HR: 1340h
AN: PP23A-1072    [Abstracts]
TI: Regional Reconstruction of Fire and Climate in Western Mongolia During the Past 1000 Years: Modern Lake Systems and Their Connection With Climate
AU: * Shinneman, A L
EM: cook0311@umn.edu
AF: University of Minnesota, Department of Geology, 310 Pillsbury Dr. SE, Minneapolis, MN 55455, United States
AU: Umbanhowar, C E
AF: St. Olaf College, Department of Biology, 1520 St. Olaf Ave., Northfield, MN 55057, United States
AU: Edlund, M B
AF: Saint Croix Watershed Research Station, 16910 152nd St. N, Marine on St. Croix, MN 55047, United States
AU: Soninkhishig, N
AF: Department of Botany, National University of Mongolia, Ulaanbaatar, 210646, Mongolia
AB: The Valley of the Great Lakes in western Mongolia is a unique ecosystem comprising a wide variety of terrestrial and aquatic habitats. Little is known about the long-term history of the region or the relative impact of climate and land-use on ecosystem development. A hydrobiological survey from 2004-2005 has elucidated patterns in the distribution of aquatic biota (ostracodes, diatoms, and chironomids) as well as patterns in lake sedimentation and terrestrial inputs (based on charcoal, loss-on-ignition, and sediment magnetic properties) related to modern climate and land-use. Over 50 modern lacustrine systems were sampled, allowing for a greater understanding of modern processes in this unique system as well as offering a method for calibration and interpretation of long- term sediment records recovered from the lakes. Low concentrations of charcoal were found in only 30% of surface samples (those fringed by thick bands of Phragmites) suggesting that fire is not a common feature in the modern landscape. Across sample sites organic content of lake sediments (2-50%) decreased from east to west and the concentration and size of magnetic particles (IRM) increased, likely reflecting decreases in effective annual precipitation. Variability in the chemical and biological characteristics among sampled lakes is strongly controlled by the precipitation to evaporation balance; ionic composition varies with lake salinity and both the composition and concentration of salts are dominant factors controlling the species diversity and richness among all sampled taxonomic groups. Correspondence analysis (CCA) demonstrates that both salinity and total phosphorous concentrations account for unique and significant fractions of the observed variability in diatom communities among the lakes, allowing for the development of inference models for down-core analyses. Using these diatom-based inference models along with a modern calibration of lake sedimentation patterns, down core changes can be assessed in terms of both P-E and nutrient loading to these systems.
DE: 1637 Regional climate change
DE: 9320 Asia
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting