PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Stand dynamics in a subalpine Englemann spruce − subalpine fir forest in north central Colorado: Changes over 17 years.
Arthur, Mary1, 1 University of Kentucky, Lexington, KY
ABSTRACT- This study documented changes in stand structure and biomass in the old-growth subalpine forest in Loch Vale Watershed in Rocky Mountain National Park. Trees greater than 2 cm DBH were tagged in twenty permanent forest inventory plots in 1984; smaller stems were measured in subplots. Earlier work described the stand structure, NPP and biomass of the forest; plots were remeasured in 2001. During the intervening 17 years, disturbance caused considerable tree mortality throughout the forested portions of the watershed. Several forest stands near avalanche-prone sideslopes were essentially completely felled and there was little evidence of significant new regeneration at the time of re-measurement. Sites more protected from avalanche activity had considerable mortality of larger trees from wind events, again without significant new recruitment. Two plots that had regenerated following fire approximately 95 years ago also had considerable mortality of the largest trees. As a result of these disturbance events, mean basal area and biomass in the subalpine forest of Loch Vale Watershed was significantly lower in 2001 compared to that measured in 1984. Previous work noted the importance of blowdowns and snow avalanches as common disturbance agents in subalpine spruce-fir forests, and the susceptibility of older trees to breakage. Large variability in stand age (from 90-250) reflects the highly stochastic nature of the dominant disturbances in this forest type. More frequent assessments of tree mortality and in-growth in the future will enable us to improve our understanding of mortality patterns in this forest type.
Key words: Picea engelmannii, Abies lasiocarpa, disturbance