PARENT SESSION
Poster Session #4: Invasions.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Assessing plant invasions from the landscape to the patch scale: Linaria vulgaris Mill. crossing Yellowstone National Park boundary.

Anibal, Pauchard¹, Paul, Alaback ¹, ¹

ABSTRACT- Ecologists have recently discovered that exotic plant invasions are a major threat to ecosystems worldwide. Since the invasion process is mediated by landscape-level phenomena such as dispersal and disturbance, it is critical to study invasions across a range in scales to elucidate causal mechanisms. The boundaries of protected areas represent a unique opportunity to understand the landscape dynamics of invasion. We documented Linaria vulgaris Mill. invasion at the landscape, population and patch scale in Yellowstone National Park and Gallatin National Forest near West Yellowstone. We found that L. vulgaris is invading preferentially human disturbed areas but increasingly invading pristine or naturally disturbed areas in harsh, high elevation sites. The species reaches densities of up to 200 plants/m² in dense patches and by vegetative reproduction can form solid patches in old clearcuts, riparian corridors, roadsides and naturally disturbed soils. The multiple scale approach indicates that the invasion process is at its early stages where much of the populations are located in heavily disturbed National Forest lands and satellite populations are establishing in Yellowstone National Park. Our data suggest that even high elevation protected areas may be susceptible to exotic plant invasion, especially when propagules sources exist in outlying areas.

KEY WORDS: protected areas, plant invasions, Linaria vulgaris, Yellowstone National Park