Fig. 4

A conceptual model of the changes in fuel types over time in sagebrush-dominated ecosystems that are not experiencing pinyon-juniper expansion. Increases in shrub fuels over time occur due to a combination of succession, fire suppression, or livestock grazing and may result in decreases in perennial native grasses, perennial native forbs, and annual native forbs. In warmer and drier ecosystems with relatively low resilience and resistance, perennial native grasses and forbs decrease while invasive annual grasses increase. Ecosystems with high levels of shrub and/or invasive annual grass fuels are at risk of transitioning to alternative states dominated by the invaders after wildfires or management treatments that remove shrubs as indicated by the shaded area