Disturbances such as fire, windthrow, and insect outbreaks are principal drivers of vegetation dynamics within Rocky Mountain and boreal ecosystems and can interact to affect the size structure, species composition, and successional stage of vegetation, as well as ecosystem processes and biogeochemical cycling. Outbreaks of the spruce beetle (Dendroctonus rufipennis (Kirby)), which infests spruce species (Picea spp.), have increased in recent years, leading to widespread mortality and carbon losses throughout the western US and Canada. The frequency and severity of spruce beetle outbreaks, as well as wildfire, are predicted to increase with climate change, potentially leading to increased drought- and disturbance-related mortality, and shifts in species zonation. The future of spruce forests is thus becoming increasingly unclear as climate change and disturbances act in concert to modify their structure, composition, and internal dynamics. Through ecological modeling, we have the capacity to examine forest processes at multiple temporal and spatial scales, allowing for the testing of complex interactions between vegetation, climate, and disturbances. In this presentation, I will examine the applicability of an individual tree-based model (UVAFME) to the southern Rocky Mountains region, and discuss the development of a spruce beetle infestation submodel. I will also discuss future steps with UVAFME and plans for its application in interior Alaska. Successful validation and application of such individual-based models advance our understanding of the possible futures for North American forests, which are a valuable part of the global carbon budget.
Adrianna Foster is a forest ecologist and ecological modeler, particularly interested in vegetation – climate – disturbance interactions. During her PhD at the University of Virginia, she investigated interactions between climate, vegetation, and bark beetle outbreaks in the southern Rocky Mountains. She utilized individual tree-based modeling to predict change in biomass, stand structure, and species composition of subalpine vegetation as a result of shifting climate and disturbance regimes. During this time she also investigated early-stage indicators of spruce beetle infestation using field spectrometry and Landsat imagery. She recently started a postdoc with Jon Ranson at Goddard Space Flight Center, and plans to use individual-based modeling and high-resolution remote sensing data to study forest dynamics in the Alaskan boreal zone.