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Cheatgrass (Bromus tectorum) invasion 

Cheatgrass is one of the most problematic weeds of the western United States, especially in the Great Basin. Invaded areas are most conspicuous after flowering when the plants have a reddish hue. This annual grass is problematic because it displaced native species, is not a desirable forage species, and produces a continuous fuel cover thought to cause more intense and frequent fires. This change in the fire cycle is especially problematic for Wyoming big sagebrush (Artemisia tridentata), a keystone species in many invaded areas, which does not resprout following fire and can take decades to re-establish.

The 55,000 acres at the Fort Keogh Livestock & Range Research Laboratory in eastern Montana, where these pictures were taken, typically have relatively low levels of cheatgrass. Instead, Japanese brome (Bromus japonicus), another non-native brome, is more typical but less of a management concern. However in 2009, we observed much greater amounts of cheatgrass. Weather conditions appeared ideal for cheatgrass establishment this year. The interactive panorama below shows one of the most heavily invaded areas on Fort Keogh. Some of the invaded patches are shown with arrows. Because of the dry conditions, the red coloring of the cheatgrass was already dissipating as the plants cured. A couple of years ago a prairie dog town was located here. They disappeared completely from this site, probably from sylvatic plague. Now the site is heavily invaded by cheatgrass. I suspect the prairie dogs altered the site in ways that facilitated invasion by cheatgrass.

This is an interactive panorama represented as a QuickTime VR movie. Click and drag the mouse to pan and tilt the view. Depress the shift and control keys to zoom in or zoom out.