Persistent Link:
http://hdl.handle.net/10150/191076
Title:
Past vegetation and climate of the Mogollon Rim Area, Arizona
Author:
Jacobs, Bonnie F.(Bonnie Fine)
Issue Date:
1983
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:
This study reconstructs vegetation and climate encompassing pre-full glacial and Holocene time for the Mogollon Rim region of Arizona. Implications for the southwestern United States are discussed. Pine species (some currently disjunct) or species groups are identified. Two lakes were cored, the sediments were analyzed for pollen content, and dates were obtained by radiocarbon analysis. Hay Lake (2780 m) is surrounded by mixed conifer forest in the White Mountains, Arizona (34°N and 109°30'W). Jacob Lake (2285 m, 34°25' N and 110°50' W) is surrounded by ponderosa pine forest. Extrapolated dates for basal sediments are approximately 42,000 B.P. and 20,000 B.P. for Hay Lake and Jacob Lake respectively. Based on pollen, local vegetation at Hay Lake between approximately 42,000 and 29,000 B.P. consisted of mixed conifer forest dominated by Pinus aristata, P. flexilis and/or P. strobiformis with Picea codominant. Of the identified pine species, 98% are haploxylon and most are pinyon pine. Pinyon pine was more widespread at lower elevations than today. The proposed 1 Mid-Wisconsin climate has greater winter precipitation and summers cooler than today. However, the climate was warmer and probably drier than the full-glacial. Treeline was above the site. The period 29,000 to 25,000 B.P. is climatically and vegetationally transitory to the full glacial. Yellow pines (p. ponderosa/contorta) are present for the first time and Picea pollen increases from previous levels. The full glacial (25,000 to 13,700 B.P.) at Hay Lake is characterized by an association of Picea and Gramineae pollen and at Jacob Lake by Picea and Artemisia pollen. A high elevation parkland at the forest-tundra ecotone surrounded Hay Lake. Open coniferous forest surrounded Jacob Lake. A conservative estimate of treeline depression is 570 m. Winters during the full glacial were warmer and wetter and summers were cooler and drier than today. The early and middle Holocene is characterized by an increase in open vegetation and in herbaceous pollen taxa; Artemisia at Hay Lake and Gramineae at Jacob Lake. The climate was cooler and wetter than today but less so than during the Pleistocene. Iron-mottled sediments and a hiatus in the pollen record at Jacob Lake (between about 11,850 and 900 B.P.) together with expansion of Artemisia at Hay Lake represent overall drought during the middle Holocene when compared with today although summer monsoons may have been intensified. Modern pollen assemblages begin at Hay Lake about 1700 B.P. and are not datable at Jacob Lake. The transition to modern conditions may have resulted from increased fire frequency at Hay Lake and from fire suppression by early settlers at Jacob Lake.
Type:
Dissertation-Reproduction (electronic); text
Keywords:
Hydrology.; Geology, Stratigraphic -- Holocene.; Geology, Stratigraphic -- Pleistocene.; Vegetation and climate -- Arizona -- Mogollon Rim Region.
Degree Name:
Ph. D.
Degree Level:
doctoral
Degree Program:
Geosciences; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Davis, Owen K.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titlePast vegetation and climate of the Mogollon Rim Area, Arizonaen_US
dc.creatorJacobs, Bonnie F.(Bonnie Fine)en_US
dc.contributor.authorJacobs, Bonnie F.(Bonnie Fine)en_US
dc.date.issued1983en_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.abstractThis study reconstructs vegetation and climate encompassing pre-full glacial and Holocene time for the Mogollon Rim region of Arizona. Implications for the southwestern United States are discussed. Pine species (some currently disjunct) or species groups are identified. Two lakes were cored, the sediments were analyzed for pollen content, and dates were obtained by radiocarbon analysis. Hay Lake (2780 m) is surrounded by mixed conifer forest in the White Mountains, Arizona (34°N and 109°30'W). Jacob Lake (2285 m, 34°25' N and 110°50' W) is surrounded by ponderosa pine forest. Extrapolated dates for basal sediments are approximately 42,000 B.P. and 20,000 B.P. for Hay Lake and Jacob Lake respectively. Based on pollen, local vegetation at Hay Lake between approximately 42,000 and 29,000 B.P. consisted of mixed conifer forest dominated by Pinus aristata, P. flexilis and/or P. strobiformis with Picea codominant. Of the identified pine species, 98% are haploxylon and most are pinyon pine. Pinyon pine was more widespread at lower elevations than today. The proposed 1 Mid-Wisconsin climate has greater winter precipitation and summers cooler than today. However, the climate was warmer and probably drier than the full-glacial. Treeline was above the site. The period 29,000 to 25,000 B.P. is climatically and vegetationally transitory to the full glacial. Yellow pines (p. ponderosa/contorta) are present for the first time and Picea pollen increases from previous levels. The full glacial (25,000 to 13,700 B.P.) at Hay Lake is characterized by an association of Picea and Gramineae pollen and at Jacob Lake by Picea and Artemisia pollen. A high elevation parkland at the forest-tundra ecotone surrounded Hay Lake. Open coniferous forest surrounded Jacob Lake. A conservative estimate of treeline depression is 570 m. Winters during the full glacial were warmer and wetter and summers were cooler and drier than today. The early and middle Holocene is characterized by an increase in open vegetation and in herbaceous pollen taxa; Artemisia at Hay Lake and Gramineae at Jacob Lake. The climate was cooler and wetter than today but less so than during the Pleistocene. Iron-mottled sediments and a hiatus in the pollen record at Jacob Lake (between about 11,850 and 900 B.P.) together with expansion of Artemisia at Hay Lake represent overall drought during the middle Holocene when compared with today although summer monsoons may have been intensified. Modern pollen assemblages begin at Hay Lake about 1700 B.P. and are not datable at Jacob Lake. The transition to modern conditions may have resulted from increased fire frequency at Hay Lake and from fire suppression by early settlers at Jacob Lake.en_US
dc.description.notehydrology collectionen_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.typetexten_US
dc.subjectHydrology.en_US
dc.subjectGeology, Stratigraphic -- Holocene.en_US
dc.subjectGeology, Stratigraphic -- Pleistocene.en_US
dc.subjectVegetation and climate -- Arizona -- Mogollon Rim Region.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.chairDavis, Owen K.en_US
dc.contributor.committeememberMarkgraf, Veraen_US
dc.contributor.committeememberTurner, Raymonden_US
dc.contributor.committeememberBrown, Jamesen_US
dc.contributor.committeememberMartin, Paul S.en_US
dc.contributor.committeememberFlessa, Karlen_US
dc.identifier.oclc213094024en_US
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