Vegetation inventory project report, Lake Roosevelt National Recreation Area

Erixson, John; Cogan, Dan

The NPS Vegetation Inventory Program (NVIP) funded an effort, beginning in 2006, to inventory and document (map) the vegetation to better understand the plant community distribution at LARO. The Upper Columbia Basin Inventory and Monitoring Network (UCBN) coordinated the LARO vegetation inventory effort as part of a network-wide project. A four-year, four-phase program was initiated to complete the tasks of sampling, classifying, and mapping the vegetation types within LARO. Phase-one, directed by UCBN staff in conjunction with Northwest Management Incorporated (NMI) and the Idaho Conservation Data Center (ICDC) resulted in the plant association and alliance classification using the National Vegetation Classification System (NVCS). Classification was based on new, 2007 sampling efforts resulting in 431 representative classification plots and 47 observation points located within LARO. Analysis of the classification plot data by ICDC ecologists occurred in late 2008. Through this process 81 distinct plant associations were identified. Vegetation descriptions and a field key for each association are included as appendices to this report. Phase-two, directed by NMI and Cogan Technology, Inc. (CTI) resulted in the digital vegetation map and geodatabase. Mapping was conducted primarily on 2009 National Aerial Imagery Program (NAIP) products supplemented by 2002 imagery obtained from the Bureau of Reclamation (BOR). Interpreting the vegetation-specific signatures from the new imagery, CTI reliably discerned 33 vegetation, 18 land use/land cover, and five geology/sparse vegetation map units. The mapping process used primarily manual digitizing of the homogenous photo-signatures supported by on-site verification. All interpreted data were converted to Geographic Information System (GIS) databases using ArcGIS© software. The final map layer contains vegetation, land-use, and geologic exposure polygons with corresponding map class, NVC, and modifier attributes. Draft maps were printed, field tested, reviewed, and revised. Following verification, edits were applied to create the final vegetation map product for accuracy assessment (AA). In Phase-three the AA was conducted by NMI ecologists in 2009 by placing 709 random point locations throughout the study area based on frequency and abundance of the vegetation map units. AA locations were accessed by NMI field crews, the vegetation at the targets was keyed to the proper association, and representative photographs of each location were acquired. The field data were compared to the electronic vegetation map and following the final assessment revealed an overall thematic accuracy of 82%. Completion of the project in Phase-four included producing the standard project deliverables as described and presented in this report.

Vegetation inventory project report, Lake Roosevelt National Recreation Area

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