Quaking aspen (Populus tremuloides) ecology on forest service lands north of Yellowstone National Park

The primary objective of this study was to determine if quaking aspen (Populus tremuloides) density and recruitment changed on the Gallatin National Forest north of Yellowstone National Park from 1991 to 2006. Three-hundred sixteen aspen stands were surveyed on the 560 km² study area. Secondary objectives were to determine if aspen density and recruitment were influenced by elk (Cervus elaphus) browsing, conifer establishment, and cattle (Bos spp.) grazing. A 202.3 m² circular plot was established within each stand. All aspen stems within each plot were categorized into size classes: sprouts (< 1 m), saplings (1-2 m), recruitment stems (> 2 m and < 5 cm diameter at breast height), and mature stems (> 2 m and > 5 cm diameter at breast height). Recruitment stems and mature stems have grown above the height at which elk generally browse. Recruitment stems have attained this height in the past 10-15 years.