially for the purposes of land use determination. The Oregon Department of Forestry does not assume responsibility for errors, and all research information contained within the website is subject to change without notice.
Additional information is contained in the liability notice 

Oregon's Forest Atlas main page 
2010 Forest Assessment and Resource Strategy project information 
Additional questions about Oregon's Forest Atlas 2010 can be addressed by the Oregon Department of Forestry's Agency Affairs Office.