|Foliage regeneration and longevity in old-growth trees.||Multiple objective optimization, ecological models and problem solving.|
We are interested in the characteristics of long-lived trees that allow them to continue to persist in forests when they have reached maximum height increment and crown expansion. At the Wind River Canopy Crane Research Facility (WRCCRF), Ishii and Ford (2001) observed ubiquitous epicormic growth on the interior of Pseudotsuga menziesii crowns, and proposed that foliage regeneration through proleptic reiteration is a way in which P. menziesii survives at maximum crown expansion. I explored this postulate through a geometric simulation model of branch growth in P. menziesii, in contrast with Abies grandis, a species that lacks characteristic proleptic reiteration.
Kennedy, M.C. (2002). A geometric simulation model of foliage regeneration in Abies grandis and Pseudotsuga menziesii. Master of Science Thesis. University of Washington. Seattle, WA
Ishii HT, Ford ED, Kennedy MC. (2007). Physiological and ecological implications of adaptive reiteration as a mechanism for crown maintenance and longevity. Tree Physiology. 27:455.462.Return to the main page.
Ecological phenomena are defined by more than one feature, yet we lack the tools to evalute multiple features simultaneously. We assert that process models are valuable tools to aid in theory development, and to realize the full potential of these models we require multiple objectives to be optimized simultaneously as a vector objective function. Performance of the model is measured through the concept of non-dominance, or Pareto optimality. This is also a valuable tool in management problems, where there are multiple objectives of the management project that likely conflict. The Pareto optimal frontier allows decision-makers to visualize the full range of trade-offs among competing objectives.
For my dissertation, I use Pareto optimality and multi-objective optimization to assess a process model of branch development in old-growth Douglas-fir. I use a set of theoretical objectives to quantify how the branch development pattern may compensate for size-related constraints in old-growth forests.
Dissertation (with link to pdf version) completed March 2008:
Example for fire and fuels management:
Kennedy MC, Ford ED, Singleton P, Finney M, Agee JK. (2008) Informed multi-objective decision-making in environmental management using Pareto optimality. Journal of Applied Ecology. 45(1):181-192.
Lehmkuhl J, Kennedy M, Ford ED, Singleton PH, Gaines WL, Lind RL. (2007). Seeing the forest for the fuel: Integrating ecological values and fuels management. Forest Ecology and Management. 246: 73-80.