This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Natural disturbances such as fires and pests are the primary factors influencing landscape patterns and processes over broad parts of the Earth. In the montane forests of the North American west, insect outbreaks and fire constitute the dominant disturbance agents, while climate change may be an increasingly important complicating factor. Disturbances are influenced by processes occurring across a variety of spatial and temporal scales. They therefore can produce spatio-temporal patterns that can be studied in a nested hierarchical fashion. Interactions between species, such as among plants and their insect pathogens, may also be so characterized. The investigators will examine how abiotic and biotic disturbances interact using the ponderosa pine-pandora moth model system. In particular, they are interested in how disturbance ecology drives diversification in both organisms across multiple spatial and temporal scales. Ponderosa pine ecosystems are chosen as they constitute one of the most important commercially logged forests in the western United States. The native pandora moth is the most widespread insect defoliator of ponderosa pine trees, and is an important concern of forest managers. Pandora moth outbreaks produce characteristic tree-ring patterns that can be detected through the dendrochronological techniques also used to detect and date fire events and climatic conditions. Tree-ring reconstructions will be developed for pandora moth, climate, fire, and stand-age structure from ten strategically located plots within the range of the ponderosa pine-pandora moth system. The ten resulting chronologies will be examined for cyclic patterns with wavelet analysis to help distinguish the relative influences of episodic insect outbreaks, drought, and fire. The investigators will also conduct reconstructions of all of these environmental variables to document the spatial and temporal scales over which they operate, providing specific reconstructions for forest managers at each site. Spatial patterns of genetic diversity and relationships among populations of the pandora moth will be determined from DNA-based genetic markers and analyzed in conjunction with the other analyses.
The findings have the potential to result in a large network of insect outbreak histories, one that eventually will span the entire spatial extent of the pine-moth system. This network will enable analysis of insect outbreak dynamics on spatial scales that have not previously been explored, and will provide an important framework that can be used to generate and test hypotheses regarding the interaction of multiple disturbances, and the processes driving diversification in ponderosa pine and pandora moth. The results produced by this study will provide a framework for future investigations into the disturbance ecology and evolutionary biogeography of plant-herbivore systems. The research will result in a broad network of tree-ring chronologies that will fill gaps in the International Tree Ring Data Bank holdings. This project also provides resources for the involvement of a team of undergraduate and graduate students as well as K-12 teachers in the field research and laboratory analyses.
