Persistent Link:
http://hdl.handle.net/10150/184205
Title:
LATE-QUATERNARY ENVIRONMENTS OF THE SIERRA NEVADA, CALIFORNIA.
Author:
Anderson, Rodney Scott
Issue Date:
1987
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The pollen, plant macrofossil and aquatic fossil stratigraphies from a transect of sites in the Sierra Nevada, California, were examined to deduce paleoenvironmental change since the late-Wisconsinan. Fossil pollen samples were compared to modern pollen samples from both sides of the Sierra Nevada crest. Modern samples corresponded largely to modern vegetation units, validating the use of pollen for this purpose in mountainous environments. Vegetation change during the Holocene was largely contemporaneous on both sides of the crest at elevations where lake cores and meadow sections were analysed. Deglaciation occurred by ca. 12,500 yr BP at a site on the east side, and by ca. 11,000 yr BP at a west side site. Prior to ca. 10,000 yr BP, few trees were found around the higher elevation sites. An open forest with trees characteristic of the modern Sierra Montane and Upper Montane forest grew around the mid- to high elevation sites by the early Holocene. Montane chaparral species, such as bush chinquapin, mountain mahogany and probably huckleberry oak, with sagebrush, were most abundant then. Along with lowered lake levels or absence of perennially standing water, and greater affinities to modern pollen samples from the more arid east side, these observations suggest drier conditions than today. However, by ca. 6500-5500 yr BP, effective precipitation increased, as shown by increases in subalpine conifers (mountain hemlock and red fir) and higher lake levels, and less affinities to modern samples from the east side. Modern vegetation developed at most sites within the last 2-3 millenia. Specific changes in the vegetation at this time included a reduction in upper elevational limits of mountain hemlock and red fir, with possible downslope retreat of whitebark pine, indicating greater cooling and/or wetter conditions. This is consistent with the record of wet meadow genesis as well as tree-ring and Neoglacial chronologies.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Sierra Nevada (Calif. and Nev.); Paleoecology -- Sierra Nevada (Calif. and Nev.); Paleobotany -- Sierra Nevada (Calif. and Nev.); Pollen, Fossil -- Sierra Nevada (Calif. and Nev.)
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Davis, Owen K.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleLATE-QUATERNARY ENVIRONMENTS OF THE SIERRA NEVADA, CALIFORNIA.en_US
dc.creatorAnderson, Rodney Scotten_US
dc.contributor.authorAnderson, Rodney Scotten_US
dc.date.issued1987en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe pollen, plant macrofossil and aquatic fossil stratigraphies from a transect of sites in the Sierra Nevada, California, were examined to deduce paleoenvironmental change since the late-Wisconsinan. Fossil pollen samples were compared to modern pollen samples from both sides of the Sierra Nevada crest. Modern samples corresponded largely to modern vegetation units, validating the use of pollen for this purpose in mountainous environments. Vegetation change during the Holocene was largely contemporaneous on both sides of the crest at elevations where lake cores and meadow sections were analysed. Deglaciation occurred by ca. 12,500 yr BP at a site on the east side, and by ca. 11,000 yr BP at a west side site. Prior to ca. 10,000 yr BP, few trees were found around the higher elevation sites. An open forest with trees characteristic of the modern Sierra Montane and Upper Montane forest grew around the mid- to high elevation sites by the early Holocene. Montane chaparral species, such as bush chinquapin, mountain mahogany and probably huckleberry oak, with sagebrush, were most abundant then. Along with lowered lake levels or absence of perennially standing water, and greater affinities to modern pollen samples from the more arid east side, these observations suggest drier conditions than today. However, by ca. 6500-5500 yr BP, effective precipitation increased, as shown by increases in subalpine conifers (mountain hemlock and red fir) and higher lake levels, and less affinities to modern samples from the east side. Modern vegetation developed at most sites within the last 2-3 millenia. Specific changes in the vegetation at this time included a reduction in upper elevational limits of mountain hemlock and red fir, with possible downslope retreat of whitebark pine, indicating greater cooling and/or wetter conditions. This is consistent with the record of wet meadow genesis as well as tree-ring and Neoglacial chronologies.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectSierra Nevada (Calif. and Nev.)en_US
dc.subjectPaleoecology -- Sierra Nevada (Calif. and Nev.)en_US
dc.subjectPaleobotany -- Sierra Nevada (Calif. and Nev.)en_US
dc.subjectPollen, Fossil -- Sierra Nevada (Calif. and Nev.)en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorDavis, Owen K.en_US
dc.contributor.committeememberMartin, Paul S.en_US
dc.contributor.committeememberTurner, Raymond M.en_US
dc.contributor.committeememberBaker, Victor R.en_US
dc.contributor.committeememberFlessa, Karl W.en_US
dc.identifier.proquest8727919en_US
dc.identifier.oclc699819441en_US
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