As part of the Oregon Gap Analysis Program, ORBIC worked with the Defenders of Wildlife and Jim Strittholt to develop the first statewide map depicting historical vegetation. Scale varies throughout the coverage, depending on the source data, but the overall scale is 1:100,000. The map was first compiled in 1999 and is updated as needed. It integrates several sources of historical spatial data:

1. The Andrews and Cowlin timber maps for Oregon and Washington (1936-1937, digitized by USFS 1994-1996, scale = 1:253,440), 
2. GLO-based  coverage where available (compiled 1994-present by ORBIC and partners, scale = 1:24,000), 
3. NRCS SSURGO data (scale = 1:24,000), and 
4. Current land cover mapping from the USDI Bureau of Land Management (BLM).

The Andrews and Cowlin layer forms the background into which more detailed coverages were incorporated. It was mapped to forest type, with a secondary classification for young forests. Because the layer lacked detail for non-forest vegetation, ORBIC supplemented the data with more detailed information contained in the sources cited above. Because SSURGO data present potential vegetation based on soil types, they were used to replace post-settlement land cover types such as agriculture or urban occurring on well-defined riparian and floodplain soils. Where SSURGO data were not available, these types were replaced with potential pre-settlement vegetation based on the composition of adjacent polygons, and the presence of rivers and streams for riparian areas and bottomlands. Recent burns and regenerating young forests were reverted to forest. 

Download the Oregon Statewide Composite Historical Vegetation map. It is also posted on the Available Historical Maps page.

 

INR and its partners have created maps of historical vegetation and stream networks for portions of the Pacific Northwest, based on interpretation of public land survey records of the federal government's General Land Office (GLO), and, where available, U.S. Coast Survey topographic maps ("T-Sheets"). The maps depict vegetation at coarse scale (forest, woodland, savanna, prairie) and finer scale (species assemblages). In some areas where historical stream networks were altered by later agricultural and urban development, we mapped stream alignments as delineated at the time of survey.

See the pages below for use and interpretation of GLO data, links to spatial data, history, and other resources. You can also navigate through these pages using the menu at right.

• Beyond Land Surveys: Use of GLO Survey Data in Ecology and History
• Current coverage
• Available Historical Vegetation Maps
• Reports
• Methods and Vegetation Classification
• Books - Regional and General
• GLO Online Resources -- Pacific Northwest
• Acknowledgements

Established in 1812, the federal General Land Office (GLO) was charged with surveying public lands belonging to the federal government, and then conveying these lands to state or private ownership. Land surveyors, under contract with GLO, were required to follow specific survey instructions. These methods were developed first for Ohio in 1785, and refined over the decades as federal land surveys progressed westward to the Pacific Coast. The surveys created the familiar rectangular grid of townships and ranges, now called the Public Land Survey System (PLSS), that covers 30 states. In 1946, the GLO was merged with the U.S. Department of the Interior's Grazing Service to form the Bureau of Land Management (BLM).

Photo courtesy USDI Bureau of Land Management, Oregon State Office

The GLO surveys created a more or less consistent dataset spanning 200 years and covering nearly 1.5 billion acres. Since the 1920s, ecologists, historians, and others have used GLO records as a source of information on landscape condition and settlement as seen at the time of survey:

• Land surveyors routinely use historical GLO data because it is the foundation of all land ownership records, and all land survey lines are interconnected.
• Ecologists and Botanists use GLO survey lines as a grid of transects, along which surveyors recorded changes in vegetation, and information about trees and shrubs every half mile. They also had to record information at random points where lines intercepted trees, rivers, streams, lakes, and other natural features. Notes on streams and rivers often included depth, current, alluvium, and condition of the banks. Witness tree data are particularly useful in assessing historical stand density, fire history, and species distributions. They are being used to restore plant community structure, species composition, and ecological processes (see Witness Trees below).
• Historians use the GLO grid in a similar way to ecologists, because surveyors were required to record where lines intercepted man-made features such as roads, fencelines, farmyards, and towns. Surveyors routinely recorded distances and compass bearings to prominent buildings that were visible along the survey lines. These records have been used to relocate early settlements, support claims to water rights, and validate early census records. GLO users of any stripe also often are drawn to its history because they inevitably wonder who the surveyors were, what they saw, and how they did their work without roads, electronic survey equipment, chainsaws, and even maps.

The landscape described in GLO notes has often erroneously been called "presettlement," implying pristine ecosystems untouched by human hands, but in most places surveyors saw lands shaped by at least 10,000 years of occupation and management by native peoples.

Witness Trees

When trees were available in the landscape, GLO survey instructions called for two witness trees at quarter corners and at river crossings ("meander posts"), and four witness trees at section corners. When survey crews established corners, they marked them with wooden posts, rocks, or pits and mounds of soil. They then recorded compass bearings and distances to selected witness trees, and recorded the species and diameters of the trees. On each tree they cut away a patch of bark, and scribed the wood beneath with the appropriate township and range number.

Species of trees were often selected subjectively for durability, their known resistance to decay. This was done to ensure that the marked "witness" to the established survey corner would last as long as possible. In durable trees, the scribed area would heal over, leaving a scar ("cat face") on the trunk. These scars are often used to relocate survey corners, and the bark can be cut away to reveal the preserved scribe marks beneath (see photos below).

Witness tree selection is one element of uncertainty when reconstructing historical vegetation based on GLO data. Surveyors probably selected trees for a variety of reasons, including the species' durability, its ease of scribing, or simply because it was within easy reach. Therefore, ecologists cannot be certain that the species selected, its diameter, or its distance from the corner reflected characteristics of the stand of trees as a whole at the time of survey. Using witness tree data, species recorded along the section line, and species recorded in the "general description" recorded at the end of each section line, ecologists can make general inferences about stand composition and structure. However, an element of uncertainty remains and is an inherent part of working with historical data.

Scar or "cat face" on a witness tree established in 1884, prior to removal of the bark. Photo courtesy of Larry Marshik, Marshik & Associate

Witness tree with scar cut away, revealing scribe marks made when corner was established in 1884. Photo courtesy of Larry Marshik, Marshik & Associates.

Dominion Land Survey

Canada's Dominion Land Survey System (DLS) is the standard government survey system used from Manitoba west to British Columbia. Begun in 1871, it was based on American GLO/PLSS methodology. The two survey grids adjoin along the international border. Although there are some differences (courtesy Province of Saskatchewan) between the two systems, the DLS will be instantly recognizable to those familiar with GLO surveys. Much of the discussion on these web pages can also be applied to the DLS.

Historical vegetation maps are availabe for the gray shaded areas shown below. Red townships are in production. (Last updated December 2017)

 

• Downloadable Maps
• Mapping Methods

 

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Go to section:
Oregon
Washington

 

DISCLAIMER FOR GLO VEGETATION MAPS

Maps of historical vegetation are for planning and research purposes only. They are only estimates of the original occurrence, location, and extent of vegetation types and wetlands. They do not necessarily include all landscape features that may have been present historically, and the features may not be mapped in their correct historical locations or configurations. The maps should not be used as a substitute for current wetland determinations or delineations performed by a qualified wetland specialist. As a general rule, small landscape features usually are under-represented and consequently have artificially low acreages. Per current Federal and Oregon Wetland Mapping Standards, the mapping of historical wetlands is "neither designed, nor intended, to support legal, regulatory, or jurisdictional analyses of wetland mapping products, nor does it attempt to differentiate between regulatory and non-regulatory wetlands." Mapping of historical wetlands is also not intended to be a hydrography dataset, and it should not be used to infer hydrologic connectivity, or lack thereof, between wetland polygons. 

 

OREGON

Oregon Statewide Composite Historical Vegetation

Historic Vegetation, Oregon (1938). Tobalske, C. 2002. Historic Vegetation. Source: Oregon Natural Heritage Program, 1:100,000. Shapefile: 60 MB.

orstatehistoricveg_sm.jpg

General Land Office (GLO) and U.S. Coast Survey

Click on the thumbnails below for a preview of the maps. Click on the map citations to download the maps. These are ZIPped (compressed) GIS shapefiles. You will need to uncompress the files and use shapefile-viewing software to view and use the data. There are free spatial tools available from ESRI.

 

 

Deschutes National Forest Christy, J.A., L. Riibe, E. Blue & G. Davidson. 2016. GLO historical vegetation of Deschutes National Forest, 1865-1932. ArcMap shapefile, Version 2016_11. Oregon Biodiversity Information Center, Portland State University.
Eastern Columbia Gorge, Eastern Slope Mount Hood Christy, J.A. 2010. GLO historical vegetation of eastern Columbia River Gorge and east slope of Mount Hood, Oregon, 1859-1939. ArcMap shapefile, Version 2010_12. Oregon Biodiversity Information Center, Portland State University.	glo_gorge_12_09.jpg
Harney Basin Vegetation Christy, J.A. 2013. GLO historical vegetation of the Harney Basin, Oregon, 1873-1915. GIS shapefile, Version 2013_03. Oregon Biodiversity Information Center, Institute for Natural Resources, Portland State University. Streams Christy, J.A. 2013. GLO historical stream alignments in the Harney Basin, Oregon, 1873-1915. GIS shapefile, Version 2013_03. Oregon Biodiversity Information Center, Institute for Natural Resources, Portland State University.	glo._harney_basin.jpg
Oregon Coast Hawes, S.M., J.A. Hiebler, E.M. Nielsen, C.W. Alton, J. A. Christy, P. Benner. 2018. Historical vegetation of the Pacific Coast, Oregon, 1855-1910. ArcMap shapefile, Version 2018_01. Oregon Biodiversity Information Center, Portland State University.	glo_coast_sm.jpg
Klamath Basin Christy, J.A. 2006. GLO historical vegetation of Williamson River delta and southern Klamath Basin, Oregon, 1858-1898. ArcMap shapefile, Version 2006_02. Oregon Natural Heritage Information Center, Oregon State University.	glo_klamath_sm.jpg
Rogue Valley, Lower Applegate, Upper Illinois Valley Hickman, E. & J.A. Christy. 2012. GLO historical vegetation of central Rogue, lower Applegate, and upper Illinois Valleys, Oregon, 1854-1919. ArcMap shapefile, Version 2012_02. Oregon Biodiversity Information Center, Portland State University.	glo_rogue_10_09_sm.jpg
Sycan Marsh (Lake and Klamath Counties) Christy, J.A., M.P. Dougherty & S.C. Kolar. 2007. GLO historical vegetation of Sycan Marsh, Oregon, 1865-1898. ArcMap shapefile, Version 2007_11. Oregon Natural Heritage Information Center, Oregon State University.	glo_sycan.jpg
Umpqua Valley Vegetation Christy, J.A & Hawes, S.M. 2009. GLO historical vegetation of the Umpqua Valley, Oregon, 1851-1917. ArcMap shapefile, Version 2009_07. Oregon Natural Heritage Information Center, Oregon State University. Streams Christy, J.A & Hawes, S.M. 2003. GLO Historical stream alignments in the Umpqua Valley, Oregon, 1851-1917. ArcMap shapefile, Version 2003_12. Oregon Natural Heritage Information Center, Oregon State University.	glo_umpqua.jpg
Willamette Valley and Columbia River Floodplain Vegetation Christy, J.A., E.R. Alverson, M.P. Dougherty, S.C. Kolar, C.W. Alton, S.M. Hawes, L. Ashkenas & P. Minear. 2011. GLO historical vegetation of the Willamette Valley, Oregon, 1851-1910. ArcMap shapefile, Version 2011_04. Oregon Biodiversity Information Center, Portland State University. Streams Christy, J.A., E.R. Alverson, M.P. Dougherty, S.C. Kolar, C.W. Alton, S.M. Hawes, L. Ashkenas & P. Minear. 1999. GLO Historical stream alignments in the Willamette Valley, Oregon, 1851-1910. ArcMap shapefile, Version 1999_12. Oregon Natural Heritage Information Center, Oregon State University.	glo_willamette.jpg

WASHINGTON

General Land Office (GLO) and U.S. Coast Survey

Vegetation Christy, J.A. 2015. GLO historical vegetation of southwestern Washington, 1853-1910. ArcMap shapefile, Version 2015_02. Oregon Biodiversity Information Center, Portland State University.	glo_sw_wa.jpg
Streams Christy, J.A. 2013. GLO historical stream alignments in southwestern Washington, 1855-1910. ArcMap shapefile, Version 2013_06. Oregon Biodiversity Information Center, Portland State University.

 

 

Mapping Methods and Vegetation Classification

Back to GLO Introduction Page

The following are available reports relating to the GLO Historical Mapping Project. Click on the title of the report to download the file. 

OREGON

Douglas County

Hickman, O.E. & J.A. Christy. 2014. Historical vegetation of the Tiller Area, Douglas County. Report to Douglas County Commissioners. 82 pp.

Rogue Valley, Lower Applegate, Upper Illinois Valley

Hickman, O.E. & J.A. Christy. 2011. Historical vegetation of central southwest Oregon, based on GLO survey notes. Final report to USDI Bureau of Land Management. Medford District, Oregon. 124 pp.

Willamette Valley and Columbia River Floodplain

Christy, J.A. & E.R. Alverson. 2011. Historical vegetation of the Willamette Valley, Oregon, circa 1850. Northwest Science 85: 93-107.

 

SYNOPSIS OF METHODS USED TO MAP HISTORICAL VEGETATION IN OREGON AND WASHINGTON, BASED ON GENERAL LAND OFFICE SURVEY NOTES.

• • • John A. Christy, Oregon Biodiversity Information Center, Institute for Natural Resources, Portland State University and Edward R. Alverson, The Nature Conservancy of Oregon. December 2011. 

 

 

CLASSIFICATION OF HISTORICAL VEGETATION IN OREGON AND WASHINGTON, AS RECORDED BY GENERAL LAND OFFICE SURVEYORS

• • • John A. Christy, Edward R. Alverson, Molly P. Dougherty, Susan C. Kolar, Clifford W. Alton, Susan M. Hawes, Gene Hickman, Jennifer A. Hiebler, Eric M. Nielsen. Oregon Biodiversity Information Center, Institute for Natural Resources, Portland State University. November 2016. 

 

 

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These books provide insights on how GLO surveys were made, why they were made, and who did the original work. Links to online sources or ordering information are provided where they could be found.

OREGON AND WASHINGTON
cover_chaining_oregon_web.gif	Atwood, K. 2008. Chaining Oregon, Surveying the Public Lands of the Pacific Northwest, 1851-1855. McDonald and Woodward Publishing Co., Blacksburg, Virginia. 264 pp. Available in local bookstores or direct from McDonald and Woodward Publishing.
cover_white_glo_history001.gif	White, C.A. 2001. A Casebook of Oregon Donation Land Claims. Professional Land Surveyors of Oregon. LLM Publications, Oregon City, Oregon. 240 pp.
BRITISH COLUMBIA
madetomeasure_sm.jpg	Gordon, K. 2006. Made to Measure: A History of Land Surveying in British Columbia. Sono Nis Press, Winlaw, British Columbia. 373 pp.  Available in local bookstores or direct from Sono Nis Press.
GENERAL
cover_white_initial_points001.gif	White, C.A. 1996. Initial Points of the Rectangular Survey System. Professional Land Surveyors of Colorado. The Publishing House, Westminster, Colorado. 576 pp.
cover_white_glo_history001.gif	White, C.A. 1991. A History of the Rectangular Survey System. USDI Bureau of Land Management. 2nd printing. Stock No. 024-011-00150-6. Government Printing Office, Washington, D.C. 774 pp.
cover_running_line_web.gif	Bandy, W.R. & G.R. Haste. 1991. Running Line, Recollections of Surveyors. USDI Bureau of Land Management BLM/SC/GI-91/001+9600. U.S. Government Printing Office. 66 pp.
cover_sur_sur_pub_dom_1976_web.gif	Cazier, L. 1976. Surveys and Surveyors of the Public Domain, 1785-1975. USDI Bureau of Land Management. Stock No. 024-011-00083-6. Government Printing Office, Washington, D.C. 228 pp.

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GLO (Public Land Survey System, or PLSS)

OVERVIEW

• Overview, Oregon -- see Loy et al. (2001), Atlas of Oregon : 18-19. [Not available digitally].

SURVEY NOTES AND PLAT MAPS

• Oregon and Washington -- BLM
• Other states -- BLM
• Oregon Plat and DLC maps -- University of Oregon Library
• USGS quad maps with GLO annotations for Klamath region -- Oregon Institute of Technology

 

U.S. Coast Survey

Topographic maps ("T-sheets") of the U.S. Coast Survey (later called U.S. Coast and Geodetic Survey, and more recently the National Geodetic Survey) have been integrated whenever possible with GLO data because of the data-rich detail they impart to map products. They were based on meticulous field mapping conducted between 1852 and 1889. Cartography of the Coast Survey maps was superior to that of the GLO township plat maps, and when georeferenced, is substituted for linework shown in the plat maps. 

The Coast Suvey maps provide highly accurate delineations of small-patch vegetation and stream alignments at a level of detail not possible from GLO data, while the GLO data provide information on vegetation, streams, and cultural features that are not available from Coast Survey data. When combined, the two sources of information provide high-quality cartography on the composition and extent of various vegetation types at the time of survey.

Land cover symbology used in the Coast Survey maps was interpreted by Shalowitz (1964) and Graves et al. (1995), and provides important detail in vegetation structure and hydrology.

OREGON

• Lower Columbia River (University of Washington)

WASHINGTON

• Lower Columbia River (University of Washington). Georeferenced T-sheets and landcover maps digitized from T-sheets.
• San Juan Islands (Tom Schroeder)

 

Regional GLO and Other Historical Vegetation Websites

OREGON

• Blue Mountains (David Powell, U.S. Forest Service, Umatilla National Forest)

WASHINGTON

• Blue Mountains (David Powell, U.S. Forest Service, Umatilla National Forest)
• San Juan Islands (Tom Schroeder) 

 

History of Surveying

• Virtual Museum of Surveying
• Washington -- Olson Engineering
• BLM National Office -- Cadastral History
• Principal Meridian Project
• University of Oregon Map Library -- GLO Resources
• Surveyors Historical Society

 

Professional Surveyors Associations in Pacific Northwest

• Idaho -- Idaho Society of Professional Land Surveyors
• Oregon -- Professional Land Surveyors of Oregon
• Washington -- Land Surveyors' Association of Washington
• British Columbia -- Association of British Columbia Land Surveyors 

 

References

• Shalowitz, Aaron L., and Michael W. Reed. Shore and Sea Boundaries. Office of Coast Survey, 1964.
• Graves, Jon K., John A. Christy, Patrick A. Clinton, Peter L. Britz. Historic Habitats of the Lower Columbia River. Astoria: Columbia River Estuary Study Taskforce, 1995.

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We thank the Oregon State Office of the Bureau of Land Management (BLM) for freely providing ongoing access to GLO data and expert advice from its cadastral survey staff.

Since 1994, funding for various portions of this project has been provided by:

• City of Portland
• Lower Columbia River Estuary Partnership
• Metro
• Oregon Community Foundation
• Oregon Department of Fish and Wildlife
• Oregon Department of State Lands
• Oregon Watershed Enhancement Board
• The Nature Conservancy
• USDI Bureau of Land Management (Eugene District, Medford District, Roseburg District, Salem District, Oregon State Office)
• U.S. Environmental Protection Agency
• USDA Forest Service