Vegetation Inventory Project: Oregon Caves National Monument and the Proposed Expansion Area

Odion, Dennis; DiPaolo, Dominic; Groshong, Lorin; Starr, Daniel; Mohren, Sean

The National Park Service Vegetation Inventory Program funded an effort, beginning in 2009, to classify and map the vegetation at Oregon Caves National Monument and its proposed expansion area (inclusive of the headwaters of Cave and Lake Creeks). Southern Oregon University staff performed the inventory work. The Klamath Network, Inventory and Monitoring Program coordinated the effort. To classify the vegetation, we sampled 142 representative classification plots throughout the 1,820.8 hectare (4,499.3 acre) project area using traditional phytosociological methods (i.e., relevé sampling). The relevé plots were located and sampled primarily in 2009 and 2010. We identified 397 different vascular plant species in the classification plots, including many that were not previously recorded on the monument’s species list. We classified the plot data into 34 plant associations using accepted statistical analyses. A key to the plant associations and description of each association are provided in Appendices B and C of this report. Mapping of the vegetation polygons was completed via manual digitizing using the most recent National Agriculture Imagery Program (NAIP) imagery. A number of plant associations could not be separated based on unique photo-signatures in the imagery or because they were spatially intermixed forming physiognomic vegetation classes (equivalent to complexes and mosaics). Based on this analysis we therefore defined 19 physiognomic vegetation mapping classes. The map also captures management activities in the year in which they occurred. These activities included major forest vegetation manipulations such as clear-cutting and plantation establishment. The percent cover attribute for the primary and secondary (if present) vegetation in each polygon was added and coded. The final map product is a geographic information system (GIS) database with far greater descriptive power than the predefined areal units of a standard chloropleth map, and it can also be generalized into a standard map. We conducted the accuracy assessment (AA) in 2011 by placing 444 stratified random accuracy assessment plots throughout the project area. The field data were compared to the vegetation map resulting in an overall thematic accuracy (area weighted) of 80.4%.