HR: 0800h
AN: GC31A-0106    [Abstracts]
TI: Forest responses to late Holocene climate change in north-central Wisconsin: a high- resolution study from Hell's Kitchen Lake.
AU: * Urban, M A
EM: murban3@uwyo.edu
AF: University of Wyoming, Department of Botany, Laramie, WY 82071, United States
AU: Booth, R K
EM: robert.booth@lehigh.edu
AF: Leigh University, Earth & Environmental Science Department, Bethlehem, PA 18015, United States
AU: Jackson, S T
EM: jackson@uwyo.edu
AF: University of Wyoming, Department of Botany, Laramie, WY 82071, United States
AU: Minckley, T A
EM: minckley@uwyo.edu
AF: University of Wyoming, Department of Botany, Laramie, WY 82071, United States
AB: Forest dynamics at centennial to millennial timescales can be identified using paleoecological records with high spatial, temporal, and taxonomic resolution. These dynamics are linked to climate changes by comparing the paleoecological records with independent paleoclimate records of complementary sensitivity and temporal resolution. We analyzed plant macrofossils at contiguous 1cm intervals (representing 5 to 35 yr/cm) from late Holocene sediments of Hell's Kitchen Lake (3 ha) in north-central Wisconsin. Most of the plant macrofossils derive from trees growing on the slopes directly adjacent to the lake, and were identified to the species. We also analyzed pollen at an approximately100 year resolution to provide a regionally integrated record of forest composition. We then compared the macrofossil and pollen records with independent records of climate change in the region, particularly paleohydrological records from kettle bogs. The most notable feature of the late Holocene record occurs between 2300-2000 cal yr BP. During this period yellow birch (Betula alleghaniensis) macrofossils first appear in the record, along with a corresponding increase in pollen percentages. Hemlock (Tsuga canadensis) macrofossils and pollen also show a marked increase at this time. These changes coincide with a major transition towards wetter conditions recorded in the testate amoebae record of Hornet Bog (~200km northwest) and in a number of other kettle bog records from the region. Directly following this transition, tamarack (Larix laricina) and Sphagnum macrofossils at Hell's Kitchen Lake increase dramatically, likely representing the initiation of bog-mat growth along the southwest margin of the lake during the wet period. . We are continuing our high-resolution sampling downcore at Hell's Kitchen Lake. This will permit us to examine additional ecologic and climatic events in the early and mid-Holocene.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1632 Land cover change
DE: 1637 Regional climate change
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting