Initial Invasion of Cheatgrass (Bromus tectorum) into Burned Piñon-Juniper Woodlands in Western Colorado

Abstract

We studied initial invasion of cheatgrass (Bromus tectorum) into burned pinon-juniper woodlands to determine: (1) if particular features enhance invasion and (2) if particular grasses promote or retard invasion. We compared cheatgrass cover among roads, burn edges, seeded interiors, unseeded interiors and unburned woodlands and quantified grasses present or absent near cheatgrass. Invasion was favored by burn edges, roads and seeded interiors, but not unseeded interiors. Odds of finding cheatgrass were seven times higher near prairie junegrass (Koeleria macrantha), but six times lower near James' galleta (Hilaria jamesii) and two times lower near intermediate wheatgrass (Agropyron intermedium). Invasion may be favored: (1) in burn edges because of higher seed-bank survival, (2) along roads because of moisture, disturbance and dispersal and (3) in seeded interiors because of seed-mix contamination or seeded species that enhance invasion.