Mapping Vegetative Change

This article was originally published in The Midden – Great Basin National Park: Vol. 25, No. 1, Summer 2025.

Figure 1. View from Snake Valley of snow-covered Doso Doyabi and Wheeler Peak, with Strawberry Canyon on the right. NPS/M. Horner

by Meg Horner, NPS Biologist

Look up at the South Snake Range from Snake Valley and changes in the vegetation growing on the mountain side may not be obvious, especially if your view of Doso Doyabi or Wheeler Peak is new or brief (Figure 1). But changes are happening. Some are subtle like the change in needle color of conifers stressed or killed by insects. Some are more dramatic like the immediate change that comes after a wildfire. Other changes are harder to see because of their scale or location. We can visualize all these changes with the help of satellite imagery, remote sensing, and mapping vegetation at a broad scale.

To map vegetation and measure change, the park partnered with The Nature Conservancy (TNC). This partnership started almost 20 years ago when TNC produced the first vegetation map for Great Basin National Park. We partnered with them again in 2022 to expand the study area to lands outside the park and look at changes in park vegetation since the first mapping effort (Figure 2).

Figure 2. Vegetation map of Great Basin National Park and surrounding lands (2024). The Nature Conservancy

Between 2007 and 2022, a significant portion of the park’s vegetation appeared to change. Some changes were simply differences in the way vegetation was categorized or labelled like when the name of a plant species changed. Other changes were what we called ‘true change’ (Figure 3). A few examples of true change include expected changes a plant community experiences in composition and structure as they age; localized, and sometimes drastic, change from wildfire; and the result of deliberate manipulation of vegetation through active management like prescribed fire.

Figure 3. True vegetative change in Great Basin National Park from 2007-2022, shown in orange. Recent fires are outlined in black. NPS/M. Horner

Figure 4. Map showing invasive cheatgrass in yellow growing at the north end of Great Basin National Park, in the Strawberry Fire boundary, and near the south end of the Park, in the Granite and Black Fire boundaries. NPS/M. Horner

Recent large fires, like the 2016 Strawberry Fire, were captured in satellite imagery as dominant vegetation changed over a short period of time and continued to change as the area recovered. Remote sensing and interpretation of imagery described the details of these changes.

For the Strawberry Fire, some of the most noticeable change was an increase in annual species – cheatgrass in this case (Figure 4). Mapping highlighted other issues harder to see from the ground like the loss of aspen, a fire adapted species (Figure 5). The park has lost aspen clones in some areas because of fire exclusion – giving even more urgency to reintroduce fire to the landscape to prevent further loss of ecologically and aesthetically important vegetation.

Figure 5. Map of Great Basin National Park showing where aspen have disappeared (in green) from 2007-2022. The boxes highlight several areas of the Park where this has occurred. NPS/M. Horner

Comparing the same landscape at two different time periods reveals management challenges. But it also highlights opportunities for restoration, fuels reduction and prescribed fire projects, and helps the park prioritize where to work. As with all modeling and remote sensing exercises, it can only get us so far. Making informed decisions requires getting out into the field to properly plan and implement successful management and restoration.

This project was funded by the Bureau of Land Management SNPLMA (Southern Nevada Public Land Management Act) Program.

Part of a series of articles titled
The Midden – Great Basin National Park: Vol. 25, No. 1, Summer 2025.

Previous:
Uncovering the Patterns and Processes of Plant Life on Great Basin Summits

Next:
Cave Climates of Great Basin National Park

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