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Thesis (M.S. - Geosciences)--University of Arizona. / Includes bibliographical references.

Thesis (M.A.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vi, 33 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references (p. 29-33).

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The problem of standardizing closed-canopy forest ringwidth series is investigated. A biological model for the tree-ring standardization problem indicated that one class of non-climatic variance frequently responsible for standardization problems could be objectively minimized in theory. This is the variance caused by endogenous stand disturbances which create fluctuations in ringwidth series that are non-synchronous or out-of-phase when viewed across trees in a stand. A time series method based on the autoregressive process is developed which minimizes the timewise influence of endogenous disturbances in detrended ringwidth series. Signal-to-noise ratio (SNR) properties of this method are derived which indicate that autoregressive modelling and prewhitening of detrended ringwidth indices will result in a higher SNR when endogenous disturbances are present in the series. This enables the verification of the SNR theory and the error variance reduction property of the standardization method.

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Our objective was to document the effect of fire-history sampling on the mortality of mature ponderosa pine trees in Oregon. We examined 138 trees from which fire-scarred partial cross sections had been removed five to six years earlier, and 386 similarly sized, unsampled neighbor trees, from 78 plots distributed over about 5,000 ha. Mortality was low for both groups. Although mortality was significantly higher for the sectioned trees than their neighbors (8% versus 1 %), removing a partial section did not appear to increase a tree's susceptibility to death from factors such as wind or insect activity. Specifically, the few sectioned stems that broke did so well above sampling height. Most sectioned trees (79 %) had evidence of insect activity in 1994/95, while only an additional 5% had such evidence in 2000. Mortality among sectioned trees in this study was low probably because we removed relatively small sections, averaging 7 cm thick and 8% of the tree's cross-sectional area, from large trees of a species with effective, resin-based defenses against insects and pathogens. Sampling live ponderosa pine trees appears to be a non-lethal method of obtaining information on past fire regimes in this region because it only infrequently led to their death in the early years after sampling.

Dendrochronological analysis of fire scars requires tree survival of fire exposure. Trees survive fire exposure by: (1) avoidance of injury through constitutive protection and (2) induced defense. Induced defenses include (a) compartmentalization processes that resist the spread of injury and infection and (b) closure processes that restore the continuity of the vascular cambium after fire injury. Induced defenses are non-specific and are similar for fire and mechanical injury. Dissection of central hardwood species in a prescribed fire treatment area in southeastern Ohio provided an opportunity to place features seen in dendrochronological samples into their biological context. Terms for these features are proposed and further discussion is solicited.

We analyzed the radial growth response of seven boreal tree species growing on an island of Lake Duparquet, northwestern Québec. The species investigated were Betula papyrifera, Abies balsamea, Thuja occidentalis, Picea glauca, Picea mariana, Pinus banksiana and Pinus resinosa. Seven species chronologies were developed as well as seventy individual tree chronologies. Coniferous species were positively correlated to warm April and to cool-wet July. This indicates that early spring and positive water balance during the growth season favor radial growth. In contrast, the radial growth of B. papyrifera was mainly correlated to June precipitation. The response of individual trees to climate was variable but the differences between B. papyrifera and the coniferous species were maintained. No microsite factors or tree characteristics were associated with this variability. Except for B. papyrifera, it is speculated that climate change could have a similar qualitative physiological consequence on the growth of coniferous species found on homogeneous insular landscapes.