@mastersthesis {558,
	title = {Tree-Ring Reconstruction of Western Spruce Budworm Outbreaks in the Rio Grande National Forest, Colorado},
	volume = {Master of Science},
	year = {1999},
	pages = {97},
	school = {University of Arizona},
	address = {Tucson},
	abstract = {<p>\&nbsp;</p><p>Tree-ring records were used to reconstruct the spatial and temporal patterns of western spruce budworm (Choristoneura occidentalis Freeman) outbreaks in the Rio Grande National Forest (RGNF) of southern Colorado. Reconstructions at 11 host stands showed a synchronous pattern of outbreaks with a peak in the number of trees recording outbreaks over the entire RGNF on average every 24 years. These synchronous periods of outbreaks coincided with periods of increased moisture as indicated by an independently reconstructed summer Palmer Drought Severity Index, while relatively few trees recorded outbreaks during dry periods. The reconstruction on the RGNF does not support the hypothesis that human land use has significantly altered outbreak patterns. Tree response to outbreaks in the RGNF was different from prior studies as reductions in the growth were typically detectable only when growth was compared to that of nonhost tree species.</p>},
	keywords = {colorado, dendrochronology, department of agriculture, forest service, national forest, outbreak, palmer drought severity index, RGNF, rio grande, tree ring, western spruce budworm},
	author = {Ryerson, Daniel E.}
}
@mastersthesis {830,
	title = {A Dendrochronological Record of Pandora Moth (Coloradia Pandora, Blake) Outbreaks in Central Oregon},
	volume = {MS},
	year = {1997},
	pages = {159},
	school = {University of Arizona},
	address = {Tucson},
	abstract = {Pandora moth (Coloradia Pandora Blake) is a phytophagous insect, defoliating ponderosa pine trees in the western United States. However, long-term studies of this insect and its effects on the forest ecosystem have not been conducted. Using dendrochronological techniques, I examined past timing and intensity of defoliation through its effects on radial growth of trees in the forests of south central Oregon.  Pandora moth leaves a distinctive ring-width "signature" that was easily identifiable in the wood.  The growth for the first year of the signature was half the normal ring-width with narrow latewood.  The following two years produced extremely narrow rings, with the entire suppression lasting from 4 to 18 years.

Twenty-two individual outbreaks were reconstructed from this 620 year chronology.  I found that pandora moth outbreaks were episodic in individual sites, with a return interval of 9 to 156 years.  Conversely, on the regional scale of south central Oregon, outbreaks demonstrated a 37-year periodicity.  On average, pandora moth defoliation caused a 29\% mean periodic growth reduction in defoliated ponderosa pine trees.  Spread maps of the first year that sites demonstrated suppression were plotted revealing an apparent annual spread of the outbreaks.  Examination of a fire history on one pandora moth outbreak site suggested that pandora moth outbreaks delay fire by interrupting the needle fall needed for fire spread.  Superposed epoch analysis showed that the year that the outbreak was first recorded was significantly dry and the fourth year prior was significantly wet.  Therefore, climate may be a triggering factor in pandora moth outbreaks.  The stem analysis demonstrated that the percent volume reduction was the greatest at the base of the tree and declined further up the bole.  The percent volume reduction in the canopy of the trees was variable with outlying high and low values.  THe mean volume reduction per outbreak was .053 m3 per tree.

Although this insect is considered a forest pest and causes inconvenience for people living nearby, pandora moth is not as widespread and damaging as some other phytophagous insects.  However, its very distinctive ring-width signature and the length of the ponderosa pine record enables reconstruction of very long outbreak histories, which may deepen our understanding of the interaction between defoliating insects and their ecosystem. 
},
	keywords = {Coloradia pandora, dendrochronology, entomology, fire, fire history, growth, insect, Oregon, outbreak, pandora moth, phytophagous, ponderosa pine, ring-width, tree ring},
	author = {Speer, James Hardy}
}
