View thesis.
Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank may compromise site resiliency. During disturbances that disrupt current vegetation, a reduction in recruitment from the seed bank could cause the site to be more vulnerable to colonization by weedy species or could lead to a reduction in the amount of cover protecting the soil surface and thus increase site susceptibility to erosion. This research evaluated the effects of the relative abundance of J. occidentalis on the soil seed bank. Questions addressed were: 1) is species richness negatively correlated with J. occidentalis cover; 2) does the diversity of weedy species increase along a gradient of J. occidentalis cover; and 3) does seed density decrease as J. occidentalis cover increases?