%0 Thesis %B Geography %D 2009 %T Spatial and temporal validation of fire-scar fire histories %A Farris, Calvin Arthur %Y Swetnam, T. %X

Accurate information about historical fire regimes is needed to understand the long-term effects of fire and climate on ecosystem dynamics and guide ecosystem restoration. Fire scars are used widely to reconstruct historical fire regimes around the world but few empirical validation studies have been conducted. This dissertation consists of three integrated studies aimed at addressing the following questions: (1) how accurate are fire-scar fire histories compared to known patterns of fire occurrence; (2) how do these relationships vary spatially and temporally; (3) how representative statistically are search-based (“targeted”) fire-scar sampling techniques? I utilized an empirical corroboration approach to validate fire-scar reconstructions against documentary fire perimeters for a 2,780 hectare ponderosa pine landscape in Saguaro National Park, Arizona (USA). Resampling statistics and spatial modeling were used to quantify interactions between spatial scale, sample size, and fire size. Statistical properties of targeted sampling were assessed by analyzing three case studies containing paired examples of targeted and non-targeted sampling (i.e., systematic and census). I found strong linear relationships between fire-scar synchrony (samples scarred in a given year) and annual area burned. Fire-scar derived estimates of fire frequency metrics, such as Mean Fire Return Interval and Natural Fire Rotation, did not differ significantly from the documentary record, and there was strong spatial coherence between fire frequency maps interpolated from fire-scar data and documentary maps. Scale and sample size dependence of fire-scar detection probabilities were variable for small fire years but relatively weak for widespread fires. This resulted in consistent and predictable influences on fire frequency reconstructions: statistical measures dependent on area burned were relatively stable and robust across a range of scale, sample size, and fire size. Targeted sampling did not differ statistically from non-targeted datasets, but targeted fire-scar data contained proportionately greater sample depth and longer temporal records with fewer samples. These results demonstrate collectively that key temporal and spatial fire frequency parameters can be reconstructed accurately from point-based fire-scar data. They also reaffirm general interpretations and management implications from past fire history research indicating that frequent, widespread burning was an important component of pre-settlement fire regimes in Southwestern ponderosa pine.

%B Geography %I University of Arizona %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1937808421&sid=2&Fmt=2&clientId=43922&RQT=309&VName=PQD %0 Thesis %D 2004 %T Scaling Rules for Fire Regimes %A Falk, Donald Albert %Y Swetnam, T. %X Forest fire is a keystone ecological process in coniferous forests of southwestern North America. This dissertation examines a fire regime in the Jemez Mountains of northern New Mexico, USA, based on an original data set collected from Monument Canyon Research Natural Area (MCN). First, I examine scale dependence in the fire regime. Statistical descriptors of the fire regime, such as fire frequency and mean fire interval, are scale-dependent. I describe the theory of the event-area (EA) relationship , analogous to the species-area relationship, for events distributed in space and time; the interval-area (IA) relationship , is a related form for fire intervals. The EA and IA also allow estimation of the annual fire frame (AFF), the area within which fire occurs annually on average. The slope of the EA is a metric of spatio-temporal synchrony of events across multiple spatial scales. The second chapter concerns the temporal distribution of fire events. I outline a theory of fire interval probability from first principles in fire ecology and statistics. Fires are conditional events resulting from interaction of multiple contingent factors that must be satisfied for an event to occur. Outcomes of this kind represent a multiplicative process for which a lognormal model is the limiting distribution. I examine the application of this framework to two probability models, the Weibull and lognormal distributions, which can be used to characterize the distribution of fire intervals over time. The final chapter addresses the theory and effects of sample size in fire history. Analytical methods (including composite fire records) are used in fire history to minimize error in inference. I describe a theory of the collector’s curve based on accumulation of sets of discrete events and the probability of recording a fire as a function of sample size. I propose a nonlinear regression method for the Monument Canyon data set to correct for differences in sample size among composite fire records. All measures of the fire regime reflected sensitivity to sample size, but these differences can be corrected in part by applying the regression correction, which can increase confidence in quantitative estimates of the fire regime. %I University of Arizona %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=845727371&sid=3&Fmt=2&clientId=43922&RQT=309&VName=PQD %0 Thesis %B Geoscience %D 1992 %T Statistical Relationships Between Tree Growth and Climate in Western North America %A Shao, Xuemei %Y Fritts, H. %X

The objective of this study is to examine large-scale spatial patterns of tree growth and climatic variation and to investigate the possible role of climate in determining tree growth patterns over space. This study represents one of the first uses of geostatistical methods to extract information about the spatial variation of climate from tree rings in western North America. It is also one of the first uses of data in spatial series to study the relationships of spatial variations between climate and tree growth. Geostatistics analyzes the spatial structure of the variables by assuming that adjoining data are correlated with each other over space and that the particular relationship expressing the extent of spatial correlation can be analytically and statistically captured in a function. It is applied to both June Palmer Drought Severity Index (PDSI) and ring-width index data from western North America. One basic assumption of applying geostatistics in this study is that the spatially uncorrelated small-scale variations are insignificant and represent background noise in large-scale dendroclimatic studies. The statistical relationships between the spatial variations of June PDSI and ring-width index are studied by simple scatter diagrams and correlation analysis. This is done in terms of yearly variations and variations of spatial patterns. Both of them support the contention that the large-scale spatial variations in ring-width index data can be used to infer the spatial variations of climate variables. Based upon the results of this research it can be concluded that geostatistics is a viable method to characterize the spatially correlated variations in dendroclimatology. By applying geostatistics to data sets, information about the spatial variations of climate contained in tree-ring data are enhanced, and the large-scale variations of climate are emphasized. The analysis of yearly relationships over space is particularly useful for identifying statistical relationships between climate and tree growth in a geographic region. The main factors of climate controlling ring-width index are identified as well as the less frequent limiting events. Once the statistical relationships are validated, they can be used to infer the spatial variations of past climate from variations in tree-ring index.

%B Geoscience %I University of Arizona %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=746968761&sid=9&Fmt=2&clientId=43922&RQT=309&VName=PQD %0 Thesis %B School of Renewable Natural Resources %D 1985 %T A Time Series Analysis Approach to Tree Ring Standardization %A Cook, Edward Roger %Y Fritts, H. %X

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.

%B School of Renewable Natural Resources %I University of Arizona %V PhD %G eng %0 Thesis %D 1984 %T Climatic Change and Water Supply in the Great Basin %A Flaschka, Irmgard Monika %Y Stockton, C. %X

The climatological literature contains considerable evidence that increasing concentrations of atmospheric carbon dioxide will result in global warming. In order to investigate the effects of resultant climatic changes on runoff in the Great Basin, a water balance model based on average monthly precipitation and temperature was applied to four watersheds in the region.

%I University of Arizona %V MS %G eng %0 Thesis %D 1984 %T A Dendroclimatological Reconstruction of Past Climate, Zermatt, Switzerland %A Freeman, A.L. %I University of Manchester %V BSc (Hons) %G eng %0 Thesis %D 1983 %T La Precipitacion como indicador de la variacion climatica en la peninsula de baja california y su relacion dendrocronologica %A Fernandez, Samuel Rueda %K Fishery Science %I National Polytechnic Institute of Marine Science Interdisciplinary Center %V MS %G eng %0 Thesis %B Geoscience %D 1982 %T Eastern U.S. Tree-Ring Widths and Densities as Indicators of Past Climate %A Conkey, Laura Elizabeth %Y Fritts, H. %X Long-lived trees preserve a record of environmental conditions during their lifetime in the pattern of yearly xylem widths and in changing wood density within and among the increments. Crossdated earlywood, latewood, and total ring widths, and minimum earlywood and maximum latewood densities, from three sites in the mountains of Maine, are analyzed visually and statistically to evaluate their relationships to one another and to external, environmental factors which affect the ring width and density through internal, physiological processes. Maximum density values show highest levels of similarity within and among the three site chronologies, thus implying a good degree of sensitivity to climate; minimum density values, however, showed lowest sensitivity to climate. Two biologically reasonable hypotheses concerning climate--tree growth interactions are proposed: (1) that maximum density is related to spring temperatures prior to its formation; and (2) that maximum density is related to summer water relations as the latewood forms. With the help of response function analysis, simple correlation, and multiple linear regression, these two hypotheses are tested: (1) maxmum density as a single predictor explains up to 37% of spring temperature variance; with earlywood widths at one site, 47% of spring temperature variance is explained; (2) maximum density as a single predictor explains up to 45% of summer temperature variance, 11% of summer precipitation variance, and 23% of the variance of Thornthwaite water deficit values; with total ring widths at one site, 22% of the variance of summer stream runoff is explained. Regression equations were applied to the 201- to 310-year tree-ring records to form reconstructions of these past climatic events. Independent verification testing of the reconstructions strongly validates the relationship between maximum density and spring temperature; the relationship to summer water relations is not as strongly verified, but results encourage further testing of this relationship. Results from this study may be applied both to (1) an increased understanding of relationship of climate to the formation of wood density; and (2) further development of dendroclimatology in mesic regions such as northeastern North America. %B Geoscience %I University of Arizona %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=748496351&sid=24&Fmt=2&clientId=43922&RQT=309&VName=PQD %0 Thesis %D 1980 %T The Effect of Air Pollution on Western Larch as Detected by Tree-Ring Analysis %A Fox, Carl Alan %X The growth response of western larch (Larix occidentalis Nutt.) to sulfur dioxide was studied in the Columbia River Valley near the lead-zinc smelter at Trail, British Columbia. A dendroecological (tree-ring) analysis was employed to assess the relative importance and longterm effects of sulfur dioxide on tree growth. Increasing sulfur emissions in the early 1900’s, reaching a maximum in 1930, resulted in a concomitant decrease in annual tree growth. After 1930, sulfur emissions decreased dramatically with the implementation of pollution abatement measures. However, the growth recovery of western larch to the decreased sulfur emissions was not immediate and reflected the residual nature of the sulfur dioxide effect on tree growth. Correlation and regression analyses were utilized to develop multivariate models for the larch sites sampled at varying distances from the Trail smelter. Climatic models developed for the control site (tree-ring) chronology were applied to site chronologies located within the sulfur dioxide affected area to remove the effects of climate on tree growth and examine the residual response of the system. The pattern of the residuals closely resembled the sulfur emissions from the smelter with the most negative residuals occurring when sulfur emissions were greatest. Further regression modelling identified the relative importance of sulfur emissions, prior growth, temperature, and precipitation to annual tree growth. In those sites closest to the smelter, sulfur emissions accounted for the greatest proportion of the variance calibrated by the regression models. As distance from the smelter increased, sulfur emissions became less important in the site models. In all the site models temperature, particularly summer temperature, appeared to be a primary limiting climatic factor. Prior growth also accounted for considerable variance in the models with precipitation variables appearing to be of lesser importance in explaining the variance in the site chronologies. The results of this study demonstrate the applicability of tree-ring analysis in identifying and quantifying the long-term effects of air pollution on forest communities. It also provides a basis for examining the interrelationships between air pollution, climate, and annual tree growth. %I Arizona State University %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=749712461&sid=13&Fmt=2&clientId=43922&RQT=309&VName=PQD %0 Thesis %B Geoscience %D 1979 %T An Attempt to Verify Dendroclimatic Reconstructions using Independent Tree-Ring Chronologies %A Duvick, Daniel Nelson %Y Fritts, H. %X An attempt was made to verify dendroclimatic reconstructions of July Palmer Drought Severity Indices (PDSI) and of seasonal temperature and precipitation in the contiguous United States by means of tree-ring chronologies not used in the calibration procedure. Eight tree-ring chronologies were developed from white oak (Quercus alba L.) on five sites in Iowa and were used in statistical verification procedures along with 26 other chronologies from the eastern and central U.S. Six types of statistical test were used to detect linkages between tree-ring series and actual or reconstructed climatic series. Only those chronologies showing significant linkages with actual climatic data were used in verification attempts. Successful verifications of two PDSI reconstruction sets for two regions of Iowa using the Iowa chronologies were attributed to validity of these reconstructions and strong linkages of the Iowa chronologies to actual July PDSI data, and it was concluded that verification of dendroclimatic reconstructions using independent tree-ring chronologies is possible. Unsuccessful verification attempts in all areas tested for the temperature precipitation reconstructions and for one PDSI reconstruction in four regions of the Ozarks area were attributed to invalidity of these reconstructions and secondary to weaker linkages of the independent chronologies to actual data of these variables. %B Geoscience %I University of Arizona %V MS %G eng %0 Thesis %B Geoscience %D 1979 %T Dendroclimatology in the Northeastern United States %A Conkey, Laura Elizabeth %Y Fritts, H. %X Canonical correlations and regressions were calculated between a set of 7 tree-ring width chronologies and a set of 12 temperature or 15 precipitation records from the northeastern United States. The regressions calibrated 38.5% of the winter temperature variance, 26.5% of the winter precipitation variance, 20.9% of the spring precipitation variance in the dependent period, 1905-1960. The regression equations were then applied to the 275-year record of the 7 tree-ring chronologies to obtain estimates of past temperature and precipitation. Reconstructions wee tested for statistical verification with climatic data not used in the regressions, and the series that showed highest verification in each season was selected for further study. The best winter temperature reconstruction passed 50% of the verification tests, the best winter precipitation reconstruction passed 12.5% of the tests, and the best spring precipitation reconstruction passed 26.8% of the tests. The reconstructions of the stations which passed the most verification tests in each season were averaged, and the regional averages were smoothed and plotted. These presented as a first, tentative approximation of past climate. %B Geoscience %I University of Arizona %V MS %G eng %0 Thesis %B School of Renewable Natural Resources %D 1975 %T The Historical Potential of Snowfall as a Water Resources in Arizona %A Tunnicliff, Brock Matthew %Y Ffolliott, P. %K Watershed Management %X …Tree-ring chronologies from the San Francisco Mountains and White Mountains region of central Arizona where used to reconstruct past annual snowfall water equivalents for up to the last 500 years… %B School of Renewable Natural Resources %I University of Arizona %V MS %G eng %0 Thesis %B Geoscience %D 1973 %T Past Air-sea Interactions off Southern California as Revealed by Coastal Tree-Ring Chronologies %A Douglas, Arthur Vern %Y Fritts, H. %B Geoscience %I University of Arizona %V MS %G eng %0 Thesis %D 1973 %T Some Relationships Between Glaciers and Climate in Alaska %A Fahl, Charles Byron %I University of Alaska %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=760346601&sid=12&Fmt=1&clientId=43922&RQT=309&VName=PQD %0 Thesis %B Hydrology and Water Resources %D 1971 %T The Feasibility of Augmenting Hydrologic Records using Tree-Ring Data %A Stockton, C. %Y Fritts, H. %K Hydrology %X

Two catchments of diverse hydrologic character were chosen in which to test the hypothesis that tree-ring indices contain information about runoff that is of pertinent interest to the hydrologist…[Bright Angel Creek basin, Arizona and Upper San Francisco River basin, Arizona/New Mexico]

%B Hydrology and Water Resources %I University of Arizona %V PhD %G eng %U http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=760166291&sid=14&Fmt=1&clientId=43922&RQT=309&VName=PQD %0 Thesis %B Watershed Management %D 1967 %T Stomatal Activity in Semi-arid Site Pnderosa Pine %A Drew, Allan P. %Y Fritts, H. %X A pressure-infiltration technique for estimating stomatal opening in conifers was used with success on ponderosa pine growing on a semi-arid site. A diurnal pattern of stomatal opening during the day and closing at night was readily discernible. Variations in this pattern such as changes in rates of opening, daytime closure, and opening at night have been measured and related to changes in the environment. Incoming radiation, air and soil temperature, and soil moisture strongly influenced stomatal activity. %B Watershed Management %I University of Arizona %V MS %G eng %0 Thesis %B Botony %D 1966 %T Variation in Water Stress of Ponderosa Pine %A Cunningham, Gary Lynn %Y Fritts, H. %X Seasonal and diurnal variations in water stress of the one year old needles in ponderosa pine were followed using the Schardakow method of estimating diffusion pressure deficit and the relative turgidity method of estimating moisture deficit. Soil moisture, vapor pressure deficit of the atmosphere and changes in trunk radius were measured to ascertain their relationships to needle water stress. Diffusion pressure deficit increased with decreasing solid moisture until growth was initiated. At that time diffusion pressure deficit values were markedly reduced and this is attributed to changes in solute content resulting from high carbohydrate metabolism and translocation. Diurnal variations in diffusion pressure deficit followed closely the diurnal variations in vapor pressure deficit, but the measured changes in relative turgidity did not follow closely the changes in diffusion pressure deficit. Measurements of changes in truck radius appear useable for estimating needle tissue water status except during periods of terminal and cambial activity. %B Botony %I University of Arizona %V MS %G eng