Landslide-driven distribution of aspen and steppe on Kathul Mountain, Alaska

The patchy arrangement of woodland and steppe on the south face of Kathul Mountain, Alaska, challenges common distribution theories based on slope, aspect, and elevation, and poses questions about the effects of disturbance and the process of succession in the bluff environment.Populus tremuloides(quaking aspen) andPopulus balsamifera(balsam poplar) on Kathul Mt. show a strong affinity for areas prone to frequent, catastrophic landslide disturbance and associated substrate. A study of substrate and vegetation reinforces surficial evidence and eliminates some possible explanations. Slope, aspect, elevation, and soil type were found to have no discernible effect upon distribution. The failure of existing theory to explain this distribution prompts several hypotheses, based on topographic effects on snowfield accumulation, vegetative influences upon soil moisture, and competitive attributes of the steppe community. Many of these processes have long been recognized in semi-arid grasslands around the world.