Vegetation information for the Whiskeytown National Recreation Area Vegetation Inventory Project

Humboldt State University Sponsored Programs Foundation

Final report about the WHIS vegetation inventory project. This work was done in response to a Federal Government program to reduce risk to life and property by more effectively managing hazardous fire fuels. A crucial step of vegetation management is the production of a vegetation map. We mapped the Whiskeytown Unit of the Whiskeytown-Shasta-Trinity National Recreation Area. Vegetation was classified and mapped to the Association-Alliance level, the Alliance level and, for some classes, to the mixed alliance level to facilitate cross walk to fuel types. Recent advances in satellite imaging capabilities (1-meter spatial resolution) and pattern recognition software that considers neighborhoods of picture elements facilitated the compilation of this electronic map and database. The previously developed, vegetation classification at Whiskeytown National Recreation Area served as the basis for making the vegetation map. We modified this classification to reflect actual conditions in the study area. We produced three versions of the vegetation map of the Whiskeytown Unit. The Association-Alliance map offers maximum classification detail with 38 classes (31 plant associations, 5 alliances, 1 Disturbed class and a Barren class). Because we sometimes experienced confusion by the contextual classifier when defining associations, we aggregated to the alliance level (20 alliances, Disturbed, and Barren classes) and finally to an appropriately mixed alliance level of classes that we defined as “Mapping Units” (13 alliances, 3 mixed alliances called Mapping Units, and a combined Barren - disturbed class). Results of mapping at the vegetation association-alliance level indicated that two abundant classes covered 24 percent of the landscape: the Canyon live oak/whiteleaf manzanita association and the Mixed conifer alliance in near equal proportion. Six classes covered between 5 and 9 percent each for a total of 44 percent of the land area. The remaining thirty classes were rarer, covering 32 percent of the land area. In the alliance level map, four alliances (Canyon live oak forest, Ghost pine woodland, Mixed conifer forest, Ponderosa pine forest) covered between 11 and 17 percent of the landscape each for a total of 56 percent of the land area. Another four alliances covered between 5 and 9 percent of the landscape for a total of 30 percent. The remaining 14 least abundant alliances covered 14 percent of the land area. In the Mapping Unit level map, four Mapping Units (Canyon live oak forest, Ponderosa pine forest, Mixed conifer forest, Mixed pine – mixed oak) covered between 11 and 24 percent of the land area each for a total of 64 percent of the landscape. The remaining ten, less abundant Mapping Units covered 14 percent of the land area. In order to assess the accuracy of the vegetation map that we have compiled for the Whiskeytown Unit, we sampled the mapped vegetation polygons in the field. A sampling protocol is provided as required by this Task Agreement. We allocated approximately 500 plots according to the NPS standard allocation percentages, producing a plot distribution that considers class abundance such that more abundant classes receive more sample plots. This protocol assumes a production rate of approximately 10 plots per day and a budget to cover approximately 50 days.

Vegetation information for the Whiskeytown National Recreation Area Vegetation Inventory Project

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