BOISE — Driving along most rural roads in Idaho, it’s hard to miss sagebrush — an iconic rangeland plant species with its characteristic spicy, bitter smell and gnarled wood.
But sagebrush is disappearing across the West.
Recent research reveals how the sagebrush landscape is being changed by humans, invasive species and wildfire.
“Sagebrush maintains a healthy grazing land for cattle, maintains the natural heritage of the West and it is habitat for animal species like sage grouse and pygmy rabbits. Sagebrush also plays an important role in the water cycle by trapping snow so that it slowly melts in the spring to support wildlife and plants,” said Trevor Caughlin in an interview with the Idaho Statesman. Caughlin is an assistant professor in the department of biological sciences at Boise State University.
The Great Basin is the largest desert in the U.S., covering 190,000 square miles from Badwater Basin in Death Valley in the south to Mount Whitney in the Sierra Nevada in the west to the Columbia Plateau in the north. It includes southern Idaho. This vast landscape covers a diverse range of climate and topography, making it difficult for scientists to separate how humans and the climate impact the landscape.
Today’s technology allows scientists for the first time to run computer models to show how humans are changing species distribution across the landscape, like sagebrush across the Great Basin.
In the Great Basin, wildfire has a profound effect on which species dominate a landscape — as much as temperature, precipitation and elevation, according to Caughlin.
“It is alarming that wildfires are as important for sagebrush cover and abundance as topography and climate in the Great Basin,” said Caughlin “So fires are overriding the natural habitat for sagebrush. Fires have the power to transform Western landscapes.”
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One species that thrives with range land wildfire is cheatgrass.
“Historically, sagebrush was the dominant plant across a million acres of range land. But as cheatgrass became more prevalent in the West, sagebrush has seen 50-60% reductions. Cheatgrass promotes wildfires, and cattle cannot eat it,” said Caughlin.
Cheatgrass is an invasive grass from Europe brought here by European settlers. Today it can be found dominating large swatches of the West. This dry, brown plant dries out faster than native vegetation, increasing wildfire spread. Cheatgrass in urban areas like the Boise Foothills can be a threat to pets and children because the dry, brittle grass can lodge itself in eyes as well as increase wildfire risk near homes.
Range land managers with state and federal agencies can use their computer models to specify where limited funds will have the biggest impact to restore sagebrush in the Great Basin.
“Using this information, we can have a better picture of where sagebrush will persist into the future and where more vulnerable habitats and populations are,” said Douglas Shinneman, supervisory research fire ecologist with the U.S. Geological Survey. “This model is a blueprint to identify places where conservation practices might be most important to where sagebrush is most viable and at most risk.”
With climate change, ecosystems will be changed by natural and human causes. In the Great Basin, precipitation and temperature patterns are predicted to shift, as will fire cycles.
“How much do we value these landscapes and the natural resources they provide and the wildlife they support?” asked Shinneman. “Sagebrush has been seen as boring drive-through land. But dozens of species depend on it for their existence, and hundreds more use it. Sagebrush is a more iconic part of the natural heritage of the West than cheatgrass.”