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This point data set represents both where Oregon White Oak has been detected as well as where there is no significant oak presently detected. We placed points where we were confident the tree canopy was Oregon white oak. The points do not necessarily represent individual oak trees. We were conservative because we didn’t want to portray false positives, therefore we likely omitted some small oaks, mixed forest oaks where oak was mostly overtopped by conifers, and some individual trees that we were not certain were oak.
Extent
This release, OakQuest 2020, of The Intertwine Alliance's OakQuest data incorporates new data from southwestern Washington and previous releases from 2016-18 plus minor edits to previous data releases. With this 2019 release, we consider the whole of the Oregon and Washington portions of the RCS planning area within which Oregon white oak was historically prominent, complete. The oak data show concentrations of oak as well as areas where oak is likely very sparse or absent.
This “full coverage” area of 1,790 sq. miles of northwestern Oregon and 375 sq. miles of southwestern Washington shows portions of the landscape where oak was mapped using a combination of aerial photo interpretation and limited field work. This “full coverage” area documents the search area within which oak were identified with high confidence and/or determined absent with moderate to high confidence. Across this full coverage area we have high confidence that oak is present where mapped and we believe that few or no significant stands of oak were missed. The additional 699 sq. miles within the RCS boundary beyond the full coverage areas has been spot-checked for oak but not searched thoroughly due to habitat conditions deemed not conducive to oak, e.g. areas above approximately 1,000 ft. elevation. Clark County partners may decide to expand their mapping extent in the future if it is determined that some unmapped areas may contain oak; although not likely necessary, if needed such adjustments can be made on the Oregon side as well in future data releases.
Methods
Version I of the OakQuest data was developed from field observations and inspection of high-resolution aerial photography in GIS, as well as other records checked and compiled from existing regional tree inventories in 2014 which included available street, heritage, and other regional tree inventories. During July-Oct 2014 and August-November 2015, community volunteers and natural resource professionals collected field observations of oak and other tree species using a custom smart phone app. Data collected in the field were later spatially adjusted and error-checked within ArcGIS. During inspection of oak field observations with aerial photos in ArcGIS, Metro staff developed an eye for spotting Oregon white oak and additional oak trees visible in high-resolution aerial photography were digitized. Data were converted to a common projected coordinate system and observations were coded by source and category of origin.
Data release versions II and III included additional full coverage areas beyond Version I, including urban and rural areas, for approximately 824 sq. miles and 766 sq. miles of the Oregon portion of the Intertwine Alliance RCS planning area, respectively. For portions of the region where high-resolution Metro or NAIP aerial photography was available, we used heads-up digitizing of points representing Oregon white oak tree canopy centers in ArcGIS. In outlying rural areas where Metro or NAIP aerial photos were not available, we used heads-up digitizing of oak tree canopy centers over Google and Bing aerial photography in Quantum GIS.