@mastersthesis {531, title = {Human response to environmental hazards: Sunset Crater as a case study}, volume = {MA}, year = {2008}, school = {University of Arizona}, abstract = {Natural disasters and rapid environmental changes have resulted in a continuum of responses by human societies throughout history. A model is proposed that incorporates cultural and environmental aspects of human response to natural disasters. The 11 th century eruption of Sunset Crater volcano in northern Arizona is used as a case study in which the archaeological record and dendrochronological and geomorphological evidence are combined to characterize the nature of the human response. The model predicts that the population at Sunset Crater would have been pressured to move, or to move and make cultural or technological adaptations following the eruption. The model has utility in diverse conditions and can be used to interpret archaeological remains and facilitate modern disaster response.}, keywords = {Archaeology}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1564017781\&sid=16\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {May, Elizabeth} } @mastersthesis {539, title = {Using False Rings to Reconstruct Local Drought Severity Patterns on a Semiarid River}, volume = {PhD}, year = {2008}, school = {University of Arizona}, abstract = {In this research, I describe the use of false rings to reconstruct local histories of seasonal drought in riparian ecosystems in semiarid regions. In tree-ring analysis, false rings are boundary-like features often formed as a response to drought within the growing season. Drought can be a common feature in hydrologic regimes of dryland rivers but in recent decades drought has been intensifying due to climate change and increasing water use by cities, agriculture and industry. Identifying when and where water availability has decreased along the river course is critical for understanding, and therefore managing, these generally endangered ecosystems. The higher density of trees compared to instrumental data make them ideal candidates for reconstructing site-specific drought patterns. The first part of this dissertation is an observational study conducted on the San Pedro River in southeastern Arizona during 2002. I used dendrometer data and local hydrological data to show that a period of negligible radial growth in cottonwood during the middle of the growing season coincided with a channel drying event. Tree-ring core samples confirmed that false-rings had formed in each of the instrumented trees. The second part of this dissertation is an experimental study designed to evaluate the effect of different levels of water stress on false-ring formation in cottonwood and willow. I showed that experimental decreases in water availability for periods as short as ten days were enough to induce false-ring formation in willow. Longer periods of reduced water availability were generally required to induce false-ring formation in cottonwood. In the final part of this dissertation, I reconstructed false-ring occurrence in Fremont cottonwoods at three sites along the San Pedro River. I infer from false-ring frequencies that the severity of summer drought has been increasing over the last four to six decades but that the drought severity varies along a hydrological gradient. Overall, the findings in this body of research confirm that false rings in riparian tree species can be used as indicators of seasonal drought and underscore the importance of identifying site-specific responses to reduced water availability along the riparian corridor.}, keywords = {Geography}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1500068401\&sid=3\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Morino, Kiyomi Ann} } @mastersthesis {842, title = {Fire History and Fire Climate Relationships in Upper Elevation Forests of the Southwestern United States}, volume = {Ph.D}, year = {2007}, note = {

Please contact the Laboratory of Tree Ring Research for a copy of this dissertation. The file is too large to be uploaded at this time.

}, pages = {182}, school = {University of Arizona}, type = {Dissertation}, address = {Tucson}, abstract = {

Fire history and fire-climate relationships of upper elevation forests of the southwestern United States are imperative for informing management decisions in the face of increased crown fire occurrence and climate change. I used dendroecological techniques to reconstruct fires and stand-replacing fire patch size in Madrean Sky Islands and Mogollon Plateau. Reconstructed patch size (1685-1904) was compared with contemporary patch size (1996-2004). Reconstructed fires at three sites had stand-replacing patches totaling \> 500 ha. No historical stand-replacing fire patches were evident in the mixed conifer/aspen forests of the Sky Islands. Maximum stand-replacing fire patch size of modern fires (1129 ha) was greater than that reconstructed from aspen (286 ha) and spruce-fir (521 ha). Updated spruce-fir patches may be evidence of larger (\>2000ha) stand-replacing fire patches.

To provide climatological context for fire history I used correlation and regionalization analyses to document spatial and temporal variability in climate regions, and El-Nino Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) teleconnections using 273 tree-ring chronologies (1732-1979). Four regions were determined by common variability in annual ring width. The component time score series replicate spatial variability in 20th century droughts (e.g., 1950\’s) and pluvials (e.g., 1910\’s). Two regions were significantly correlated with instrumental SOI and AMO, and three with PDO. Sub-regions within the southwestern U.S. varied geographically between the instrumental (1900-1979) and the pre-instrumental periods (1732-1899). Mapped correlations between ENSO, PDO and AMO, and tree-ring indices illustrate detailed sub-regional variability in teleconnections.

I analyzed climate teleconnections, and fire-climate relationships of historical upper elevation fires from 16 sites in 8 mountain ranges. I tested for links between Palmer Drought Severity Index and tree-ring reconstructed ENSO, PDO and AMO phases (1905-1978 and 1700-1904). Upper elevation fires (115 fires, 84 fire years, 1623-1904) were compared with climate indices. ENSO, PDO, and AMO affected regional PDSI, but AMO and PDO teleconnections changed between periods. Fire occurrence was significantly related to inter-annual variability in PDSI, precipitation, ENSO, and phase combinations of ENSO and PDO, but not AMO (1700-1904). Reduced upper elevation fire (1785-1840) was coincident with a cool AMO phase.

}, keywords = {AMO, climate, dendrochronology, dendroclimatology, ENSO, environment, fire, fire history, forest, madrean sky islands, mogollon plateau, mountain, PDO, southwest, teleconnection, tree ring, upper elevation, Watershed Management}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=1375523671\&sid=1\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD.}, author = {Margolis, Ellis Quinn} } @mastersthesis {910, title = {Stand Replacing Fire History and Aspen Ecology in the Upper Rio Grande Basin}, volume = {Master of Science}, year = {2003}, pages = {94}, school = {University of Arizona}, address = {Tucson}, abstract = {

Dendroecological techniques were applied to reconstruct stand-replacing fire history in mixed conifer and spruce-fir forests in northern New Mexico and southern Colorado. Stand-replacing fire dates with annual accuracy and precision were determined using four lines of evidence for each of twelve sites within a 75,000 square kilometer area. The four lines of evidence were: (1) aspen inner-ring dates, (2) conifer death dates, (3) tree-ring width changes, or other morphological indicators of injury, and (4) fire scars. The annual precision of dating allowed the identification of significant synchrony of stand replacing fires among the 12 sites and regional surface fire events previously reconstructed from the large network of fire scar collections in the Southwest. Nearly all of these synchronous stand-replacing and surface fire years coincided with extreme droughts. This suggests that stand-replacing fire activity occurred primarily when drought conditions allowed fires to ignite and spread within these high elevation forests and/or for the spread of surface fires between lower and upper elevations. Fifty percent of reconstructed stand-replacing fires pre-dated large-scale Euro-American settlement in this region. This may suggest that land use practices (such as logging and mining) were not as important in promoting stand-replacing fires in these study sites, as compared with other areas in Colorado.

}, keywords = {aspen, basin, colorado, conifer, dendrochronology, dendroecology, Ecology, fire, fire history, new mexico, rio grande, spruce fir, stand replacing, tree ring}, author = {Margolis, Ellis Quinn} } @mastersthesis {535, title = {A model for assigning temper provenance to archaeological ceramics with case studies from the American Southwest}, volume = {PhD}, year = {1998}, school = {University of Arizona}, abstract = {Well-designed provenance studies form the basis from which questions of human economy and behavior are addressed. Pottery is often the subject of such studies, requiring geological and archaeological evidence to establish patterns of ceramic economy. A generalized theoretical and methodological framework for provenance studies is presented, followed by specific considerations for ceramic provenance studies. Four main sources of variation affect pottery composition: geological distribution of resources, geological resource variability, differential economic factors affecting resource use, and technological manipulation of materials. Post depositional alteration is also considered. This ceramic provenance model provides explicit guidelines for the assessment of geological aspects of provenance, since geological resource availability affects acquisition by humans and thus archaeological research designs, in which interdependent geological and archaeological scalar factors must be balanced against budgets. Two case studies illustrate the model. The first is of sand-tempered pottery from the Tonto Basin, Arizona, where the bedrock geology is highly variable giving rise to geographically unique sands. Zones with similar sand compositions are modeled using actualistic petrofacies, the Gazzi-Dickinson point-counting technique, and multivariate statistics. Methods used to create a petrofacies model are detailed, as is the model{\textquoteright}s application to sand tempered utilitarian sherds from three Tonto Basin project areas. Data analysis reveals strong temporal and spatial ceramic production and consumption patterns. The second is of crushed-schist-tempered Hohokam pottery. Crushed schist was often used to temper pre-Classic Hohokam plain ware pottery in central Arizona{\textquoteright}s middle Gila River valley. Systematic investigation of rocks from the Pinal Schist terrane in the middle Gila River valley was conducted to assess how many sources were exploited prehistorically, and whether schist or schist-tempered pottery were exchanged. Chemical analysis shows that the sources can be statistically discriminated from one another. Schist source data were compared to schist extracted from plain ware sherds and to unmodified pieces of schist recovered from two archaeological sites. Preliminary indications are that schist was derived from several sources. This model provides a flexible, archaeologically relevant framework for assessing temper provenance. Hopefully, archaeologists and petrologists alike will use it to define ceramic provenance research problems and communicate effective solutions to one another.}, keywords = {Geology}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=737676271\&sid=19\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Miksa, Elizabeth J.} } @mastersthesis {538, title = {Reconstruction and Interpretation of Historical Patterns of Fire Occurrence in the Organ Mountains, New Mexico}, volume = {Master of Science}, year = {1996}, pages = {144}, school = {University of Arizona}, address = {Tucson}, abstract = {

The purpose of this research was to reconstruct and interpret the history of fire in the Organ Mountains, New Mexico. I used dendrochronological techniques to date fire scars on 90 trees comprising ten sites within the Fillmore Canyon watershed. Two fire regimes were identified during the pre-settlement period. Fire Regime I, 1650-1805, was characterized by a high fire frequency (ca. once every two years) and a predominance of patchy fires. Fire Regime II, 1805-1874, was characterized by a lower fire frequency (ca. once every 3.5 years) and a predominance of widespread fires. During the post-settlement period fire was virtually non-existent. I hypothesize that Apache use-of-fire influenced patterns during the pre-settlement period, while Euro-American land use activities influenced patterns during the post-settlement period. Fire-precipitation associations suggest that low fuel moisture levels were a pre-condition for widespread fires.

}, keywords = {dendrochronology, fillmore canyon, fire, Geography, historical, new mexico, organ mountains, reconstruction}, author = {Morino, Kiyomi Ann} } @mastersthesis {540, title = {Growth responses of giant sequoia to fire and climate in Sequoia and Kings Canyon National Parks, California}, volume = {MS}, year = {1994}, school = {University of Arizona}, abstract = {I investigated the radial growth responses of giant sequoia (Sequoiadendron giganteum) to fire in Sequoia and Kings Canyon National Parks. Mean ring-width indices were used to compare growth between burned and unburned sites and between four different levels of fire severity. Mean growth increased in all sites in the post-burn periods relative to pre-burn periods. Favorable climatic conditions contributed to these growth increases. Post-fire mean growth for four out of seven burn sites, however, was significantly higher than that on unburned sites. In general, lower severity fire resulted in lower magnitude growth increases than those observed after moderate to higher severity fire. Very high severity fire that caused extensive foliage damage resulted in post-burn growth suppressions. Post-fire growth increases occurred whether post-burn years were wet or dry. Fire effects on site conditions may moderate climatic impacts on sequoia growth. Giant sequoia seedling establishment was favored by a combination of high severity fire and wet post-burn conditions.}, keywords = {Forestry}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=743039441\&sid=4\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Mutch, Linda Susan} } @mastersthesis {725, title = {Modeling changes in faunal use and availability on the Pajarito Plateau, New Mexico}, volume = {M.A.}, year = {1994}, school = {University of Arizona}, abstract = {This thesis tests the hypothesis that resource depletion accompanied aggregation on the Pajarito Plateau. It does so by examining changes in faunal resource availability and resource use during the Coalition and early Classic periods. The prehistoric deer population was estimated using precipitation data, following Young (1979). This estimation was used as a measure of potential resource availability for the periods concerned. Based upon the model, the mule deer population was expected to increase from the Coalition period to the early Classic period. Resource use was measured using faunal assemblages from 10 sites from the Pajarito Plateau. The sites examined in this thesis support various expectations which would suggest that resource depletion occurred on the Pajarito Plateau. It was found that changes in resource use could not be explained by environmental change alone. Thus, it appears that resource depletion on the Pajarito Plateau may have been due to human impact on the environment. }, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=748075101\&sid=57\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Rebeeca McKim} } @mastersthesis {665, title = {The Russian Molokan Colony at Guadalupe, Baja California: Continuity and change in a sectarian community}, volume = {PhD}, year = {1992}, school = {University of Arizona}, abstract = {Migration, ethnicity and cultural pattern are reviewed. The research questions how accurately the prehistoric archaeologist can interpret migration and ethnicity by means of a review of the modern migration of a group of Russian sectarians to Baja California, Mexico. Excavations undertaken in seven households at different levels of assimilation with their Mexican and Indian neighbors suggests that material culture does reflect ethnicity under these best of all archaeological circumstances. A methodology for the determination of prehistoric migrations is suggested. It concludes that "cultural pattern" is a more useful concept than "ethnicity" in the determination of archaeological migrations.}, keywords = {Mexico}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=746278161\&sid=4\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Therese Muranaka} } @mastersthesis {729, title = {Forest structure and succession over a ten year period in six undisturbed South Florida plant communities}, volume = {M.S.}, year = {1990}, school = {University of Arizona}, abstract = {Data were collected on woody vegetation for 10 years in 6 undisturbed plant communities including slash pine forest, wet prairie, hardwood hammock, edge and interior old-growth cypress forests, and freshwater marsh at National Audubon Society{\textquoteright}s Corkscrew Swamp Sancturary in South Florida. Forested communities all showed a trend toward greater successional maturity. Numbers and total basal areas generally decreased over the 10 year period for early successional species and tropical species affected by the 1982 freeze in hammock and edge cypress communities. Otherwise, total basal areas steadily increased for all species in the forested communities. Initially the slash pine forest contained only canopy pine, but hardwoods entered the sites 3-4 years after fire and continued to increase in number throughout the study. Woody vegetation in the two marsh communities were less stable, partially due to fire. Fire and hydrologic conditions had measureable impacts on community structure and growth patterns.}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=747620471\&sid=8\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Jean McCollom} } @mastersthesis {532, title = {A New Computerized X-ray Densitometric System for Tree-Ring Analysis}, volume = {MS}, year = {1984}, school = {University of Arizona}, abstract = {

A new facility for X-ray densitometric analysis is in operation at the Laboratory of Tree-Ring Research. Tree-ring specimens are cute to a uniform thickness of 1.0 mm and contact radiographs are produced. The radiographs are scanned by a modified Joyce-Loebl optical microdesitometer interfaced with an Apple II microcomputer. The film optical densities are sampled at 0.02 mm increments and stored on magnetic disks. A battery of computer programs has been developed to edit and process these data, and to transform them into annual time series of various wood density characteristics for each specimen. Several of the programs employ interactive high-resolution graphics to enable the operator to ensure that the resulting series are accurate and complete. Data produced include maximum latewood density, minimum earlywood density, total ring width, average annual density, and integrated annual density. These parameters can be employed as paleoenvironmental indicators.

}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=753909891\&sid=1\&Fmt=1\&clientId=43922\&RQT=309\&VName=PQD}, author = {McCord, Virgil Alexander Stuart} } @mastersthesis {534, title = {{\"U}ber den Witterungseinflu{\ss} auf die Jahrringstruktur der Gemeinen Keifer (Pinus silvestris L.)}, volume = {PhD}, year = {1984}, school = {University of Freiburg}, author = {Merkel, Hubert} } @mastersthesis {533, title = {Applications of Box-Jenkins Methods of the Time Series Analysis to the Reconstruction of Drought from Tree Rings}, volume = {PhD}, year = {1981}, school = {University of Arizona}, abstract = {The lagged responses of tree-ring indices to annual climatic or hydrologic series are examined in this study. The objectives are to develop methods to analyze the lagged responses of individual tree-ring indices, and to improve upon conventional methods of adjusting for the lag in response in regression models to reconstruct annual climatic or hydrologic series. The proposed methods are described and applied to test data from Oregon and Southern California. Transfer-function modeling is used to estimate the dependence of the current ring on past years{\textquoteright} climate and to select negative lags for reconstruction models. A linear system is assumed; the input is an annual climatic variable, and the output is a tree-ring index. The estimated impulse response function weights the importance of past and current years{\textquoteright} climate on the current year{\textquoteright}s ring. The identified transfer function model indicates how many past years{\textquoteright} rings are necessary to account for the effects of past years{\textquoteright} climate. Autoregressive-moving-average (ARMA) modeling is used to screen out climatically insensitive tree-ring indices, and to estimate the lag in response to climate unmasked from the effects of autocorrelation in the tree-ring and climatic series. The climatic and tree-ring series are each prewhitened by ARMA models, and crosscorrelation between the ARMA residuals are estimated. The absence of significant crosscorrelations implies low sensitivity. Significant crosscorrelations at lags other than zero indicate lag in response. This analysis can also aid in selecting positive lags for reconstruction models. An alternative reconstruction method that makes use of the ARMA residuals is also proposed. The basic concept is that random (uncorrelated in time) shocks of climate induce annual random shocks of tree growth, with autocorrelation in the tree-ring index resulting from inertia in the system. The steps in the method are (1) fit ARMA models to the tree-ring index and the climatic variable, (2) regress the ARMA residuals of the climatic variable on the ARMA residuals of the tree-ring index, (3) substitute the long-term prewhitened tree-ring index into the regression equation to reconstruct the prewhitened climatic variable, and (4) build autocorrelation back into the reconstruction with the ARMA model originally fit to the climatic variable. The trial applications on test data from Oregon and Southern California showed that the lagged response of tree rings to climate varies greatly from site to site. Sensitive tree-ring series commonly depend significantly only on one past year{\textquoteright}s climate (regional rainfall index). Other series depend on three or more past years{\textquoteright} climate. Comparison of reconstructions by conventional lagging of predictors with reconstructions of the random-shock method indicate that while the lagged models may reconstruct the amplitude of severe, long-lasting droughts better than the random-shock model, the random-shock model generally has a flatter frequency response. The random-shock model may therefore be more appropriate where the persistence structure is of prime interest. For the most sensitive series with small lag in response, the choice of reconstruction method makes little difference in properties of the reconstruction. The greatest divergence is for series whose impulse response weights from the transfer function analysis do not die off rapidly with time.}, keywords = {Hydrology}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=753124981\&sid=10\&Fmt=2\&clientId=43922\&RQT=309\&VName=PQD}, author = {Meko, David Michael} } @mastersthesis {536, title = {Within-and between Tree Variation in Ceratin Properties of Annual Rings of Sessile Oak, Quercus (Mattuschka) Liebl. As A Source of Dendrochronological Information}, volume = {PhD}, year = {1979}, school = {Liverpool Polytechnic}, author = {Milsom, Stephen John} } @mastersthesis {587, title = {Paleoecology and the Prehistoric Maya: A History of Man-Land Relationships in the Tropics}, volume = {MS}, year = {1974}, school = {University of Arizona}, abstract = {A series of modern soil samples were collected in lowland Guatemalan rainforest, savannah, milpa, and lakeside association or pollen analysis{\textellipsis}}, keywords = {Geoscience}, author = {Wiseman, Fredrick Matthew} } @mastersthesis {594, title = {A Neoglacial Pollen Record from Osgood Swamp, California}, volume = {MS}, year = {1973}, school = {University of Arizona}, abstract = {A core from Osgood Swamp, California, which is located south of Lake Tahoe, in the Sierra Nevada, was analyzed every odd centimeter to depth of 61 cm. The Hypsithermal to Neoglacial transition occurs in the 51 to 49 cm interval. Pinus shows four distinct peaks and troughs, varying more than the other pollen types in the core. The Ericaceae show two distinct peaks accompanying the Pinus lows. Pollen analytical and ecological considerations indicate that bog heaths are the source of the Ericaceous record. The Ericaceae peaks are believed to represent periods of moist coldness corresponding to Neoglacial events in the Sierra Nevada. Correlation of an ash layer at 180 cm, immediately above a radio carbon date of 699 {\textpm} 300 B.P. with an ash layer at 170 cm in my core, and other considerations, give an inferred sedimentation rate of about 47 yr/cm in my core. This places the Ericaceae peaks at about 100 A.D. and 1630 A.D., and the Hypsithermal to Neoglacial transition in Osgood Swamp at about 2400 B.P.}, author = {Zauderer, Jeffrey Norman} } @mastersthesis {537, title = {An Analysis of Periglacial Climatic Indicators of Late Glacial Time in North America}, volume = {PhD}, year = {1972}, school = {University of Wisconsin}, keywords = {Meterology}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com/pqdweb?did=759016511\&sid=7\&Fmt=1\&clientId=43922\&RQT=309\&VName=PQD}, author = {Moran, Joseph Micheal} } @mastersthesis {440, title = {Some Palynological Applications of Multivariate Statistics}, volume = {PhD}, year = {1970}, school = {University of Arizona}, keywords = {Geochronology}, author = {Adam, David Peter} } @mastersthesis {592, title = {Some Ecological Studies on Bristlecone Pine in the White Mountains of California}, volume = {PhD}, year = {1963}, school = {University of California}, abstract = {Bristlecone pine, Pinus aristata, was studied in the White Mountains of California. The climate is dry, with annual precipitation in the bristlecone zone averaging 12 to 13 inches. The trees are found in a zone from approximately 9,500 feet to 11,500 feet elevation. Three geologic substrates are widely exposed in the bristlecone zone: dolomitic limestone, sandstone and granite. Vegetation was sampled on these substrates, using line transects. Bristlecone pine is restricted principally to dolomite. Sagebrush, Artemisia tridentate and A. arbuscula, is distributed in a complementary pattern, restricted largely to sandstone and granite. Bristlecone pine and sagebrush constitute the bulk of the vegetation. Dolomite in the White Mountains is a nearly white rock, whereas sandstone and granite are dark. The white rock reflects more solar radiation than do the other substrates, and as a result the dolomite soil averages several degrees centigrade cooler than sandstone soil. This lower temperature acts as a moisture conserving mechanism on dolomite, delaying soil drought. Dolomite also has higher moisture capacity than sandstone and granite. Through use of an infrared gas analyzer, the effect of soil drought on photosynthesis of bristlecone pine was measured. Photosynthesis was depressed by soil drought in the same range as the attained in field soils during dry periods in summer. Photosynthesis of sagebrush as a function of soil drought was also measured. Sagebrush was found more tolerant of drought than bristlecone pine. Drought tolerance may be one factor contributing to maximum development of bristlecone pine on dolomite, and of sagebrush on sandstone and granite. Bristlecone pine reaches maximum development on north slopes, and sagebrush reaches maximum development on south slopes. This supports the conclusion that drought tolerance is a decisive factor in determining substrate-oriented distribution patterns. Sagebrush and bristlecone pine seedlings both grew poorly on dolomite in pot trails. It was suggested that the high pH of dolomite soil, averaging 8.1, results in low mineral nutrient availability, and that sagebrush, with its shallow root system, is less efficient in obtaining mineral nutrient requirements than is the deep rooted pine. Photosynthesis measurements demonstrated that bristlecone pine is tolerant of shading. Furthermore, it was shown by growth measurements that bristlecone pine seedlings grow much more slowly than sagebrush seedlings. These findings indicate that the pine seedling would not succeed in the shade of sagebrush seedlings, another response that contributes to the substrate-oriented distribution of bristlecone pine. Maximum elevation of bristlecone pine is the same on all substrates, and was found to be limited by air temperature during the growing season. Minimum elevation is lower on dolomite than on the other substrates, and is under the control of soil drought. Attainment of great age was shown to be associated with death of the tree trunk around most of its circumference. Lack of krummholz at tree line shows both genetic resistance to deformation, and the influence of a very dry climate.}, url = {http://ezproxy.library.arizona.edu/login?url=http://proquest.umi.com.ezproxy2.library.arizona.edu/pqdweb?did=763335561\&sid=2\&Fmt=1\&clientId=43922\&RQT=309\&VName=PQD}, author = {Wright, Robert Dennison} }