A detailed 2,000-year late holocene pollen record from lower Pahranagat Lake, Southern Nevada, USA
- Univ. and Community College System of Nevada, Reno, NV (United States)
Preliminary analysis of 128 pollen samples and seven radiocarbon dates from a 5-meter long, 10-cm diameter sediment core retrieved from Lower Pahranagat Lake (elevation - 975 in), Lincoln County, Nevada, gives us a rare, continuous, record of vegetation change at an interval of every 14 years over the last 2,000 years. During this period increasing Pinus (pine) pollen values with respect to Juniperus Ouniper pollen values reflect the increasing dominance of pinyon in southern Nevada woodlands during the last 2,000 years. Today Pinus pollen values indicate that pinyon pine is more frequent in the southern Great Basin since the end of the Neoglacial 2,000 years ago. During the same time frame, a general decrease in Poaceae (grass) pollen values with respect to Artemisia (sagebrush) pollen values reflect the general trend of increasing dominance of steppe and desert scrub species with respect to grasses. Variations in these two species reflect not only the generally more xeric nature of climate during the last 2,000 years, but also periods of summer shifted rainfall - 1,500 years ago that encouraged both a period of grass and pinyon expansion. The ratio of aquatic to littoral pollen types indicates generally deeper water conditions 2 to 1 ka and more variable, but predominately more marshy, conditions at the site during most of the last 1 ka. Investigation of ostracodes from the same record being conducted by Dr. R. Forester at the USGS corroborate the pollen record by evidencing shifts between open and closed hydrologic systems including lake, marsh and even stream habitats. Analysis of an additional 10 meters of core recovered in the summer of 1994 with a basal date of 5.6 ka promises to provide the best record of middle through late Holocene vegetation and climate history for southern Nevada.
- Research Organization:
- Rust Geotech, Inc., Grand Junction, CO (United States)
- OSTI ID:
- 198214
- Report Number(s):
- CONF-9409325-; ON: DE96003275; TRN: 96:001174-0005
- Resource Relation:
- Conference: Workshop on climate change in the four corners and adjacent regions: implications for environmental restoration and land-use planning, Grand Junction, CO (United States), 12-14 Sep 1994; Other Information: PBD: Sep 1995; Related Information: Is Part Of Climate change in the four corners and adjacent regions: Implications for environmental restoration and land-use planning; Waugh, W.J. [ed.]; PB: 199 p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
A CHRONOLOGICAL FRAMEWORK FOR THE HOLOCENE VEGETATIONAL HISTORY OF CENTRAL MINNESOTA: THE STEEL LAKE POLLEN RECORD
Great Basin semi-arid woodland dynamics during the late quaternary