PARENT SESSION
Contributed Oral Session 131: Biogeography: Ranges; Species Area; Populations
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 515 A, Level 5, Palais des congrès de Montréal
A hierarchical framework for the study of treeline dynamics: challenges in linking information across scales.
Danby, Ryan*,1, Hik, David1, 1 University of Alberta, Edmonton, Alberta, Canada
ABSTRACT- Explicit recognition of scale has been an important advance in ecology over the past two decades, but its consideration is still ad hoc in most studies. We developed a framework for the study of alpine treeline in the southwest Yukon that incorporated scale from the outset. It includes multiple levels within the biological hierarchy, examines both pattern and process at multiple spatial and temporal scales, and utilizes both experimental and relational research approaches. At the organism level we experimentally warmed individual trees to quantify the role of temperature as a limiting factor in their growth and observed increased vertical growth and photosynthetic rates in treated individuals. At the population level we examined both pattern and process of change via dendrochronology-based studies of stand dynamics coupled with analysis of sequential aerial photography. We observed varied dynamics of tree populations, ranging from gradual increases in stand density to episodic advance of the treeline's upper limit. Finally, at the landscape level we used a GIS-based analysis to examine the spatial structure of the ecotone relative to potential biophysical controls and found significant relationships between solar aspect and treeline elevation and land cover composition. Each of these investigations have yielded noteworthy results in their own right, but it is the integration of their results that holds the most promise in taking full advantage of the scale-based framework. Formulating a model of treeline dynamics that incorporates these cross-scale linkages is the next real challenge.
Key words: scale, treeline, ecotones