PARENT SESSION
Poster Session # 14: Forest Ecology.
Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Variation in sky exposure and establishment of conifer seedlings at the alpine-treeline ecotone across three ranges in the Rocky Mountains.
Maher, Eliza *,1, Germino, Matthew1, 1 Idaho State University, Pocatello, ID, USA
ABSTRACT- Factors affecting the recruitment of trees into alpine and subalpine meadows are fundamental to understanding the dynamics of alpine-treeline ecotones (ATE), the transition from forest to alpine meadows. However, little is known about the factors affecting establishment patterns in the ATE. The purpose of this research was to determine if and how the range of sky exposures (%SKY) for conifer seedlings in the ATE varies among three mountain ranges. %SKY is a quantitative and integrated measure of the complex canopy (surrounding plants and distance to trees) above seedlings, and is determined using hemispherical photography. %SKY and surrounding vegetation was observed repeatedly for natural seedlings of Picea engelmannii, Abies lasiocarpa, and Pinus albicaulis found along transects positioned throughout the ATEs of the Snowy Range, Teton, and Beartooth mountains. The range of %SKY measured for all species combined differed among mountain ranges, with the greatest number of seedlings occurring at high %SKY in the Beartooths, and the least in the Tetons. Greater %SKY for seedlings in the Beartooths appeared due to a greater relative abundance of P. albicaulis, which occurred at higher % SKY than the other species. The range of %SKY for each species also varied among mountain ranges. Considering this, differences in climate, vegetation community, and unique biological properties among conifer species may be collectively influencing the variation seen in conifer seedling distribution in the ATE. Therefore, these factors may be necessary for more complete explanations of treeline dynamics that are transferable among these and other mountain ranges.
Key words: seedling establishment, sky exposure, alpine-treeline ecotone, Pinus albicaulis