Invaders break assembly rules to beat the natives: How cheatgrass cheats
This study created plots of different native and invasive grasses to test the progression of species following a grassland disturbance.
Human interaction with U.S. forests and grasslands dates back well over 10,000 years, with our footprint growing as populations expanded. Our relationship with these lands has evolved to a point where both the direct and indirect influence of human activities is evident across nearly all landscapes. Invasive grass species threaten the health of grasslands and rangelands – and therefore our food supply.
A better understanding of how invasive annuals like cheatgrass dominate grassland ecosystems can help managers manage plant community trajectories following a disturbance. Explaining how some introduced plants become problematic pests while others simply become naturalized is a central question in invasion ecology. Scientists examined the differences in native, naturalized, and invasive plant behavior following a disturbance in a grassland ecosystem. Traditionally, faster growing annuals establish populations first, and then the area transitions to be dominated by slower growing perennials. Researchers found that invasive plants, like cheatgrass and Japanese brome, behave very differently and don’t follow this pattern.
During the study, both native and naturalized annuals stewarded the plant community through transitions – the annuals that established first actively facilitated the growth of perennial seedlings. In contrast, invasive annuals established and maintained robust populations and at high biomass while suppressing native perennial seedlings. Because of the high biomass, these invasive plants created much higher levels of litter. The researchers found that high litter levels were strongly related to the suppression of perennial seedlings.
Forest Service scientists are at the forefront of protecting forests and responding to forest health challenges through research. Forests and rangelands are vulnerable to environmental stresses such as fire, insect infestation, diseases, invasive species, and drought.