Page 76 - Mapping the Nation: Taking Climate Action

75 The data of each survey pass can be easily displayed on a map alongside the path the helicopter took and what was observed. "Southern Oregon, southern Idaho, and Utah have had a big problem with cheatgrass, but Nevada has had a cheatgrass invasion," Schroeder said. In winter, mule deer rely on brush sticking up out of the snow. When cheatgrass is present, native shrubs aren't, so deer have nothing to eat. The grass flourishes in Nevada's lower arid elevations, where it has altered ecosystems. "We've documented how cheatgrass changes the natural fire frequencies from 100- to 300-year cycles down to 3- to 5-year cycles," Schroeder said. "It used to be that fires in our ranges were rare, but now they burn over and over." Feral Horses Multiply, Squeezing Out Other had been a paper-based process, using buttons rather than entry fields to standardize observations. Using ArcGIS, notes and photos are tagged with position, and data goes right to a shared database. The time saved on data wrangling gives biologists a chance to reflect on and study the data to see trends. Species For mule deer and other species, the data supports queries about the cause of the decline. "We used GIS to map the overlap between where mule deer and feral horses are and their preferred habitat," Schroeder said. "We're also looking at other things that are impacting them, such as invasive grass, the drought, and where mountain lions cluster and have kills." The Cheatgrass Problem One of the most vexing problems that Nevada land managers face is the growing impact of cheatgrass (Bromus tectorum), a type of grass that steals water from native vegetation, which sprouted in large areas where big fires have burned sagebrush habitat. More than 80 percent of the land in Nevada is public, and much of it is managed by the Bureau of Land Management (BLM), which is responsible for herd management of burros and feral horses. BLM sets the appropriate management level of herds and works to keep populations down, noting that an appropriate number in Nevada would be 12,811. However, it estimates there were 42,994 horses and 4,087 burros as of March 2021 statewide. Schroeder teamed with David Stoner from Utah State University and other researchers on a paper about the impact of feral horses on other big-game species. The research involved the spatial analysis of the range of different species such as mule deer, bighorn sheep, elk, and pronghorn antelope overlapped with the range of feral horses. The paper noted that expanding populations of feral horses are a concern for all species. Researchers are using GIS to study how feral horses impact waterholes during drought and on land with little to no