Death Valley National Park (DEVA) is a very large, 3.4-million-acre (1.4 hectares) unit of the National Park Service (NPS) located in California on the eastern border with Nevada. DEVA is the hottest, driest, and lowest of all the national parks in the United States and is the largest unit of the NPS in the lower 48 states. As its name implies, DEVA is a desolate and arid place. Contained within its borders are playas, broad alluvial fans, desert washes, sand dunes, volcanic formations, badlands, and mountain ranges. Although DEVA is known for its seemingly barren vistas, the vegetation at DEVA is actually quite diverse and widespread. Low and mid elevations support vast expanses of shrubs common to the Mojave Desert and Great Basin ecosystems. The vegetation at high elevations is robust and contains stands of pinyon/juniper woodlands and sub-alpine limber and bristlecone pine forests. Throughout the park are plant communities uniquely adapted to the various conditions that sort themselves into lifeforms mostly based on elevation, moisture, salinity, and substrates. To better understand and document the vegetation diversity at DEVA, the NPS, the National Vegetation Inventory Program (NVIP), and the NPS Mojave Desert Inventory and Monitoring Network (MOJN) opened a vegetation inventory effort here in 2010.
Work began in 2011 on a ten-year, six-phase project with the creation of a workplan that included a thorough legacy data review and plant community summary. In phase two, the NPS, California Native Plant Society (CNPS) in conjunction with researchers from the University of Nevada, Las Vegas (UNLV) collected 111 classification plots and 518 observation points across the landscape. Field data was then entered into the NVIP-specific PLOTS database along with an additional 1,242 samples from a variety of past studies. In phase three, CNPS analyzed the PLOTS data to classify 85 plant alliances using the revised U.S. National Vegetation Classification (rUSNVC) standard. From this list, 186 plant associations were estimated to occur at DEVA. During phase four, Cogan Technology, Inc. (CTI) created the digital vegetation map layer for the project area that covered 3,432,213 acres (1,389,016 hectares). In the accuracy assessment (AA) phase, contracted field crews collected data at 919 locations that were randomly placed by map class throughout the project area. In the final phase, CTI finalized the classification, reported the AA results, revised the final vegetation map, and delivered the final products to the NVIP.
The resulting spatial database and vegetation map layer were created using a combination of 2020 (California) and 2019 (Nevada) National Agriculture Imagery Program (NAIP) basemap data, ground-based verification efforts, and a two-step, or hybrid mapping approach that used both manual and automated techniques. By comparing the vegetation signatures on the imagery to the field data, 90 map units (74 vegetated and 16 land-use/land-cover) were developed and used to delineate the plant communities. The interpreted vegetation polygons were then digitized into a Geographic Information System (GIS) layer that was field-tested, reviewed, and revised. The final DEVA vegetation map layer was assessed for overall thematic accuracy at 82% with a Kappa value of 89%.
Products developed for DEVA are described and presented in this report and stored in the accompanying project digital files. Project deliverables include the final report, the spatial geodatabase, digital field photos, metadata, a classification report, and a field key to the vegetation alliances. For a full list of the DEVA NVIP products please visit the National Park Vegetation Inventory Product website.
