Applying GIS analysis to herbarium georeferencing

In March 2005 the Oregon State University Herbarium launched its new, free online Oregon\ud Vascular Plant Atlas for public use. This Atlas allows users to access location information\ud from over 385,000 vascular plant specimen and observation records in the state of Oregon.\ud The potential applications of such spatial information are almost limitless; users can examine\ud the spatial relationships between plants and a variety of environmental variables within plant\ud communities (soils, precipitation, elevation etc.). The maintenance and accuracy of this\ud database is therefore critically important in order to provide the highest quality information\ud to Atlas users. Several projects were identified to increase the accuracy and precision of the\ud Plant Atlas spatial data including: (1) correction of points with mismatched township/range\ud and county information, (2) comparison of Oregon State University (OSU) Herbarium and\ud Oregon Natural Heritage Information Center (ORNHIC) georeferencing results, (3) creation\ud of quarter section and quarter-quarter section location names, and (4) analysis of elevation\ud information using digital elevation models. These projects were completed using geographic\ud information system (GIS) software, as well as Microsoft Access data management software.\ud New location names, or LocNames, were created for township/ranges bisected by county\ud lines, increasing the accuracy of the referenced location. LocNames were also created for\ud specimens with quarter section and quarter-quarter section information. These combined\ud projects resulted in the creation of 1,876,587 new location names. Analysis of the ORNHIC\ud and OSU Herbarium georeferencing results showed the majority of points were similarly\ud georeferenced, however, one-third had some quality issue. Finally, the quality of the\ud elevation information stored in the Vascular Plant Atlas database was shown to include\ud potential data entry conflicts between meters and feet, as well as potential georeferencing\ud problems. The results of these projects will help increase the accuracy of georeferenced\ud specimen locations, as well as provide important information to help herbarium staff identify\ud areas of needed quality control